Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements ana...Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements analysis of 289 samples collected from the outcrop sections around and wells drilled in the basin and using a series of identification indexes of paleo-climate, paleo-salinity and paleo-redox conditions, such as CaO/MgO?Al2 O3, Sr/Cu, Rb/Sr, Rb/K2 O, Th/U, V/(V+Ni), the content of element B tested from the mudstone. Comprehensive analysis shows that in sedimentary period of the Chang 7, the paleo-climate was warm temperate to subtropical climate with temperature higher than 15 ?C, the water body was continental brackish water to freshwater, and the sediments were deposited under strong reduction conditions. Suitable temperature, extensively deep lake basin and strongly reductive paleo-sedimentary environment led to the blooming, enrichment and preservation of organic matter in the submember Chang 73. As a result, a set of high-quality source rock was formed, laying material foundation for large-scale accumulation of shale oil.展开更多
In this paper the boron contents and boron isotopic composition of acid-soluble phases in loess and paleosol samples are determined for the first time. The boron contents of acid-soluble phases in the Luochuan loess s...In this paper the boron contents and boron isotopic composition of acid-soluble phases in loess and paleosol samples are determined for the first time. The boron contents of acid-soluble phases in the Luochuan loess section (S0 S2) vary within the range of (0.8—2.7)?0-6 and their d 11B values vary from 1.8?to +18.6? mostly within the range of 0—+10? The boron contents and d 11B values of paleosol layers are higher than those of loess layers, especially in the loess layer S1. Varying chemical weathering intensity and loess adsorption capability are the main fac-tors leading to the variations of boron contents and d 11B values of acid-soluble phases in the loess section. The variation of chemical weathering intensity in response to the variation of climatic con-ditions seems to be the main factor leading to the variations of boron contents andδ11B values of acid-soluble phases in the loess section.展开更多
基金Supported by the National Key Basic Research and Development Program(973 Project)National Science and Technology Major Project(2016ZX05050,2017ZX05001002)
文摘Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements analysis of 289 samples collected from the outcrop sections around and wells drilled in the basin and using a series of identification indexes of paleo-climate, paleo-salinity and paleo-redox conditions, such as CaO/MgO?Al2 O3, Sr/Cu, Rb/Sr, Rb/K2 O, Th/U, V/(V+Ni), the content of element B tested from the mudstone. Comprehensive analysis shows that in sedimentary period of the Chang 7, the paleo-climate was warm temperate to subtropical climate with temperature higher than 15 ?C, the water body was continental brackish water to freshwater, and the sediments were deposited under strong reduction conditions. Suitable temperature, extensively deep lake basin and strongly reductive paleo-sedimentary environment led to the blooming, enrichment and preservation of organic matter in the submember Chang 73. As a result, a set of high-quality source rock was formed, laying material foundation for large-scale accumulation of shale oil.
基金the State Outstanding Young Scientists Foundation(Grant No.94625304)and the"Climbing Program"sponsored by the Ministry of Science and Technology(Grant No.95-yu-39)
文摘In this paper the boron contents and boron isotopic composition of acid-soluble phases in loess and paleosol samples are determined for the first time. The boron contents of acid-soluble phases in the Luochuan loess section (S0 S2) vary within the range of (0.8—2.7)?0-6 and their d 11B values vary from 1.8?to +18.6? mostly within the range of 0—+10? The boron contents and d 11B values of paleosol layers are higher than those of loess layers, especially in the loess layer S1. Varying chemical weathering intensity and loess adsorption capability are the main fac-tors leading to the variations of boron contents and d 11B values of acid-soluble phases in the loess section. The variation of chemical weathering intensity in response to the variation of climatic con-ditions seems to be the main factor leading to the variations of boron contents andδ11B values of acid-soluble phases in the loess section.
