Based on the main driving force of plate motion(the slab pull force generated by the descent of the oceanic plate in subduction zones) and the three primary mechanisms for magma generation(adding fluid, increasing tem...Based on the main driving force of plate motion(the slab pull force generated by the descent of the oceanic plate in subduction zones) and the three primary mechanisms for magma generation(adding fluid, increasing temperature, and decreasing pressure), the continent-continent collisional process has been divided into three stages, including initial collision, ongoing collision, and tectonic transition. These stages are characterized by normal calc-alkaline andesitic magma(dehydration of the oceanic crust to release fluids), the migration of calc-alkaline magma toward the trench(dehydration of the oceanic crust or an increase in temperature) or small-scale crust-derived peraluminous magma(heat from intra-crustal shearing), and extensive magmatism with compositional diversity induced by slab break-off(increasing temperature and decreasing pressure), respectively.On the basis of the obtained age of slab break-off, the timing of the initial continent-continent collision can be quantitatively back-dated using the convergence rate, depth of slab break-off, and subduction angle. The spatio-temporal migration of the magmatic activity of the Gangdese Batholith, the onset of magmatic flare-up, and the increase of magma temperature at 52–51Ma documented by the volcanic rocks of the Linzizong Pana Formation were most likely the result of the break-off of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere at approximately 53 Ma. This proposed age of slab break-off suggests that the initial India-Asia collision likely occurred at approximately 55–54 Ma, which is consistent with the collision ages constrained by other abundant geological data(60–55 Ma). This magmatic method has been applied to the Bitlis orogenic belt in southern Turkey in the Arabia-Eurasia continental collision zone, yielding an age range of approximately 29–22 Ma for the initial Arabia-Asia continental collision that is close to the collision ages recently obtained by apatite fission-track dating(approximately20 Ma) and regional tectonic shortening(a展开更多
A zonal teleconnection has been found along the Asian jet over the Eurasian continent during summer. In this study, the authors investigated circulation anomalies in the extratropics, in particular for the zonal telec...A zonal teleconnection has been found along the Asian jet over the Eurasian continent during summer. In this study, the authors investigated circulation anomalies in the extratropics, in particular for the zonal teleconnection, under different combinations of subtropical convection anomalies over the northern Indian continent （IND） and the westem North Pacific （WNP）. The outof-phase configuration （i.e., stronger （weaker） IND convection and weaker （stronger） WNP convection） was found to be more common than the in-phase configuration （i.e., stronger （weaker） IND convection and stronger （weaker） WNP convection）, which is consistent with previous results. Composite results indicated that circulation anomalies for out-of-phase configurations of 30-60-day convection oscillations are much stronger in the middle latitudes than those for in-phase configurations. In addition, zonal teleconnection patterns are predominant for the out-of-phase configurations, particularly for the configuration of strong IND convection and weak WNP convec- tion; however, they are either weak or obscure for the in-phase configurations. These results suggest that the zonal teleconnection pattem along the Asian jet is dependent on different combinations of the 1ND and WNP subtropical convection anomalies.展开更多
基金supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB03010301)the National Key Research and Development Project of China (Grant No. 2016YFC0600304)the National Natural Science Foundation of China (Grant No. 41225006)
文摘Based on the main driving force of plate motion(the slab pull force generated by the descent of the oceanic plate in subduction zones) and the three primary mechanisms for magma generation(adding fluid, increasing temperature, and decreasing pressure), the continent-continent collisional process has been divided into three stages, including initial collision, ongoing collision, and tectonic transition. These stages are characterized by normal calc-alkaline andesitic magma(dehydration of the oceanic crust to release fluids), the migration of calc-alkaline magma toward the trench(dehydration of the oceanic crust or an increase in temperature) or small-scale crust-derived peraluminous magma(heat from intra-crustal shearing), and extensive magmatism with compositional diversity induced by slab break-off(increasing temperature and decreasing pressure), respectively.On the basis of the obtained age of slab break-off, the timing of the initial continent-continent collision can be quantitatively back-dated using the convergence rate, depth of slab break-off, and subduction angle. The spatio-temporal migration of the magmatic activity of the Gangdese Batholith, the onset of magmatic flare-up, and the increase of magma temperature at 52–51Ma documented by the volcanic rocks of the Linzizong Pana Formation were most likely the result of the break-off of the Yarlung-Zangbo Neo-Tethyan oceanic lithosphere at approximately 53 Ma. This proposed age of slab break-off suggests that the initial India-Asia collision likely occurred at approximately 55–54 Ma, which is consistent with the collision ages constrained by other abundant geological data(60–55 Ma). This magmatic method has been applied to the Bitlis orogenic belt in southern Turkey in the Arabia-Eurasia continental collision zone, yielding an age range of approximately 29–22 Ma for the initial Arabia-Asia continental collision that is close to the collision ages recently obtained by apatite fission-track dating(approximately20 Ma) and regional tectonic shortening(a
基金supported by the Chinese Academy of Sciences (Grant No. KZCX2-YW-220)the National Basic Research Program of China (Grant No. 2006CB403601)the National Natural Science Foundation of China (Grant No. 40725016)
文摘A zonal teleconnection has been found along the Asian jet over the Eurasian continent during summer. In this study, the authors investigated circulation anomalies in the extratropics, in particular for the zonal teleconnection, under different combinations of subtropical convection anomalies over the northern Indian continent （IND） and the westem North Pacific （WNP）. The outof-phase configuration （i.e., stronger （weaker） IND convection and weaker （stronger） WNP convection） was found to be more common than the in-phase configuration （i.e., stronger （weaker） IND convection and stronger （weaker） WNP convection）, which is consistent with previous results. Composite results indicated that circulation anomalies for out-of-phase configurations of 30-60-day convection oscillations are much stronger in the middle latitudes than those for in-phase configurations. In addition, zonal teleconnection patterns are predominant for the out-of-phase configurations, particularly for the configuration of strong IND convection and weak WNP convec- tion; however, they are either weak or obscure for the in-phase configurations. These results suggest that the zonal teleconnection pattem along the Asian jet is dependent on different combinations of the 1ND and WNP subtropical convection anomalies.
