“登封群”内部的底砾岩和登封花岗-绿岩地体的构造演化

THE BASAL CONGLOMERATE WITHIN “DENGFENG GROUP” AND THE TECTONIC EVOLUTION OF THE DENGFENG GRNAITE-GREENSTONE TERRAIN

嵩山地区"登封群"内部发现了证据充分的底砾岩,底砾岩的特征表明其为正常沉积形成,而不是其它地质作用所造成的假底砾岩.底砾岩的发现使长期被作为太古宙的"登封群"解体为2500Ma前的石牌河杂岩和2500～2200Ma的君召群.花岗质的石牌河杂岩被周围的君召群表壳岩不整合复盖.石牌河杂岩内的表壳岩包体是3000Ma前的青阳沟型绿岩的残留体,而不是君召群的捕虏体.

The well evidenced basal conglomerate within 'Dengfeng group' has been discovered in the Songshan area. Its characterjstics show that it is the basal conglomerate developed in normal deposition rather than the pseudo-conglomerate resulted from the other geological processes. For the discovery of the basal conglomerate, the 'Dengfeng group' is dissected into the Shipaihe complex developed before 2500Ma and the Junzhao group formed during the period from 2500Ma to 2200Ma. The granitic Shipaihe complex is unconformably overlied by the Junzhao supracrustal rocks. Inclusions of supracrustal rocks in the Shipaihe complex are the relicts of the Qingyanggou type greenstone belt developed before 3000 Ma rather than the xenoliths of the Junzhao group.