【摘要】 巴罗型中压变质带与巴肯型低压高温变质带的成因与大陆板块边缘的碰撞造山及陆内造山作用之间有着紧密的联系。根据变质带的空间时间配置关系、压力类型、变质作用pTt轨迹、伴生的岩浆岩等等,可以区分出3种类型的大陆造山模式:弧-陆拼贴型、陆-陆碰撞型(可进一步分为中高压型碰撞造山带和双变质型山带型(paired metamorphic mountain belt)陆-陆碰撞带)、陆内造山地壳加厚-伸展型。巴罗型中压变质带普遍出现于地壳加厚-热弛豫的构造环境,但巴肯型低压变质带形成的构造背景及物理化学条件在不同的造山带有不同的表现形式,其热源至少有:壳内岩浆侵入或岩浆板底垫托、沉降盆地放射性同位素的衰变热、构造热穹隆、变质核杂岩、地下热流体传热等。大陆边缘造山带中巴罗型变质带的倒转以及板内造山带中变质带问断等现象与造山动力学过程密切相关,记录了造山过程中的重要的地质事件,也是探讨造山历史的理想场所。由于四川丹巴地区松潘—甘孜造山带形成于很独特的3个板块双极性构造环境,表现出与世界上典型造山带诸多相似的地方,如巴罗型中压变质带、巴肯型低压高温带同时在一系列变质穹隆中发育,但又有其特殊性和复杂性,如通常只发育在大陆边缘的倒转的巴罗带和陆内造山过程中的变质相间断同时出现,显然这与本?更多还原

【Abstract】 The origins of barrovian type and buchan type of metamorphism are commonly associated with orogenesis at continental collisional margins or within plates. On the basis of the temporal and spatial association relationship between barrovian type and buchan type of metamorphic zones, metamorphic pressure types, pressure-temperature-time paths and associated intrusives, three types of continental o-rogenic models can be determined, i. e. , juxtaposition of arc and continents, intraplate orogenic crustal thickening and thinning, and continent-continent collision of which two subtypes of orogenic models, the paired metamorphic mountain belt and the medium- to high-pressure collisional orogenesis, can be found. In general, barrovian metamorphism results from crustal thickening and the thermal relaxation after thickening. However, the tectonic settings and physicochemical conditions of buchan metamorphism are extremely different in various orogenic belts. The heat sources that formed the buchan metamorphism at least include the magma intrusion and underplating within or beneath the crust, high content of radiogenic elements in the burial sedimentary basins, tectonic uplift of the geothermal gradient, exhumation of metamorphic core complex, and thermal fluids in the mobile tectonic zones. The inverted isograds of barrovian metamorphic zones and the discontinuities in buchan metamorphic grade are directly related to the dynamic processes of the continental orogenesis. They recorded the important tectonic events of the continental orogenesis. The Songpan-Garze orogenic belt in the western Sichuan Province, China, was formed in very distinctive tectonic settings of three plates with two plate subduction polarities, so it is very similar to the typical continental orogenic belt around the world in many aspects, for example, both the barrovian and buchan metamorphic sequences coexist in a series of metamorphic domains. However, it is a paradox that in the Songpan-Garze orogenic belt the inverted barrovian metamorphic sequences that commonly resulted from collisional orogenesis at continental margins associates with the discontinuity of metamorphic sequences mostly from intraplate orogenesis. This is obviously attributed to the multiphase tectonic movements and deformation, thrusting and stacking of slabs, uplifting of hot domains, and the strike-slip tectonics during the Songpan-Garze orogenesis.更多还原