The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the midMesozoic,yet has experienced episodic phases of deformation since that time.In this paper,we document field evidence to c...The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the midMesozoic,yet has experienced episodic phases of deformation since that time.In this paper,we document field evidence to characterize and date the intra-plate tectonic history of the Gobi Altai region from the Triassic to the present.To this end,we provide detailed mapping of the structure and stratigraphy of the eastern flanks of Mt.Ih Bogd that contains the widest variety of rock-time units in the area.We carry out geochronological analysis of basaltic lavas and basement granite in the area.We demonstrate that a crystalline basement with a 502 ± 8 Ma granitoid（U/Pb） underwent two phases of basin formation in the Mesozoic.which we date with new40Ar/39Ar lava ages of 218.5 ± 1.5,123.2 ± 0.7 and 124.8 ± 1.2 Ma,respectively.Both phases are linked to deposition of fluvio-lacustrine sediments and trap-like basaltic volcanics,with cumulative thicknesses of 1000-1500 m.Both basins were likely north-facing half-grabens that developed underN-S extension,but were subsequently overthrusted by Paleozoic and older crystalline basement during a less well constrained,but likely mid-Cretaceous phase of N-S shortening and basin inversion.Our results are consistent with recent seismic imaging of rift basins100 km to the NE of the study area where a similar history was reconstructed.The multiple phases of intra-plate deformation appear to have parallel structural trends,most likely due to reactivated Paleozoic basement structures created during the original terrane amalgamation of the Central Asian Orogenic Belt continental crust.This strong basement heterogeneity may predispose it to reactivation,and make it sensitive to changes in the overall stress field of the Eurasian plate driven by forces at its margins and base.Detailed study of Mongolia’s multi-stage tectonic history may thus provide a key proxy for the long-term dynamics of the Eurasian plate.In addition,the repeated reactivation of the Gobi Altai region during the la展开更多
The Narmada Son Lineament(NSL)is a major palaeo-rift system and seismically active intra-plate region.In this paper,we processed and analyzed the GPS data from 2009 to 2016 to study the geodynamic characteristics of N...The Narmada Son Lineament(NSL)is a major palaeo-rift system and seismically active intra-plate region.In this paper,we processed and analyzed the GPS data from 2009 to 2016 to study the geodynamic characteristics of NSL.The velocities derived from GPS were used to calculate the associated deformation and crustal strain,while the slip deficit was estimated using the horizontal motion of GPS sites.The investigation reveals that the maximum deformation of western NSL is 1.6 mm per year,and the upper bound of the seismic moment(M;)is 2.0×10;dyn/cm,corresponding to an earthquake of about 6.0 magnitude.The study highlights the significance of Aravalli and Satpura mobile belts.The estimated strain of 0.03μstrain/yr is low but comparable to the stable continental region,and a close association of factors(the fragility,crustal conductors,and compressive tectonics)is considered responsible for seismogenic activities in western NSL.展开更多
基金UK NERC Grant NER/D/S/2003/00671 to WDCThe 2005 fieldwork of DJJvH was partly supported by an E.J.Garwood Grant of the Geological Society of London+1 种基金GBS was supported by the Molengraaff Foundation and the KF Hein FoundationDJJvH acknowledges funding through ERC Starting Grant 306810(SINK)and an NWO VIDI grant
文摘The Gobi Altai region of southern Mongolia has been in the Eurasian plate interior since the midMesozoic,yet has experienced episodic phases of deformation since that time.In this paper,we document field evidence to characterize and date the intra-plate tectonic history of the Gobi Altai region from the Triassic to the present.To this end,we provide detailed mapping of the structure and stratigraphy of the eastern flanks of Mt.Ih Bogd that contains the widest variety of rock-time units in the area.We carry out geochronological analysis of basaltic lavas and basement granite in the area.We demonstrate that a crystalline basement with a 502 ± 8 Ma granitoid（U/Pb） underwent two phases of basin formation in the Mesozoic.which we date with new40Ar/39Ar lava ages of 218.5 ± 1.5,123.2 ± 0.7 and 124.8 ± 1.2 Ma,respectively.Both phases are linked to deposition of fluvio-lacustrine sediments and trap-like basaltic volcanics,with cumulative thicknesses of 1000-1500 m.Both basins were likely north-facing half-grabens that developed underN-S extension,but were subsequently overthrusted by Paleozoic and older crystalline basement during a less well constrained,but likely mid-Cretaceous phase of N-S shortening and basin inversion.Our results are consistent with recent seismic imaging of rift basins100 km to the NE of the study area where a similar history was reconstructed.The multiple phases of intra-plate deformation appear to have parallel structural trends,most likely due to reactivated Paleozoic basement structures created during the original terrane amalgamation of the Central Asian Orogenic Belt continental crust.This strong basement heterogeneity may predispose it to reactivation,and make it sensitive to changes in the overall stress field of the Eurasian plate driven by forces at its margins and base.Detailed study of Mongolia’s multi-stage tectonic history may thus provide a key proxy for the long-term dynamics of the Eurasian plate.In addition,the repeated reactivation of the Gobi Altai region during the la
基金DG,ISR,DST(GoG),and MoES(GoI)for the required supportmonitoring program of ISC(www.isc.ac.uk)and[37,38,77,80]。
文摘The Narmada Son Lineament(NSL)is a major palaeo-rift system and seismically active intra-plate region.In this paper,we processed and analyzed the GPS data from 2009 to 2016 to study the geodynamic characteristics of NSL.The velocities derived from GPS were used to calculate the associated deformation and crustal strain,while the slip deficit was estimated using the horizontal motion of GPS sites.The investigation reveals that the maximum deformation of western NSL is 1.6 mm per year,and the upper bound of the seismic moment(M;)is 2.0×10;dyn/cm,corresponding to an earthquake of about 6.0 magnitude.The study highlights the significance of Aravalli and Satpura mobile belts.The estimated strain of 0.03μstrain/yr is low but comparable to the stable continental region,and a close association of factors(the fragility,crustal conductors,and compressive tectonics)is considered responsible for seismogenic activities in western NSL.
