Palaeogeothermal response and record of the effusing of Emeishan basalts in the Sichuan basin

Abstract

Thermal history of the Sichuan basin is reconstructed based on vitrinite reflectance from boreholes in the basin using a paleo-heat flow method. The results show that the Sichuan basin experienced a relatively low heat flow period in the Early Paleozoic，and an elevated paleo-heat flow, ranging 60−80 mW/m 2 with a maximum as high as 100 mW/m 2 around 259 Ma, from the beginning of the Late Paleozoic to the end of the early Permian, and a decreased paleo-heat flow from the late Permian to the late Triassic, and then maintained nearly stable to the present. The Late Paleozoic paleo-heat flow was quite high where there were extensive Emeishan flood basalts or concealed basalts which erupted between the early and the late Permian, such as the southwestern and northeastern areas of the Sichuan basin. According to the distribution of paleo-heat flow, it can be inferred that, the northeastern Sichuan basin was also influenced by the Emeishan magmatic activity during the Dongwu movement though there was lack of Emeishan flood basalts. In addition, the results of thermal history reconstruction of the Sichuan basin provide paleogeothermal evidence for the existence and onset of the Emaishan mantle plume. vitrinite reflectance, paleo-heat flow method, thermal history, Emeishan mantle plume, Sichuan basin Citation: Zhu C Q, Xu M, Yuan Y S, et al. Palaeogeothermal response and record of the effusing of Emeishan basalts in the Sichuan basin. Chinese Sci Bull, 2010, 55: 949−956,

Oxygen and Carbon Isotopic Composition of Carbonate Rocks of the Permian Qixia Formation, Sichuan Basin: Thermal Effects of Emeishan Basalt

“…Zhu et al, (2010) has demonstrated that the paleo-heat flow in the west of the Sichuan Basin reached a maximum at the end of the middle Permian at about 259 Ma (Fig. 4a).…”

“…Due to the influence of the thermal events related to the eruption of the Emeishan basalt, the paleoheat flow in the western Sichuan Basin reached the highest level during the end of the middle Permian. The maximum paleo heat flows experienced by most wells were between 60 and 80 mW/m 2 , and a few wells have exhibited maximum paleo heat flows higher than 100 mW/m 2 (Zhu et al, 2010). During this period, the Qixia Formation was at the stage of shallow burial (depth=500~100m) (Fig.…”

Present-Day Heat Flow, Thermal History, and Tectonic Subsidenceof the Jianghan Basin

“…Secondly, other elements (climate change, underground water, topography, etc.) also significantly perturb subsurface temperatures (Wang et al, 1986;Kukkonen et al, 1998;Majorowicz et al, 1999;Zhu et al, 2009). In our study, some abrupt changes of temperature shown in Figure 3b may be related to groundwater, but they do not influence the regional thermal field of the basin.…”

The thermal history of the Sichuan Basin, SW China: Evidence from the deep boreholes

“…Most studies focused on the uplift history or the hydrocarbon generation history since the Late Mesozoic. During the Early Permian-Middle Triassic, the Sichuan Basin experienced regional lithospheric extension and Emeishan mantle plume development, both of which importantly influenced the thermal evolution (Zhu et al, 2010a;He et al, 2011). The thermal effects of lithospheric extension and the Emeishan mantle plume have been simulated based on different geodynamical models and discussed by He et al (2011He et al ( , 2014a, and the results show that the thermal evolution of the inner zone above the plume head was greatly influenced by plume activity, but the outer zone and its outside area where the Sichuan Basin is located were only slightly affected (He et al, 2011).…”