Cal cu la tion of salt ba sin depth us ing fluid in clu sions in ha lite from the Or do vi cian Ordos Ba sin in China
Anatoliy R. GALAMAY1, Fanwei MENG2, *, Krzysztof BUKOWSKI3, *, Aleksandr LYUBCHAK1, Yongsheng ZHANG4 and Pei NI5
1 Na tional Acad emy of Sci ences of Ukraine, In sti tute of Ge ol ogy and Geo chem is try of Com bus ti ble Min er als, Naukowa 3A, 79-060 Lviv, Ukraine
2 Chi nese Acad emy of Sci ences,State Key Lab o ra tory of Palaeo bi ol ogy and Stra tig ra phy, Nanjing In sti tute of Ge ol ogy and Palae on tol ogy and Cen ter for Ex cel lence in Life and Paleoenvironment, 39 East Beijing Road, 210008 Nanjing, China
3 AGH Uni ver sity of Sci ence and Tech nol ogy, Fac ulty of Ge ol ogy, Geo phys ics and En vi ron men tal Pro tec tion, Al.
Mickiewicza 30, 30-059 Kraków, Po land
4 Chi nese Acad emy of Geo log i cal Sci ences, In sti tute of Min eral Re sources, Beijing 100037, China
5 Nanjing Uni ver sity, State Key Lab o ra tory for Min eral De pos its Re search, In sti tute of Geo-Fluid Re search, School of Earth Sci ences and En gi neer ing, Nanjing, 210093, China
Galamay, A.R., Meng, F., Bukowski, K., Lyubchak, A., Zhang, Y., Ni, P., 2019. Cal cu la tion of salt ba sin depth us ing fluid in - clu sions in ha lite from the Or do vi cian Ordos Ba sin in China. Geo log i cal Quar terly, 63 (3): 619–628, doi: 10.7306/gq.1490 As so ci ate Ed i tor – Jacek Szczepañski
Dur ing the Mid dle Or do vi cian, the salt de pos its of the Majiagou For ma tion of the Ordos Ba sin in North China formed, the ha - lite in clud ing var i ous ge netic types of fluid in clu sion. In this study, fit-test ing of pri mary in clu sions was per formed to re con - struct the phys i cal and chem i cal con di tions dur ing orig i nal ha lite sed i men ta tion. Dur ing the post-sed i men ta tion stage, salt was sub jected to el e vated tem per a tures (62–70°C) and pres sures of tens of megapascals. From these mea sure ments and math e mat i cal cal cu la tions, the gas pres sure was iden ti fied in the pri mary fluid in clu sions, which al lowed us to es ti mate that the brine col umn thick ness in the salt ba sin was ap prox i mately 40 m.
Key words: ha lite, gas-liq uid in clu sion, brine depth, Ordos Ba sin, Or do vi cian evap o rate.
INTRODUCTION
The de ter mi na tion of crys tal li za tion con di tions in an cient salt bas ins plays an im por tant role in palaeogeographic re con - struc tions, and rel e vant meth ods have been de vel oped since the mid dle of the 20th cen tury (Borchert and Muir, 1964). How - ever, there are no re li able cri te ria ac cord ing to which a ba sin’s depth can be di rectly de ter mined (Ivanov and Voronova, 1972;
B¹bel and Schreiber, 2014). Sup port ers of the deep wa ter hy - poth e sis of evaporite bas ins (i.e., that they were de pos ited at hun dreds of metres of wa ter depth) have built their as sump tions on the im men sity of im men sity of some an cient bas ins and the con sid er able thick nesses of salt de pos its within such bas ins (e.g., Schmalz, 1969). On the other hand, the sup port ers of a
shal low wa ter hy poth e sis (i.e., that the salts were de pos ited in wa ter up to 15 m deep) (e.g., Strakhov, 1967; Valyashko, 1962) have in ter preted the con sid er able thick nesses of salts as a func tion of struc tural-tec tonic con di tions in which salt ac cu mu - lated by anal ogy to pres ent-day “sa lina” bas ins (B¹bel, 2007).
Dur ing the late 1980’s, sci en tists de vel oped a method for cal cu lat ing the depths of salt bas ins, start ing from the gas (CH4
+ N2) sat u ra tion of brines in the pri mary, sin gle-phase fluid in clu - sions within ha lite (Petrichenko, 1988). Ac cord ing to data on pres sure, tem per a ture and geo chem is try, the thick nesses of the brine col umns in an cient salt bas ins ranged from 6–450 m dur ing the ha lite sed i men ta tion stage, and from less than 8 up to 50 m dur ing the stage that pre ceded the crys tal li za tion of po - tas sium salts (Petrichenko, 1988). How ever, even re cently the fol low ing state ments are of ten found in the lit er a ture: “very deep water”, “deep water”, “rel a tively deep wa ter”, and “shal low wa ter”, with out the depth hav ing ac tu ally been de ter mined in the course of a given study.
The Ordos Ba sin rep re sents one of the larg est oil and gas pro duc tion re gions in China and has there fore been the fo cus of many pre vi ous stud ies (e.g., Feng et al., 1998; Wang and Al-Aasm, 2002; Yu et al., 2017). The re cent dis cov ery of a new
* Corresponding authors, e-mail: Fanwei Meng
(fwmeng@nigpas.ac.cn) and Krzysztof Bukowski (buk@agh.edu.pl) Received: February 22, 2019; accepted: July 19, 2019; first published online: September 30, 2019
tight car bon ate gas ex plo ra tion field, within the Mid dle Or do vi - cian Majiagou For ma tion, in the east ern part of the ba sin (Zhang et al., 2018) has con trib uted to the re eval u a tion of the res er voir’s po ten tial. The brine depth dur ing Or do vi cian eva - poritic sed i men ta tion in the Ordos Ba sin has been the sub ject of con tro versy and was dis cussed by Xue (1986), Zhang et al.
(1991), and Bao et al. (2004). Un til re cently, it was ac cepted that the Or do vi cian Majiagou For ma tion de vel oped as a gently in clined car bon ate plat form in a very shal low epicontinental sea, and that evaporites oc curred in a re stricted, shal low, and hypersaline en vi ron ment (Feng et al., 1998; Wang and Al- Aasm, 2002; Yang et al., 2005; Li et al., 2011). Zhang et al.
(1991) con cluded that at the be gin ning of ha lite pre cip i ta tion, the salt were formed within a deep ba sin, and the next eva - poritic ba sin grad u ally ex pe ri enced the shallowing of the ba sin to a sabkha en vi ron ment by the end of de po si tion. Our case study cal cu lates the depth of the Ordos Ba sin dur ing salt sed i - men ta tion by eval u at ing the size of the gas phase of the pri - mary, gas-liq uid in clu sions within ha lite, im me di ately af ter the in clu sions were depressurized. Such in for ma tion is im por tant for un der stand ing salt sed i men ta tion and the en vi ron men tal evo lu tion of the Ordos Ba sin.
GEOLOGICAL SETTING
The Ordos Ba sin, also known as the Shaanxi-Gansu- Nin - gxia Ba sin, is the sec ond larg est sed i men tary ba sin in China, with a sur face area of ~250,000 km2. Geo log i cally, the Ordos Ba sin is a plat form-type ba sin, lo cated within the west ern sec -
tion of the North China Mas sif (Fig. 1). The ba sin has ex pe ri - enced sev eral evo lu tion ary stages since the base ment was formed, in clud ing Archean–Pro tero zoic base ment for ma tion in the con ti nen tal ac cre tion stage, Early Pa leo zoic terrigenous shal low ma rine con di tions in the pas sive con ti nen tal mar gin stage, a Cal edo nian–Hercynian re gional up lift ing stage, and a Late Pa leo zoic intra-con ti nen tal de pres sion stage of the North China Craton. Since the Me so zoic, the ba sin be gan to shrink and un der went de nu da tion. Dur ing the Ce no zoic, strong struc - tural zones de vel oped along the ba sin mar gin, ac com pa nied by the in tru sion and erup tion of ig ne ous rocks (Yu et al., 2017).
The to tal thick ness of the sed i men tary suc ces sion in the Ordos Ba sin is es ti mated to be ap prox i mately 5–10 km. Hy dro car bons are mainly pro duced from the Tri as sic, Ju ras sic, and Or do vi - cian sys tems.
In the Early Pa leo zoic, when the North ern China Block moved to the 20th par al lel of the south ern hemi sphere (Sco - tese, 2014), con ti nen tal low lands were ex ten sively flooded, and a shal low epeiric sea ex isted dur ing Or do vi cian times. On the mar gins of that in land sea, sev eral an cient land masses pro - vided bar ri ers to the flow of sea wa ter be tween the intracratonic plat form and the open sea (Chen et al., 2019). Con se quently, car bon ate rocks interbedded with evaporites were formed within shal low plat form en vi ron ments. In the Ordos Ba sin, the Or do vi cian suc ces sion is usu ally 600–800 m thick, and it mainly con sists of car bon ates (do lo mite and lime stone), with inter - bedded anhydrite and ha lite.
The main evaporite-bear ing unit in the Ordos Ba sin is found within the Majiagou For ma tion. Sec tions 1, 3, and 5 of the Majiagou For ma tion are mainly evaporite suc ces sions, while sec tions 2, 4, and 6 are dom i nantly car bon ate suc ces sions
Fig. 1. Lo ca tion of the Ordos Ba sin in China The most im por tant petroliferous bas ins are shown on the map
(Bao et al., 2004; Meng et al., 2018, 2019).
Car bon ate iso tope stra tig ra phy has in di - cated that the Majiagou For ma tion formed dur ing the Mid dle Or do vi cian (Meng et al., 2019). Evaporite de pos its in this unit are rep re sented by fre quent al ter na tions be - tween fine silty do lo mite, ha lite, and anhy - drite (Fig. 2). They are both un der lain and over lain by ma rine car bon ate de pos its, in - clud ing lime stones and dolomites.
The evaporites in the Or do vi cian Majia - gou For ma tion are plat form de pos its formed in la goons that re ceived the re stricted seep - age of ex ter nal ma rine wa ters. In those la - goons, the brine sur faces re sponded to slow, low-am pli tude 4th-or der eustatic rises and falls in sea lev els, and the re sult ing bed - ded evaporites were interbedded with nor - mal ma rine plat form car bon ates (Chen et al., 2019). Cur rently, the evaporitic sed i - ments of the Majiagou For ma tion are rec og - nized in bore holes at depths >2 km, in the east ern and cen tral sec tions of the Ordos Ba sin (Figs. 1 and 2).
FLUID INCLUSIONS IN HALITE
The de ter mi na tion of fluid in clu sions in ha lite, which is nec es sary to de fine ge netic type, is a com plex task as such in clu sions oc cur within the sed i men tary tex tures of the ha lite in the Majiagou For ma tion.
PRIMARY FLUID INCLUSIONS
The crys tal li za tion mech a nism of ha lite at the bot tom of mod ern evaporite bas ins is well-known (e.g., Valyashko, 1952; Lowen - stein and Hardie, 1985; B¹bel and Schrei - ber, 2014). Mod ern ha lite crys tals fea tur ing chev ron tex tures rep re sent the same mech a nism of or i gin as those formed in an - cient salt bas ins (Kovalevych et al., 2009;
Kovalevych and Vovnyuk, 2010; Galamay and Bukowski, 2011). The struc tural fea - tures of chev ron ha lite are as so ci ated with a zonal dis tri bu tion of micro inclusions, par - al lel to the crys tal growth fac ets. Two types of min eral in clu sion dis tri bu tion can be dis - tin guished in ha lite, those with non-sys tem - atic and those with rhyth mic zonation (Petri chen ko, 1988). In ha lite with rhyth mic zona tion, the width of the rhythms (i.e., the zone with in clu sions + the zone with out in - clu sions) in di cates the daily rates of ha lite growth. Cloudy -white zones with in clu sions formed dur ing rapid crys tal li za tion, while trans par ent ones with out in clu sions formed dur ing slow crys tal li za tion. All pri mary in - clu sions in each growth zone have iden ti cal val ues of pres sure and tem per a ture (P-T) pa ram e ters and the same chem i cal com - po si tion of their re spec tive brines.
Fig. 2. Lithological col umn re sponses for the Yu-9 and Zhengjia-1 bore holes (af ter Meng et al., 2018) with sam pling sites
SECONDARY FLUID INCLUSIONS IN CHEVRON AND TRANSPARENT RECRYSTALLIZED HALITE
In ad di tion to pri mary in clu sions, sec ond ary in clu sions of var i ous gen er a tions have been de tected within sed i men tary and trans par ent post-sed i men ta tion ha lite, and the lat ter are lo - cated ei ther non-sys tem at i cally or along re sis tive frac tures. It is pos si ble to nom i nally dis tin guish the fol low ing groups of in clu - sions as rep re sent ing early and late diagenesis: small and large sizes, reg u lar and ir reg u lar shapes, sin gle-phase (liq uid) and gas-liq uid in clu sions, re spec tively (Galamay et al., 2004).
HALITE GAS-LIQUID INCLUSIONS
Since chev ron ha lite crys tal lizes at the bot tom of salt bas - ins, the brine col umn thick ness in creases with higher hy dro - static pres sures and cor re spond ingly, the gas sat u ra tion of the brine in clu sions is also higher. Based on ob ser va tions of gas pres sures in pri mary fluid in clu sions of ha lite, we can es ti mate the depth of the an cient salt ba sin. Gas microinclusions (e.g., microoccluded gases) in the rock salt mass are wide spread, oc - cur ring in the fluid in clu sions of ha lite in a dis solved state. If the ha lite crys tal lized at tem per a tures above 42°C, or if it was sub - ject to over heat ing in the range of 50–110°C dur ing post-sed i - men ta tion trans for ma tion, gas would also have been pres ent in fluid in clu sions in the form of sep a rate phases (Petrichenko, 1973; Acros and Ayora, 1997).
In the pri mary fluid in clu sions found in Phanerozoic ha lite de pos its, the fol low ing com po nents are pres ent: ni tro gen, car - bon di ox ide, meth ane, and hy dro gen, gen er ally in the or der of:
N2>CO2>CH4>H2. Three types of in clu sion are dis tin guished by gas com po nents: one with sub stan tial ni tro gen (N2>CO2>CH4), one with sub stan tial meth ane (CH4>N2>CO2), and one with ni - tro gen-meth ane (N2³ CH4>CO2) (Litvinyuk, 2007). The meth - ane con tent pre vails over ni tro gen in the fluid in clu sions of ha - lite, as meth ane is drawn from the salt-bear ing lay ers, rich in or - ganic mat ter (Galamay and Baranenko, 2004; Kovalevych et al., 2006).
Pre vi ous stud ies on the com po si tion of gas in the brines of pri mary and early diagenetic in clu sions within ha lite dur ing var i ous time pe ri ods of the Phanerozoic (Litvinyuk, 2007;
Wiêc³aw et al., 2008), par tic u larly dur ing the Or do vi cian (Kovalevych et al., 2006), show that the sum of N2 + CH4 in the in clu sions amounts to >70%, with CO2 com pris ing 0–23.8%
(mean = 7.1%). The hy dro gen data in the gas mix ture are not in for ma tive due to the abil ity of hy dro gen to dif fuse freely through the crys tal struc ture of the min eral. The sources of these com po nents in the bot tom brine of the salt ba sin were bio chem i cal pro cesses and the at mo sphere (Weiss, 1969;
Kovalevych et al., 2008). The ab sence of ox y gen in the gas mix ture is as so ci ated with ox y gen con sump tion dur ing chem i - cal and bio chem i cal ox i da tion.
MATERIALS AND METHODS
Dur ing our case study, we ob served 2 sam ples col lected from bore holes Yu-9 and 10 sam ples from bore hole Zhengjia-1, lo cated in the mid dle sec tion of the Ordos Ba sin (Figs. 1 and 2).
The sam ples in cluded mainly recrystallized rock salts, with trans par ent ha lite crys tals rang ing from 1–1.5 cm in size, fre - quently with in clu sions of green ish-black clay par ti cles. How - ever, only in three sam ples have we doc u mented rel ics of sed i - men tary ha lite (i.e., in bore holes Zjy-47-21c, Zjy-24-057 and Yu-33; Fig. 2).
Ha lite plates (1–2 mm thick), cut par al lel to the cleav age sur face, were pol ished to de ter mine the ho mog e ni za tion tem - per a tures of two-phase (gas-liq uid) and three-phase (gas-liq - uid-daugh ter crys tal) in clu sions. Ha lite plates were slowly heated to the tem per a ture of in clu sion ho mog e ni za tion in a spe - cial thermo-cham ber made by Kalyuzhny (1982). The heat ing rate did not ex ceed 0.2°C/min. when it ap proached the ho mog - e ni za tion tem per a ture. The er ror in mea sur ing the ho mog e ni za - tion tem per a ture is ~1°C. Since the fluid in clu sions ob served con tained not only gas bub bles and sylvite daugh ter crys tals, but also clay par ti cles and xenogenic crys tals, we mainly de ter - mined the ho mog e ni za tion tem per a ture of the in clu sions in the pres ence of such in sol u ble phases.
To de ter mine the in ter nal pres sure within the in clu sions, ha - lite plates with pri mary gas-liq uid in clu sions were slowly dis - solved in glyc erin, with a min i mum amount of wa ter. Pa ram e - ters such as the di am e ter of the gas phase be fore and af ter depressurization of the in clu sions were mea sured un der the op - ti cal mi cro scope. The mea sure ments were made with a Huygens eye piece, equipped with a fine-ad just ment screw and in stalled in the field of view at the scale. Based on math e mat i cal cal cu la tions and the graph i cal struc ture, we iden ti fied the ab so - lute pres sure in the pri mary fluid in clu sions.
RESULTS AND INTERPRETATIONS
FLUID INCLUSIONS IN HALITE
Pri mary chev ron struc tures of the Majiagou For ma tion are char ac ter ized by non-sys tem atic zonation with gas-liq uid in clu - sions (Fig. 3C, D).
In some in clu sions, small anisotropic crys tals of anhydrite were found. The in clu sions are cu bic, with the lengths of the edges of cubes vary ing from a few micrometres to 30 mm (Fig. 3).
In Sam ple Zjy-47-21c, in clu sions 80–100 mm in size are pres ent (Fig. 3A, B). The in ter nal pres sure of the in clu sions is slightly higher than the nor mal at mo spheric pres sure which was re - corded at the time of col lec tion. Brines are pres ent un til the mid - dle stage of ha lite de po si tion, and they char ac ter ize the sea wa - ter as a Na-K-Mg-Ca-Cl (Ca-rich) type (Meng et al., 2018). In our study three groups of sec ond ary in clu sions were dis tin guished:
1. Early diagenetic gas-liq uid in clu sions up to 1 mm in size, cu bic or close to cu bic. Iso tro pic sylvite daugh ter crys tals were found in the in clu sions. The pres ence of K salt min er als in di cated a high con cen tra tion of brines dur ing po tas sium salt pre cip i ta tion (Meng et al., 2018).
The in clu sions were ar ranged non-sys tem at i cally in the chev ron ha lite and on the pe riph ery of the chev rons (Fig.
4A–C). The in ter nal pres sure was close to the pres sure in the pri mary in clu sions. Ev i dence of in clu sion crack ing was not re corded.
2. An oma lously large, late diagenetic, gas-liq uid in clu - sions up to 2–3 mm across and ir reg u lar in shape. These in clu sions of ten con tained nu mer ous anisotropic, small crys tals of anhydrite and black clay par ti cles. The in clu - sions were lo cated in trans par ent recrystallized ha lite (Fig. 4D). The in ter nal pres sure in these in clu sions was higher than that in the pri mary in clu sions. Au re oles of small fluid in clu sions in re sis tive frac tures were found around large in clu sions.
3. Late diagenetic sin gle-phase (liq uid) and gas-liq uid in - clu sions that are cu bic (size: 50–200 mm). The in clu - sions were lo cated in se cant cracks in ha lite (Fig. 4E, F).
In ter nal pres sure there was close to the nor mal at mo - spheric pres sure. The brine com po si tion was char ac ter - ized by re duced val ues of all ma jor ions rel a tive to sed i - men ta tion and early diagenetic types, and the type of brine did not change.
The ho mog e ni za tion tem per a tures of the pri mary and early diagenetic fluid in clu sions of the Majiagou For ma tion were sim i - lar, and sylvite crys tals in the early diagenetic in clu sions com - pletely dis solved at 46–54°C (Ta ble 1). An oma lously large, gas-liq uid, late diagenetic in clu sions were not ho mog e nized.
The tem per a ture of ho mog e ni za tion of the late diagenetic gas-liq uid in clu sions, lo cated in the in ter sected cracks, was re - corded in the range of 27–30°C.
The salt de pos its of Majiagou For ma tion formed un der var i - ous P-T con di tions. The sed i men ta tion tem per a ture was not de ter mined due to over heat ing at tem per a tures of 62–70°C dur ing one of the post-sed i men ta tion stages. Large sec ond ary fluid in clu sions of recrystallized ha lite were depressurized un - der such con di tions and over filled at an el e vated pres sure. The for ma tion of late-diagenetic in clu sions, rep re sent ing low pres - sure, was the re sult of the cleav ing and stretch ing of in di vid ual salt blocks dur ing tec tonic pro cesses (Matukhin et al., 1985).
The preservational in teg rity of the pri mary fluid in clu sions in the Majiagou Fmormation ha lite in di cates that the chem i cal com po - si tions of these in clu sions are the same, and that they are dif fer - ent in com par i son to those of the sec ond ary fluid in clu sions (Meng et al., 2018).
INTERNAL PRESSURE WITHIN FLUID INCLUSIONS
The pri mary in clu sions of sed i men ta tion ha lite, ob served in the ma jor ity of salt-bear ing for ma tions, were char ac ter ized by
their pres sures be ing close to the nor mal at mo spheric pres - sure. Some au thors men tioned a pres sure in crease in the pri - mary sin gle-phase fluid in clu sions (Moscowskiy, 1983) and in the pri mary fluid in clu sions con tain ing a gas phase (Litvinyuk, 2007). In the Majiagou ha lite (Zjy-47-21c), we in ves ti gated gas-liq uid pri mary in clu sions (Fig. 3), with sizes rang ing from 20–45 mm. Im me di ately af ter the in clu sions had depressu rized, the gas phase in creased by 1.8–2 times in di am e ter (Ta ble 2).
If all of the gas was in a dif fer ent phase, the ini tial pres sure (be fore in clu sion depressurization) was equal to the cu bic de - gree of the ab so lute in crease of the gas phase ra dius, al though in our case, only a cer tain por tion of gas cap tured dur ing crys tal - li za tion was con tained in the gas bub ble. Tak ing into ac count the fact that the sol u bil ity of gas com po nents in creases with in - creas ing pres sure and de creas ing tem per a ture, we de rived the fol low ing equa tion:
[ ]
P P
P
P k RT
P V ri r
n n
P P i
1
0 0
2
0 1
1 0
= - -
=
å
max
( ) ( )
[1]
where: P0 = 101325 [Pa] – stan dard pres sure (af ter in clu sion de - pressu rization), P1 [Pa] – ini tial pres sure (be fore in clu sion de - pressurization), and Pmax [Pa] – max i mum pos si ble pres sure in the in clu sion (with out tak ing into ac count the pres sure of gas dis solved be fore in clu sion depressurization). Ad di tion ally, R = 8.31441 [J / K mol] is taken as the uni ver sal gas con stant, T = 291 [K] (18°C) is the test tem per a ture, r(p1) and r(p0) are the sol u bil i ties of each gas com - po nent (i) at the ini tial and stan dard pres sures, re spec tively, in mol/m3. Fi nally, n – amount of com po nents in a gas mix ture, íi – mo - lar part of the gas com po nents, and k2 – ra tio of the brine in clu sion vol ume to the ini tial vol ume of the gas bub ble, such that:
k L
2 R
1
3 3
4 1
= × ×æ èç ö
ø÷ - p
[2]
Fig. 3. Zonation of sed i men tary ha lite chev ron for (A, B) sam ple Zjy-47-21c, (C) sam ple Zjy-24-057, and (D) sam ple Yu-33
where: L – length of the in clu sion edge and R1 – gas phase ra dius be fore in clu sion depressurization.
Tak ing into ac count the change in pres sure above a curved sur face (Zhukhovitsky and Shvartsman, 1968), the max i mum pos si ble pres sure is ex pressed by the fol low ing equa tion:
p
P k
R P k
max ( )
0 1
3
1 0
1
2 2
= + × 1
×s × - [3]
where: s – co ef fi cient of the sur face ten sion for highly con cen trated so lu tions. Within the range of 0.073–0.093 [H/m], this value does not sig nif i cantly af fect the ac cu racy of cal cu la tions; we as sumed a value of s = 0.083 [H/m]. The co ef fi cient of the lin ear in crease in the gas phase (k1) was de fined as the ra tio of the stan dard (R0) to the ini - tial (R1) ra dius of the sur face cur va ture:
k R
1 R
0 1
= [4]
Since an un known value (P1) ap pears on the left and right sides of Equa tion [1], it is better to per form those cal cu la tions us ing a graphic method, which re quires a min i mum num ber of cal cu la tions. Equa tion [1] is the lin ear func tion of P1/P0, from r(p1)
– r(p0), where the ex pres sion be fore the square brack ets is the co ef fi cient of the an gu lar in cli na tion of the solid lines, and Pmax/P0 is the value on the P1/P0 axis that de ter mines their ini tial points (Fig. 5). The dis per sion of solid lines is as so ci ated with mea sure ment er rors. The in ter sec tion points of the long bro ken lines and solid lines in Fig ure 5 de ter mine the par tial (re duced to stan dard) gas pres sure (Ta ble 3).
The de ter mi na tion of the com po si tions of gas mix tures in the pri mary in clu sions of the Majiagou ha lite was dif fi cult since the late-diagenetic in clu sions greatly pre vailed in vol ume. How - ever, the gas dis solved in the brines of pri mary in clu sions of ha - lite con tained pre dom i nantly N2 and CH4. For that rea son, we cal cu lated the pres sure val ues for gas mix tures that var ied in the com po si tions oc cur ring in the pri mary in clu sions in the ha lite of Phanerozoic de pos its (Ta bles 4 and 5). One can con clude from these cal cu la tions, re gard less of the com po si tion of the Fig. 4. Early diagenetic in clu sions with a sylvite daugh ter crys tal at the mar gin of ha lite
zonation in (A) sam ple Zjy-24-057 and (B, C) sam ple Yu-33; late diagenetic in clu sions in trans par ent recrystallized ha lite in (D) sam ple Yu-33; late diagenetic sin gle-phase fluid in clu - sions (E), and two-phase (gas-liq uid) in clu sions (F) in the in ter sected frac tures of ha lite in sam ple Yu-33
gas, that pres sure was pro por tional in the in clu sions. At pres - sures of 0.47–0.58 MPa., a brine col umn thick ness of 37–46 m cor re sponded to the pres sure pre vail ing at the bot tom of the salt ba sin.
DISCUSSION
Ha lite is a unique sed i men tary min eral. Among the min er als found in sed i men tary rocks, only in ha lite (and very rarely in
sylvite) pe cu liar skel e tal forms are es tab lished, which are uniquely iden ti fied as sed i men tary crys tal line tex tures. They con tain nu mer ous fluid in clu sions, which are the con served microdroplets of the brines of an cient salt wa ter bas ins (Kovalevych and Vovnyuk, 2010). The pres ence of rhyth mic zonation in ha lite, man i fested by in clu sion-rich bands sep a rated by clear ha lite bands with out in clu sions, caused by tem per a ture fluc tu a tions form ing dur ing the day, is typ i cal for shal low salt bas ins. How ever, the types of chev ron struc ture zonation can be re lated to var i ous physicochemical con di tions of ha lite crys - tal li za tion and zonation did not al ways in di cate the depth of ba - sin (af ter Petrichenko, 1988). In the pres ent study, ha lite sam - ples did not rep re sent typ i cal rhyth mic chev ron zonation, but there was non-sys tem atic zonation with rather poorly dis played rhythms (Fig. 3).
Our con clu sions are based on the re sults of a study of super heated fluid in clu sions in ha lite, from a depth more than 2.5 km, and thus with out con clu sive ev i dence of the re li abil ity of the re sults ob tained, these re sults can not be con sid ered valid.
The ques tion of the cor re spon dence of the physicochemical data ob tained from the study of fluid in clu sions in ha lite to the con di tions of the salt for ma tion still re mains con tro ver sial. The rea son for this is the high plas tic ity and sol u bil ity of ha lite, for T a b l e 1
Ho mog e ni za tion tem per a tures of the pri mary and sec ond ary fluid in clu sions, with gas bub bles
and sylvite daugh ter crys tals
Fluid in clu sion Size [mm]
Ho mog e ni za tion tem per a ture [°C]
Gas
bub ble Sylvite Sam ple Yu-33
pri mary 30 66 –
–//– 50 66 –
early diagenetic 300x200 64 50
–//– 200 70 46
Sam ple Zjy-24-057
pri mary 30 65 –
–//– 30 62 –
early diagenetic 70 64 53
–//– 250x180 66 54
Sam ple Zjy-47-21c
pri mary 50–100
58, 62, 62, 67, 68, 68, 68, 68, 70,
72
–
Lines in di cate that data were un avail able
T a b l e 2 Mea sured pa ram e ters: cube edge of the in clu sions (L);
gas-phase ra dii be fore (R1) and af ter (R0) in clu sion depressurization
In clu sion No.
In clu sion and gas phase pa ram e ters
[mm]
Co ef fi cients
L R1 R0 k R T
2 P
0
× ×
Pmax/P0
1 25.8 4.5 8.6 0.605 7.83
2 17.4 3.15 6.0 0.528 8.11
3 30.5 5.3 10.1 0.613 7.64
4 30.1 5.5 10.5 0.510 7.65
5 22.9 3.9 7.4 0.659 7.79
6 44.9 7.7 14.6 0.643 7.30
7 20.8 3.5 6.7 0.689 8.11
k2 – ra tio of the brine in clu sion vol ume to the ini tial vol ume of the gas bub ble; P0 – ini tial pres sure; Pmax – max i mum pres sure; R – uni ver - sal gas con stant; T – tem per a ture
Fig. 5. De pend ence of dissolvability of pure gases on pres sure
The long bro ken lines rep re sent the solvability of these gases and are drawn ac cord ing to Pav lov et al. (1987);
the solid lines rep re sent the num bers of in clu sions based on the data from Ta ble 2
which a change in tem per a ture or pres sure in the salt col umn can lead to the de vel op ment of such pro cesses as stretch ing and the mi gra tion or de struc tion of pre vi ously arisen fluid in clu - sions (Holdoway, 1974; Roedder, 1984). How ever, the lim its of per mis si ble changes in P-T con di tions at which fluid in clu sions in ha lite re tain their in for ma tion con tent are still poorly stud ied.
Many phys i cal and chem i cal ob ser va tions (Petrichenko, 1973, 1988; Bukowski et al., 2000; Galamay et al., 2003;
Galamay and Bukowski, 2011; Meng et al., 2014) sug gest that, af ter ex po sure of ha lite con tain ing ini tially liq uid in clu sions, at tem per a tures rang ing from 50 to 110°C and with in creased pres sure, the in for ma tive value of pri mary in clu sions in ha lite may be pre served. The gas phase can ap pear due to stretch ing or par tial crack ing in in clu sions af ter heat ing to >50°C (Roedder, 1984), and the ho mog e ni za tion tem per a ture of such in clu sions cor re sponds to the tem per a ture of salt de posit over - heat ing (Petrichenko, 1973). The in teg rity of early diagenetic in - clu sions with the pri mary fluid in clu sions in the Majiagou For - ma tion ha lite have been pre served. This in di cates that they are of the same chem i cal com po si tion, and that the sec ond ary fluid in clu sions have a dif fer ent com po si tion (Meng et al., 2018).
The brine depth dur ing the de po si tion of Or do vi cian evaporites in the Ordos Ba sin has been the sub ject of much con tro versy (Xue, 1986; Zhang et al., 1991; Bao et al., 2004).
The li thol ogy and the vari a tion in fa cies and sed i men tary struc - tures of the evaporites clearly show that those of the 5th mem - ber of the Majiagou For ma tion formed in a ma rine epi conti - nental ba sin, in which the fa cies dis tri bu tions are sim i lar to a bull’s eye pat tern, with rock salts in the cen ter of the ba sin (Xue, 1986). There are two con trast ing mod els for the sed i men tary fa cies of the Or do vi cian evaporites in the Ordos Ba sin. One is a clas sic car bon ate plat form model (Yao et al., 2008), and the other is a car bon ate ramp model (Hou et al., 2002). Ac cord ing to Chen et al. (2019), dur ing sea level lowstands, the wa ter depth of the in ner epeiric la goon was less than the depth of the nor mal sea wa ter, thereby re sult ing in a higher sa lin ity wa ter
body with an in creas ing sa lin ity gra di ent to ward its cen tre. In this high-sa lin ity cen tral la goon, with oc ca sion ally strat i fied brine, the pre cip i ta tion of ha lite crys tals and the de po si tion of a large amount of thickly bed ded rock salt oc curred (Fig. 6). Dur - ing highstands, when con nec tions to the ex ter nal ocean in - creased, the in ner epeiric la goon was dom i nated by the sed i - men ta tion of car bon ate rocks with scarce evaporites.
In the bore holes be low the salt de pos its, there are mainly ma rine lime stones (Fig. 2) cre ated dur ing sea level highstand.
Above the salt de pos its, there are dolomites with shal low-wa ter depositional fea tures, such as ero sional sur faces and brec cia.
There fore, Zhang et al. (1991) con cluded that in the be gin ning, ha lite was formed in a deep ba sin, and then the evaporitic ba sin grad u ally shallowed to a sabkha en vi ron ment. Mac ro scopic ob - ser va tions of the salt types and dis tri bu tional pat terns of the microfacies (Bao et al., 2004) sup port such vari abil ity. The or i - gin of the var i ous colours of evaporites is as so ci ated with the depth and en vi ron ment of salt sed i men ta tion, where dark ha lite is found in the lower parts of cores and changes into white ha lite in the mid dle parts, and fi nally into red ha lite con tain ing high po - tas sium con tents in the up per parts of the cores. The ha lite in - ves ti gated co mes from the lower part of the Ma-5 sec tion, which was de pos ited when the evaporitic ba sin was still rel a tively deep (~40 m), as shown in pre vi ous stud ies (Zhang et al., 1991;
Bao et al., 2004).
Our re search in di cates the pos si bil ity of us ing a method of math e mat i cal cal cu la tions to es ti mate the depth of the ba sin.
These stud ies were car ried out on se lected sam ples with in clu - sions larger than 10–15 mm, suit able for re search un der op ti cal mi cros copy. We do not have enough data from other sec tions of the Majiagou For ma tion (Fig. 2) to de ter mine the po ten tial changes in the depth of the Ordos Ba sin.
Such depth changes were re corded for ex am ple in the De - vo nian Pripyat Ba sin (Petrichenko, 1988). The cal cu lated depth of that ba sin was 22–30 m at the be gin ning of ha lite sed i men ta - tion, while af ter the sed i men ta tion of a 250 m thick rock salt suc - ces sion, the cal cu lated depth de creased to 8–10 m. In the Perm ian Dnie per-Donetsk Ba sin, the cal cu lated ba sin depth grad u ally changed from 13–15 m to 50 m dur ing the sed i men ta - tion of a 40 m rock salt layer. In the up per part of the pro file, ha - lite de po si tion was abruptly re placed by the sed i men ta tion of cal cium sulphates, and the cal cu lated depth reached 50–55 m (Petrichenko, 1988).
CONCLUSIONS
Stud ies of two-phase in clu sions (liq uid + gas) in halites from an cient ma rine salt-bear ing for ma tions make it pos si ble to cal - cu late the depth of the salt ba sin. How ever, such re search T a b l e 3
Par tial (re duced to stan dard) gas pres sure when gas con tained only N2, CH4, CO2, and H2
No, of lines (in clu sions)
Ini tial / stan dard pres sure P1/P0 [MPa]
N2 CH4 CO2 H2
1 0.59 0.46 0.15 0.56
2 0.63 0.50 0.13 0.61
6 0.54 0.43 0.12 0.52
T a b l e 4 Var i ous gas mix tures in brines of the pri mary
in clu sions in ha lite
Gas mix ture op tions
Con tent amount Ni [vol.%]
N2 CH4 CO2 H2
A 75 16 5 4
B 5 93 1 1
C 56 32 8 4
D 95 4 0.5 0.5
T a b l e 5 Par tial pres sure (re duced to stan dard)
of var i ous gas mix tures
No. of lines (in clu sions)
P1/P0 = S (P1/P0)i Ni / 100% [MPa]
A B C D
1 0.55 0.46 0.51 0.58
2 0.58 0.50 0.51 0.62
6 0.49 0.43 0.47 0.53
Mean 0.54 0.47 0.49 0.58
should be pre ceded by iden ti fi ca tion ge netic types of in clu sions.
Only fluid in clu sions for which the chem i cal com po si tion of brines was un changed due to depressurization dur ing their stretch ing or par tial crack ing are suit able for cal cu lat ing ba sin depth.
The salt de pos its of the Majiagou For ma tion dur ing the post-sed i men ta tion stages were over heated at tem per a tures of 62–70°C. The coarse, late-diagenetic fluid in clu sions of the recrystallized ha lite were depressurized un der such con di tions and over filled at an el e vated pres sure. Mean while, the pri mary in clu sions re tained their in teg rity.
Slightly higher pres sure of gas (rel a tive to the at mo spheric pres sure) in the pri mary in clu sions of bot tom-grown ha lite crys - tals in di cates a brine col umn thick ness of ~40 m.
Our find ings also sup port pre vi ous con clu sions re gard ing the sed i men ta tion model of the Or do vi cian Majiagou For ma tion based on pet ro log i cal and sed i men tary stud ies (Zhang et al., 1991; Bao et al., 2004; Chen et al., 2019).
Ac knowl edge ments. This re search was sup ported by the Na tional Nat u ral Sci ence Foun da tion of China (Grant No.
41561144009) and the Nat u ral Sci ence Foun da tion of Jiangsu Prov ince (Grant No.: BK20151611) and Ba sic Fron tier Sci en - tific Re search Pro gram of the Chi nese Acad emy of Sci ences (No. ZDBS-LY-DQC021). We also sin cerely thank J. Szcze - pañski, T. Peryt, and an anon y mous re viewer for their com - ments and sug ges tions which im proved the text.
REFERENCES
Acros, D., Ayora, C., 1997. The use of fluid in clu sions in ha lite as en vi ron men tal ther mom e ter: an ex per i men tal study. In: Eu ro - pean Cur rent Re search on Fluid In clu sions Bi en nial Sym po - sium: 10–11.
Bao, H., Yang, C., Huang, J., 2004. “Evap o ra tion dry ing” and
“reinfluxing and redissolving”– a new hy poth e sis con cern ing for - ma tion of the Or do vi cian evaporites in east ern Ordos Ba sin (in Chi nese with Eng lish sum mary). Jour nal of Palaeo ge ogra phy, 6: 279–288.
B¹bel, M., 2007. Depositional en vi ron ments of a sa lina-type evaporite ba sin re corded in the Badenian gyp sum fa cies in north ern Carpathian Foredeep. Geo log i cal So ci ety, Lon don, Spe cial Pub li ca tions, 285: 107–142.
B¹bel, M., Schreiber, B.C., 2014. Geo chem is try of evaporites and evo lu tion of sea wa ter, In: Trea tise on Geo chem is try (2nd ed.), vol. 9 (ed. F. Mac ken zie): 484–548. Sed i ments, Diagenesis, and Sed i men tary rocks, Elsevier.
Borchert, H., Muir, R.O., 1964. Salt De pos its: the Or i gin, Meta mor - phism and De for ma tion of Evaporites: Van Nostrand Co., Ltd.
Bukowski, K., Galamay, A.R., Goralski, M., 2000. In clu sion brine chem is try of the Badenian salt from Wieliczka. Jour nal of Geo - chem i cal Ex plo ra tion, 69: 87–90.
Chen, A., Yang, S., Xu, S., Ogg, J., Chen, H., Zhong, Y., Zhang, C., Li, F., 2019. Sed i men tary model of ma rine evaporites and im pli ca tions for pot ash de pos its ex plo ra tion in China. Car bon - ates and Evaporites, 34: 83–99.
Feng, Z., Zhang, Y., Jin, Z., 1998. Type, or i gin, and res er voir char - ac ter is tics of dolostones of the Or do vi cian Majiagou Group, Ordos, North China plat form. Sed i men tary Ge ol ogy, 118:
127–140.
Galamay, A.R., Baranenko, O.V., 2004. Hy dro car bons in the Badenian salts of the Fore-Carpathian and Transcarpathian re - gions (in Ukrai nian). Min er al og i cal Re view, 54: 132–136.
Galamay, A.R., Bukowski, K., 2011. Chem i cal com po si tion of Ba - de nian brines from pri mary fluid in clu sions in ha lite (Trans - carpathian Ba sin, Ukraine) (in Pol ish with Eng lish sum mary).
Ge ol ogy, Geo phys ics and En vi ron ment, 37: 245–267.
Galamay, A.R., Bukowski, K., Czapowski, G., 2003. Chem i cal com po si tion of brine in clu sions in ha lite from clayeysalt (zuber) fa cies from the Up per Ter tiary (Mio cene) evaporite ba sin (Po - land). Jour nal of Geo chem i cal Ex plo ra tion, 78–79: 509–511.
Galamay, A.R., Bukowski, K., Poberezhskyy, A.V., Karoli, S., Kovalevych, V.M., 2004. Or i gin of the Badenian salts from East Slovakian Ba sin in di cated by the anal y sis of fluid in clu sions.
Annales Societatis Geologorum Poloniae, 74: 267–276.
Holdoway, K.A., 1974. Be hav ior of fluid in clu sions in salt dur ing heat ing and ir ra di a tion. North ern Ohio Geo log i cal So ci ety, 1:
303–312.
Hou, F.H., Fang, S.X., Zhao, J.S., Dong, Z.X., Li, L., Wu, Y., Chen, Y.N., 2002. Depositional en vi ron ment model of Mid dle Or do vi - cian Majiagou For ma tion in Ordos Ba sin (in Chi nese with Eng - lish summary). Ma rine Or i gin Pe tro leum Ge ol ogy, 7: 38–46.
Ivanov, A.A., Voronova, M.L., 1972. Halogenic For ma tions: Min eral Com po si tion, Types, and For ma tion En vi ron ments (Meth ods of the Pros pect ing and Ex plo ra tion of Min eral Salt De pos its) (in Rus sian). Nedra.
Kalyuzhny, V.A., 1982. The Foun da tions of Teach ing about Min - eral-form ing Flu ids (in Rus sian). Naukova Dumka, Kyiv.
Kovalevych, V.M., Vovnyuk, S.V., 2010. Fluid in clu sions in ha lite from ma rine salt de pos its: are they real mi cro-drop lets of an cient sea wa ter? Geo log i cal Quar terly, 54 (4): 401–410.
Fig. 6. Model of the Or do vi cian evaporite ba sin at the stage of ha lite sed i men ta tion
Kovalevich, V.M., Jarmo³owicz-Szulc, K., Peryt, T.M., Pobere - gski, A.V., 1997. Messinian chev ron ha lite from the Red Sea (DSDP Sites 225 and 227): fluid in clu sion study. Neues Jahrbuch für Mineralogie Monatshefte, 10: 433–450.
Kovalevych, V.M., Peryt, T.M., Zang, W., Vovnyuk, S.V., 2006.
Com po si tion of brines in ha lite-hosted fluid in clu sions in the Up - per Or do vi cian, Can ning Ba sin, West ern Aus tra lia: New data on sea wa ter chem is try. Terra Nova, 18: 95–103.
Kovalevych, V.M., Peryt, T.M., Shanina, S.N., Wieclaw, D., Lytvyniuk, S.F., 2008. Geo chem i cal au re oles around oil and gas ac cu mu la tion in the Zechstein (Up per Perm ian) of Po land:
Anal y sis of fluid in clu sions in ha lite and bi tu mens in rock salt.
Jour nal of Pe tro leum Ge ol ogy, 31: 245–262.
Kovalevych, V.M., Paul, J., Peryt, T.M., 2009. Fluid in clu sions in ha lite from the Röt (Lower Tri as sic) salt de posit in Cen tral Ger - many: ev i dence for sea wa ter chem is try and con di tions of salt de po si tion and recrystallization. Car bon ates and Evaporites, 24: 45–57.
Li, R.X., Guzmics, T., Liu, X.J., Xie, G.C., 2011. Mi gra tion of im mis - ci ble hy dro car bons re corded in cal cite-hosted fluid in clu sions, Ordos Ba sin: a case study from North ern China. Rus sian Ge ol - ogy and Geo phys ics, 52: 1491–1503.
Litvinyuk, S.F., 2007. Geo chem i cal ha los in salts over hy dro car bon de pos its (ac cord ing to the re sults of the study of in clu sions in ha lite) (in Ukrai nian with Eng lish sum mary). Ge ol ogy and Geo - chem is try of Min er als, 4: 95–111.
Lowenstein, T.K., Hardie, L.A., 1985. Cri te ria for the rec og ni tion of salt-pan evaporites. Sedimentology, 32: 627–644.
Matukhin, R.G., Petrichenko, O.Y., Sokolov, P.N., 1985. Gas-liq - uid in clu sions in ha lite as an in di ca tor of the for ma tion con di - tions of the De vo nian salt-bear ing sed i ments of Si be ria (in Rus - sian). In: Lith o logic-fa cies and Geo chem i cal Prob lems of Salt Ac cu mu la tion (ed. A.L. Yanshin): 194–203. Nauka.
Meng, F-W., Galamay, A.R., Yang, C-H., Li, Y-P., Zhuo, Q-G., 2014. The ma jor com po si tion of a mid dle-late Eocene salt lake in the Yunying de pres sion of Jianghan Ba sin of Mid dle China based on anal y ses of fluid in clu sions in ha lite. Jour nal of Asian Earth Sci ences, 85: 97–105.
Meng, F., Zhang, Y., Galamay, A.R., Bukowski, K., Ni, P., Xing, E., Ji, L., 2018. Or do vi cian sea wa ter com po si tion: ev i dence from fluid in clu sions in ha lite. Geo log i cal Quar terly, 62 (2): 344–352.
Meng, F-W., Zhang, Z-L., Yan, X-Q., Ni, P., Liu, W-H., Fan, F., Xie, G-W., 2019. Stromatolites in Mid dle Or do vi cian car bon - ate–evaporite se quences and their car bon and sul fur iso topes stra tig ra phy, Ordos Ba sin, north west ern China. Car bon ates and Evaporites, 34: 11–20.
Moskovskyi, G.A., 1983. Re search of phys i cal and chem i cal sed i - men ta tion con di tions of the Kungurian salt sed i ments of the west ern part of the Cas pian syncline based on in clu sions in min - er als (in Rus sian). Ph.D. the sis, Mos cow Uni ver sity.
Petrichenko, O.I., 1973. Meth ods of study of in clu sions in min er als of sa line de pos its (in Ukrai nian). Fluid In clu sion Re search, 12:
214–274.
Petrichenko, O.I., 1988. Physico-chem i cal con di tions in the sed i - men ta tion of the an cient halo gen bas ins (in Rus sian). Naukova Dumka.
Roedder, E., 1984. Fluid in clu sions In: Re views in Min er al ogy 12.
Min er al og i cal So ci ety of Amer ica.
Schmalz, R.F., 1969. Deep-wa ter evaporite de po si tion: a ge netic model. AAPG Bul le tin, 53: 798–823.
Scotese, C.R., 2014. At las of Si lu rian and Mid dle-Late Or do vi cian Paleogeographic Maps (Mollweide Pro jec tion), Maps 73–80 (vol. 5): The Early Pa leo zoic. PALEOMAP At las for ArcGIS, PALEOMAP Pro ject.
Strakhov, N.M., 1967. Prin ci ples of Lithogenesis. New York. Springer.
Wang, B.Q., Al-Aasm, I.S., 2002. Karst-con trolled diagenesis and res er voir de vel op ment: ex am ple from the Or do vi cian main - reservoir car bon ate rocks on the east ern mar gin of the Ordos ba sin, China. AAPG Bul le tin, 86: 1639–1658.
Weiss, R.F., 1969. Dis solved ar gon, ni tro gen and to tal car bon ate in the Red Sea brines. In: Hot Brines and Re cent Heavy Metal De - pos its in the Red Sea: a Geo chem i cal and Geo phys i cal Ac count (eds. E.T. Degens and D.A. Ross): 254–260. Springer-Verlag.
Wiêc³aw, D., Lytvyniuk, S.F., Kovalevych, V.M., Peryt, T.M., 2008.
Fluid in clu sions in ha lite and bi tu mens in rock salt from Mio cene evaporites in the Ukrai nian Fore-Carpathian re gion: as in di ca - tors of hy dro car bon ac cu mu la tions in the un der ly ing strata (in Pol ish with Eng lish sum mary). Przegl¹d Geologiczny, 56:
837–841.
Valyashko, M.G., 1952. Ha lite, its prin ci pal va ri et ies found in salt lakes and its struc tural fea tures (in Rus sian). Pro ceed ings of the All-Un ion In sti tute of Halurgy, 23: 25–53.
Valyashko, M.G., 1962. The prin ci ple of form ing of salt de pos its (in Rus sian). Mos cow, MGU.
Xue, P., 1986. Or i gin of evaporites in a vast epicontinental plat form sea (in Chi nese with Eng lish sum mary). Geo log i cal Re view, 32:
59–66.
Yang, Y., Li, W., Ma, L., 2005. Tec tonic and strati graphic con trols of hy dro car bon sys tems in the Ordos ba sin: a multicycle cratonic ba sin in cen tral China. AAPG Bul le tin, 89: 255–269.
Yao, J-L., Zhao, Y-G., Lei, B-J., Hao, H-Y., 2008. Se quence lithofacies paleogeography of west ern Ordos Ba sin in Majiagou Stage (in Chi nese with Eng lish sum mary). Jour nal of South west Pe tro leum Uni ver sity, 30: 33–37.
Yu, Q., Ren, Z., Li, R., Wang, B., Qin, X., Tao, N., 2017.
Paleogeotemperature and ma tu rity evo lu tion ary his tory of the source rocks in the Ordos Ba sin. Geo log i cal Jour nal, 52:
97–118.
Zhang, J., Zeng, S., Huang, J., Ma, Z., Wang, Z., 1991. The oc cur - rence and sig nif i cance of ha lite in East ern Ordos (in Chi nese with Eng lish sum mary). Acta Sedimentologica Sinica, 9: 34–43.
Zhang, F., Li, J., Wei, G., Liu, X., Guo, J., Li, J., Fan, L., She, Y., Guan, H., Yang, S., Shao, L., 2018. For ma tion mech a nism of tight sand stone gas in ar eas of low hy dro car bon gen er a tion in - ten sity: a case study of the Up per Pa leo zoic in north Tianhuan de pres sion in Ordos Ba sin, NW China. Pe tro leum Ex plo ra tion and De vel op ment, 45: 79–87.
Zhukhovitsky, A.A., Shvartsman, L.A., 1968. Phys i cal Chem is try (in Rus sian). Met al lurgy, Mos cow.
