Appendix 1: Geological map of the study^area Eastern Crete 0 10 20km
i
c O a E w O U . 3 O 500m 1km Post Miocene Shoreface Floodplain / Deitaplain Estuarine Coarse fluvial elastics Patch reef / Debris Mass flow/ Fluvial conglomeratesI
Conglo sheet A Conglo sheet G "--A^ jhrust faulta
Conglo sheet B gTop/ fore set £ Conglo sheet 0 CQ 3 O Q . Conglo sheet D Conglo sheet E Conglo sheet F Older Miocene elastics Tripoliza Series PQ series Sections Normal fault Erosional 'contact m Resort , Main roads Chapel
m
Monastery X WindmillsFigures from the appendices
Figure A1: Section 1, talken from the top of section 2 (see appendix 1), looking east. Photo by J.T. Eggenhuisen.
Figure A2: detail from section 1, see text for details. Hammer for scale, photo by J.T. Eggenhuisen.
Figure A3: Section 2, as see from tine base of section 1, looking west. Photo by J.T. Eggenhuisen.
Figure A4: Section 3, as seen looking northeast, from top set level of sheet B. Photo J.T. Eggenhuisen.
Figure A5: Collection of leave (1) and stem (2) remains, and an iron concreted root (3), found in section 3. Hammer for scale, photo by H.W. van Gent.
Figure A6: Section 5, as seen from the top of section 2, looking north. Photo by J.T. Eggenhuisen.
Figure A7: Detail of section 5. The black clay layer (1) is overlain by a very clean, lagoonal carbonate (2). Also the first unit of sheet C (3) is shown. Photo by J.T. Eggenhuisen.
Figure A8: Section 6, as seen from the top of sheet G. Photo by J.T. Eggenhuisen.
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Appendix 8: Section 1 17/5/05 total section length 54.9m Description (see also figure A1):
The base of the section is located in a conglomerate body with scouring base and internal layering and cross-bedding. Red sandy lenses are Incorporated In the body. MPS is 20 cm. The conglomerate Is overlain by fine sands and silts which show grey red mottling. The roughly 4m thick fine interval is not very well exposed but in small patches of outcrop the same sands and silts and some more clay rich layers can be recognized. In the last 1.5m of the interval brown grey clay is incised by a gravel sand body of 1 m thickness. MPS is 10 cm. Lateral accretion planes dip in a northerly direction. From the side of the gravel body a 20 cm thick calcrete horizon extends sideways. The upper boundary of the unit has a relief of 50 cm. The lowermost point of the boundary is located directly above the gravel body. The gravel body is topped by a several cm thin calcrete horizon. The relief above the gravel body is filled with a 15 cm thick clay layer with brown and dark yellowish laminations. The higher sides above the gravel body contain mottled sand and silt layers. Burrows extend from the higher parts of the contact 70 cm into the sandy and silty layers. The burrows are filled with the overlying lithology. Boulders up to 35 cm in diameter are embedded in the contact itself (see figure A2).
The 3-4 meter thick interval following this contact shows a coarsening upwards trend. In the lower 3 m two pebble strings are present. The sands are homogeneous and grey throughout the level. The top half meter is made up of 10-20 cm thick gravel layers which show a consistent cross bed dip direction that averages at 245 degrees. A badly exposed 40 cm thick medium coarse sand layer is topped by distinguished hard dm thick white limey sand layer which contains red speckles. From the south western valley side this white layer has been observed to extend along the entire hillside.
Directly on top of the white layer brownish dark grey clays have been deposited. The clays contain abundant plant remains and fragile thin undifferentiated shells. At 2.5 meters in this fine interval a couple of non-continuous 20-40 cm thick gravel layers with MPS of 4 cm show crossbedding in different directions but it is difficult to measure flow directions. Above the gravel layer a badly exposed interval in which clays similar to the lower interval part can be dug up in isolated patches. This transides into a 1.2 meter thick layer coarsening upwards up to MPS 3cm pebbles. The silts and sands in the bottom of this coarsening upward unit contain plant remains and Fe-root concretions. The overlying sandstone transits into a purple-pinkish and brown laminated clay layer which is incised by a 50 cm thick very badly sorted coarse sand layer. This sand is topped by a 5-10 cm thick MPS 5cm gravel layer with a very straight top. This thin layer is continuous over the entire 20 m wide outcrop at the where the section has been logged. Above the gravel layer the same coarse unsorted sands extend for a further 20 cm and are followed by a 25 cm silt and clay layer. The bottom of this layer is mottled and the finer top shows the same purple-pinkish and brown laminations as the clay at the 17 meter level. The top is burrowed and the burrows are filled with the overlying very coarse badly sorted green sands that
contain sliell fragments. This sand layer is about half a meter thick and contains another MPS 3cm, 3-8 cm thick pebble liner. Finely laminated pink green yellow sands are burrowed with an infill from the overlying 50 cm thick coarse sandstones. Another 5 cm thick laminated very fine sand interval is followed by a 70 cm thick homogenized yellow medium coarse sand layer. The transition to the overlying conglomerate is chaotic. It is 20-30 cm thick and contains blobs, isolated patches and tunnels filled with the conglomerate.
This 70 cm thick conglomerate is very badly sorted. MPS is 5 cm and it contains very angular clasts which almost gives it a breccia like appearance, and shell and oyster fragments. At places the conglomerate is matrix supported. The above fine sands contain a lot of shell fragments, several Clypeaster echinoids, pects, and a lot of gastropods. This fossil rich homogenous sand layer is topped by a 1.10 meter thick Heterostegina bed. This bed is made up out of Heterostegina foraminifera for roughly 50%. It further contains fine-coarse sand, pects and gastropods. The Heterostegina bed can be laterally followed and it leads to a
Cyphastrea patch reef which is underlain by Bryozoans debris and the same
coarse green unsorted sands and root mottled fine laminated stuff.
Right on top of the Heterostegina bed lays a brown-dark grey clay and silt deposit. In this clay an Ostracod has been identified to be most likely of a fresh or brackish water variant. It also contains a lot of plant remains. The amounts of fossils and plant remains diminishes upwards and at 2.5 meter within the bed, a sudden colour change takes place at the transition to barren red pinkish clay. This clay layer is very thick. At 5 meters the first 1mm thick very fine grey sand lamination has been observed. Over the following three meters a gradual increase of the amount and thickness of the sand laminations occurs until over half of the lithology is sand in up to 2 cm thick layers. The 2.1 meters above are 100% sandstones, very fine to medium coarse and contain an incidental pebble. The sand has been deposited in lobate bodies which show low angle truncations at their top. Some climbing ripples have been identified near the top of the sand bodies. The following four metres show a continuation of the same type of sand bodies but now with more climbing ripples and alternated with a few cm- 0.5 meter thick gravel bodies which are slightly incised into the sand intercalations. The top layer of conglomerate is topped by a 10 cm thick hard cemented sand layer. The pink clay-grey sand alternation just like between the 30 and 33 meter levels returns above the conglomerates. Near the top of the 9m thick exposed inten/al the clay-sand distribution is roughly 50-50. The transition into the gravel containing layers is located in a 1m thick unexposed interval. Above this interval, fore sets are 5m high and up to 1.4m thick, but most around several dm thick with MPS 15cm. The fore sets are divided by sand intervals which are slightly incised and show climbing ripples. The horizontal conglomeratic top sets are 1.5m thick. They are followed by a finer interval. Details of this interval are described elsewhere.
Appendix 9: Section 2,19/5/05 total section length 35.7m Description (See also figure A3):
This section was tal<en along the road to the garbage dump, and thus does not represent a fully vertical section.
The lowest 8 meter of this section consist of an alteration of brown yellow silts and fine to medium sands layers of several centimetres thick. Wood fragments and roots are abundant in the fines. Occasional pebble strings (MPS 1cm) and brown laminated clays are also found in this part of the section. This succession is cut into by up to 1.6m thick conglomeratic channels which have a horizontal layering. These channels have a high height/width ratio and are not traceable over large lateral distances. On top of this succession 4m of fine yellow, mottled silts are found. These silts contain wood fragments and roots. In this silt layer two 20-30 cm thick conglomerates with MPS of 3cm are located. On top of the silts an up to 1.6m thick, matrix supported conglomerate is found (MPS 20cm). Small scale fore sets are observed in this body, but the top of this conglomerate is structure less and contains hardly any matrix. It resembles a washed out conglomerate sheet. When this body is followed laterally in both directions, it quickly (within 20m) changes in a 30cm thick pebble stringer with MPS 13cm. On top of the conglomerate lens an up to 2.4 m high Cyphastrea reef is located. The patch reef has a limited lateral extend (25m) and is flanked by fine sands, which contain a lot of burrows and some wood fragments. The Cyphastrea reef itself contains some lenses of the same sand and also has incorporated some pebbles, up to 2 cm in diameter. The Cyphastrea corals reach diameters of 40cm. Above the reef, the flanking sands continue for 2m, and while wood fragments are abundant at the base of these sands, these disappear towards the top. There are many burrows in this layer (including angular burrows) and some are iron plated. Towards the top, the grain size changes from fine to middle sand and though much of the bed is completely homogenized, some crossbedding
laminae are recognizable in this coarser interval. Also a number of individual clasts (that is pebbles not belonging to a discrete bed or sheet) up to 10cm are found. This bed is topped by a slightly scouring, 2.5m thick conglomerate bed, which has fore sets that cross nearly the entire bed. Between the gravely forests, up to 60cm thick, coarse sand are deposited which contain individual clasts. The top of this bed is almost cleared of matrix sands, and can be considered a washed out top. On top of this gravel bed a 90cm thick mottled silt bed is deposited, which is red/grey at the base and brown with white specs at the top of the bed. There are wood fragments and roots found in this layer. On top, at 21.4m from the bottom of the section, a thin dark brown clayey silt layer is found with white calcrete horizons in it. This layer has been interpreted as a soil horizon. Over this horizon 1.6m of fine grey sand and a 50 cm thick clay layer which contains small clasts with diameters up to 1cm is found, which also contains wood fragments. After this pebbly clay layer the same fine grey sand as below extend for another 90cm. This sand however contains a number individual pebbles, a very clear pebble lag at the basis of the layer and towards the top pebble stringers. These stringers are orientated with the same angle as the fore sets ofthe conglomerate that covers it. This conglomerate is 2.1 meters thick and contains sandy intervals between the fore sets. The MPS in this conglomerate is 20cm. A 70cm coarse coarsening upward sand inten/al covers the conglomerate.
This sand contains the fossils of pects, oysters, and of a bryozoans variety. This bed grades into a very coarse sand layer with a very pronounced white calcite matrix. Above this 40cm thick layer, another 80cm of coarse burrowed sand with shell fragments and individual pebbles with sizes up to 1.5cm. This bed grades in roughly 5m of clean, intensely bioturbated sand, with fine to coarse grain size. This layer contains the fossils of Clypeaster echinoids, pects, oysters and gastropods, as well as a large number of burrows. This bed is topped by sandstone of 2.5m with an increasing number of Heterostegina foraminifera towards the top. At the top of the bed, it contains roughly 50% Heterostegina. Op top of this sandstone of medium grain size pink clays are found, but the quality of outcrop is so reduced that the section ends here.
Appendix 10: Section 3, 21/5/05, total section length 125m. Description (see also figure A4):
The base of this section is formed by chaotic, poorly sorted up to 2m thick conglomerate, which contains a number of reddish coarse to very coarse sandstone layers. These layers show some cross lamination of undeterminable orientations. The conglomerate itself is matrix supported, where the matrix consists of a red, coarse sandstone, and has a MPS of 16cm. There are numerous imbrications to be found in this body, but these are randomly orientated. Above this conglomerate a 2m thick interval with mottled silts is located. These silts contain some thin pebbly inten/als. Towards the top, these silts coarsen to fine sands, below a 40cm thick fining upward conglomerate with a red matrix. On top of this conglomerate a 14 meter thick section is found which is a dm-scale alteration of red and yellow silts and middle to coarse sands. All layers are laterally continuous for only a few meters. At the stratigraphic level of 8m from the section bottom, a 1.2m thick conglomerate channel with a scouring base is found. A number of cross bedded middle sand layers are found within the conglomerate witch has a MPS of 6cm. In the top 7 meters of the finer interval, pink clay layers are observed as well, along with mottling and wood fragments. At irregular intervals thin pebble levels, of 1 to 5cm thickness are found, these coarse clastic intervals make up less than 10% of the deposits. A 4.5meter thick channel conglomerate is cutting into the fines. The base of the channel has a relief of roughly 1.5m. The conglomerate is clast supported, with a maximum pebble size of 35cm, and lenticular middle to coarse sand layers are observed within the body. Above the channel a 3.5m fining upward sequence is found. White middle sands with in-situ roots with root concretions are found at the base but these grade into brown clayey silts, and into pink clays at the top. Throughout this sequence plant remains and in situ roots are found as well as a mixed clay/pebble interval. Small pebbles (0.5cm diameter) have been found mixed with the silts throughout the deposits, but the last 1.5 meter of the succession the pink clays become very clean, except for plant remains. Overlying is a coarsening upwards middle to very coarse sand deposits of 3.1m thickness. The base of the sands contains a pebble lag, and vertical marine burrows extend into the underlying clay. Individual pebbles and small pebble strings (MPS 5cm) are
found throughout this heavily bioturbated sand body, but they are most abundant in the lower portion of the body. Here also plant remains are found. The top of the sandy succession is formed by a thin layer of silts, with vertical burrows, just below a slightly incised; 1.2 meter thick conglomerate bed is located. The MPS of this bed is 30cm and it is fining upward. The body has a cross bedded character throughout the sheet in a consistent WSW direction. Though no top set level was found, these cross sets have a fore set character. The 3 meters consist of a fining upward sequence of greenish coarse sands with pebble strings and individual pebbles which grades into fine sands towards the top. These sands are burrowed. The top meter is characterized by exquisite examples of wave reworked pebble strings and washout structures (see also figure 19). A number of erosional surfaces (probably related to the wave reworking) are also obsen/ed. The burrows present in this inten/al are covered in iron minerals. Many of the pebble strings are connected to the fore sets of an overlying 0.8m thick conglomerate. The forests are up to 30cm thick with MPS 20cm. Then a I m thick middle sand body is found with again a large number of pebble strings and washout structures, followed by a 2m thick inten/al with conglomerate fore sets, which show a SW propagation direction. In between the fore sets dm thick coarse sand levels are found. The cross bedding in these layers indicates a NE flow direction.
On top of the conglomerate several dm of red silts are found, which contain iron concreted root remains. The next 6m are not exposed, but the first visible bank is a sandy conglomerate ofwhich 30cm is exposed. The MPS ofthis conglomerate is 5cm. Next are 2.9m of fine sand/silt alternation. The colours of these deposits are pinkish purple, they show sign of mottling, and root concretions are found here as well. The transition to the next bank is not exposed, but it is topped by a conglomerate. The base of this 2.7m thick bank is rather chaotic and is matrix to clast supported. Towards the top, of this bank the conglomerate becomes less chaotic, and several coarse sand layers can be found. This conglomerate is topped by a meter of red brownish grey mottled silts which contains iron encrusted roots. The next 4m show a complex lateral pattern of silts and incised channels. The first incised body is a I m thick, coarse, cross laminated sand bodies, with a dip direction for the cross bedding of 130(degrees). This sand body contains a number of individual pebbles and pebble lenses, with a MPS of 2cm. This body, and the surrounding silts are it self incised by a 60cm thick conglomerate channel. These bodies are laterally not continues. After again 30cm of silts containing plant material, a 1.8m thick coarsening upward channel is incised. This body contains fore sets which are conglomeratic. Overall, the grain size increases from coarse at the base to conglomeratic with a MPS of 20cm. The top 20cm of the bed is somewhat finer, where very coarse sand is found. This sand displays crossbedding, with a dip direction of 130(degrees). On top of this bank, red, coarse, homogenised sands are found. These merge into green coarse, homogenised sands after roughly 40cm, on the location of iron concretion layer. The total bed thickness for these sands is 1.4m. It contains individual pebbles and pebble stringers with clasts up to 20cm. Burrows are obsen/ed as well. The next 60cm consist of a scoured conglomerate bed with
MPS 8cm. The very coarse sands that cover this conglomerate shows fore sets that are covered by conglomerate strings. The sands in between the stringers show laminations in the other direction. The conglomeratic fore sets are connected to the forests of the overlying conglomerate. This conglomerate is 1.8m thick and contains a number of coarse sand lenses. On top of this conglomerate a 7.8m thick coarsening upward sequence is found. The base of the interval consists of grey very fine sand, with a thin grey silt layer 60cm of the base. This silt layer contains red dots, that is, areas where the grains are red. Above this layer, the grain size increases to coarse at the top. Climbing ripples are obsen/ed in the interval, with a westward flow direction. The rest of the interval is bioturbated and burrowed, but in those levels where the bioturbation is not as extensive, parallel laminations were observed. In the top 3m, individual pebbles and a pebble lens were obsen/ed. On top 1.1m of brown and grey silts and very fine sands are found. These are covered by 1.5m of lobate, middle sand bodies, the tops of which are covered by climbing ripples. The lobes themselves are no more than 40cm thick. A thin silt layer is found directly overlying these sands, above which a coarsening upwards sand body is located which coarsens from middle to coarse sand. In these sands vertical calcite coated burrows were found. Cross lamination is also found within the body. In the top of the sands pebble strings are found which merge into the next bed, a 2.8m thick sandy conglomerate sheet. The sandy part of this succession is burrowed. The sandy conglomerate is incised by a 4m thick conglomerate, which contains a number of sand lenses. The MPS is 30cm. On top a 1.4m thick very coarse sandstone is found which contains pebble layers and pebble lenses. The laminations in this body are both to parallel and cross cutting. This is topped by 90cm of middle to coarse sand which contains parallel laminations, followed by 3.2m of coarse sand that contains cross stratification. Within this bed a tapering conglomerate body of 1.9m is found. The MPS of this body is 10cm. The following deposit is a 30cm thick layer of brown clays, which contains a calcrete soil remnant, followed by 50cm of grey, well sorted middle sand. Though this sand is well cemented, it contains clearly visible large pores. The next 4.8m show an deposits of pink/yellow/grey, mottled silts, which contains iron concreted root remains, and a number of laterally non-continuous, thin (up to 40cm) conglomerate sheets, with a maximum pebble size of 3cm. There are 6 of these layers. A 2m thick conglomerate with a scouring base tops these silts. There are a number of middle sand layers and lenses within this body. 1.2m of silts with root concretions and calcrete is next. In these silts a number of individual pebbles are found. The following bed is 7m conglomerate with a large number of internal channels. These stacked conglomerate channels them self show a lot of internal structure in the form of cross stratification. The MPS is 35cm, and the bed looks chaotic, ranging from clast to matrix supported. The next 6m are badly exposed, but individual small outcrops show an alternation of mottled silts and chaotic conglomerate sheets of less than a meter thick. The next 19m is an alternation of pink and yellow silts, clays and white/yellow very fine sands. A number of clays with pebbles (MPS 0.5cm) are observed, as well as coarse sand layers up to 60cm thick. The coarser intervals are increasing towards to the top. A large
number of stem, leave and other plant fossils are preserved in the silts and clays (see figure A5) as well as iron encrusted roots. These fines are topped by a 80cm interval of coarsening upward yellow sands, which contains a lot of burrows, and some cross stratification. These sands then grade into 7m exposed chaotic conglomerate. No clear fore sets or top sets can be observed in this conglomerate, but there are a large number of sand lenses and layers within the deposits.
Appendix 11: Section 4, 25/5/05, total s e c t i o n length 23.1m Description:
This section starts with a middle sand stone of undeterminable thickness. At least 2.3m of it is exposed, and it contains an abundant fossil record including many
Heterostegina, gastropods, which are particularly abundant in the lower part of
the exposure, pects, and echinoids, including Clypeaster. There are distinct levels within the sandstone which contain abundant echinoids. Within the sandstone there are levels of slightly alternating grain size, but the bulk of the bed is thoroughly bioturbated, burrows were only obsen/ed in the lower part of the section. Directly on top of the Heterostegina bed, a 30cm thick clay layer was found which contains a large number of fossils, which were mostly not identifiable, though some thin shelled ostracods were observed. Wood fragments were also found in this level. The following 1.6m are not exposed, but on top a 2.3m interval is found that contains finely laminated grey clay with an irregular intercalation of mm-scale very fine, green coloured sand layers. These make out les then 10% of the total bed. After a very distinct colour change from grey to yellowish, the sand laminations become slightly thicker, now on cm-scale. This 1.3m interval contains a lot of plant remains, and also is finely laminated. The next 3.5m is characterized by a fine lamination of pink clay and very fine sand, the laminations measure between 1 and 5cm, and there is about as much sand as clay. In this inten/al, there are six dm-scale layers of medium size green sand. The following 4.8m contain mainly sand ranging in size from fine to middle. In the middle sand inten/als very nice climbing ripples were found, particularly in the lower portion of the succession. More to the top parallel lamination dominates. In both the fine and the middle sand several individual pebbles (up to 4cm in diameter) were found, and some of the levels displayed small scale slump structures. A red clay of only a few cm thickness was obsen/ed near the base of the bed. Flow directions for this interval average at 225degrees (SSW). Towards the next unit the medium sands coarsen to coarse, and several burrows are obsen/ed. In the next 2.2m five banks of pebbles are found, with a MPS of 20cm. These banks taper from 40cm at the top to 5cm near the bottom in a kind of pebble string geometry. Between these banks very coarse sands are found which have mainly parallel laminations, though some troughs are obsen/ed. These indicate a flow direction of roughly 50degrees (NE) while the conglomeratic fore sets have paleo-directions to the SW. The bottom four conglomerates beds do not have any internal structure, but the top one has a number of intercalated sand lenses and displays cross bedding. The entire bed
of conglomeratic fore sets is topped by a 50cm thick top set level. The next 4.5m are badly exposed, but small isolated outcrops show middle sands which have been burrowed, and laminations which hint at HCS. On top of this a 2m thick chaotic, matrix supported, poorly sorted conglomerate. This chaotic body has a MPS of 10cm, and an overall reddish colour.
Appendix 12: Section 5, 26/5/05, total section length 111m Description (see also figure A6):
This section was taken along the unused road that runs uphill behind the Dyonisos Village Hotel. The section starts with roughly 5m high conglomeratic fore sets. These conglomerates have a MPS of only 8cm and there is not much sand between the fore sets. The top set level is roughly 1.2m thick. On top a poorly exposed 11m long section contains a very fine sand and white silts and pink and brown clay alterations in cm-scale bedding. Some clayey intervals are present containing sand grains with grain sizes up to 'very coarse'. Very coarse sand layers are obsen/ed in dm-scale beds. At the stratigraphic level of 14m a 60cm thick very coarse bed is incised into white silts. This body contains lenticular intercalations of pebbles up to 10cm thick. The next 1.2m are again filled with the rather messy alternation of clay, silt and sand The next sand body is 1.8m thick and contains a number of through shaped intercalations of middle sand. Also there are a number of individual pebbles present in this body, with diameters up to 5cm. On top, again the messy brown clays are found. In the entire succession a large number of iron plated root channels were found, as well as wood remains and the silts displayed mottling colours. Seen the nature of the exposure (and the added complexity of the presence of occupied beehives) it was necessary to make a 200m lateral sidestep. Here a large conglomeratic body was found on the same level as a conglomerate is present above the just described section. Below this conglomerate pink clays are found with iron concreted roots and well preserved plant remains. The base of this conglomerate is formed by a highly cemented coarse sandstone of only several centimetres thick. The conglomerate it self is 2.8m thick, and has a MPS of 8cm. It contains a lot of red and bright green clasts. In side the body a number of coarse sand lenses are found. The top of the conglomerate is again formed by a highly cemented sand layer. The next 8m are formed mainly by a irregular succession of coarse green sands, green silts and purple clayey silts, which contain a lot of plant material. There is one middle sand body located 1.5m from the conglomerate, and a 60cm thick conglomerate with a scouring base at 3m. This conglomerate has a MPS of 5cm and is topped by a pealeosol level. There are three additional soil levels in the top 2m of this section, and the exposed section is topped by a 70cm deep reddish purple level of clay. The next 3m are unexposed, but the following 6.5m consist of mottled red/grey silts. A few fine sand layers (cm-scale) were found in the succession, but there are a large number of soil horizons. Iron plated root concretions are found throughout the deposits. The mottling is found throughout the exposed section, and the grain size is much finer than in the last part. On top a 20cm thick deep reddish purple
clay bank was found. The next 6m are unexposed due to the nature of the winding road.
In the next cun/e a 40cm dark brown layer was found containing a fossil of a terrigenous gastropod. The next 9m are not different from the mottled silts described above, but a number of very coarse to conglomeratic lenticular bodies, of thicknesses in the order of 10-50cm are found. The conglomeratic intervals have a MPS of 1cm. The number of these intercalations is increasing towards the top of the 9m succession, and the number of soils is decreasing in the same direction. Also the grain size of the silts increases slightly. The mottling is found through the entire succession. The next 2m is unexposed, but again a 60cm thick deep reddish purple clay bank is located below a highly cemented coarse sand layer of 40cm. The cementation is the result of iron concretion within the layer. Above a meter thick bed of yellow marls is outcropping. The next 7m is composed of very badly exposed silts. Above this bad exposure 1.3m of black and dark grey, finely laminated clays was found. Yellow sulphur rich deposits are found on exposed sections of this deposit. The black colour is the result of high amounts of organic mater within the layer. Lateral reductions of the amount of organic matter are obsen/ed. This followed by 0.5m of dark brown to grey clays, which contains mottling, plant remains and a large amount of small gastropods. Within these clays a few cm-thick laminated limestones are found, which grade into a 3.4m thick finely laminated yellow limestones (see figure A7). These are deprived of fossils, but sand and silt layers up to 3cm thick and individual pebbles are obsen/ed within these carbonates. On top of the carbonates the black clays return for 30cm. In the following 20cm clays without any organic matter were found. The next 3.5m consist of fining up, and then coarsening up, poorly sorted, very coarse to middle to coarse sands. In the lowest 25cm a number of individual clasts are found as well as a dense oyster bed, with individual oysters up to 15cm. In the coarsening upward part ofthe sands the number of clasts increases again upward until pebble complete pebble strings are obsen/ed. These pebble strings grade into a 2.6m thick low angle conglomeratic fore set level, truncated by a 1 m thick top set. Between the fore sets, coarse sand layers show reversed laminations (that is, flow directions opposite to the conglomeratic fore sets) and fore sets. On top, a 2m thick, very coarse sand body shows low angle fore sets. A number of pebble strings are obsen/ed at the base of the body. The entire sand body is truncated by a 30cm thick top set level.
A mottled brown yellow clay with irregular laminations and white speckles is found in the next 30cm, which is topped by a 0.5 tol.lmthick grey mottled silt layer with an undulating top. In the top of the bed with gastropods and shell are found, very similar to those found below the limestones, as described above. On the highest part of these silts, a 40cm thick oyster bed is deposited. Individual oysters reach sizes of up to 35cm and particularly those in the top part of the bed are in -situ with both halves of their shell in place. Very coarse sand is deposited in the next 2.5-3m. These sand s contains both individual pebbles and pebble strings. Particularly the latter are becoming more abundant towards the top and the sand is also getting better sorted. A sand/conglomerate body with a scouring base is emplaced on top of this. The bed thickness is 3.8m and it contains fore
sets with a SSW to S paleoflow directions. The sand is very coarse, but the conglomerate fore sets have MPS of 12cm. The top of this body has been scoured and eroded in troughs by the overlying sand body. This very coarse body contains a large number of large-scale troughs, and is fining upwards. After 0.5m a succession of 3m of very low angle tapering very coarse sand is found. There are a number of very thin pebble strings within this body that can be followed over large lateral distances and individual pebbles, though spaced up to 50cm are aligned on the tapering surfaces. The next 4 meters consist of silts, fining up to clays. The silts are mottling and display calcrete concretions up to 1cm in diameter. The clays are light grey in colour, and contain a large number of leave remains. On top a cm thick pitch-black clay is found, full of organic matter. This layer is very similar to the black clay found under the limestone inten/al. These clays are incised by an erosional contact. Above the contact yellow poorly sorted, up to middle sandstones are found. Though some banking is present, the bulk of the 10m thick sandstone is thoroughly burrowed and homogenized. It contains a large number of marine fossils, such as pects, oysters (and cluster of oysters up to 20 individual shells), and many echinoids. After 9m a prominent
Heterostegina bed is found within the sands. On top of the sands two, closely
spaced purple silty clays are found. These layers are 80 and 40cm thick and spaced by 50cm. Above these beds the same marine sands are found again, and after 3m two further Heterostegina beds were found, a meter from each other. Higher in the cliff face, a possible third purple silty clay was observed, in roughly 20 additional meters of marine sands. However this was a vertical cliff face and a further unexposed hill slope. Evidence of recent rock fall (boulders of 6m diameter had recently obliterated a reinforced concrete wall) persuaded the authors not to risk their lives any further, and thus the section ends here. Visual obsen/ations of the remainder of the hill indicates that the yellow sands make up the remainder of the cliff (roughly 10m), and rest of the hill slope is not exposed, and no beds are obsen/ed to stick out of the vegetation. The top of the hill is formed by a massive hard rock, which is visually similar to other out cropping conglomerate sheets.
Appendix 13: Section 6, 31/5/2005, total section length 42.4m Description (see also figure AS):
This section starts with a Heterostegina bed, roughly 12m above the top sets of sheet 2. The Heterostegina bed is 50cm thick and consists of middle sand. The layer also contains a number of burrows. The next 7.8m contains 8, roughly 0.4¬ 0.7 cm thick, fine sand layers within a succession of yellow silts. In the next 90cm, more yellow silts are found, with three thin bands of red clay. These clays have been sampled for further analysis. On top ofthe yellow silts a further, 0.5cm thick fine sand layer was found, followed by another 70cm of yellow silts. Though burrows were present in the entire section described up to this point, in these silts, the burrows are encrusted with iron. These silts have been scoured slightly by the next layer, a 1.2m thick, poorly sorted sand body, with grain sizes ranging from fine to coarse. The top 40cm of the body seems to consist of a separate
scouring ciiannel, which is fining upwards. A number of very large burrows are present in this layer (diameter up to 6cm) and a number of shell fragments were found also. In the body, and particularly in the top 40cm, a number of truncations are obsen/ed. The next 70cm consist of yellow silts to very fine sands. On top, 70cm of heavily bioturbated sands, with large burrows are found. A number of individual pebbles are found in this layer. Again 40cm of yellow silts to very fine sands are found. These silts grade into 3.9m of middle to coarse sand. The coarser inten/als are located in a number of channel like lenses, and there are also a couple of conglomeratic lenses, with maximal pebble size up to 12cm. The entire body is heavily bioturbated, and a large number of burrows are found. Only towards the top, some parallel laminations are obsen/ed. In the next 2.2m yellow silts to very fine sands are found, which contain a single 0.4m thick medium coarse sand layer. This sand layer is lenticular in shape and contains a number of individual clasts, up to 12cm in diameter. Directly above this lenticular sand body a very thin (1-2cm) pink to red clay layer is found. These silts contain a number of iron encrusted burrows. On top of the silts, a 2.1m thick sand body, with a scouring base is found. This body has a clear pebble lag and is very coarse at the base. The base also contains a number of shell fragments. The rest of the body is thoroughly homogenized, and is has a medium grain size. Above this body 3.2m of yellow silts to very fine sands are found, with three 10-30cm thick fine sand layer. Within the silts to very fine sands, a number of individual pebbles and iron encrusted burrows are found. The next 3.9m are filled with a homogenized, fine sand body. Though almost the entire body is homogenized, some levels show truncations. The top of the bed contains Heterostegina and other foraminifera, as well as oyster, shell and echinoid fragments. The next 7m consist of yellow silts to fine sands, which contain iron concreted burrows. Within this succession the top 4m, a 1.3m thick medium sand body with a scouring base is located. This body consist of two banks, were the top bank cuts into the top of the first bank. Though the bulk of the bed has parallel lamination, cross lamination is also, locally obsen/ed in this bed, particularly in the top bank, as well as burrows. On top of the silty inten/al another 1.8m thick middle sand is found. This middle sand contains burrows and displays prominent horizontal lamination. In the top o f t h e bed some through shaped cross lamination is found, and the top of the bed is incised by troughs up to 60cm deep. The last 6.4m of this section consist of fine sands, ofwhich the top 3.5m are better cemented than the bottom. This body is dominated by parallel lamination. Within the top 3m of the body pebble lenses with MPS up to 6cm, pebble strings and individuai pebbles, as well as burrows are found.
Appendix 14: Correlation panel of the observations 7 7 -? 7 -? 5 m V.E. = 18x 500 m Heterostegina level K e y estruarine carbonates
•
floodpialn/overbank patchreef and associated debris•
fluvial channel (complex) m a s s fiow conglomeratesLJ
delta distributary (mouthbar)•
wave infiuenced topsetfa n delt a shoreface
•
foreset fa n delt a•
shallow marine/estuary botlomsetfa
n
delt
a
—
maximum flooding surface ( H S T ) drowning surface ( D S ) ( T S T )
seatevel drop ( S B ) erosinal contact
Astronomically punctuated delta progradation in
the Sitia Basin
(Late Miocene, Eastern Crete, Greece)
Text volume
August 2005
J.T. Eggenhuisen (9807047) H.W. van Gent (0021776)
Abstract:
Previous studies of in tiie iVIiocene intermontane Sitia basin in eastern Crete (Greece) iiinted to tlie possible link of astronomically forced climate variations and coarse clastic delta progradation. Eccentricity maxima in a section of hemipelagic deposits in the basin centre w e r e found to correlate well with prograding Tortoninan fan deltas sheets of the Toplou formation, on the eastern basin edge. However, the correlation between this so called Petras section and the fan deltas was based only on the correlation of two marker beds, and additional field data w a s required. The aims of this field trip included strengthening this correlation, to find independent evidence that the delta progradation w a s caused by climate variations, and to find evidence for lower or higher order Milankovitch cycles.
Detailed field data w a s gathered during a three w e e k field trip, which includes 6 detailed sections, facies interpretations and the collections of samples for microscopic analysis. Field data from other authors was reviewed.
The correlation between the Petras section and the Toplou formation is not reviewed as result o f t h i s study. In fact it degraded as a red marker bed, found in the Toplou formation which w a s correlated to a similar bed in the Petras section, was found to be a c o m m o n red clay, observed on several stratigraphic levels throughout the study area.
Despite the loss of the correlation, the field data suggests that the delta progradation is the result of climate variations. Also a new, southward transporting feeder system was found in addition to the original, westward transporting feeder system. Our observations have also given new insight into the nature of the top set levels of the fan deltas. Also observations of flooding surfaces, reefal build up, additional, less developed conglomerate levels and the identification of separate conglomerate units within the sheets have provided a detailed frame work for the development of the Tortonian Toplou formation.
Unlike previous workers w e recognize not five but seven delta sheets. Based on our field observations w e conclude that the development of different delta sheets and the units within them are primarily forced by climate variations. As the correlation between the Petras section and the Toplou formation is essentially non-existent, a Milankovitch forcing mechanism can not be proven, but the close proximity of a proven astronomically forced variation of fresh water input in the basin centre does lead us to assume that the delta sheet variations are eccentricity controlled and their internal architecture is precession controlled, in the entire Toplou formation w e estimate 7-10 present eccentricity cycles.
Introduction:
The island of Crete is located in the eastern Mediterranean and separates the Sea of Crete (Southern Aegean Sea) from the main Mediterranean body (figurel). Crete is an emerged part of the Hellenic Arc (Ten V e e n , 1998). This arc-system is associated with the Alpine subduction of the African Plate under the Eurasian Plate, which w a s initiated at least 26Ma ago (Spakman ef al., 1988) From the Late Cretaceous to the Pliocene, the tectonic evolution of Crete experienced five tectonic events, of which a phase during the Miocene w a s characterised by LT/LP N-S crustal extension (Fassoulas, 1999). The second and third phases comprise of E-W and N-S compression, and it are these phases that formed the metamorphic basement of the island. This crustal thickening episode consists of folding, imbrication of thrust slices and reverse faulting, and culminated in the Late Eocene (Ten V e e n , 1998; Ten V e e n and Meijer, 1998). The pre-Neogene rocks that form the Alpine Basement of Crete consist of a stack of metamorphosed and non-metamorphosed rocks of Permian to Eocene ages. In the Eastern Crete study area o f t h i s work, the basement is formed by the metamorphic Phyllite-Quartzite (PQ) Unit and the non-metamorphic Tripolitza Series (Ten V e e n , 1998). The PQ Unit is an alternating series of Triassic limestones and pelites and bodies of quartzite. G y p s u m , volcanics and slices of metamorphic rocks, derived from an even older Hercynian basement (Ten V e e n , 1998). T h e PQ-unit contains HP-LT minerals, such as aragonite, carpholite and lawsonite. T h e Tripolitza Series consists of Triassic to Eocene platform limestones and Eocene flysh. The total nappe pile thickness does not exceed 4¬ 5km (Ten V e e n , 1998). The folds in the basement run roughly parallel to the subduction zone.
During the Serravallian (14.8-11.2Ma) an N-S extension phase resulted in the formation of the Aegean Sea. A s a result of extension in the Aegean Sea, Crete migrated up to 300km south (Krijgsman and Tauxe, 2004). The reason for this extension is inferred to be a result of the relative plate motions of the colliding African and European plates (e.g. Jovilet, 2001). Slab pull by the heavy subducting place caused southward migration (roll back) of the subduction zone. To compensate for the southward migration of the kink point of the subducting plate, crustal extension and subsequently subsidence of the continental A e g e a n lithosphere w a s initiated in the Middle-Late Miocene (ten V e e n , 1988). This resulted in the present horst and graben geometry of Crete, and exhumation and unroofing of the metamorphic basement.
Before the initiation of crustal extension, Crete w a s a part of the so called South Aegean Landmass (Ten V e e n , 1988, Meulenkamp, 1971). This landmass
incorporated Crete, Rhodes and a large part of the presently subsided continental lithosphere of the Aegean Sea. This landmass was most likely connected to Turkey (Ten Veen and Postma, 1999). T h e break-up and subduction of this landmass due to the roll-back initiation resulted in significant paleaogeographic changes in the region (Duermeijer ef al., 1998), and the formation of the curved Hellenic Arc.
On Crete, the extensional episode resulted in the formation of N100E and N020E normal faults, which formed an orthogonal horst and graben geometry (Ten
Veen, 1998). During the Late iViiocene, the grabens and half-grabens becanne the main sites for sedimentary deposition. During the early Tortonian (11.2 -7.1 Ma) the sea invaded Crete through the complex array of fault blocks, horsts and grabens. This checkerboard pattern of geographical highs and intermontane basins has been described as an egg-box geometry (Ten Veen and Postma, 1999). The resultant deposits consist of a thick sequence of interfingering fluvial, brackish and marine strata (Ten V e e n , 1998). During the early Tortonian, deposition is in general controlled by fault activity (Postma et al., 1993). T h e middle to late Tortonian is characterised by more open marine conditions due to increased subsidence and the inability of sedimentation to keep up (Ten V e e n , 1998). The early Messinian is characterised by massive carbonate deposition, perhaps due to a basin wide climate change (similar changes have occurred in Spain and Sicily). During the Messinian salinity crisis evaporates have also been deposited on Crete.
The Sitia basin in Eastern Crete (figure 2) is an early Tortonian intermontane basin, which formed as the N20E trending Sitia Fault Zone w a s activated. Basin margin shallow water fan deltas are observed both on the western basin edge, from the village of Skopi in northern direction towards the coast (Gradstein, 1973NG; Ten V e e n and Postma, 1999), and the eastern basin margin south east o f t h e Toplou monastery (Gradstein and V a n Gelder, 1971NG; De Kramer, 1994, Ten Veen and Postma, 1999). Deposition of these delta bodies is influenced by the Sitia Fault zone, but T e n Veen and Postma (1999) conclude that the valleys due to pre-Neogene folds are of much greater importance for the paleogeography o f t h e fan deltas. These fold-related valleys form as axial parallel structures as rocks with very different erosional and competensional characteristics crop out in the cores of the syn- and anticlines.
In this study, w e will focus on the basin margin delta systems of the eastern part of the Sitia Basin. The study area is located between Palaiokastron in the east, the Toplou Monastery in the north and Agia Fotia in the west. Here Tortonian and Messinian shallow marine to terrigenous elastics are found with a Cyphastrea reef complex at the base (De Kramer, 1994). T h e shallow water fan delta system south of the Toplou Monastery (Toplou formation) consists of a stacked series of five coarse clastic delta bodies with badly exposed fines in between the bodies. Earlier research in the field area (de Kramer, 1994) has recognised five distinctive levels of coarse grained delta deposits. The deltas are supposedly fed by a N-draining fluvial system of the Kastri formation, which runs trough the Zakros Fault Zone, an antithetic fault zone parallel to the Sitia Fault Zone (Ten Veen and Postma, 1999). T h e direction of progradation of the delta bodies is W S W (de Kramer, 1994). Study of the delta sequences is made easy by the lack of post depositional tectonic disturbance, which makes on sight correlation of the deposits over the field area possible. A geological map of the study area is presented in Appendix 1.
In a gamma-ray sampling study of hemipelagic sequences on Crete, Ten V e e n and Postma (1996) showed that variations o f t h e insolation curve are recorded in the gamma-ray intensity of hemipelagic deposits. Precession controlled climate variations result in the increased deposition of Uranium minerals during insolation maxima and the increased radioactivity of theses deposits correlates can be detected and correlated to the astronomical insolation curve.
This method thus offers the possibility to determine the astronomical variations recorded in the sediments of sections on which no extensive bio- and magnetostratigraphy has been performed.
In a similar w a y a g a m m a ray curve that has been w a s constructed for a section in a hill near the hamlet of Petras (the Petras section; Ten Veen and Postma, 2005) has been correlated to a theoretical insolation curve (see figure 3, left panel). This hamlet is located roughly ten kilometres w e s t of the study area. T h e sampled sequence shows the presence of the insolation signal that is commonly found in studies of hemipelagic sediments. Fluctuating fresh water discharge caused by changing precipitation patterns during Milankovitch cycles is widely recognised as the important controlling factor that causes recording of the insolation signal in deep water sequences (See Rohling, 1994 for a review o f t h i s matter). T h e implication o f t h i s accepted hypothesis is that the discharge through the associated continental, fluvial and deltaic systems at the basin margin fluctuates significantly through Milankovitch cycles. T h e aim of this study is to explore the expression of these climatic fluctuations on Milankovitch timescales in the basin margin deposits. T o achieve this aim a good correlation between the hemipelagic section and the basin margin sequence seems imminent. Previous to this field study the compilation by Ten V e e n and Postma (2005), based on earlier experience in the area, has been constructed. This compilation correlates the five recognised coarse grained delta deposits to five distinctive eccentricity maxima (see figure 3). The original objective of the present field study w a s to refine this framework and recognise the signature of precession regulated discharge fluctuations in the different units.
The observation of (Milankovitch-scale) climate signatures in sedimentary deposits in not new. But descriptions of Milankovitch cyclicity in pro-delta turbidites from the Eastern Mediterranean Basin for the early Late Miocene (Postma et al., 1993; Postma, 2001) and Pliocene (Weitje and De Boer, 1993; Postma 2001) apply only for fine grained, deep water deposits. Also the suggestion by Bouma (2001) regarding the potential of submarine fans as a possible recorder of climate change only considers fine grained systems of slope to plain depths. T h e Toplou Formation does not conform to the fine grained-deep water characteristics, it consists of shallow marine to continental deposits of coarse to very coarse grain size (De Kramer, 1994; Ten Veen 1998), and will therefore be (one of) the first examples of Milankovitch forcing in a sedimentary system at sea level.
Hypothesis and a i m s :
The succession of five delta bodies and associated fines in the Toplou Formation is the result of climate changes, which is the result Milankovitch-forcing, more specifically eccentricity time scale orbital variations. The internal structure of these bodies is probably regulated by the precession cycle.
In this study this hypothesis will be tested. This hypothesis is based on an (unpublished) compilation of field data and stratigraphic logs from Gradstein (1973), De Kramer (1994) and Ten V e e n (1998), g a m m a ray insolation data by Postma and T e n Veen (1996, and unpublished data) and literature data, which hints at a correlation between the delta bodies and the Milankovitch forced insolation curve. This compilation will be referred to as Ten Veen and Postma (2005). T o verify the hypothesis, the following questions need to be answered;
1) Is there a solid correlation between the Petras Section and the Toplou Formation?
2) Is the presence of 5 distinct delta bodies the result of variations in the climate, and not variations in eustatic sea-level, fault-block movement, hinterland variations and autocyclic events such avulsion?
3) Is there independent evidence for the influence of climate variations on the delta bodies, other than the presence of these bodies?
4) Is there evidence for higher and lower order Milankovitch cycles between and within the coarse clastic delta bodies?
in this study detailed, new field data and stratigraphic logs and thin sections will be combined with the existing information to specifically answer these questions. The new data w a s gathered in a three w e e k field work, in May 2005.
Correlation:
The presence of an astronomically calibrated hemipelagic section close by basin margin deposits has been prime reason to select the present study area. It provides a relatively easy opportunity to correlate deposits to a known climatologic history and conclude that it is this climate signal that is preserved in the marginal deposits. T h e correlation of the Toplou formation w a s thought to be largely known before the present trip but as it has turned out, this subject deserves s o m e additional attention.
The most straightfonward and ideal w a y to correlate the two settings is by direct, visual physical correlation in a single profile. This is not possible in this part of the Sitia basin because basement rocks crop out at the coast line between the two locations. Previous attempts to perform biostratigraphy on the marine deposits in the Toplou area have been unsuccessful (de Kramer, 1994). Magnetostratigraphy of the Toplou Formation is not available at present either. Thus correlation of the Toplou Formation to the astronomical curve found in the Petras section has to be inferred from mutually present marker beds.
The first marker bed that has been recognised is a distinctive Heterostegina rich layer at the base of the Petras section. This Heterostegina event also occurs in
the lowest part of the succession in the Toplou area, where it is associated with patch reefs. This Heterostegina marker bed is thought to have formed as a basin wide transgression took place. Though this is not an exact time line, it is used as such which is justified by the relatively small distance between the locations. The second marker bed has been sought in the alleged presence of a red-white-red marker bed. If this marker bed would have been of volcanic origin, as hoped prior to this field trip, it would have been of great importance. Unfortunately, the presence of this marker bed in the Toplou area is not as unambiguous as suspected. On close examination of the sections in the area it has become clear that multiple purple-pink clay layers are present at s o m e locations. On earlier visits only one such layer has been observed, suggesting that correlation could be possible. So, it is one of these clay layers that were suspected to be correlatable with the red-white-red layer in the Petras section. Now that it has become clear that all clay deposits in the Toplou area have got a pink-purple colour it has proven impossible to solidly correlate the second marker bed. Before this field study the delta levels of the Toplou Formation were correlated with specific individual eccentricity maxima (figure 3). But this time constraint has collapsed with the absence of a second convincing marker bed. T h e correlation between the lower parts of the two locations still stands however and it is obvious that any climatic forcing present in the Petras section has also acted on the Toplou location 10km away but a correlated climatic framework does no longer exist. A n additional search for possible cyclo-chemical or biostratigraphical evidence in the most distal part o f t h e Toplou study area has remained fruitless. These difficulties with the correlation and therefore with the time constraint add pressure to the discussion of the results of the field study. T h e original objective was to investigate the expression of known climatic signals in deposits that w e r e already placed in a framework. Now, the results of the study of the deposits themselves have to support the conclusion that they are regulated by Milankovitch scale climate fluctuations.
O b s e r v a t i o n s :
Sections
Six sections have been logged in detail at 1:100 scale. For logs of the described sections, see appendices 2 to 7. T h e detailed non-interpreted section descriptions are enclosed as appendices 8 to 13 in this report. In this section the environmental interpretations are presented. In previous reports, the delta sheets have been given a number from 1-5. This study recognises 7 distinct units. T o avoid confusion sheets will be referred to with letters from A - G in this report. In table 1 the correlation between the old and new names is shown. W h e r e sub-sheet units are recognised they are indicated with a number. Visual correlation of the different sheets between the sections is very easy in the field. T h e sheet names are incorporated in the logs and interpretations.
Section 1 17/5/05 total section length 54.9m
The continental clastic fluvial deposits at the bottom the section are overlain by marine sands. T h e surface between t h e m is interpreted as a flooding surface. No
marine erosion tool< place. T h e relief of the surface appears to represent a paleorelief of a channel with levees. The clays are interpreted to be infills of the abandoned channel and belong to the continental phase. This is also suggested by the possible soil formation in the clays. The coarsening upwards sequence is thought to represent the filling of available space by a prograding s a n d -conglomerate body. The progradational direction is W S W which can be deducted from the very consistent cross bed direction. The striking white layer has been sampled and thin section analysis has revealed that this prominent layer is probably a late diagenetic feature. It is not a hard ground or soil. This first marine incursion is followed by a phase of brackish/estuarine clay deposition. T h e plant and root remains at stratigraphic level 15m support this.
Because many marine fossils as well as burrows are found in the next 4 m , a transgression needs to have taken place. The Heterostegina foraminifera and
Clypeaster echinoids suggest w a r m , shallow water conditions prevailed here.
The brackish water ostracods found at the base of the 8 m thick clay succession shows that, at least the beginning, of the deposition of this unit occurred in brackish/ lagoonal setting. T h e absence of any fossils in the rest of the unit, combined with a clear colour change towards the top do not merit that this conclusion applies for the entire unit. The inclusions of thin fine sand layers, which increase towards the top both in thickness and in abundance, are
interpreted as a prograding system related to the overlying lobate sands and low angle truncated sands in the next 6 m . Also the overlying pink clays with increasing sand contents is considered to be a progradational pro-delta system, belonging to the overlying conglomerate delta sheet.
Section 2, 19/5/05 total section length 35.7m
The coarse continental floodplain/delta plain deposits of the bottom 13.5m are overlain by a flooding surface, as indicated by the washed out conglomerate, with pebble stringers and the Cyphastrea patch reef. The shallow marine sands that cover the reef coarsen upwards and grade into a progradational conglomerate which is covered by floodplain/delta plain silts and sand. T h e clay layer with the pebbles is interpreted as the result of root reworked floodplain clays and pebble layers. This flood- or delta plain is subsequently covered by a flooding surface and a second coarse clastic conglomerate sheet progrades over it. T h e presence of gastropod, oyster and bryozoans remains and burrows above the conglomerate hint at the marine conditions that follow the progradation. The fine to coarse sand, containing the Clypeaster, Heterostegina, Oyster and other marine remains show that this deposit is of a shallow marine environment. T h e pink clays found on top have been found in other sections to be the precursor of the large scale clastic deposits (see s e c t i o n i ) .
Section 3, 21/5/05, total section length 125m.
The bottom 19m of the succession are formed by a series of continental floodplain silt and clay deposits which are cut into by large, up to 2 m thick conglomerate channels. W o o d fragments, mottling and iron concreted roots are indicators for the continental setting. Within the floodplain fines, thin pebble lags
are interpreted as small flooding events, w h e r e (root-) reworking has mixed the pebbles with the floodplain silts. T h e partly matrix supported conglomerate at stratigraphic level 19m is interpreted as a partly reworked stack of mass flow events. During the periods of rest between the events, fluvial processes washed sand out of between the clasts and deposited them in coarse grained sand lenses. A flooding surface at 25.5m marks the onset of marine conditions. Bioturbation and burrows are found in the coarsening upward middle to very coarse sand body, below a meter thick fining upward conglomerate. This conglomerate is interpreted as the first phase of infill by conglomerate sheet C, phase C i . T h e burrowed sand body above this conglomerate is interpreted as a trangressional phase, before the next conglomerate phase, C2, is deposited. The base of this sheet is formed by pebble stringers and backflow structures, showing a marine influence on the deposition of the sheet. A flooding surface is found on top of sheet C2. Also sheet C 3 shows evidence of w a v e reworking with pebble stringers and washout structures. The root remains found at stratigraphic level 37m shows that the area b e c a m e continental very shortly after conglomeratic deposition ended. T h e unexposed section between 37 and 4 2 . 5 m is suspected to be completely continental, and the deposits between 42.5 and 5 0 m indicates that this entire succession is most likely a floodplain succession, where mottled and finely laminated silts, which contain iron concreted root remains, are incised by channel conglomerates.
Between 50 and 78m a complex lateral pattern of sands, silts and conglomeratic channels is interpreted as continental floodplain, grading to shore face or coastal flood plain deposits, based on the occurrence of burrows and pebble strings at 5 3 m . The bioturbated sands deposits at 55m have abundant burrows and the pebble stringers at 56m show the influence of wave action. T h e soil found on top of the conglomerate body at stratigraphic level 78m indicates a return to terrigenous conditions. The pinkish, yellow and grey laminated silts in the interval 78-84m are similar to earlier examples of floodplain deposits, as also here iron concreted roots and mottling are found. T h e conglomerates found between 84 and 94m are interpreted as continental stacked channels with floodplain deposits in between the conglomerate sheets. The s a m e types of deposits are expected to be located in the poorly exposed section between 9 4 - 1 0 0 m , w h e r e only the conglomerates are observed. In the section 100-118m the thickness, abundance and clast size of the conglomerate decreases, while more and better preserved plant remains are found in the pink laminated floodplain silts. A number of very thin discontinuous pebble layers are found in this section as well, which are interpreted as local flooding events. On top of the floodplain deposits a thin succession of bioturbated marine sands overlies a flooding surface and is followed by the chaotic conglomerates of sheet F.
Section 4, 25/5/05, total section length 23.1m
This section represents the progradational evolution of conglomerate sheet B, similar to the evolution described in part of section 1. T h e Heterostegina rich base of the section clearly indicates a full marine environment. T h e thin ostracod rich clays with the w o o d fragments shows that continental influence has
increased for a wliile, as the thin shelled ostracods are interpreted to be of the brackish water variety and the wood fragments must have c o m e from land. T h e unexposed section between 2.5-4.5m is interpreted to be similar to this grey clay, but in presence of small sand layers show an increase of terrigenous input. The colour change from grey to yellow clay at 7 m is not completely understood, but is perhaps related to a change of hinterland source rocks, or to a change in bottom water oxygen contents.
The following 8.5m of middle, green coloured sand beds, with the coarsening upward matrix of silts to fine sands is interpreted as a coarsening upward pro-delta sequence, with intercalated turbiditic middle sand layers. These middle sand layers s h o w very nice climbing ripples, indicating that the transporting currents are rapidly loosing their load. T h e Individual pebbles in this succession can also be transported by these currents, and the slumps observed here show that these sediments w e r e deposited at an angle.
The five tapering conglomerate sheets with sands in between have been interpreted as the forests of conglomerate sheet B. T h e s e fore sets taper in de direction of progradation (SSW) while the sand beds between them show back swash directions of NE. T h e conglomeratic fore sets are topped by a 5 0 c m thick top set level. Sheet B is much thinner here than for example in section 1.
A b o v e the conglomerate sheet roughly 1m is not exposed, but the middle sand with the burrows and possible HCS correlate with field observations made more to the west. H C S w a s also observed here a few meters above the sheet B top set
level. The conglomerate which tops this section is interpreted as a continental mass flow deposit, due to its chaotic matrix supported nature and red colour. Continental mass flow conglomerates were also observed above the H C S in the west of the field work area.
Section 5, 26/5/05, total section length 111m
The conglomerate body with large fore sets and top set level at the base of this section is interpreted as delta conglomerate sheet B. On top of this delta body, a very thick (56m) succession of continental floodplain deposits is found, with alternating appearance. S o m e channel conglomerate sheets are found at the base and caliche soils are prominent above 25m, but generally all deposits in this succession are flood plain silts. Mottling, soils and plant remains are often observed, and even a land variety of gastropod w a s f o u n d . Incidental pebble layers or fine sand layers hint at flood events. The black clays, rich in organic material are interpreted as confined coastal marsh/ lagoon sediments. This marsh w a s positioned within the delta plain and experienced anoxic bottom conditions. This near coastal marsh is associated with gastropod layden clays and a clean laminated limestone. This whole package is interpreted as lagoonal. Directly above the limestones comes n oyster lag in marine homogenised sands. The oyster bed is interpreted as a transgressive surface. T h e plain on which the oyster bed formed must have remained relatively free of sedimentation for a considerable time form such a large and extensive bed of oyster fragments to form.
The fining and then coarsening upward homogenised sand layer with individual pebbles and pebble stringers is interpreted as the pro-delta of the overlying conglomerate C i sheet. This conglomerate has fore sets with washout and pebble stringers and a properly developed top set level. The very coarse sand fore- and top-sets directly above this level are interpreted as a slightly finer variety of conglomerate sheet C2. T h e presence of mottled clays at stratigraphic level 80m could be interpreted as continental soils, but the presence of gastropods and other (marine or brackish) fossils favour a near coastal facies. The presence of another oyster bed indicates the third flooding event associated with sheet C in the last 12m, with the very coarse sand with pebble strings being again the first sign of the associated coarse C 3 conglomerate sheet. S o m e indication of channel scour but no clear top set level w a s identified in this sheet, but it could be reworked by the incised low angle, tapering, clean very well sorted sands above the conglomerates. This sand body has been interpreted as beach deposits.
The very fine silt to clay deposits on top of the beach deposits represents a regression of sea level. The root concretions found here, as well as the plant remains and the black clays hint to anoxic, possibly coastal marsh conditions. The following 10m of homogenised sands with high neretic fossil contents are interpreted as marine shore face sands, above an erosional flooding surface. T h e
Heterostegina found in this succession also point to w a r m , shallow water
conditions. T h e presence of the two purple silt layers in this marine environment is striking but not interpreted as a change in depositional environment. S o m e purple deposits w e r e observed higher in the cliff face but are not reachable. The yellow marine sands are observed to dominate the rest of the cliff and expected to dominate the reminder of the hill. The hard rocks observed at the top of the hill are interpreted as the incised conglomerate sheet G.
Section 6, 31/5/2005, total section length 42.4m
From right above the top sets of conglomerate sheet 0 which is positioned only a few stratigraphic meters below this section the depositional environment is marine. The 11m thick silt succession, with intercalated, burrowed very fine sand layers can be considered as marine deposits, with sandy turbidite deposits. T h e following 10m thick section of coarse sand with pebble lenses and intercalated silts is interpreted as a distal, less coarse variety of conglomerate sheet D i . T h e presence of burrows and fossils such as pects shows that these deposits are marine in origin, but the sudden presence of individual pebbles and lenticular coarse sand and conglomerates, shows an increase in coarse clastic material. No fore sets or top set levels are encountered in these fully marine sheet C deposits. T h e abundant presence of marine fossils at stratigraphic levei 2 8 m at the top of the last unit C bank can be explained if the top of this sand body remained non-depositional for a period of time, creating a lag in the sedimentation, perhaps due to a transgression. The last 14m o f t h e section s e e m to support this, as it displays characteristics of a progradational, coarsening upward sequence. T h e presence of cross lamination and incisions in the sand and the increase in grain size, and the occurrence of pebble strings and pebble
