略论地台区的海进、海退与相邻地槽区的造盆、造山运动伴生的原因

地台区的海进、海退 ,分别与相邻地槽区的造盆和造山运动伴生这一普遍现象 ,主要是在重力均衡作用下 ,上地幔流变层 (软流层 ,异常地幔 )物质侧向迁移所致。地槽区造盆运动 ,造成该区地壳减薄 ,从而在重力均衡作用下 ,相邻地台区的上地幔流变层物质便向该区顺层流入 ,促使其上地幔隆起。地台区上地幔流变层物质大量他流 ,势必引起地壳沉降 ,产生海进。华北地台中石炭世早二叠世早期整体沉降 ,形成了中国重要的石炭二叠纪聚煤区 ,便与其南北两侧秦岭和中亚蒙古地槽区在该时期的造盆运动有关。地槽区的造山运动 ,造成该区地壳加厚 ,从而在重力均衡作用下 ,该区隆起的上地幔流变层物质 ,又流回相邻地台区 ,促使地台区地壳抬升 ,产生海退。华北地台区晚奥陶世早石炭世的抬升剥蚀和从早二叠世晚期起转入陆相沉积发展阶段 ,便分别与南北两侧的秦岭和中亚蒙古地槽区于加里东早期和华力西晚期的造山运动相联系。

REASONS WHY BASIN AND RANGE MOVEMENTS IN GEOSYNCLINAL AREAS WOULD ACCOMPANYMARINE PROGRESSION AND REGRESSION ACTIVITIES IN PLATFORM AREAS

Marine progression and regression activities in platform areas are frequently triggered by the adjacent geosynclinal areas where basin and range movements take place. The crusts of geosynclinal areas would become thinning with basin making events, so that the rheological materials of the upper mantle in the platform areas would lit par lit inject to cause mantle domings under gravitational equilibrium law. Once the mantles dome and then the materials flow outwards from the platforms, the crusts certainly go down to lead to marine progression. Universal downgoing of North China platform in the middle Carboniferous early Permian period to form the most significant coal gathering region of China, for example, was probably attributed to the basin making events of the Qinling and Central Asian Mongolian geosynclines, respectively to the south and north. In the case of range making in geosynclinal areas, the rheological materials of the upper mantle would flow back to the platform areas, bringing about their crusts to go up and marine regression. It is true with the foregoing geosynclinal areas whose range making in the early Caledonian late Variscan period resulted in North China platform's upgoing in the late Ordovician early Carboniferous period and transforming to continental sedimentation in the early Permian period.