Year-end Sale % OFF 
Abstract
In China, pre-Quaternary solid potash deposit has only been discovered in the Simao Basin, and the Lower Cretaceous Mengyejing (MYJ) Formation (Fm.) is the productive layer of potash deposit. In this study, we investigated the clay conglomerates which are distributed in upper and lower members of the potash-bearing salt rock layer. We analyzed the relative contents of major elements (Al2O3, Fe2O3T, MgO, CaO, Na2O, K2O) and trace elements (B, Ba, Co, Cr, Cu, Ga, Mn, Ni, Rb, Sr, V, Zn, Zr) in the samples. The results show that MgO and CaO in the major elements are rich relative to Post Archean Australian Shale (PAAS), whose average enrichment factor values of the MgO (EFMgO) is 2.61 and CaO (EFCaO) is 4.57, and the others major elements are relatively minor; trace elements (B, Ga, Mn, Zr) are rich relative to PAAS, and the others trace elements are minor relative to PAAS. The study of paleogeographic conditions using various parameters shows that the paleoclimate is generally dry and hot during the period of clay conglomerate deposition, but it was warm and humid in certain periods; the main sedimentary environment is weak oxidation condition with strong oxidation conditions in individual periods; the average value of paleosalinity is ~21‰, and the highest is no more than ~92‰. The significance of the paleogeographic characteristics of MYJ Fm. to potash mineralization are as follows: (1) they indicates that the clay conglomerates of MYJ Fm. are not clastic sediments in brine formed by seawater, because the paleosalinity of clay conglomerates deposition period is obviously lower than that of seawater; (2) MYJ potassic salt ore is not formed by evaporation and concentration of seawater in clay conglomerates in the sedimentary basin, because there is no carbonate rock and sulfate rock of corresponding scale after the deposition of clay conglomerates in the basin; (3) clay conglomerates of MYJ Fm. were deposited in continental shallow water basin; (4) the matter source of potash minerals is deep marine strata; (5) in the MYJ Fm. sedimentation period, deep source salt moved to the surface under the background of extensional structure, and the subsequent sedimentary clastic rock formed a protective layer of potash-bearing rock, thus completing the “deep source and shallow mineralization” metallogenic process.
Highlights
There are a lot of evaporites in the Tethys domain
The weathering degree of parent rock is relatively moderate, and calcium oxide and sodium oxide are leached to a certain extent, which will lead to higher values of chemical index of alteration (CIA), plagioclase index of alteration (PIA), and chemical index of weathering (CIW) [28,30,34]
During the clay conglomerate sedimentary period of MYJ Fm., the paleoclimate was dry and hot with slight to moderate chemical weathering, which led to the higher values of CIA, PIA, and CIW
Summary
There are a lot of evaporites in the Tethys domain. Potash deposits have been discovered in the Maha Sarakham Fm. in the Khorat Basin and the Mengyejing (MYJ) Formation (Fm.) in the Simao Basin, all in the east of Tethys. The surrounding rocks of the potash deposits in the Simao Basin are clay conglomerates, and the corresponding scale of carbonate and sulfate deposits are lacking. According to the difference in mineral composition, 4.0/). Clay conglomerates can be further divided into silty clay conglomerates, lime clay conglomerates, gypsum clay conglomerates, and salt-soluble clay conglomerates. Previous studies on clay conglomerates have mainly focused on provenance and paleoclimate during deposition [1,2,3]. There are few reports on paleosalinity and redox conditions in the sedimentary environment, and there is still space for further discussion on paleoclimate
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
