Abstract:
Objective The Hualong Basin in the northeastern margin of the Qinghai−Xizang Plateau has a huge thickness of Paleogene−Neogene clastic rock formation, which completely records the process of plateau uplift, paleoclimate and paleogeographic evolution. At the same time, its hydrochemical characteristics are related to the development and utilization of regional groundwater resources and engineering construction.
Methods In this paper, the lithology composition, fracture pore water quality and salt content of clastic rocks in the basin are investigated, analyzed and comprehensively studied from the perspective of hydraulic ring geology, and the ancient sedimentary environment is preliminarily discussed.
Results The results show that the Paleogene−Neogene clastic rocks in Qunke−Jianzha Basin are mainly glutenite, mudstone and sandstone. The salinity of fracture pore water is 0.247~1.518 g/L, and the hydrochemical types are mostly HCO3−Ca, HCO3−Na and HCO3−Ca•Mg•Na. The salt content of clastic rocks is 0.13%~0.18%, which belongs to non−saline rock. The clastic rocks in Xunhua Basin are mainly sandy conglomerate and mudstone, containing gypsum rock. The salinity of fissure pore water is 0.238~10.646 g/L. The hydrochemical types are mostly HCO3•SO4−Na•Ca, SO4•Cl−Na or SO4•Cl−Na•Ca. The salt content of clastic rock is 0.19%~1.65%, which is mostly saline rock.
Conclusions The paleoclimate of the entire basin during the Eocene, Oligocene and Miocene was characterized by aridity. The Xunhua Basin was closer to the center of the basin and was in the terminal lake environment of concentration and strong evaporation, while the Qunke−Jianzha Basin was located at the edge of the basin and was in a circulation environment with good conditions for recharge, runoff and discharge. This conclusion has certain reference value for water exploration in arid and water−deficient areas of Northwest China, groundwater resources development and utilization, engineering construction and basin paleoenvironment.
下载: