The Talas Fergana/Karatau Fault,is a major tectonic boundary separating the Kazakh-Turan domain to the west from the Tian Shan domain to the east.During the Jurassic,movements along the fault led to the opening of sev...The Talas Fergana/Karatau Fault,is a major tectonic boundary separating the Kazakh-Turan domain to the west from the Tian Shan domain to the east.During the Jurassic,movements along the fault led to the opening of several basins.Still,the Mesozoic kinematics of the fault and the geodynamic mechanism that led to the opening of these basins are largely unconstrained.Located at its southwestern termination,the Yarkand-Fergana Basin is certainly the best exposed and however still poorly understood.In this study,we provide new sedimentological description of the Jurassic series from the northern part of the Yarkand-Fergana Basin as well as new palynological data.Following a Middle-Late Triassic period dominated by regional erosion,the onset of sedimentation in the Yarkand-Fergana Basin occurred during the Sinemurian(?)-Pliensbachian.The basin opened as a half graben controlled by the Talas Fergana/Karatau Fault and separated from the Fergana Basin by basement highs.Extension persisted during the late Pliensbachian-Middle Jurassic,leading to a general widening of the YarkandFergana Basin.Finally,Late Jurassic-Early Cretaceous renewed tectonic activity in the area led to the inversion of the north Yarkand-Fergana Basin.The Early to Middle Jurassic timing of development of the Yarkand-Fergana Basin suggests that the coeval movements along the Talas Fergana/Karatau Fault are not associated to the collision of the Qiangtang block along the southern margin of Eurasia.We favor the hypothesis of an opening controlled by transtension related to far field effects of back-arc extension along the Neo-Tethys subduction zone to the west.展开更多
The paper is dedicated to consider the approach of longitudinal electrical conductivity maps construction for Central Tien Shan region and to complete the comparison analysis of these maps with related seismic tomogra...The paper is dedicated to consider the approach of longitudinal electrical conductivity maps construction for Central Tien Shan region and to complete the comparison analysis of these maps with related seismic tomography data.The results of joint analysis of longitudinal electrical conductivity distribution and seismic tomography velocity models with respect to geological and geophysical senses allow to confirm the already known and to establish the new patterns of structure and geodynamics of the Tien Shan segment of Central Asia such as the manifestation of characteristic structural ensembles,reflection of the longitudinal and transverse segmentation of the Tien Shan,the existence within the framework of a“single”orogen of segments with different near-surface and deep structure and morphological expression.As well,the correlation between the velocity characteristics and geoelectric properties was found.This correlation allows to identify signs of reflection of fault structures in geophysical fields and to clarify the territorial and structural position of both visible and hidden faults.Additionally,in the paper,the geological interpretation of geophysical anomalies is considered.展开更多
文摘The Talas Fergana/Karatau Fault,is a major tectonic boundary separating the Kazakh-Turan domain to the west from the Tian Shan domain to the east.During the Jurassic,movements along the fault led to the opening of several basins.Still,the Mesozoic kinematics of the fault and the geodynamic mechanism that led to the opening of these basins are largely unconstrained.Located at its southwestern termination,the Yarkand-Fergana Basin is certainly the best exposed and however still poorly understood.In this study,we provide new sedimentological description of the Jurassic series from the northern part of the Yarkand-Fergana Basin as well as new palynological data.Following a Middle-Late Triassic period dominated by regional erosion,the onset of sedimentation in the Yarkand-Fergana Basin occurred during the Sinemurian(?)-Pliensbachian.The basin opened as a half graben controlled by the Talas Fergana/Karatau Fault and separated from the Fergana Basin by basement highs.Extension persisted during the late Pliensbachian-Middle Jurassic,leading to a general widening of the YarkandFergana Basin.Finally,Late Jurassic-Early Cretaceous renewed tectonic activity in the area led to the inversion of the north Yarkand-Fergana Basin.The Early to Middle Jurassic timing of development of the Yarkand-Fergana Basin suggests that the coeval movements along the Talas Fergana/Karatau Fault are not associated to the collision of the Qiangtang block along the southern margin of Eurasia.We favor the hypothesis of an opening controlled by transtension related to far field effects of back-arc extension along the Neo-Tethys subduction zone to the west.
文摘The paper is dedicated to consider the approach of longitudinal electrical conductivity maps construction for Central Tien Shan region and to complete the comparison analysis of these maps with related seismic tomography data.The results of joint analysis of longitudinal electrical conductivity distribution and seismic tomography velocity models with respect to geological and geophysical senses allow to confirm the already known and to establish the new patterns of structure and geodynamics of the Tien Shan segment of Central Asia such as the manifestation of characteristic structural ensembles,reflection of the longitudinal and transverse segmentation of the Tien Shan,the existence within the framework of a“single”orogen of segments with different near-surface and deep structure and morphological expression.As well,the correlation between the velocity characteristics and geoelectric properties was found.This correlation allows to identify signs of reflection of fault structures in geophysical fields and to clarify the territorial and structural position of both visible and hidden faults.Additionally,in the paper,the geological interpretation of geophysical anomalies is considered.
