Ardiansyah KOESHIDAYATULLAH2 and Khalid AL-RAMADAN2, *
1 Saudi Ara bian Oil Com pany, Dhahran, Saudi Ara bia
2 King Fahd Uni ver sity of Pe tro leum and Min er als, Earth Sci ences De part ment, PO Box 1400, Dhahran 3126, Saudi Ara bia
Al-Hussaini, A., Koeshidayatullah, A., Al-Ramadan, K., 2015. For ma tion con di tions and diagenetic evo lu tion of sand roses in clastic sabkhas along the Ara bian Gulf Coastal Re gion, East ern Saudi Ara bia. Geo log i cal Quar terly, 59 (1): 71–78, doi:
10.7306/gq.1207
This field, petrographic and geo chem i cal study aims at con strain ing the for ma tion and diagenetic evo lu tion of sand roses (desert roses) in interdune sabkhas in East ern Saudi Ara bia. These “roses”, which are mainly ce mented by gyp sum, car bon - ate, and clay min er als, oc cur as disc-shaped and spher i cal flower-like crys tals. Sands, within the sand roses, are mod er - ately-sorted, me dium-grained, and sub-arkosic. Gyp sum typ i cally ex ceeds 20% of the vol ume of the roses, and lo cally gyp sum is partly trans formed to anhydrite. In ad di tion to gyp sum and anhydrite, early diagenetic mod i fi ca tions in clude pre - cip i ta tion of grain coat ing clay, dis so lu tion of un sta ble grains (e.g., feld spar grains), and weak me chan i cal com pac tion. Iron ox ide ce ment was formed when the sand roses ex posed to the sur face. The XRD and petrographic data in di cate an in crease in amounts of gyp sum ce ment from the wa ter ta ble up ward to wards the sabkha sur face. The sand roses also are larger and lighter in col our away from the wa ter ta ble. The for ma tion of sand rose at the wa ter ta ble is at trib uted to the nonpedogenic pro cess where dy namic in ter ac tions be tween me te oric vadose and phreatic zone oc cur. This study is ex pected to pro vide a better un der stand ing of the mode of sand roses for ma tion in the interdunes ar eas, as well as the diagenetic al ter ations in both phreatic and vadose zones.
Key words: sand roses, desert, diagenesis, gyp sum, East ern Saudi Ara bia.
INTRODUCTION
Sand rose (desert rose) is a sed i men tary rock formed at very shal low depths mostly as a re sult of the crystallisation of gyp sum in ter res trial, lac us trine, and supratidal ma rine sed i men tary en vi - ron ments (Wat son, 1985). Gyp sum ce ment is formed when cal - cium- and sul phate-rich wa ters are pumped by cap il lary ac tion to the sur face of po rous sed i ments and sub se quently evap o rate (War ren, 2006); ce men ta tion by gyp sum cre ates a unique ro - sette shape. Ac cord ing to Mougenot (2000), sand roses are orig - i nally formed at the wa ter ta ble be fore ex po sure to the sur face by ero sion. Sand roses with the in clu sion of sand par ti cles have been found at some lo cal i ties in the world in clud ing North Af rica, mainly cen tral Al ge ria and Tu ni sia (Wat son, 1988; Drake et al., 2004). One of the most well-known ex am ples of sand roses is the large crys tal ag gre gates from the Laguna Madre, Texas (Masson, 1955). Shal low gyp sum crusts are doc u mented in the Namib Desert (Wat son, 1988; Eckardt and Spiro, 1999; Eckardt et al., 2001), and Aus tra lia (War ren, 1982; Chivas et al., 1991;
Chen, 1997). Gyp sum crusts in clud ing sand roses have been found through out the Mid dle East, in clud ing Egypt (Ali and West,
1983; Aref, 2003), Syria (Eswaran and Zi-Tong, 1991), Jor dan (Turner and Makhlouf, 2005), Iraq (Tucker, 1978), and Ku wait (El Sayed, 1993). Saudi Ara bia is one of the larg est desert coun tries in the world with prom i nent arid cli ma tic con di tions, which are suit able for the for ma tion of sand roses (Mougenot, 2000; Al Juaidi et al., 2003). These sand roses, which oc cur in interdune ar eas (in land sabkhas), are formed from brines sat u rated with re - spect to gyp sum (Fig. 1). The main goal of this study is to con - strain and better un der stand the for ma tion and diagenetic evo lu - tion of sand roses.
GEOLOGICAL BACKGROUND OF THE STUDY AREA
Pleis to cene sabkhas con tain ing gyp sum-ce mented sand roses oc cur in sev eral ar eas in the East ern Prov ince of Saudi Ara bia, along the Ara bian Gulf (Fig. 2). These sabkhas are cov - ered by mod ern sand dunes with lo cal out crops of sand stone and car bon ates of the Neo gene Hofuf, Dam and Hadrukh for - ma tions (Fig. 2). The Hofuf For ma tion is com posed of quartz sand stone at the bot tom and con glom er ate at the top. The over - ly ing Dam For ma tion com prises white, red dish brown, and ol ive col oured mudstones with mi nor interbedded chalky lime stone and co quina-rich grainstones. The Hadrukh For ma tion com - prises mainly of green, grey ish-green, or grey col oured sandy
* Corresponding author, e-mail: ramadank@kfupm.edu.sa Received: July 30, 2014; accepted: December 17, 2014; first published online: December 18, 2014
marl, sandy clay, and sandy lime stone as most of the unit with mi nor amounts of gyp sum.
Fresh sand roses are typ i cally found within the sabkha sed i - ments be tween the wa ter ta ble and the sur face (about 0.7–1.0 m be low the sur face). How ever, weath ered sand roses are lo cally found on the sabkha surface.
SAMPLING AND ANALYTICAL METHODS
A to tal of twelve fresh and weath ered sand rose sam ples were col lected and ana lysed from two dif fer ent study ar eas:
Ayn’ Dar and Gulf of Salwa, both of which are lo cated in the East ern Re gion of Saudi Ara bia (Fig. 2). Sand rose sam ples
that were col lected at the sur face of the interdune sabkhas showed weath er ing ef fects (Fig. 3). The fresh sam ples were col lected from about 10 cm to 1 m be low the sur face of the interdune sabkhas (Fig. 4).
Thin sec tions were pre pared for a to tal of eight rep re sen ta - tive sam ples se lected from dif fer ent interdunes ar eas and sub - jected to modal anal y ses by 300 points in each thin sec tion. The sam ples were pre pared in the ab sence of freshwa ter to pre vent ex ces sive dis so lu tion of wa ter-sol u ble min er als (pri mar ily ha - lite). The thin sec tions were ground with ac e tone to pre vent the de hy dra tion of hemihydrate (bassanite) and gyp sum. Scan ning Elec tron Mi cros copy (SEM), back scat tered elec tron im ag ing (BSEI), and pow der X-ray dif frac tion (XRD) were per formed for five rep re sen ta tive sam ples in or der to de ter mine the chemical and mineral composition of the sand roses.
72 Abdulkarim Al-Hussaini, Ardiansyah Koeshidayatullah and Khalid Al-Ramadan
Fig. 1. Il lus tra tion of the gyp sum roses (sand roses) for ma tion in the sabkha or interdunes area (Mougenot, 2000)
Fig. 2. Gen eral geo logic map of East ern Prov ince, Saudi Ara bia (adapted from John son et al., 1978; Roger, 1985)
The close-up view of the study area show ing the four stud ied lo ca tions and oil field sur rounds (mod i fied from Al-Saad and Ibrahim, 2002)
Fig. 3A – interdune area where the first oc cur rence of sand roses were found; B – sand roses with blades of gyp sum crys tals with coarse sand grains; C, D – weath ered sand roses at the sur face
of interdune area in Salwa area
Fig. 4. Field pho tos from Gulf of Salwa
Four dif fer ent oc cur rences of sand roses were suc cess fully doc u mented and rec og nized from one dig ging hole;
sam ples of sand roses that were found just above the wa ter ta ble
RESULTS
FIELD OBSERVATIONS OF SAND ROSES
In both Ayn’ Dar and Gulf of Salwa ar eas, the subsurface sand roses, which were lo cated at the wa ter ta ble (~1 m), are dark brown in col our and small in size (±10 cm across). Mov ing away from the wa ter ta ble to ward the sur face, the sand roses pro gres sively be came lighter in col our and larger (~20–50 cm across).
PETROGRAPHIC AND CHEMICAL ANALYSIS OF SAND ROSES
In gen eral, all sam ples were fine- to me dium grained and mod er ately sorted (Fig. 5). The frame work grain com po si tions of the stud ied sam ples were dom i nated by quartz (av. 70%) feld spar (av. 11%; K-feld spar and plagioclase), and lithic frag -
ments (av. 6.8%). The lithic frag ments in clude car bon ate, chert and shale.
The ma jor type of ce ment in the stud ied sam ples is gyp sum that con sti tutes 40–50% on av er age (Fig. 5). Blocky gyp sum is pres ent as inter gra nu lar and poikilotopic ce ment (19.7% av er - age from modal anal y sis). Poikilotopic gyp sum crys tals have mainly len tic u lar hab its that vary in di men sions. Other ce ment phases ob served in thin sec tions and sup ported by XRD anal y - ses in clude do lo mite (<2.7%), sid er ite (<1.6%), anhydrite (<0.5%), bar ite (<0.4%) and haematite (1.6%). Most of the frame work grains are float ing in the ce ments but some grains showed point to elon gate con tacts.
The XRD anal y sis of sand roses re vealed strik ing ev i dence that the amount of gyp sum in the roses in creases to ward the sabkha sur face, from about 1.1% near the wa ter ta ble (Fig. 6) to about 3.2% near the sur face in Ayn’ Dar area; and a sim i lar trend in the Gulf of Salwa area, from 12.8% at the first oc cur - rence near the wa ter ta ble to 15.2% to wards the interdune sur - face (Fig. 6B).
74 Abdulkarim Al-Hussaini, Ardiansyah Koeshidayatullah and Khalid Al-Ramadan
Fig. 5A – bi modal well-sorted quartzose sand stone; lami na tions are de fined by vari a tions in grain size; coarser laminae shows well-rounded grains, whereas finer laminae show sub-rounded grains and an abun dance of sed i men tary lithics; B – clay coat ings on quartz grain (Q) pre dat ing gyp sum ce ment; C – fine-grained clasts (i.e., quartz, feld spar) en gulfed by poikilotopic gyp sum ce - ment; D – well-pre served grain dis so lu tion pores (PD) in di cate grain re moval post gyp sum ce men ta tion; E – tan gen tial grain coat - ings on quartz grains de fine that quartz over growth; fi brous gyp sum (FG) ce ment can be seen etch ing quartz grain rims, caus ing lo cal ized al ter ation; F – gra nitic rock frag ments, well-rounded and found scat tered within the stud ied sam ples; G – ex ten sive me - chan i cal com pac tion ob served from the sam ples col lected near the wa ter ta ble; H – me dium to well-sorted sand roses sam ple mostly com prised of mono- and polycrystalline quartz; I – len tic u lar gyp sum habit
DISCUSSION
MODES OF SAND ROSES FORMATION
The sandy coast of the East ern Re gion of Saudi Ara bia pro vides an ideal con di tion for sand rose for ma tion. The sabkha brines of the Ara bian Gulf are con cen trated through the evap o ra tion pro cess from the sur face of the interdune sabkhas when it seep up ward by cap il lary ac tion into the sand (Mougenot, 2000). The fluc tu a tions of the wa ter ta ble re sult in
con tin u ous pre cip i ta tion of gyp sum crys tals in the pore spaces of sands be tween the wa ter ta ble and the sabkha sur face, dis - plac ing the loosely- packed sand grains. Ce men ta tion by gyp - sum may ex plain the trans for ma tion of the dark sand and black gyp sum crys tal to white crys tal and light col our sand roses (Fig. 7). These con di tions are con trolled by the dif fer ence in com po si tion of wind- blown sand and gyp sum crys tal it self and the in ten sity of evap o ra tion, which be comes more in ten sive near the sur face of the interdune area (Wat son, 1985). The in - crease in the amount of gyp sum to ward the interdune sur face is thus at trib uted to the pro gres sively in creas ing rate of evap o - Fig. 6. XRD anal y sis shows the increase of gyp sum con cen tra tion to wards the sur face
In con trast, the con cen tra tion of cal cite, do lo mite and ha lite are de creas ing to the sur face;
this trends is found in both stud ied ar eas
Fig. 7. The sche matic model the modes of sand rose for ma tion in this re cent study Dark and small sand roses were found near the wa - ter ta ble whereas the lighter and larger sand roses were found in the near sur face (adapted from Mougenot, 2000)
ra tion (Fig. 6). One in trigu ing fea ture that has been found in any study of sand roses is the ap pear ance of slightly to strongly weath ered sand roses on the sur face with dis tinct out - sized sand roses (around 60 cm to 1 m across). The most im - por tant pro cess in ex plain ing the ap pear ance of weath ered sand roses in the interdunes sur face is prob a bly ex po sure caused by wind ero sion and de fla tion of the ae olian sands in as so ci a tion with wa ter ta ble fluc tu a tions.
Re sults ob tained from the pres ent study sug gest that sand rose for ma tion can oc cur via two dif fer ent mech a nisms: pedo - genic and nonpedogenic pro cesses. Pedogenic pro cess has been used to ex plain the de vel op ment of sand roses by dif fer - ent au thors (e.g., Wat son 1983; Eckardt et al., 2001). This pro cess de scribes the ac cu mu la tion of gyp sum as a re sult of illuviation or cap il lary rise pro cesses. It re quires large amounts of wa ter to gen er ate a thin crust of gyp sum, hence must be as - so ci ated with wet ter cli mate (Reheis, 1987). The sec ond mech a nism, which is non-pedogenic pro cess, has been pro - posed to elu ci date the for ma tion of sand rose in the lac us trine en vi ron ments or near to the ground wa ter ta ble where dy namic in ter ac tions be tween me te oric vadose and phreatic zone oc - cur. In this model, gyp sum in the sand rose crusts in the phreatic zone was prob a bly formed by the evap o ra tion of ground wa ter where the wa ter ta ble is lo cated around 1 or 2 m be neath the sur face. In this study, non-pedogenic model of sand rose for ma tion has been sug gested to de scribe the for - ma tion of gyp sum close to the ground wa ter ta ble based on the hydrodynamical and hydro chemical sta bil i ties that al lows the for ma tion of coarse-crys tal line gyp sum (Castens-Seidell and Hardie, 1984). In con trast, the pedogenic mech a nism has failed to ex plain the for ma tion of sand roses in this study due to the lack of clear ev i dence of illuviation pro cesses and also the arid cli ma tic con di tion of the study area.
DIAGENESIS AND PARAGENETIC SEQUENCE OF SAND ROSES
A com pos ite, in ferred paragenetic se quence for the stud ied sand rose sam ples is pre sented in Fig ure 8. Early diagenesis started by lo cally de vel oped, tan gen tial to ra di ally ori en tated clay (Fig. 9). These grain-coat ing clays pre-date grain dis so lu - tion and gyp sum de vel op ment. Weak me chan i cal grain com - pac tion is com monly found in the sam ples by the pres ence of point to long grain con tacts that may in di cate near sur face burial. The per co lat ing clay rich wa ter into the po rous interdune sands may ex plain the pres ence of clay coat ings around sand
grains in the pres ent study. This pro cess is known as illuviation (Fedoroff, 1997; Buurman et al., 1998) and the depth where the clay sus pended wa ter can reach is con trolled by down ward ve - loc ity of per co lat ing wa ter, the amount of sus pended clay and the sand po ros ity. As wa ter evap o rates, it leaves be hind a clay film known as coat ing (Stoops, 2003). The pres ence of patches of iron ox ide ce ments is rec og nized only on the weath ered sand rose sam ples due to subaerial ex po sure.
Gyp sum ce ment (Fig. 9) is in ter preted to be formed un der a near sur face con di tion and pri mary pre cip i tated from over - saturated brine. Gyp sum crys tals are re stricted to en vi ron ments where an nual rain fall is less than 200 mm/yr. and where there is a monthly ex cess of evap o ra tion over pre cip i ta tion through out the year (Wat son, 1985). The de vel op ment of len tic u lar habit has been at trib uted to be con trolled by the pres ence of cer tain or ganic mat ter within the host sed i ments (Cody, 1979; Fig. 6).
Anhydrite ce ment is likely to be a sec ond ary pre cip i ta tion as a prod uct of trans for ma tion and de hy dra tion of pri mary gyp sum.
In ad di tion, the oc cur rence of anhydrite patches ce ment within gyp sum ce ments in the stud ied sam ples may also sup port the sec ond ary for ma tion of anhydrite. Sev eral au thors have ar gued the pos si bil ity of pri mary anhydrite pre cip i ta tion in mod ern eva - porites de posit due to the abun dance of ac ti vat ing cat ions in sea wa ter and lit tle pres er va tion chance of pri mary anhydrite caused by un fa vour able el e vated hu mid ity con di tions (Ritchter, 1961; War ren, 1989).
Hardie (1967) found that de hy dra tion of gyp sum to anhy - drite de pends on tem per a ture (i.e., de gree of evap o ra tion) and low er ing the ac tiv ity of wa ter (H2O).
Some moldic pores re sulted from com plete dis so lu tion of un sta ble grains (e.g., feld spar grains) may sug gest freshwa ter diagenesis. Dur ing in fre quent pe ri ods of heavy rain fall, the sabkha sur faces are of ten flooded, and this freshwa ter may in - fil trate the sands be tween the sabkha sur face and the wa ter ta - ble, over time al ter ing the feld spar grains. Most of ten, the mouldic pores are pre served as secondary porosity.
CONCLUSIONS
The for ma tion of sand roses along the Ara bian Gulf Coastal Re gion is con trolled by the fluc tu a tions of the wa ter ta ble, which leads to the pre cip i ta tion of gyp sum crys tals in the pore spaces, dis plac ing the loosely-packed sand grains. This study showed an in crease in the amount of gyp sum to ward the interdune sabkha sur face due to pro gres sively in creas ing rate of evap o ra - 76 Abdulkarim Al-Hussaini, Ardiansyah Koeshidayatullah and Khalid Al-Ramadan
Fig. 8. Paragenetic se quence for stud ied sand rose sam ples
Fig. 9A – gyp sum (GY) ce ment ing quartz and feld spar grains (KF); thin, tan gen tial clay grain coat ings (ar - rows) on quartz grains pre-dat ing gyp sum ce ment; B – me dium grained quartz arenite with gyp sum ce ment lo cally trans formed to anhydrite (noted from thin sec tion anal y sis); traces of feld spar grains (KF) and heavy min er als (HM); thin tan gen tial clay grain coat ings on quartz grains; C – me dium grained quartz arenite;
inter gra nu lar ar eas are filled by gyp sum ce ment that is lo cally trans formed to anhydrite; D – gyp sum, show - ing platy/sheet-like tex ture, en clos ing quartz grains; E – do lo mite clast en closed by gyp sum ce ment; F – quartz grains en closed by gyp sum ce ment; sheet-like tex ture of gyp sum ce ment; me dium to coarse grained, quartz arenite; G – tan gen tial grain coat ing clays pre-dat ing gyp sum ce men ta tion (ar rows); com - mon rounded cal cite grains; H – well-rounded grains; com mon lithic grains com pris ing cal cite and chert;
thin tan gen tial clay coat ings on grains have been en gulfed by later gyp sum ce men ta tion
tion. We sug gest the non-pedogenic model as a mech a nism for the pre cip i ta tion of gyp sum close to the ground wa ter that can pro vide prolonged hydrochemical stability.
The diagenetic evo lu tion of the sand roses in cludes in chro - no log i cal or der the fol low ing pro cesses: de vel op ment of clay coat ings around the sand grains, un sta ble grain dis so lu tion and pre cip i ta tion of poikilotopic gyp sum ce ments from an over - saturated brine.
Acknowledegments. The au thors would like to thank King Fahd Uni ver sity of Pe tro leum and Min eral (KFUPM) for spon - sor ing the pro ject and spe cif i cally the dean ship of stu dent af - fairs. Our thanks are ex tended to all col leagues in the Earth Sci - ence De part ment for their sup port. The manu script bene fited greatly from the com ments of S. Franks and the Geo log i cal Quar terly ref er ees.
REFERENCES
Al-Juaidi, F.A., Millington, A., Mc Laren, S., 2003. Eval u at ing im - age fu sion tech niques for map ping geomorphological fea tures on the east ern edge of the Ara bian Shield 234 (Cen tral Saudi Ara bia). Ge og ra phy Jour nal, 169: 117–131.
Al-Saad, H., Ibrahim, M.I., 2002. Stra tig ra phy, micropaleontology, and paleoecology of the Mio cene Dam For ma tion, Qa tar.
GeoArabia, 7: 9–28.
Ali, Y.A., West, I., 1983. Re la tion ships of mod ern gyp sum nod ules in sabkhas of loess to com po si tion of brines and sed i ments in north - ern Egypt. Jour nal of Sed i men tary Pe trol ogy, 53: 1151–1168.
Aref, M.A.M., 2003. Clas si fi ca tion and depositional en vi ron ments of Qua ter nary pedogenic gyp sum crusts (gypcrete) from east of the Fayum De pres sion, Egypt. Sed i men tary Ge ol ogy, 155: 87–108.
Buurman, P., Jongmans, A.G., Pi-Pujol, M.D., 1998. Clay illuviation and me chan i cal clay in fil tra tion – is there a dif fer - ence? Qua ter nary In ter na tional, 51: 66–69.
Castens-Seidell, B., Hardie, L.A., 1984. Anat omy of a mod ern sabkha in a rift val ley set ting, north west Gulf of Cal i for nia, Baja Cal i for nia, Mex ico. AAPG Bul le tin, 68: 460.
Chen, X.Y., 1997. Pedogenic gypcrete for ma tion in arid cen tral Aus - tra lia. Geoderma, 77: 39–61.
Chivas, A.R., An drew, A.S., Ly ons, W.B., Bird, M.I., Don nel ly, T.H., 1991. Iso to pic con straints on the or i gin of salts in Aus tra - lian playas. 1. Sul phur. Palaeo ge ogra phy, Palaeoclimatology, Palaeo ec ol ogy, 84: 309–332.
Cody, R.D., 1979. Len tic u lar gyp sum: oc cur rences in na ture, and ex per i men tal de ter mi na tions of ef fects of sol u ble green plant ma te rial on its for ma tion. Jour nal of Sed i men tary Pe trol ogy, 49:
1015–1028.
Drake, N.A., Eckardt, F.D., White, K.H., 2004. Sources of sul phur in gypsiferous sed i ments and crusts, and path ways of gyp sum re dis tri bu tion in south ern Tu ni sia. Earth Sur face Pro cesses and Land forms, 29: 1459–1473.
Eckardt, F.D., Spiro, B., 1999. The or i gin of sul phur in gyp sum and dis solved sul phate in the Cen tral Namib Desert, Namibia. Sed i - men tary Ge ol ogy, 123: 255–273.
Eckardt, F.D., Drake, N., Goudie, A.S., White, K., Viles, H., 2001.
The role of playas in pedogenic gyp sum crust for ma tion in the Cen tral Namib Desert: a the o ret i cal model. Earth Sur face Pro - cesses and Land forms, 26: 1177–1193.
El Sayed, M.I., 1993. Gypcrete of Ku wait – field in ves ti ga tion, pe - trog ra phy and gen e sis. Jour nal of Arid En vi ron ments, 25:
199–209.
Eswaran, H., Zi-Tong, G., 1991. Prop er ties, gen e sis, clas si fi ca tion and dis tri bu tion of soils with gyp sum. Soil Sci ence So ci ety of Amer ica, Spe cial Pub li ca tion, 26: 89–119.
Fedoroff, N.,1997. Clay illuviation in Red Med i ter ra nean soils.
Catena, 28: 171–189.
Hardie, L.A., 1967. The gyp sum-anhydrite equi lib rium at one at mo - sphere pres sure. Amer i can Min er al o gist, 52: 171–200.
John son, D.H., Kamal, M.R., Pierson, G.O., Ramsay, J.B., 1978.
Sabkhas of East ern Saudi Ara bia. In: Qua ter nary Pe riod in Saudi Ara bia (eds. S.S. Al-Sayari and J.G. Zoetl): 84–93.
Springer, New York.
Masson, P.H., 1955. An oc cur rence of gyp sum in South-west Texas.
Jour nal of Sed i men tary Pe trol ogy, 25: 72–77.
Mougenot, D., 2000. Sand Roses of Saudi Ara bia. Adapted from Poster Pre sen ta tion. GEO 2000 Conf and Exhib, Bah rain.
Reheis, M.C., 1987. Cli ma tic im pli ca tions of al ter nat ing clay and car bon ate for ma tion in semiarid soils of south-cen tral Montana.
Qua ter nary Re search, 27: 270–282.
Rich ter, R.W., 1961. The Or i gin and En vi ron men tal Sig nif i cance of Gyp sum and Anhydrite. Uni ver sity of Oklahoma.
Roger, J., 1985. In dus trial Min eral Re sources Map of Ad Dammam, King dom of Saudi Ara bia. Scale 1:100,000. GM-111.
Stoops, G., 2003. Guide lines for Anal y sis and De scrip tion of Soil and Regolith Thin Sec tions. Soil Sci ence So ci ety of Amer ica, Mad i son, WI.
Tucker, M.E., 1978. Gyp sum crusts (gypcrete) and pat terned ground from north ern Iraq. Zeitschrift für Geomorphologie, 22:
89–100.
Turner, B.R., Makhlouf, I., 2005. Qua ter nary sand stones, north east Jor dan: age, depositional en vi ron ments and cli ma tic im pli ca - tions. Palaeo ge ogra phy, Palaeoclimatology, Palaeo ec ol ogy, 229: 230–250.
War ren, J.K., 1982. The hy dro log i cal set ting, oc cur rence and sig nif - i cance of gyp sum in Late Qua ter nary salt lakes in South Aus tra - lia. Sedimentology, 29: 609–637.
War ren, J.K., 1989. Evaporite Sedimemology. Prentice Hall, Englewood Cliffs, NJ.
War ren, J.K., 2006. Evaporites: Sed i ments, Re sources and Hy dro - car bons. Berlin, Springer.
Wat son, A., 1983. Gyp sum crusts. In: Chem i cal Sed i ments and Geo mor phol ogy Pre cip i tates and Residua in the Near Sur face En vi ron ment (eds. A.S Goudie and K. Pye): 133–161. New York:
Ac a demic Press.
Wat son, A., 1985. Struc ture, chem is try and or i gins of gyp sum crusts in south ern Tu ni sia and Cen tral Namib Desert. Sedi - mentology, 32: 855–875.
Wat son, A., 1988. Desert gyp sum crusts as palaeoenvironmental in di ca tors: a micropetrographic study of crusts from south ern Tu ni sia and the cen tral Namib Desert. Jour nal of Arid En vi ron - ments, 15: 19–42.
78 Abdulkarim Al-Hussaini, Ardiansyah Koeshidayatullah and Khalid Al-Ramadan
