摘要
本区位于南岭东西复杂构造带东段,是我国钨矿的重要产区之一。区内钨矿床多集中于北北东—北东向与三条东西向主要构造岩浆带的交接部位(图1),具有类型多、规模大、分布广、品位高的特点。
Northern Guangdong is situated at the eastern part of the Nanling E-W tectonic zone.It is one of the important productive areas of tungsten ores in China.In this area,many tungsten ore deposits are concentrated in places where major NNE-NE trending tectonomagmatic zone intersect three other E-W trending ones.These deposits are characterized by diversity of ore types,large size,wide distribution and high grade.According to the genesis and commercial value,and in consideration of their occurrence and distribution,the tungsten ore deposits in this area can be divided into five types:(A)hydrothermal deposits associated with granites which are further subdivided into 4subtypes:(1)disseminated ores in granites;(2)stockwork disseminated ores in greisens;(3)mineralized skarns;(4)quartz-veins;(B)hydrothermal deposits associated with porphyry;(C)volcano-sedimentary-hydrothermal reworked deposits;(D)sedimentary reworked deposits;and(E)placers.The tungsten ore deposits of disseminated type are found only recently and possess always bigger reserves.They occur in the composite intrusive granitic masses and were formed through the deuteric alteration of the later granites by the magmatic hydrothermal solutions.Sometimes they are associated with the deposits of the quartzvein type.The K-Ar dating of the granites is from 138 to 152 m.y.and that of the deposits is about 143 m.y..The mineral association consists mainly of scheelite,wolframite and molybdenite.This type is characterized by big size,consistent grade and convenience to be mined and dressed.It is now the main object for prospecting.The deposits of quartz-vein type are the most numerous and widespread in the present area.They possess also the biggest reserve as a whole.They have distinct vertical zoning of mineralization.The veinlets in the upper part of the deposits frequently converge and join together,passing into big veins in the lower part.Mineralization of this type is closely related to granites in depth.Generally speaking,the deeper the granite is situated,the larger the depth of mineralization extent is.The K-Ar dating of mineralization is from 134to 157 m.y..In prospecting of this type of deposits,it is important to pay attention also to search for those of the skarn type,disseminated ores in granite and sedimentary reworkingtype.The volcano-sedimentary-hydrothermal reworked deposit is a new type recognized recently.It is in close relation to the paleovolcanism and of medium to large reserves and is found in the polymetallic deposits occurred in the Donggangling limestone of the middle Devonian.The major mineral is scheelite,and the subordinate is wolframite.The ores are laminated,banded or massive,with clear sedimentary rhythm.The associated spherulitic pyrite shows concentric ring structure,which is fromed through the replacement of the algae by iron-bearing material.There are a lot of redeposited tuffaceous rocks and volcanic breccias in the mineralized beds,which are nearly concordant with the strata and orebody.The porphyry tungsten is often found in areas of volcanic rocks.The mineralization takes place both inside and outside the poryphyry body,the location of the deposits and rich orebodies is controlled clearly by the crossing fractures.The mineralization is intimately related to the intermediate-acidic poryphyry rocks of calci-alkalic series of the middle-late Yanshanian.The sedimentary reworking type is also a new type found recently.It occurs in certain strata mainly in disseminated form.The ore-bearing quartzveins may appear sporadically in the same horizon.The ore-forming materials may be derived in situs from the strata on the one hand and come from the magma at depth on the other.This type of deposit exhibits a combined character of sedimentation,activation and reenrichment,and is now one ofthe main object for prospecting.
作者
陈赓礼
Chen Gengli(Metallurgical and Geological Institute of Guangdong Province)
出处
《地质学报》
1983年第2期142-153,共12页
Acta Geologica Sinica
