皖南兰田残留向斜不是构造窗

Lantian Relict Synclinal Basin in South Anhui, not a tectonic window

兰田地区翔实的1∶5万区调填图工作,收集了丰富的前震旦系实测地层剖面资料、震旦系休宁组底界角度不整合资料及后期构造变动的证据,证实了皖南属晋宁期造山带,并存在元古宙地层的完整层序,而震旦系—寒武系则为原地沉积在前震旦系基底之上的盖层。加里东期区域伸展体制条件下兰田地区产生滑覆断层体系,震旦系—寒武系盖层残留在前震旦系基底之上形成向斜构造。中生代的构造作用对兰田地区构造轮廓产生了不可忽视的改造,但未造成翻天覆地的造山作用,不存在“兰田构造窗”。

The 1 : 50,000 regional geological mapping of the Lantian area collected abundent data of Presinian sections, angular unconformity interface between the Xiuning Formation (Sinian) and the underlying strata as well as subsequent tectonic events, confirming that the area belongs to the Neoproterozoic orogen, that there exists the Mesoproterozoic formations with intact sequence on the Lantian area, and that the Sinian - Cambrian strata are a sedimentery cover uncon-formably overlying the Presinian. Then this cover formed a synclinal basin as a relic on the slide - superposition system under the condition of regional stretch mechanism during the Caledonian cycle. The structure action in the Mesozoic period reformed remarkbly only the structural framework of this area. It caused neither orogenies nor the..tectonic window.