Abstract:

Controlled by the conversion of tectonic mechanism from continental margin collision orogenesis to intra-continental orogenesis in the eastern segment of the central orogenic belt since the Middle Triassic,the foreland basin on the southern margin of the Dabie-Sulu orogenic belt experienced a whole process of evolution from initiation to flourish and finally to extinction and is featured in continuous transition from continental margin to intra-continent and from marine to continental in terms of tectonic setting.According to the tectonic mechanism conversions and tectonic evolution stages reflected by the structural sequences of the foreland basin,the evolution of the foreland basin can be divided into four stages:1)pre-orogenic passive margin(P₃—T₁—T₂¹),consisting of three sub-stages(partial faulted depression-continuous subsidence-fading residual basin);2)peripheral foreland basin during the main orogenic period(T₂²—T₃),a stage characterized by continuous tectonic evolution of marine-continental transitional(T₂²)to continental(T₃)foreland basin;3)intracontinental foreland basin during intra-continental orogeny(J_1-2),featured in coal-bearing clastic rock deposited in intracontinental foreland area;4)post-orogenic extensional-extensional faulted depression basin(J₃-E),a period when the foreland basin dies out.

Key words: conversion of tectonic machanism, continental margin orogenesis, intracontinental orogenesis, peripheral foreland basin, intracontinental foreland basin, southern margin of the Dabie-Sulu orogenic belt