| 下扬子区加里东期构造古地理问题 |
| |
| 引用本文： | 吴浩若.下扬子区加里东期构造古地理问题[J].古地理学报,2005,7(2):243-248. |
| |
| 作者姓名： | 吴浩若 |
| |
| 作者单位： | 中国科学院地质与地球物理研究所,北京,100029 |
| |
| 摘 要： | 一般将江绍断裂作为扬子地块和华夏地块在下扬子区的分界,但江绍断裂是晋宁期缝合带,二者在加里东期的关系需要解决。赣东北和皖南元古界变质岩构成复背斜核部,两翼的寒武-奥陶系由里向外由盆地-斜坡相转为台地相,相界线标志出扬子台缘位置在皖南石台-泾县一线,华夏台缘位置在浙西江山-开化-临安一线,中央的变质岩区应为当时江南海盆的一部分。奥陶纪末沉积格局有重大变化,显示这里的江南海盆转化为陆屑来源的楔形”江南隆起”。复背斜两翼寒武-奥陶系的构造变形则由外向里增强,直至同斜倒转的褶皱形态,表明江南隆起属加里东褶皱带。隆起两侧及东北方有很厚的志留系碎屑岩,沉积序列自下而上由浅海相转为滨海相和三角洲相以至陆相沉积。空间上往东北方江苏境内海相沉积更为发育,志留纪晚期仍有海相记录,与泥盆系之间为平行不整合接触,到印支期才发生构造变形。在下扬子区,扬子和华夏地块之间,加里东褶皱带和印支褶皱带并存。
|
| 关 键 词： | 下扬子区 早古生代 构造古地理 加里东褶皱带 |
| 文章编号： | 1671-1505(2005)02-0243-06 |
| 修稿时间： | 2004年10月20 |
Discussion on tectonopalaeogeography of Lower Yangtze Area during the Caledonian Period |
| |
| Wu Haoruo.Discussion on tectonopalaeogeography of Lower Yangtze Area during the Caledonian Period[J].Journal of Palaeogeography,2005,7(2):243-248. |
| |
| Authors: | Wu Haoruo |
| |
| Institution: | Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 |
| |
| Abstract: | The Jiangshan-Shaoxing Fault is generally regarded as the boundary bet ween the Yangtze Block and Cathaysian Block in the Lower Yangtze Area.However, it was a suture formed in the Proterozoic.The relationship between the Yangtze and Cathaysian Blocks during the Caledonian Period is still a problem.The Proteroz o ic metamorphic rocks form the core part of an anticlinorium in northeastern Jian gxi and southern Anhui.The Cambrian and Ordovician sediments on its two limbs v ary from basin-slope facies to platform facies from insides toward outsides.Th e facies boundaries mark the Yangtze Platform margin along a line from Shitai to Jingxian in southern Anhui,and the Cathaysian Platform margin along a line from Jiangshan through Kaihua to Lin'an in western Zhejiang during the Cambri an and Ordo vician.The intermediate area occupied by metamorphic rocks was a part of the " J iangnan Basin" at that time.An important change on the sedimentary pattern hap p ened at the end of Ordovician.This area transferred into a tapered "Jiangnan U plift":a terrigenous material source area.The deformation of the Cambrian and Ordovician sedimentary rocks in two limbs of the anticlinorium becomes stronger from outsides toward insides where the isoclinal and overturned folds appear.T his indicates that the Jiangnan Uplift belongs to a Caledonian fold belt.The Si lurian terrigenous sediments with large thickness occur on both sides of the Jia ngnan Uplift and its northeast.The sedimentary sequences vary from shallow mari ne sediments upwards into littoral or deltaic sediments and finally into non-ma r ine sediments.The marine sediments become increasingly abundant towards northea st and developed in later Silurian in Jiangsu Province.Here the Silurian rocks are overlain disconformably by the Devonian.They were probably deformed until the Indosinian period.The Caledonian foldbelt and Indosinian foldbelt coe xist between the Yangtze and Cathaysian Blocks in Lower Yangtze Area. |
| |
| Keywords: | Lower Yangtze Area Early Paleozoic tectonopal aeogeography Caledonian foldbelt |
| 本文献已被 CNKI 维普 万方数据 等数据库收录！ |
| 点击此处可从《古地理学报》浏览原始摘要信息 |
| 点击此处可从《古地理学报》下载免费的PDF全文 |
|
