中文摘要：

四川西部丹巴地区最为引人注目的地质构造是穹状变质地体的发育。华北、扬子和羌塘三个板块之间的南北向和东西向双向收缩，引起区内发育了大小不等的十几个穹状变质地体，自北而南有马奈、春牛场、丹巴、公差、格宗等变质穹隆。多数穹隆的核部出露的是前寒武纪的片麻岩和混合岩，例如春牛场侵入体。其中的片麻岩原岩、黑云母和角闪石质片麻岩均属本区最老的岩石。它不整合于志留纪地层之下，年代学研究证明其年代属新元古代（大约865-785Ma）。混合岩从形态上说，多为条带状，偶见角砾状的角闪石质混合岩。但是也有不少穹隆，核部是花岗岩类。岩石化学研究证明，它们大多属于S型花岗岩，仅个别为Ⅰ型。穹状变质地体的外围变质带可分三类：（1）巴罗带型区域递增变质带，有的显示变质带的倒转；（2）巴肯型变质带；（3）低级区域变质带，多数是中压绿片岩相。巴罗带变质的泥质岩，多数变晶矿物如黑云母、十字石、石榴石均具早期低级变质矿物的定向包襄物，显示明显叠加变质的信息。变质泥质岩的∑REE=（195-274）×10^-6，（La／Yb）n=0．811～1．917。稀土配分曲线和微量元素蛛网图具Nb、P、Ti负异常，显示大陆地壳的特征，是陆缘碎屑物质区域变质产物。巴肯带出露于丹巴以北，主要变质泥质岩是夕线石片麻岩类，常见铁铝榴石而少见堇青石，说明原岩富铁贫镁，局部出现锌铁尖晶石。由北侧的巴肯带到巴罗型变质的公差穹隆到南部的格宗穹隆变质带是从高温到低温连续变化的。因之，我们倾向于认为松潘-甘孜造山带的东南缘是一个规模较大的、呈NE向分布的低一中压区域变质带，总体是一条热轴，垂直走向，向东南温度逐步降低。据前人同位素年龄资料：M1巴罗型区域变质发生于约210～205Ma，马奈花岗?

英文摘要：

The most prominent tectonic feature in the Danba region of western Sichuan province is the development of a domal metamorphic terrane. North-south and east-west two-sided contraction between the North China, Yangtze and Qiangtang blocks had led to the development of more than ten domal metamorphic terranes of various size. From north to south, these include the Manai, Chunniuchang, Danba, Gongchai and Gezong domes. Pre-Sinian gneissic rocks and migmatites are exposed in the core of these domes. For example, in the core of Chunniuchang dome are biotite-hornblende gneissic rocks considered to be the oldest rocks in this region. They are unconformably overlain by Silurian strata. Geochronological study indicates that the age of the gneiss is Neoproterozoic（ca. 865-785 Ma）. The migmatites are mostly stromatic, but occasionally agmatitic. There are many granite-cored domes, including those of Rongxuka, Changzheng, Jiajika and Waduo, scattered in areas north of Yajiang. Petrochemical and geochemical study of some of these granites demonstrate that they are S-type granites, but with a volcanic arc geotectonic setting. According to their associated metamorphic rocks the domal terranes can be subdivided into 3 types： （1） Barrovian prograde, but in some cases inverted; （2） Buchan type; （3） low-grade metamorphic rocks of greenschist facies. Most of the Barrovian metapelitic rocks contain index minerals such as biotite, staurolite, garnet, and kyanite occurring as porphyroblastic minerals with numerous mineral inclusions of earlier age. It is obvious that these index minerals are developed across earlier mineral assemblages. The REE distribution pattern, ∑REE = （195-274） ×10^-6 , （La/Yb） n = 0. 811-1. 917 with a negative Eu anomaly, and trace element spider diagrams for the metapelites with Nb, P and Ti negative anomalies show characteristics of the upper continental crust. The Buchan type metapelites are almandine garnet-bearing, but are rare in cordierite, thus indicating high-Fe and low-