大别-苏鲁造山带南缘前陆盆地演化特征

Tectonic evolution characteristics of the foreland basin on the southern margin of the Dabie-Sulu orogenic belt

受中三叠世以来中央造山带东段从陆缘碰撞造山—陆内造山的构造机制转换控制,大别-苏鲁造山带南缘前陆盆地具有从陆缘—陆内,从海相—陆相的连续过渡特征,经历了发生—兴盛—消亡的完整过程。依据造山带构造机制转换及前陆盆地构造层序所反映的盆地演化的阶段性,具体划分为4个阶段:即1)前造山期被动陆缘(P3—T1—T21)阶段,包括局部裂陷、持续沉降、萎缩残留3个亚阶段;2)陆缘主造山期周缘前陆盆地(T22—T3)阶段,具有海陆过渡相(T22)—陆相(T3)前陆盆地的连续演化特征;3)陆内造山期陆内前陆盆地(J1-2)阶段,发育陆内山前含煤碎屑岩沉积;4)后造山期转换伸展-伸展断陷盆地(J3—E)阶段,前陆盆地消亡。

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-eontinent 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 - T2^1 ）, consisting of three sub-stages（ partial faulted depression-continuous subsidence-fading residual basin）;2 ）peripheral foreland basin during the main orogenic period（T2^2 -T3 ）, a stage characterized by continuous tectonic evolution of marine-continental transitional （ T2^2 ） to continental （ T3 ） foreland basin ;3 ） intracontinental foreland basin during intra-continental orogeny （J1-2）, 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.