摘要
本文根据野外工作和大量岩石学、岩石化学资料研究了桐柏地区的蛇绿岩块体。研究区内的蛇绿岩并非前人所描述的那样完整,真正属于蛇绿岩成员的仅是呈外来块体形式出现的超镁铁岩带,其中信阳卧虎的阿尔卑斯型超镁铁岩代表了蛇绿岩序列的变质的橄榄岩部分,桐柏大河一带的超镁铁杂岩代表了堆积岩层序。在同一地区出现的基性侵入岩和基性火山岩不是蛇绿岩的成分,应将它们剔出。基性火山岩是在弧后的边缘海盆地喷发的。蛇绿岩的侵位时代是早古生代末,大体与基性火山岩的喷发同时。上述事实表明,在早古生代沿松扒断裂带曾存在一个沟-弧-盆体系。
In Tongbai area, there is a large scale belt of ultramafic rocks, there are also amount of metamorphosed basic volcanic rocks. Many researchers have proposed the concept of the Tongbai ophiolite. After the working on petrology, petrochemistry and geology, author found that the socalled 'Tongbai ophiolite' is not as completely as others described. The new established ophiolite in Tongbai only includes metamorphosed peridotites which distribute in western Xinyang county and are mainly composed of harzburgite, and ultramafic cumulate complexes which appear in northern Tongbai's Dahe aera and are composed of many kinds of rocks, their major types are websterite clinopyxenite, harzburgite and dunite etc. The basic dike associated with ultramafic rocks and basic volcanic rocks which erupted in a backarc maginal sea basin are not the components of the ophiolite. At about the end of early Palaezoic are, the ophiolite took its present position as nappes. Such age is roughly as same as the erupting time of the basic volcanic rocks. The facts mentioned above indicate that there existed a trench-arc-back arc basin system along the Sunba fault in early Palaezoic era.
出处
《地质论评》
CAS
CSCD
北大核心
1990年第6期494-503,共10页
Geological Review
