A series of confirmed and suspected dammed palaeo‐lake sedimentary successions is scattered within the middle Yarlung Tsangpo valley in Tibet. However, the chronology, the genesis of the dam and its location, the water level of the dammed lake, the process of dam failure and the spatiotemporal relationships between the sedimentary successions remain controversial. Here, we focus on one sedimentary succession of the suspected dammed palaeo‐lake at Xigazê. We measured the grain‐size distribution, magnetic susceptibility, organic and inorganic carbon content, and δ13Corg and δ15Ntotal ratios of the sediments. In addition, we measured the δ18Oshell and δ13Cshell values of modern and fossil Radix sp. shells, and the δ18Owater and δ13CDIC values of the ambient water with different hydrological regimes. The results indicate that the δ18Oshell values of modern Radix sp. and the δ18Owater of the ambient water body significantly depend on its hydrological status. In addition, a strong positive relationship was observed between δ18Oshell values of modern Radix sp. shells and the δ18Owater of the ambient water on the Tibetan Plateau. According to this correlation, the δ18Owater values of the palaeo‐water body are reconstructed using the δ18Oshell values of Radix sp. fossil shells in the Xigazê section. Further, based on the δ18Oshell values of fossil Radix sp., the reconstructed δ18Owater of the palaeo‐water body and the specific habitats of Radix sp., we infer that the sedimentary succession in the Xigazê broad valley was mainly formed within the backwater terminal zone of a dammed palaeo‐lake and that the elevation of the water level of the lake was approximately 3811 m a.s.l. AMS 14C dating indicates that the deposits of the dammed palaeo‐lake were formed at about 33–22 cal. ka BP. Finally, the presence of Radix sp. fossil shells within the Xigazê section suggests that Radix sp. survived the late Last Glacial Period on the Tibetan Plateau. 相似文献
The hydrocarbon potential of the Hangjinqi area in the northern Ordos Basin is not well known, compared to the other areas of the basin, despite its substantial petroleum system.Restoration of a depth-converted seismic profile across the Hangjinqi Fault Zone(HFZ) in the eastern Hangjinqi area shows one compression that created anticlinal structures in the Late Triassic, and two extensions in ~Middle Jurassic and Late Early Cretaceous, which were interrupted by inversions in the Late Jurassic–Early Early Cretaceous and Late Cretaceous, respectively.Hydrocarbon generation at the well locations in the Central Ordos Basin(COB) began in the Late Triassic.Basin modeling of Well Zhao-4 suggests that hydrocarbon generation from the Late Carboniferous–Early Permian coal measures of the northern Shanbei Slope peaked in the Early Cretaceous, predating the inversion in the Late Cretaceous.Most source rocks in the Shanbei Slope passed the main gas-migration phase except for the Hangjinqi area source rocks(Well Jin-48).Hydrocarbons generated from the COB are likely to have migrated northward toward the anticlinal structures and traps along the HFZ because the basin-fill strata are dipping south.Faulting that continued during the extensional phase(Late Early Cretaceous) of the Hangjinqi area probably acted as conduits for the migration of hydrocarbons.Thus, the anticlinal structures and associated traps to the north of the HFZ might have trapped hydrocarbons that were charged from the Late Carboniferous–Early Permian coal measures in the COB since the Middle Jurassic. 相似文献
This paper briefly presents the research progress of the State Major Basic Research Project 2001CB309400, “Theory and Application
for Retrieval and Fusion of Spatial and Temporal Quantitative Information from Complex Natural Environment”. Based on the
rapid advancement of synthetic aperture radar (SAR) imagery technology, information theory of fully polarimetric scattering
and applications in polarimetric SAR remote sensing are developed. To promote the modeling of passive microwave remote sensing,
the vector (polarized) radiative transfer theory (VRT) of complex natural media such as inhomogeneous, multi-layered and 3-dimensional
VRT is developed. With these theoretical progresses, data validation and retrieval algorithms for some typical events and
characteristic parameters of earth terrain surfaces, atmosphere, and oceans from operational and experimental remote sensing
satellites are studied. Employing remote sensing, radiative transfer simulation, geographic information systems (GIS), land
hydrological process, and data assimilation, the Chinese land data assimilation system (CLDAS) is established. Towards the
future development of China’s microwave meteorological satellites, employing remote sensing data of currently available SSM/I
(special sensor microwave/imager), AMSU (advanced microwave sounding unit), MTI (microwave temperature imager), etc., with
ground-based measurements, several operational algorithms and databases for atmospheric precipitation, water vapor and liquid
water in clouds, and other hydrological/hydrological applications are developed. To advance China’s SAR and InSAR (interferometric
SAR) technologies, the image processing and analysis of ERS (European remote sensing), Radarsat SAR, and Chinese SAR, etc.,
the software platforms are accomplished. Based on the researches of multi-information fusion, some simulations, identification,
and information extractions of the targets from complex background clutter scenes are studied. Some experiments of radio wave
propagation in anomalous atmospheric status are also carried out.
Translated from Advances in Earth Science, 2007, 22(2): 111–125 [译自: 地球科学进展] 相似文献