The Cenozoic terrestrial chemical weathering records from the surrounding areas of the Tibetan Plateau are of great significance for understanding the relationship between Tibetan Plateau uplift, chemical weathering and global cooling. In this study, detailed mineralogical and geochemical analysis were performed on the early Cenozoic sediments from the Hongliugou section (54-26 Ma) in the Qaidam Basin, the Xiejia section in the Xining Basin (52-26 Ma) and the Caijiachong section in the Qujing Basin (46.6-36 Ma). Then a comprehensive chemical weathering history of the Early Cenozoic (54-26 Ma) in the northeastern and southeastern Tibetan Plateau was established. Specially, clay minerals of 315 samples from the Hongliugou section, 131 samples from the Xiejia section and 230 samples from the Caijiachong section were analyzed using Bruker D8+ X-ray diffraction analyzer. Major and trace elements of 310 samples from the Hongliugou section, 120 samples from Xiejia section and 201 samples from the Caijiachong section were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES; Leeman Labs Prodigy-H) and inductively coupled plasma mass spectrometry (ICP-MS; X-7; Thermo-Elemental, USA), respectively. While the hematite content of 835 samples from the Hongliugou section were determined using a Purkinje General TU1901 UV-VIS spectrophotometer. The regional chemical weathering intensity as suggested by clay mineral assemblage (i.e. (illite/smectite mixed layers + smectite)/illite), elemental geochemical indices (e.g., CIA) and hematite content shows a long-term decreasing trend in 54-26Ma, resembling the contemporary benthic oxygen isotopes variations, thus indicating that global temperature is the main controlling factor regulating the reginal chemical weathering in the early Cenozoic.
FANG Xiaomin , FANG Xiaomin, HAN Wenxia HAN Wenxia
Collision between the Indian and Eurasian plates produced concomitant uplift of the Tibetan Plateau and its basin-ridge geomorphological systems. Surface relief of the Tibetan Plateau has significant dynamic and thermal effects on atmospheric circulation and on regional and global climate. It has been considered as one of the key drivers for the formation of the Asian monsoon, enhanced erosion and weathering, global decreased CO2 during the Cenozoic. Finally, this uplift caused global cooling in the Cenozoic. However, at present, the driving mechanisms of these processes still remain controversies and have not been clearly confirmed by records of chemical weathering from the Tibetan Plateau. This dataset includes major elemental compositions of the Fenghuoshan Group (thick of ~4500 m) from the Hoh Xil Basin which has been dated back to the Late Cretaceous-Eocence. Element was measured in the Institute of Geology and Geophysics, Chinese Academy of Sciences using XRF-1500. The resconstructed Paleogene chemical weathering sequences allow us to constrain the trends of chemical weathering history of the studied area. We found that intensity of chemical weathering is well correlated with global temperature change. These results provide further data supprot for discussing the dynamic mechanisms and links among the Paleogene chemical weathering in the Hoh Xil Basin, uplift of the Tibetan Plateau, and global change.
JIN Chunsheng
The samples were collected from the suobcha section of Wenquan area, South Qiangtang sag, Qiangtang basin, Tibet. The carbon isotope data were measured by thermo Finnigan mat-253 carbon isotope mass spectrometer at Beijing Institute of uranium geology, CNNC. The mass extinction event of the Late Triassic is relatively poorly-known among the five major extinction events in the Phanerozoic. Moreover, the typical marine Triassic-Jurassic (T-J) records are absent in regions other than the western Tethys and Boreal realms, and thus major questions remain as to the global significance and cause(s) of the event. Especially in the eastern Tethys, no marine sedimentary records of the T-J transition are known from open marine facies, and thus the extent and significance of the marine T-J transition are unclear. We show the first high-resolution carbonate carbon-isotope record, geochemistry, palaeontologic and lithological data from a marine T-J section (Wenquan section). In the columnar profile, we place the T-J boundary at the top of grainstone layers representing the shallowest water deposit. Our results reveal that the carbonate carbon-isotope record contains two different excursions in the Wenquan section of northern Tibet, China. These are consistent with the “initial” and “main” negative carbon-isotope excursions (CIEs) found in the global stratotype section and point (GSSP), strongly suggesting their global nature. A biological crisis together with paleoceanographic changes was identified near the main CIE. This means that a mass of isotopically light carbon was rapidly released into the air and oceans, resulting in environmental changes and biological crisis.
HU Fangzhi
The influence of deformation and metamorphism of post volcanic massive sulfide on the trace elements and sulfur lead isotopic composition of sulfide is still unclear. The Keketale VMS Pb Zn (- Ag) deposit provides an opportunity to solve the above problems; Five ore samples from No.7 and No.9 orebodies were crushed and screened for lead isotope analysis of bulk minerals, 17 polished thick sulfide samples were used for in-situ trace element and sulfur lead isotope analysis, 66 trace element determination points were analyzed, and 25 sulfur isotope points were determined; A total of 18 point pairs of different minerals were selected for lead isotope analysis, and LA-ICP-MS method was used
YU Pengpeng, ZHENG Yi
This data set comes from shallow marine carbonate sections at Tingri and Gamba, south Tibet. The age of these samples is about 56 Ma (at the Paleocene-Eocene boundary). At Tingri, we studied two parallel sections (13ZS section and 10-11TM section), and at Gamba, we studied one section (11TMG). From the 13ZS section, we analyzed carbon and oxygen isotopic compositions and calcium carbonate content of the whole carbonate rock, as well as the in-situ carbon isotopic compositions and element contents of the foraminifera shell. From the 10-11TM section, we analyzed carbon, oxygen and strontium isotopic compositions of the whole rock. From the 11TMG section, we analyzed carbon and oxygen isotopic compositions of the whole carbonate rock. Carbon and oxygen isotopic compositions of the whole rock were measured by gas isotope mass spectrometer (MAT251), strontium isotope by thermal ionization mass spectrometry (TIMS), calcium carbonate content by acid dissolution, in-situ carbon isotopic compositions by SIMS, and in-situ element contents by LA-ICPMS. Among these data, in-situ carbon isotope data were obtained from the laboratory of Professor John Valley at the University of Wisconsin-Madison in the United States, and the rest are from the relevant laboratories of the Department of Geosciences at the University of Bremen in Germany. Based on these data, we published three peer-reviewed papers on Journals of Gondwana Research, GSA Bulletin, and Global and Planetary Change.
ZHANG Qinghai
The data include the carbonate content, carbon isotope and oxygen isotope analysis results of inorganic carbonates of 79 samples from 850 m natural section of the middle late Eocene in the salkuli basin. The carbon and oxygen isotopes of carbonate in the sediments record the hydrological and vegetation information in the geological history, which is one of the main indicators of paleoenvironmental tracer research. After grinding and sieving, the carbon and oxygen isotope analysis is completed by the sample processing unit (carbonate device) and MAT252 isotope mass spectrometry online automatic online system. The analytical accuracy of the sample is: carbon isotope is better than ± 0.06 ‰, and oxygen isotope is better than ± 0.08 ‰. Through the analysis of carbon and oxygen isotope data of solkuli section, the evolution history of arid environment since Eocene can be reconstructed, and the paleoclimate effect of the Tibetan Plateau uplift and global climate change can be discussed.
SUN Jimin
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