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大别造山带从南到北可分为 5个变质构造单元 :扬子北缘蓝片岩带、宿松变质杂岩带、南大别碰撞杂岩带、北大别变质杂岩带和北淮阳变质带。各个变质构造单元中不同岩石的变质作用可划分为 3种类型 :( 1 )超高压型。以含柯石英 (及金刚石 )的榴辉岩为代表 ,仅见于南大别碰撞杂岩带中。这类岩石的 PT轨迹反映洋壳 B型俯冲的特点。 ( 2 )高压型。见于大别山南部的蓝片岩带、宿松变质杂岩带和南大别杂岩中的变质沉积岩及部分片麻岩中 ,与扬子陆壳的 A型俯冲有关 ,由南向北变质作用的 PT条件递增 ,反映陆壳俯冲作用的方向及不同深度。 ( 3)中低压型变质作用。在大别造山带广泛分布 ,与大规模的碰撞作用形成的地壳加厚区出现的热松弛效应有关。变质程度以北大别变质杂岩带最高 ,为角闪岩相 (局部出现麻粒岩相 ) ,向南和向北都有规律地递减为绿帘角闪岩相和绿片岩相 ,不同变质相带之间的界线与晚期走滑和滑脱断层一致。这期变质作用不同程度地改造了早期的高压、超高压变质岩。南大别碰撞杂岩带至少由这 3种不同变质历史或 PT轨迹的岩石混杂而成。大别地区的这 3类变质作用以及变质带的分布记录了大别造山带从洋壳 B型俯冲→陆壳 A型俯冲→陆壳碰撞推覆→隆起滑脱的演化历史。
The Dabie orogenic belt can be divided into five metamorphic tectonic units from south to north: the blue-lithofacies belt in the northern margin of the Yangtze, the metamorphic complex in Susong, the Southern Dabie collision complex, the North Dabie metamorphic complex and the Northern Huaiyang metamorphic belt . The metamorphism of different rocks in each metamorphic tectonic unit can be divided into three types: (1) EHV type. As represented by eclogite with coesite (and diamond), it is only found in the Southern Dabie collision complex belt. The PT trajectories of these rocks reflect the characteristics of the B-type subduction of the oceanic crust. (2) high-pressure type. The blue-lithofacies belt, Susong metamorphic complex belt and metamorphic sedimentary rocks and some gneisses found in the southern Dabie Mountains are related to the A-type subduction of the Yangtze continental crust and the PT conditions from south to north metamorphism are increasing , Reflecting the direction and depth of subduction of the continental crust. (3) medium and low pressure metamorphism. Extensive distribution in the Dabie orogenic belt is related to the thermal relaxation effect in the thickened area of the crust formed by the large-scale collision. The degree of metamorphism is highest in the northern Dabie metamorphic complex, which is amphibolite facies (granulite facies appears locally), and decreases both to the south and north to the verdigris facies and greenschist facies, and the metamorphic facies belt The boundary line is consistent with the late strike-slip and slip-off faults. The metamorphism changed the high-pressure and ultrahigh-pressure metamorphic rocks to varying degrees. The Southern Dabie collision complex belt is made up of at least three rocks of varying metamorphic or PT trajectories. These three types of metamorphism in the Dabie area and the distribution of the metamorphic belt record the evolution history of the Dabie orogen from the B-type oceanic crust subduction → continental crust A-type subduction → continental crust collision → uplift and slippage.