The pre-Cenozoic formation in the Cenozoic depositon centres in eastern North China reached its maximum temperature at present, and the earlier paleo-temperature, therefore, has been overprinted, but the record of pal...The pre-Cenozoic formation in the Cenozoic depositon centres in eastern North China reached its maximum temperature at present, and the earlier paleo-temperature, therefore, has been overprinted, but the record of paleo-temperature by the vitrinite reflectance (Ro) has not been overprinted by the later thermal events in the pre-Cenozoic formation located in the uplift or in the Paleozoic-Mesozoic residual basins out of the Cenozoic depositon centres. The reconstruction of paleo-temperature gradient and paleo-heat flow, based on the vitrinite reflectance in the Paleozoic and the Mesozoic structural layers in boreholes, indicated that the eastern North China was characterized by much higher paleo-temperature gradient (40-55℃/km) and heat flow (>80 mW/m2) during the Middle-Late Mesozoic than those in the Early Mesozoic and at present. The higher paleo-heat flow during the Middle-Late Mesozoic implies that the thickness of the 'thermal' lithosphere at that time was just 50-55 km, it had been much thinned relative to the thickness (135-148 km) at the Early Mesozoic. The transition of near-surface thermal regime in eastern North China occurred around 110 Ma, and the corresponding deep tectonothermal processes should take place at ~160 Ma.展开更多
The Sichuan Basin is a superimposition basin composed of terrestrial and marine sediments that is well known for its abundant petroleum resources. Thermal history reconstruction using paleogeothermal indicators, inclu...The Sichuan Basin is a superimposition basin composed of terrestrial and marine sediments that is well known for its abundant petroleum resources. Thermal history reconstruction using paleogeothermal indicators, including vitrinite reflectahoe and thermochronological data, shows that different structural subsections of the Sichuan Basin have experienced various paleogeothermal episodes since the Paleozoic. The lower structural subsection comprising the Lower Paleozoic to Middle Permian （Pz-P2） successions experienced a high paleogeothermal gradient （23.0-42.6℃/km） at the end of the Middle Permian （P2）, whereas the upper structural subsection comprising Late Permian to Mesozoic strata underwent a relatively lower paleogeothermal gradient （13.2-26.9℃/km） at the beginning of the denudation （Late Cretaceous or Paleocene in the different regions）. During the denudation period, the Sichuan Basin experienced a successive cooling episode. The high paleogeothermal gradient resulted from an intensive thermal event correlated to the Emeishan mantle plume. The heat flow value reached 124.0 mW/m2 in the southwestern basin near the center of the Emeishan large igneous province. The low geothermal gradient episode with heat flow ranging from 31.2 to 70.0 mW/m2 may be related to the foreland basin evolution. The cooling event is a result of the continuous uplift and denudation of the basin.展开更多
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...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/m2 with a maximum as high as 100 mW/m2 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.展开更多
基金the Chinese Academy of Sciences(Grant No.KZCX1-07) the National Basic Research Programme(973)(Grant No.G1999075504) the National Natural Science Foundation of China(Grant No.40172100).
文摘The pre-Cenozoic formation in the Cenozoic depositon centres in eastern North China reached its maximum temperature at present, and the earlier paleo-temperature, therefore, has been overprinted, but the record of paleo-temperature by the vitrinite reflectance (Ro) has not been overprinted by the later thermal events in the pre-Cenozoic formation located in the uplift or in the Paleozoic-Mesozoic residual basins out of the Cenozoic depositon centres. The reconstruction of paleo-temperature gradient and paleo-heat flow, based on the vitrinite reflectance in the Paleozoic and the Mesozoic structural layers in boreholes, indicated that the eastern North China was characterized by much higher paleo-temperature gradient (40-55℃/km) and heat flow (>80 mW/m2) during the Middle-Late Mesozoic than those in the Early Mesozoic and at present. The higher paleo-heat flow during the Middle-Late Mesozoic implies that the thickness of the 'thermal' lithosphere at that time was just 50-55 km, it had been much thinned relative to the thickness (135-148 km) at the Early Mesozoic. The transition of near-surface thermal regime in eastern North China occurred around 110 Ma, and the corresponding deep tectonothermal processes should take place at ~160 Ma.
基金the National Natural Science Foundation of China(Grant No.41102152)the PetroChina Innovation Foundation(Grant No.2013D-5006-0102)+1 种基金the National Basic Research Program of China(Grant No.2012CB214703)the Science Foundation of China University of Petroleum,Beijing(Grant No.YJRC2013-002)
文摘The Sichuan Basin is a superimposition basin composed of terrestrial and marine sediments that is well known for its abundant petroleum resources. Thermal history reconstruction using paleogeothermal indicators, including vitrinite reflectahoe and thermochronological data, shows that different structural subsections of the Sichuan Basin have experienced various paleogeothermal episodes since the Paleozoic. The lower structural subsection comprising the Lower Paleozoic to Middle Permian （Pz-P2） successions experienced a high paleogeothermal gradient （23.0-42.6℃/km） at the end of the Middle Permian （P2）, whereas the upper structural subsection comprising Late Permian to Mesozoic strata underwent a relatively lower paleogeothermal gradient （13.2-26.9℃/km） at the beginning of the denudation （Late Cretaceous or Paleocene in the different regions）. During the denudation period, the Sichuan Basin experienced a successive cooling episode. The high paleogeothermal gradient resulted from an intensive thermal event correlated to the Emeishan mantle plume. The heat flow value reached 124.0 mW/m2 in the southwestern basin near the center of the Emeishan large igneous province. The low geothermal gradient episode with heat flow ranging from 31.2 to 70.0 mW/m2 may be related to the foreland basin evolution. The cooling event is a result of the continuous uplift and denudation of the basin.
基金supported by the National Natural Science Foundation of China (Grant No.40672197)
文摘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/m2 with a maximum as high as 100 mW/m2 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.
