The boundary between lithosphere and asthenosphere essentially represents a thermal boundary (the solidus). Temperature variation across this boundary can lead to the change of lithosphere thickness. In the case of el...The boundary between lithosphere and asthenosphere essentially represents a thermal boundary (the solidus). Temperature variation across this boundary can lead to the change of lithosphere thickness. In the case of elevated temperatures in a lithospheric layer above 1 200℃, partial melting will begin and the result of that is a thinned lithosphere. The other mechanism that can also thin lithosphere is extension. Stretching during an extension event can result in a thinner and longer lithosphere. The two mechanisms above are the reason why we can alserve large variations in lithosphere thickness spatially across various continents and temporally throughout the geological history.展开更多
A comprehensive study on geothermal history of the Turpan-HamiBasin by vitrinite reflectance, fluid inclusion geothermometry, apatite fission track and 40Ar-39Ar dating displays that the main effects influencing geote...A comprehensive study on geothermal history of the Turpan-HamiBasin by vitrinite reflectance, fluid inclusion geothermometry, apatite fission track and 40Ar-39Ar dating displays that the main effects influencing geotemperature distribution are burial depth of the basement, heat flow, magmatic activities, as well as tectonic movement, having a rugulation to be higher in the east and north, lower in the west and south, as well as higher in the past and lower at the present. The heat of the mantle source and the Indo-China tectonic thermal event have extremely influenced matura-tion of source rocks of the upper Lower Permian and the Middle and Upper Triassic in the lndo-China epoch. While, the geothermal gradient and the weak tectonic geothermal event of the Early Yanshan Movement provided necessary heat for the maturation of source rock in coal-bearing strata of the Middle and Lower Jurassic.展开更多
Crustal deformation shows different patterns at different depths due to changes in the physical properties of rock.Tectonic levels can be defined based on the geometry and deformation mechanisms of crustal deformation...Crustal deformation shows different patterns at different depths due to changes in the physical properties of rock.Tectonic levels can be defined based on the geometry and deformation mechanisms of crustal deformation patterns. Nujiang Gorge, with a high riverbed drop, great erosion depth, and strong deformation, has rock exposures at different tectonic levels and thus provides an ideal lab for deformation study. This paper takes the Nujiang Gorge from Chawalong to Fugong as the object to identify structural deformation patterns at different depths through field study and deformation analysis. At depth, the primary form of deformation is flow deformation, as shown on the outcrops at Maji. Ductile shear deformation can be found in many outcrops within the study region, e.g., the Gaoligong dextral shear zone and Puladi-Songta sinistral shear zone that lie to the south and north of Maji, respectively. Further to the north of Puladi, the dominated deformation pattern is similar fold and dense sub-vertical foliation. In addition, brittle faults, as evidence of shallow deformation, can be seen overprinting on the deeper deformation features all over the region. Based on those observations, this paper identifies four tectonic levels from depth to the surface: flow deformation, ductile shear deformation, similar fold, and brittle fault deformation, all of which result from the NEE-SWW compressive stress field. Further evidence from studies on the region′s thermal evolution and regional tectonics suggests that the development of different tectonic levels is closely linked to the discrepant uplift or denudation since the Miocene(~21 Ma).展开更多
文摘The boundary between lithosphere and asthenosphere essentially represents a thermal boundary (the solidus). Temperature variation across this boundary can lead to the change of lithosphere thickness. In the case of elevated temperatures in a lithospheric layer above 1 200℃, partial melting will begin and the result of that is a thinned lithosphere. The other mechanism that can also thin lithosphere is extension. Stretching during an extension event can result in a thinner and longer lithosphere. The two mechanisms above are the reason why we can alserve large variations in lithosphere thickness spatially across various continents and temporally throughout the geological history.
文摘A comprehensive study on geothermal history of the Turpan-HamiBasin by vitrinite reflectance, fluid inclusion geothermometry, apatite fission track and 40Ar-39Ar dating displays that the main effects influencing geotemperature distribution are burial depth of the basement, heat flow, magmatic activities, as well as tectonic movement, having a rugulation to be higher in the east and north, lower in the west and south, as well as higher in the past and lower at the present. The heat of the mantle source and the Indo-China tectonic thermal event have extremely influenced matura-tion of source rocks of the upper Lower Permian and the Middle and Upper Triassic in the lndo-China epoch. While, the geothermal gradient and the weak tectonic geothermal event of the Early Yanshan Movement provided necessary heat for the maturation of source rock in coal-bearing strata of the Middle and Lower Jurassic.
基金supported by the Project of the China Geological Survey (Grant No. 12120113013700)the Director Fund project of China Earthquake Disaster Prevention Center (Grant No. 201604)
文摘Crustal deformation shows different patterns at different depths due to changes in the physical properties of rock.Tectonic levels can be defined based on the geometry and deformation mechanisms of crustal deformation patterns. Nujiang Gorge, with a high riverbed drop, great erosion depth, and strong deformation, has rock exposures at different tectonic levels and thus provides an ideal lab for deformation study. This paper takes the Nujiang Gorge from Chawalong to Fugong as the object to identify structural deformation patterns at different depths through field study and deformation analysis. At depth, the primary form of deformation is flow deformation, as shown on the outcrops at Maji. Ductile shear deformation can be found in many outcrops within the study region, e.g., the Gaoligong dextral shear zone and Puladi-Songta sinistral shear zone that lie to the south and north of Maji, respectively. Further to the north of Puladi, the dominated deformation pattern is similar fold and dense sub-vertical foliation. In addition, brittle faults, as evidence of shallow deformation, can be seen overprinting on the deeper deformation features all over the region. Based on those observations, this paper identifies four tectonic levels from depth to the surface: flow deformation, ductile shear deformation, similar fold, and brittle fault deformation, all of which result from the NEE-SWW compressive stress field. Further evidence from studies on the region′s thermal evolution and regional tectonics suggests that the development of different tectonic levels is closely linked to the discrepant uplift or denudation since the Miocene(~21 Ma).
