【作者】 董铁柱；

【导师】 颜丹平；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2005， 硕士

【摘要】 松潘-甘孜造山带夹于塔里木-柴达木地块、羌塘和扬子地块之间,呈一个“倒三角形”,其主体范围:西以义敦岛弧带与羌塘地块相隔,北界为阿尼玛卿混杂岩带,东界及南界为龙门山-盐源前陆逆冲带。许志琴称其为中国“地质百慕大”。该地区三叠系分布极广,出露面积超过10 万km2,绝大多数区域以发育极低级变质作用和较强的变形为特征。　极低级变质作用介于沉积成岩作用与变质作用之间,缺乏新形成的变质平衡矿物组合,很难找到确定变质作用的矿物温压计的物理条件,构筑精细的P-T-t轨迹图解非常困难。因此,极低级变质作用研究成为地质作用研究的难点。自20世纪60 年代起,国际上先后有Weaver、Kubler　、Martin　Frey 和　Doug　Robison对极低级变质作用提出划分方案。在国内,毕先梅、索书田等人,通过测定板岩中伊利石、云母、绿泥石等矿物及多形矿物的结晶度和其它成熟度参数,可大致判断极低级变质作用的温度、压力区间,厘定极低级变质作用的上、下限。　为了对松潘-甘孜地区三叠系强变形浅变质的特征及变质与变形的对应关系作出解释,揭示变质与变形的温-压条件,本论文总结前人研究成果,通过野外地质调查和实测剖面研究,结合室内薄片鉴定、电子探针和流体包裹体测试分析,对松潘-甘孜地区三叠系主体岩性(板岩、砂板岩、变质砂岩及千枚岩)的变质作用得出5 个认识结论:1、整个松潘-甘孜地区经受了自北向南的强大挤压;2、变质矿物组合简单,除雏晶黑云母外,典型的变质矿物组合为Al+Chl+Ser(Mu)+Cc+Q等,变质矿物主要沿区域性劈理面(S1)的劈理域发育,具有区域动力变质作用特征,属于低级变质作用中的硬柱石-钠长石-绿泥石相;3、区域变质作用P-T 变化集中在T:180～200oC,P:1～2kbar(<0.2Gpa)。4、变质作用形成的时代为175～159Ma;5、在大地构造事件上,属于印支期碰撞造山后,加厚地壳重力调整及伸展作用的结果。更多还原

【Abstract】 Songpan-Garze Orogenic zone lies between Tarim -Qaidam block,Qiangtang block and Yangtze block. It appears an ‘inversed triangle’. The main body of this zone: the west is Yidun island belt and separated from Qiangtang block;the north is Animaqing mélange belt;the east and south is Longmenshan-Yanyuan foreland thrust belt. Xu Zhiqin considered it ‘Geology Bermuda’. In this region Triassic stratum distributes very widely, and its area exceeds 100 thousand km2. The most zone develops very-low-grade metamorphism and obvious transformation. The very-low-grade metamorphism intervenes between sedimentary and metamorphism,and it is short of new metamorphosed balanced mineral combination. It is difficult to find mineral index of temperature and stress in this process. To construct elaborate P-T-t diagram. Therefore it becomes a nodus in geological process study. Since 1960s, Weaver, Kubler, Martin Frey,and Doug Robison have put forward compartmentalization projection in the international. In country, Bi xianmei, Suo shutian, etc. can only estimate the temperature and stress interval of this metamorphism and centigram the upper and lower limit by mensurating the crystallinity and other maturity degree parameters of illite, mica, and chlorite, etc. in slate. For giving an explaintion of strong transmogrification but feebleness metamorphism of and their corresponding relation of the Triassic stratum in Songpan-Ganzi area and opening out the temperature and stress condition, this paper summarized study production of predecessors, and put forward 5 conclusions about Songpan-Ganzi area Triassic main lithology(slate, sandrock,and blastopsammitic) through field geological investigation , actual measurement section plane study and combining indoor slice identification , electron probing and fluid enclosure testing analysis:1.Field outcrop strongly transmogrification, and often developed same cleavages(S1) erection or approximately erection ‘B’fold and symmetry similituded fold. 2.The metamorphosed mineral combination is simple, and the typical metamorphosed mineral combination is Al+Chl+Ser(Mu)+Cc+Q, etc. The metamorphosed mineral develops mainly along the cleavages of the territorial cleavages faces(S1), bearing territorial dynamic metamorphism character and belonging to the lawsonite-albite-chlorite face of slightly metamorphism. 3.Territorial metamorphism P-T change focus on T:180～200oC, P:1～2kbar(<0.2Gpa).4.The age of the metamorphism is 175～159Ma; 5.It is the result of lithosphere gravity adjust and stretch function after Indo-chinese epoch impinging orogen in geotectonic events.更多还原