陕西镇安—山阳地区南羊山组重力流沉积作用及其意义

The Gravity Flow Sedimentation of the Nanyangshan Formation in the Zhen′an-Shanyang District, Shaanxi and Its Significance

陕西镇安—山阳地区的南羊山组发育陆源细碎屑岩和碳酸盐岩组成的多种重力流沉积，是构成台前斜坡和局限台盆沉积的主体和标志岩相。重力流沉积作用、火山－热液活动提供Ａｕ－Ｓｂ－Ａｓ－Ｈｇ等深部成矿物质、同生断裂活动、岩相古地理分异具有时空统一性，并在局限台盆中形成陆源细碎屑岩与碳酸盐岩高频交替叠覆、横向上递变、以重力流沉积占主导、含显量火山凝灰物质和沉积成岩黄铁矿的旋回性沉积，构成了本区微细浸染型层控Ｓｂ－Ａｕ矿床的矿源层。

A series of gravity flow sediments composed of terrigenous fine grained clastic rocks and carbonate rocks, which are the predominant and index lithofacies of the both limited platform basin and front platform slop sediments, occur in the Nanyangshan Formation of the Zhen′an Shanyang district in Shannxi. It is the time space unity among the gravity flow sedimentation, volcano hydrothermal activity, contemperaneous fault activity and paleogeography differiating, that gives birth to the limited platform basin sediments dominatedly by gravity flow, with the distinguished features of the terrigenous fine grained clastic rocks covered frequently by the carbonate rocks, changing from west to east, containing minor volcanic tuffaceous and sedimentary diagentic pyrite, which is the source bed of the micro dissiminated strata bound Sb Au deposits in this district.