江南造山带东段新元古代至早中生代多期造山作用特征  

Characteristics of Neoproterozoic—Early Mesozoic multiphase orogenic activities of eastern Jiangnan Orogen

作　　者：徐先兵[1] 汤帅[1] 李源[2] 章泽军[1] 

机构地区：[1]中国地质大学(武汉)地球科学学院,湖北武汉430074 [2]中国地质大学(武汉)地质调查研究院,湖北武汉430074

出　　处：《中国地质》2015年第1期33-50,共18页Geology in China

基　　金：国家自然科学基金青年基金(41402174);中国地质调查局地质大调查项目(1212011120837)联合资助

摘　　要：新元古代江南造山带远离晚中生代活动大陆边缘,是研究华南地区新元古代至早中生代多期造山作用的理想对象。文章通过对江南造山带东段沉积建造、岩浆活动、构造变形以及同位素年代学数据的综合分析,总结了其晋宁期、广西期以及印支期造山作用的特征。江南造山带东段在晋宁期经历了南北两侧大洋俯冲和两期碰撞造山作用。新元古代早期（880-860 Ma）双溪坞岛弧与扬子陆块东南缘发生弧-陆碰撞作用,形成淡色花岗岩、高压蓝片岩、NNE向褶皱-逆冲构造以及弧后前陆盆地。新元古代中期（约850 Ma）,扬子陆块北缘开始发育由北向南的大洋俯冲。随着俯冲作用的进行,弧后盆地发生关闭,扬子陆块与华夏陆块发生陆-陆碰撞并形成新元古代（820-810Ma）江南造山带,导致近E-W走向褶皱-逆冲构造、韧性变形以及过铝质花岗岩的发育。江南造山带东段在约810Ma开始发生后造山垮塌和裂谷作用,以发育南华纪早期（805-750 Ma）花岗岩、中酸性火山岩、基性岩以及裂谷盆地为特征。江南造山带东段万载—南昌—景德镇—歙县断裂带以南地区卷入了华南广西期造山作用,发育近E-W走向由南向北的逆冲构造（465-450 Ma）、NNE向正花状构造（449-430 Ma）以及后造山近E-W走向韧性走滑剪切带（429-380 Ma）。印支期造山作用导致了NNE向褶皱-逆冲构造和花岗岩的发育,并奠定了江南造山带东段的基本构造面貌。The Jiangnan Orogen is a suitable region for deciphering Neoproterozoic to Early Mesozoic multiphase orogenicactivities of the South China Block because it is far away from the Late Mesozoic active continental margin. Based on a comprehensive analysis of such factors as deposition, magmatism, structural deformation and geochronology, the authors summarized the features of Neoproterozoic, Early Paleozoic and Early Mesozoic orogenies in the eastern Jiangnan Orogen. The eastern Jiangnan Orogen underwent southern and northern subductions as well as two stages of collisions in Neoproterozoic. In 880- 860 Ma of the early Neoproterozoic period, arc-continent collision between the Shuangxiwu island arc and the southeastern margin of Yangtze Block induced the formation of 880-860 Ma light granites, high-pressure blueschist, NNE-striking fold-and-thrust structures and retro-arc foreland basins. Southward subduction along the northern margin of Yangtze Block commenced at about 850 Ma. This subduction resulted in the clasure of back-arc basin and final collision between the Yangtze and Cathaysia blocks, and triggered nearly EW-striking fold-and-thrust structures, ductile deformation and peraluminous granodiorites in the eastern Jiangnan Orogen. The eastern Jiangnan Orogen started to collapse and rift at about 810 Ma, and produced 805-750 Ma granites, felsic volcanic rocks, mafic dikes and rift basins. Early Paleozoic orogeny occurred in the southern area of the Wanzai-Nanchang- Jingdezhen-Shexian fault zone within the Jiangnan Orogen. This orogeny led to the formation of nearly EW-striking top-to-the north thrusting, NNE-striking positive flower structures and post-orogenic nearly EW-striking dextral shear zones. The Early Mesozoic orogeny brought about NNE- striking fold and thrust structures and granites, which established the basic features of the present eastern Jiangnan Orogen.

关 键 词：造山作用 沉积建造 岩浆作用 构造变形 年代学 江南造山带东段 

分 类 号：P542.2[天文地球—构造地质学]