4 . it is the first time that eclogite conglomerates are discovered in maotangchan and fenghuangtai formations . this suggests that ultra - high pressure metamorphic rocks in the dabie orogenic belt exhumed to the earth ' s surface in lower cretaceous . the geochemistry data indicates that the protoliths of the eclogite gravels formed in a structure setting of volcanic arc 首次在毛坦厂组、凤凰台组中发现了榴辉岩砾石，这一发现表明大别造山带超高压变质岩在早白垩世已经折返到地表，而且地球化学研究表明这些榴辉岩砾石的原岩形成于岩浆岛弧构造背景。
