内蒙古中部中元古代韧性剪切变形及其形成的构造背景

现代地质 ›› 2004, Vol. 18 ›› Issue (4): 497-504.

内蒙古中部中元古代韧性剪切变形及其形成的构造背景

陈志勇^1,2，张宏²，许立权^1,2，张志祥²

1. 中国地质大学地球科学与资源学院，北京 100083 ；
2. 内蒙古自治区地质调查院，内蒙古呼和浩特 010020

收稿日期:2004-01-20 修回日期:2004-09-07 出版日期:2004-04-20 发布日期:2004-04-20
作者简介:陈志勇，男，正高级工程师，博士研究生，1962年出生，构造地质学专业，从事区域地质的调查与研究工作。
基金资助:
国家自然科学基金重点项目（40234051 ）。

HE DUCTILE SHEAR DEFORMATION AND ITS TECTONIC BACKGROUND IN MIDDLE-PROTEROZOIC, CENTRAL INNER MONGOLIA

CHEN Zhi-yong^1,2, ZHANG Hong², XU Li-quan², ZHANG Zhi-xiang²

1. China University of Geosciences, Beijing 100083, China
2. Geological Survey Institute of Inner Mongolia, Huhhot, Inner Mongoliannn 010020, China

Received:2004-01-20 Revised:2004-09-07 Online:2004-04-20 Published:2004-04-20

摘要/Abstract

摘要：

内蒙古中部新太古界色尔腾山岩群、新太古代和古元古代片麻状英云闪长岩（基底岩系）与白云鄂博群长城系都拉哈拉组、尖山组和渣尔泰山群长城系书记沟组、增隆昌组（盖层）之间的韧性剪切变形特征相同。糜棱面理走向近东西，总体倾向北，倾角变化较大。不同区域的糜棱面理上发育程度不同的矿物拉伸线理，其指示的运动学方向为上盘岩系向北（北西或北东）的斜落。接触带基底岩系由糜棱片岩、糜棱岩等组成；接触带盖层下部岩系由糜棱岩化石英岩、糜棱岩化灰岩、板岩等组成，盖层上部岩系书记沟组、都拉哈拉组石英岩发育掩卧褶皱，尖山组、增隆昌组板岩和灰岩发育石香肠构造和褶叠层构造。变质相由基底岩系的低角闪岩相—高绿片岩相逐渐过渡为上覆盖层的低绿片岩相。沉积特征、变质变形特征、运动学特征等均显示白云鄂博群、渣尔泰山群长城系为同一被动陆缘沉积，韧性剪切变形是同一期构造作用的产物。形成机制为长城系相对于基底岩系的大规模向北（北西或北东）伸展拆离，形成于低温、低压环境，起始时间为长城纪末期（1400Ma）。内蒙古中部中元古代韧性剪切、隆升、裂谷作用是同一伸展构造作用不同阶段的产物。

关键词: 基底岩系, 长城系, 韧性剪切变形, 拆离, 中元古代, 内蒙古中部

Abstract:

The characteristics of the ductile shear deformation developed between the Neoarchaeozoic Se’erdengshan Group, and Neoarchaeozoic to Paleoprozoic gneissic tonalite (the basement)，and the Dulahala and Jianshan formation of the Baiyun’ebo Group, and the Shujigou and Zenglongchang formations of the Zha’ertaishan Group, Changcheng System ( the cover) are identical. The mylonitic foliations of the ductile deformation in this region strike nearly east-west, and dip to the north with the angle from 35°to 50°. The kinematic direction inferred from mineral stretching lineations shows that the cover slides to the north(northwest or northeast). The rock system of the basement at contact zone consists of mylonitic schist and mylonite; the lower part of the cover consists of mylonitic quartzite, mylonitic limestone, slate. Recumbent folds are developed in the quartzite of the Shuijigou and Dulahala formation, whereas boudinage and folding layer are developed in the slate and limestone from low amphibolite--high green-schist facies of the basement to low green-schist of the cover. It is shown by the characteristics of sedimentary, metamorphism and deformation that the Changcheng System of the Baiyun’ebo and Zha’ertaishan Group are the sediments of stable passive continental margin, and the ductile shear deformation developed in the Baiyun’ebo, Zha’ertaishan Group is a production of the same structural process in the same stage. The tectonic background of the ductile shear deformation is the extensional detachment of the Changcheng System. The deformation environment belongs to a lower temperature-pressure one, and the age when the ductile shear deformation began is in the end of the Changcheng period (1,400Ma). The ductile-shearing, upwarping and rifting in the Middle-Proterozoic in the middle part of Inner Mongolia were producted at different stages in one extensional tectonic event.

Key words: basement system, Changcheng System, ductile shear deformation, detachament, Middle-Proterozoic, central Inner Mongolia

中图分类号:

P54
P534.3

陈志勇. 张宏. 许立权. 张志祥.. 内蒙古中部中元古代韧性剪切变形及其形成的构造背景[J]. 现代地质, 2004, 18(4): 497-504.

CHEN Zhi-yong, ZHANG Hong, XU Li-quan, ZHANG Zhi-xiang. HE DUCTILE SHEAR DEFORMATION AND ITS TECTONIC BACKGROUND IN MIDDLE-PROTEROZOIC, CENTRAL INNER MONGOLIA[J]. Geoscience, 2004, 18(4): 497-504.

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