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总结了近年来有关新疆西南天山超高压变质带研究取得的进展.根据新发现的柯石英矿物包体,结合以前报道的一些超高压变质矿物学证据,在西南天山蓝片岩-榴辉岩带中确定了长约80 km,宽10 km以上的超高压变质带,这是目前出露规模最大的洋壳岩石深俯冲超高压变质带,并确定了其由南向北的俯冲带极性.对含有柯石英的石榴石云母片岩中变质生长锆石边的定年,获得超高压变质时代为320±3.7 Ma,结合退变榴辉岩中获得的233-226 Ma变质边锆石的时代,确定了其退变过程经历了漫长的变质演化.根据详细的岩石学相平衡模拟计算,确定了西南天山含柯石英榴辉岩和石榴石多硅白云母片岩的P-T轨迹都具有热弛豫特征,即温度峰值期滞后于压力的峰值期,表明超高压变质岩石在俯冲通道中经历了缓慢的、长时间的升温减压抬升过程.根据少量的榴辉岩透镜体包裹于大面积的云母片岩中的野外产状特征,而且含柯石英榴辉岩和云母片岩都具有相似的P-T轨迹,提出了西南天山超高压变质榴辉岩的抬升可能是由于大面积的低密度的云母片岩抬升折返过程中把密度较大的榴辉岩携带到地表的新认识.
Based on the newly discovered coesite mineral inclusions and some previously reported ultrahigh-pressure metamorphic mineralogical evidences, in the South Tianshan blue schist-eclogite belt The UHP metamorphic belt with a length of about 80 km and a width of 10 km has been identified. This is the most extensive exhumation of the deep-subducted UHP metamorphic belt in the oceanic crust, and the polarity of the subduction zone from south to north is determined. The dating of metamorphic growth zircons in garnet-mica schist containing coesite was 320 ± 3.7 Ma during the UHP metamorphism dating to the era of 233-226 Ma metamorphic marginal zircons from degenerate eclogites, The degenerate process has undergone a long metamorphic evolution.According to the detailed petrographic phase equilibrium simulation calculation, it is confirmed that the PT trajectories of the coesite eclogite and garnet-rich muscovite schist from the southwestern Tianshan have the characteristics of thermal relaxation, that is, The peak period of temperature lags behind the peak of pressure, indicating that the ultrahigh-pressure metamorphic rocks underwent slow and prolonged heating and decompression uplifts in the subducting channels. According to a small amount of eclogite lens wrapped in a large area And the similar PT tracts of coesite-bearing eclogites and mica schists indicate that the uplift of the ultrahigh-pressure metamorphic eclogites in the southwestern Tianshan Mountains may be due to the large area of low-density mica schist uplifted Reentry process to the density of eclogites brought to the surface of the new understanding.