| Title | Mg, C and O isotopic compositions of Late Cretaceous lacustrine dolomite and travertine in the northern Tianshan Mountains, Northwest China |
| Authors | Wang, Yizhe Wu, Chaodong Fang, Yanan Ma, Jian Shen, Bing Huang, Fang Li, Linlin Ning, Meng Zhai, Lina Zhang, Wei |
| Affiliation | Lanzhou City Univ, Bailie Sch Petr Engn, Lanzhou 730070, Peoples R China Peking Univ, Sch Earth & Space Sci, Key Lab Orogen Belt & Crustal Evolut, Minist Educ, Beijing 100871, Peoples R China Chinese Acad Sci, Nanjing Inst Geol & Palaeontol, Nanjing 210008, Peoples R China MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA Univ Sci & Technol China, Sch Earth & Space Sci, Hefei 230026, Peoples R China China Earthquake Adm, Inst Crustal Dynam, Beijing 100085, Peoples R China Chinese Acad Sci, Inst Oceanol, Qingdao 266071, Peoples R China China Univ Petr, Coll Geosci, Beijing 102249, Peoples R China |
| Keywords | TIEN-SHAN-RANGE JUNGGAR BASIN COORONG REGION PALEOENVIRONMENTAL SIGNIFICANCE PALUSTRINE CARBONATES TECTONIC EVOLUTION WESTERN ANATOLIA DOLOMITIZATION FRACTIONATION LAKE |
| Issue Date | 20-May-2020 |
| Publisher | CHEMICAL GEOLOGY |
| Abstract | The Junggar Basin was characterized by high temperature and strong tectonic activities during the Late Cretaceous, in which a dolomite-forming lacustrine depositional system associated with travertine was deposited in its southern sector adjoining the northern Tianshan Mountains. Two broad types of dolomite are identified in terms of mineralogy, including the homogeneous and anhedral dolomite-A and high order degree and euhedral dolomite-B, which are also largely varied in mineral size (10-20 mu m and 30-50 mu m in size, respectively). The dolomites display a low degrees of dolomite order (mean = 0.48) and Ca-rich (mean = 55.8). Compared with delta O-18 values (PDB) of limestones in the shore to shallow facies (-7.0 to -11.1 parts per thousand), the apparent positive delta O-18 values of dolomites (-4.2 to -5.9 parts per thousand) indicate a stronger evaporation environment, while the values of -6.8 to -8.1 parts per thousand in the salt marsh facies dolomitic limestone may reflect transitional conditions. Moreover, the more positive delta Mg-26 values of dolomites (ranging from -1.52 to -2.91 parts per thousand) than those of limestone and travertine (-3.58 parts per thousand and -4.31 parts per thousand, respectively) also indicate an origin related fractionation effect. In addition, based the occurrence of low-temperature hydrothermal minerals, including chlorite, barite, siderite and silver in the dolostone and travertine, we interpret a new travertine-related origin for the lacustrine dolomite. Thermal water entering saline and alkaline lake environments subject to strong evaporation promoted dolomitization. From the simulation of the Rayleigh and seepage reflux models, we speculate that the lacustrine dolomites formed in a near-surface environment (25-50 degrees C). Moreover, the results contain abundant information on palaeoenvironmental and palaeoclimatic changes, which are very important for reconstructing and deciphering palaeoenvironments and expanding the dolomitization model under thermal water influenced evaporative lacustrine conditions. |
| URI | http://hdl.handle.net/20.500.11897/589506 |
| ISSN | 0009-2541 |
| DOI | 10.1016/j.chemgeo.2020.119569 |
| Indexed | SCI(E) Scopus EI |
| Appears in Collections: | 地球与空间科学学院 造山带与地壳演化教育部重点实验室 |
