摘要:
广西融安县境内的泗顶-古丹铅锌矿田面积约600平方公里。它位于江南古陆之南缘,湘、桂、粤褶皱带内。本区分布有中型铅锌矿床两处,铅锌矿、黄铁铅锌矿、黄铁矿（褐铁矿）等矿点约二十多处,是寻找铅锌矿床有利地区。 区内广泛出露下古生界寒武系清溪组（∈q）浅变质的碎屑岩,上古生界中上泥盆统东岗岭组（D2d）和桂林组（D3g）碳酸盐岩及碎屑岩（图1）。早晚古生代地层与之古生代地层与之呈角度不整合接触产出，两者分别组成上下两个构造层。下构造层属于被改造了的南岭复式东西构造带北亚带的组成部分，基本构造轮廓为轴向500-70“的紧闭型同斜倒转褶皱，并发育着北东向的断裂;上构造层为轴向北北东的宽展型的褶皱，产状平缓，倾角5。-8。，发育有多阶段形成的北东向、北西向和南北向断裂，整个矿田及外围尚未发 现任何岩浆活动的迹象。
Abstract:
Based on the survey, analysis, correlation of systmatic facies section, transverse trace of outcrops, and study in the laboratory, the carbonate strata of the Upper and Middle Devonian Series in this area may be classified into two facies regions, three facies belts and six microfacies. (1) The continental margin facies region with al'ittoral facies belt which can be subdivided into a supratidal local swamp facies and a littoral terrigenous clastic shoal facies. The basic characteristic of the littoral local swamp facies is that it consists chiefly of thin beded, carbonaceous shales and micrites. In the latter there are abundant shell fossils and coral fragments together with mud-crack and birdseye structures, knotty and banded limestones are common. The littoral terrigenous clastic shoal facies is a set of coarse clastic rocks-mainly calcareous-quartz sandstones, sandstones with gravels, conglomerates and minor siltstones, containing more marine fossils. Glauconite occurs ubiquitously in these rocks. Gentle "teepee" type cross bedding and ripple bedding occur in sandstones and siltstones, they are generally reverse-graded beddings. The platform facies region contains a restricted platform facies belt and an open platform facies zone. The restricted platform facies belt can be divided into an intertidal mud flat facies and a tidal channel bar facies. The former is the most developed and consists essentially of two rock types, i.e. the first is chiefly made of limestones, which consist mainly of thin to medium beded micrites with widely developed laminated limestones and a few intercalated psephitic limestones. They are possessed of lenticular bedding, birdseye structure, etc and few fossils. The second is composed mainly of dolomites, which are considered to be formed in diagenetic stage. Relict and metasomatic-relict structures are widely developed in the rocks. Based on their structures, the original rocks restored were domina- tively micrites and lamellar limestones. The dolomites, as a petrographic unit, are regionally distributed. The tidal channel bar facies is in locally intermittent distribution. The tidal channel subfacies is characterized by oncoid limestones intercalated with bioclastic limestones,grainstones, etc, while the bar subfacies by oolite-bearing psammitic limestone, psammitiic limestone, psephitic limestone and bioclastic limestone with subaqueous scour planes. The open platform facies belt consists of a backshoal open platform facies and an intraplatform oal-biosh facies.In the former predominate micrite,algal pellet limestone and grainstone with abundant fossils and horizontal stratifications. The latter was the accumulation of bioclasts-mainly branched and massive Stromatopora. Based on the observation, these organisms grew in situ or were transported in a short distance. The abundance of lead and zinc of carbonate strata in this generally 3 to 4 times higher than the Clark Value of lead and zinc in carbonate, rocks even amounting to 6 times higher than that. The intertidal mud-flat facies about 300-meter thick is considered to control lead and zinc mineralization zone. According to the syntesis of other data, the authors infer that brines and metals for the lead and zinc mineralization were provided by the Intertidal mud-flat,facies, which was the main source-bed.
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