广西乐业大石围大型岩溶漏斗的形成特征

大石围大型岩溶漏斗位于云贵高原南缘的桂西北边陲的岩溶斜坡地带.红水河右岸百郎地下河上游的高楼至韩家沟风岩洞地下河支流的中段.地面标高1 000 m～1 500 m,漏斗口直径为500 m×380 m,口部面积为1.4×105m2,底部直径为200 m×100 m,底部面积20 000 m2,总容积为3×107m3～5×107m3.其深度和容积在世界同类大型岩溶漏斗中位居第5位或是中国的第3位.研究表明,区域构造或垂向深切"X"型共轭节理、裂隙, 对岩溶漏斗周边岩壁的崩塌和平行后退起着至关重要的作用;而第四纪以来的大幅度抬升,是造成岩溶向纵深发育或漏斗深切作用的主要原因.大石围岩溶漏斗是地表和地下岩溶的长期共同作用,逐渐崩塌、扩大其容量和增加其深度而实现的.

Formation of the World'largest Doline or Karst Funnel in Dashiwei of Leye County,Guangxi

The largest doline or karst funnel of Dashiwei is situated at the karst slope zone of the northwest Guangxi in the southern of Yunnan and Guizhou plateau.It is the middle section of the underground branch stream from Gaolou to Huanjiagou Fengyan cave in the upper reaches of Bailang undergroud river in the right bank of the Hongshuihe River.The height above ground level is from 1000 m to 1500 m in the karst area.The upper diameter of karst doline or funnel is 500 m multiplied by 380 m.The upper area of karst doline or funnle is 1.4×10.5 m².The bottom diameter of karst funnel is 200 m multiplied by 100 m.The bottom area of karst funnle is 20000 m².The total volume of karst funnle is from³×10⁷ m³ to 5×10⁷ m³.Dashiwei largest doline or karst funnle is the fifth of the world or the third of China in the depth and volume.The studies show that the regional tectonics or the vertical deep dissection of the X-type conjugate joints and fissures play important role in the formation of collapsion and parallel back for around rock cliffs of karst doline;The great uplift since Quternary,however,resulted in the main reason of the vertical development and deep disseection of karst doline.The Dashiwei karst doline was the result of the cooperation of the surface karst and underground karst with the collapsion continued,space enlarged and depth increased.