东海陆架盆地中生界构造样式及其动力学成因探讨

构造样式为盆内各类构造组合的几何形态表达,反映了盆地所处应力场性质变化与构造演化过程。本文基于近5年来针对东海陆架盆地所取得的地震资料解释成果,并综合盆地构造演化特征及其地球动力学背景,对盆地内中生界构造样式进行了系统的分类与总结,详细划分为5类构造样式:伸展构造样式、挤压构造样式、走滑构造样式、反转构造样式和底辟构造样式,并进一步细化为12种构造组合。同时,对东海陆架盆地内西部坳陷、中部低隆起、东部坳陷3个构造单元内的中生界构造样式发育情况分别进行了总结,各类构造样式自西至东具有各异的展布特征。综合盆内中生界构造样式几何学特点与展布特征可见,由于伊佐奈歧板块的俯冲、碰撞作用,区内处于挤压构造环境,进而形成了挤压背斜、断背斜、正反转等构造组合;大洋板块的后退翻卷及板块碰撞、俯冲的远程效应下,区内构造环境以伸展作用为主,形成了一系列NNE向裂陷盆地,发育了丰富的伸展构造组合;走滑-拉分构造的发育较好体现了构造环境的转变,地震剖面上见有花状断裂发育;岩浆底辟构造多发育于拉张环境下,与断裂展布息息相关,多沿NE-NNE向断裂展布。此外,新生代多期构造运动是影响中生界构造样式发育展布的重要因素。

Mesozoic tectonic styles and their dynamic mechanisms in the East China Sea Shelf Basin

Tectonic style is the geometry expression of tectonic association, reflecting stress field transformation and tectonic evolution of a single basin. Based on seismic interpretation results acquired over the last 5 years, this paper provides a summary of the development of Mesozoic tectonic styles, which include the following: extensional structures, compressional structures, strike-slip structures, inversion structures and diapir structures, and further divides the tectonic styles into 12 tectonic assemblages in the East China Sea Shelf Basin. The Mesozoic tectonic styles are diversely distributed in the West Depression Belt, the Central Uplifts Belt and the East Depression Belt from west to east. Synthesizing the geometry and distribution characteristics of Mesozoic tectonic styles, it is concluded that squeezed anticlines, faulted anticlines and positive inversions are deformed in compressional tectonic settings, due to the subduction and collision of the Izanagi Plate. Abundant extensional structures, which are distributed in NNE trending, are deformed in extensional tectonic settings, due to the rollback of ocean plate and remote effect of collision and subduction among plates. The strike -slip structures are the representative of transform between different tectonic settings, and the flower-like faults are seen in seismic profiles. The diapir structures are deformed in extensional tectonic settings and distributed along the NE~NNE trending faults, which are closely associated with faults distribution. Furthermore, the Cenozoic multi -stage tectonic evolution has an important influence on the development of Mesozoic tectonic styles.