黔南独山地区早泥盆世事件沉积记录及地质意义

Early Devonian Event-stratigraphic Records and Geological Implications in the Dushan Area, Southern Guizhou Province

事件沉积是地质学研究热点之一。黔南独山地区早泥盆世丹林组沉积时期事件沉积记录为华南板块海西早期构造演化再研究提供了新的线索。通过路线调查、剖面实测、岩相解析、实验测试查明丹林组存在砂岩液化、自形-半自形独居石及金红石、团块状黄铁矿、锑异常层等事件沉积记录。经研究本文认为,上述现象是由于黔南独山地区早泥盆世丹林组沉积时期可能存在潜火山活动引起,该潜火山活动导致了同时期的热事件沉积,并表明事件沉积环境为热水盆地。分布于独山地区的锑、铅、锌、铁、金矿化均赋存于泥盆系地层之中,且具有显著的层控特点;故而该地区的多金属矿化很可能与华南板块海西早期的构造-岩浆活动热事件启动密切相关。

Event sedimentation is still one of the hotspots of our geological society. The event sedimentation of the Upper Devonian Dalin Formation, Dushan area of southern Guizhou, provides new insights into the early Hercynian tectonic evolution of the South China Block. Field observations, profile measurements, petrographic studies, and some analyses demonstrated that the sandstone of the lowest part of the Danlin Formation had experienced liquefaction, during which a few euhedral or semi-euhedral monazite and rutile along with a large clump of pyrite were formed. Moreover, the Lower Devonian strata display regional antimony anomaly.Synthesizing available data, we suggest that there was likely hidden Early Devonian volcanic activity in the Dushan area, southern Guizhou. This hidden volcanic activity was recorded by the thermohydrous sediments.Thus, the lowest segment of the Dalin Formation likely formed in hot water basin environment. Antimony, lead,zinc, and iron mineralization in the Dushan area are all limited in the lower Devonian strata. Obviously,the polymetallic mineralization was controlled by stratigraphy and closely related to early Hercynian tectonism,which has affected a wide region of the South China Block.