AN APPROACH TO OROGENESIS-COUPLED/DECOUPLED BASIN DEVELOPMENT AND ITS KINEMATICS

Orogenesis coupled/decoupled basin development was represented as a new thinking for study on oil and gas bearing basins.The soul of the new thinking was a tectonic outlook of mobilism on basin study,which called for two new emerging academic branches:orogen stratigraphy and orogen paleogeography.Two methods should be emphasized:the mechanical and historical synthetic analysis of geological structures and the analysis of basin geodynamics.Because of the complexity and multiplicity of relations between "basin" and "orogen",the prerequisite of basin orogen analysis was to give a time restriction,namely,a unified kinematic process and geodynamic mechanics between orogenesis and basin development would be discussed within a relatively short interval.The kinematics of "basin" "orogen" coupling could be explored from four aspects.1)Compression and tension should be interdependent spatially,and the attention be paid to some large or super large basins related to collision and post orogenic basins.2)There were two kinds of strike slip faults:one was a part of the global shearing net,whose importance in tectonics of China Continent was once neglected;another was what was in the same kinematic system with tensile or compressional faults.3)The contrains of deep sea ted courses resulted in tectonic overfly,the "basin"(or "orogen")of shallow structural layers being co e xisted with the "orogen"(or "basin")of deeper structural layers.4)Tectonic escape might be regarded as a combination of the transformation of strike slip faulting and the affection of deep seated courses,but the extension and strike slipping in escaping areas should have some distinct characters.The key to understanding the inheritance or decoupling of the Indosinian "basin" "orogen" relation was a tectonic differentiation between the west and east parts of the China SE Asia Subcontinent occurred from the Jurassic.The east part became a wide Yanshanides,where the Indosinian "basin" "orogen" relation was decoupled.A subduction type orogeny occurred in the west part in the Early Cretaceous,which did not decouple the Indosinian "basin" "orogen" relation.Sandwiched in between the both Yanshanides,there existed a relatively stable zone not involved in the Yanshanian orogeny,where the reformation of the Himalayan movement was the crux if basins were reserved and oil gas accumulation was formed.