【作者】 付旭；

【导师】 张德会；

【作者基本信息】 中国地质大学(北京) ， 地质工程， 2012， 硕士

【摘要】 湖南黄沙坪矽卡岩型铅锌矿位于南岭成矿带中段北缘，其矿体类型多样，矿种丰富，前人在此做了大量的工作，但在其成矿深度上存在很大差异。本文在充分分析和综合前人工作成果的基础上，重点研究前人研究较少分歧较大的成岩成矿深度，分析对比各地质压力计的优劣，得出较为合理的黄沙坪成岩成矿深度，为其深部找矿、深部预测提供理论依据。通过对湖南黄沙坪矿床地质特征的系统分析，运用了花岗岩地质压力计、闪锌矿地质压力计和流体包裹体地质压力计分别研究了该矿区的成岩成矿深度。通过对比研究和分析，取得以下认识：（1）与该矿床成矿相关的岩体，在成矿期普遍发生了自蚀变作用，使成矿岩体组分发生变化。岩体普遍发生硅化，致使在运用花岗岩地质压力计计算成岩深度时，所得计算结果普遍偏低。花岗岩地质压力计自身具有不完善的缺陷，如花岗岩中挥发分含量不能太高，其矿物含量也是根据CIPW理论公式计算出来的，与实际情况有一些出入，所以它只能作为半定量的地质压力计。本次实验通过判定矿区的三类岩石形成的相对深度，与实地地质现象非常吻合。这说明了该方法具有相对可靠的参考价值。（2）闪锌矿地质压力计在使用的过程中，实验条件要求较为苛刻。首先必须判断闪锌矿，黄铁矿和磁黄铁矿共生，之后还要确定磁黄铁矿为六方磁黄铁矿。矿物在生长过程中，从核部到边部其元素含量不断发生变化，用电子探针测量时，即使是同一矿物颗粒，所得的元素组成也有差别。这种矿物生长的特性使同一样品压力计算结果相差很大。L T Bryndzia and SD Scott（1990）和Hutchimon andScott (1981)提出的公式的公式各有优劣，根据实际情况分别运用这两个公式计算，并以实际的地质现象为依据，选取合理的计算结果。（3）流体包裹体的方法是相对较准确的计算压力方法，其理论体系也较为完善。由于流体包裹体对压力非常敏感，后期的构造变形对包裹体形态的改变会对其测温和计算带来影响。通过岩相学和统计学分析，依据实际的地质情况，确定较为合适的压力值。（4）本文以地质事实为依据，通过花岗岩地质压力计估算，与该矿床成矿有关岩体的成岩压力为0.7—1.5Kb，闪锌矿地质压力计求得闪锌矿的成矿压力为0.45—0.69kb，石英壳中高盐度流体包裹体的形成压力为0.8—1.5Kb。根据静岩压力，按照270bar/km地压梯度，该矿床成岩深度为2.6—5.5Km，闪锌矿的成矿深度为1.7—2.5Km，考虑到在闪锌矿以下在矽卡岩中还有辉钼矿和白钨矿的矿化，所以黄沙坪矿区整体上成矿深度应该为1.7—3Km。更多还原

【Abstract】 Lying in the northern margin of the middle section of Nanling metallogenic belt,Huangshaping lead-zinc deposit is a skarn type in Hunan province. Many scholarshave paid attention to it for its rich types; however, the researches about its diageneticand metallogenic depths have much differences in results. Based on former studies,this paper is focused on the depth study of the deposit which has been given a littleattention to and is in most controversial condition. By comparing geobarometers ofvarious types, a reasonable data for diagenetic and metallogenic depths ofHuangshaping deposit will be reached to provide theoretical foundation to deepprospecting and deep prediction.Through systematically analyzing geological characteristics of Huangshapingdeposit in Hunan province, its diagenetic and metallogenic depths are studied by usinggranite geobarometer, sphalerite geobarometer and fluid inclusion geobarometerrespectively. After comparison and analysis, the results as followed:(1) Rock related to the mineralization of this deposit has gone throughself-alteration in the forming, which leads to the changes of rock composition. As thesilicification is common for rock in its change, the calculated results of metallogenicdepth measured by granite geobarometer are low. Besides, there are some defects ofgranite geobarometer, such as the percentage of volatile matter in granite should notbe high and the mineral content, obtained according to CIPW theoretical formula, isnot accurate enough. Thus, this result is only counted as a semi-quantitative one. Inthe paper, the experiment results for relative diagenetic and metallogenic depths ofthree kinds of rocks in the Huangshaping deposit are extremely consistent with theactual geological phenomenon there. From this perspective, the methods used in thepaper have some reference value.(2) For sphalerite geobarometer, there are more requirements for experimentalconditions. At first, whether sphalerite, pyrite and pyrrhotite inter-grew and thenwhether the pyrrhotite is hexa-pyrrhotite should be clear known. As the percentage of each element has been changing from the inner part to marginal part throughout theprocess of the mine’s formation, even results of the same mineral particle measuredby EMPA would be different in different conditions. Because of characteristics of thismine’s formation, the results calculated from the same sample differ greatly.Therefore, the formulas, proposed by L T Bryndzia&SD Scott（1990） andHutchimon&Scott (1981) which have their own advantages, will be applied inaccordance with the actual situation. Based on the real geological phenomenon, areasonable result will be reached.(3) Pressure calculation of fluid inclusion has the advantage of being moreaccurate besides having well-developed theories. Since the fluid inclusion is sensitiveto pressure, changes of fluid inclusion during the structural deformation in post-oreperiod influence its temperature-measuring and calculation. However, throughpetrographical and statistics analysis, a proper pressure would be determined in theconsideration of actual geological condition.(4) On the basis of geological phenomenon and with the help of granitegeobarometer, diagenetic pressure of rock body in the Huangshaping deposit is0.7—1.5Kb, metallogenic pressure of the sphalerite is0.45—0.69kb and the formingpressure of high-salinity fluid inclusion in silica is0.8—1.5Kb. By the considerationof lithostatic pressure and pressure gradient of270bar/km, the diagenetic depth ofHuangshaping deposit is2.6—5.5Km and metallogenic depth of sphalerite is1.7—2.5Km. However, the metallogenic depth of the whole deposit in Huangshapingtown should be1.7—3Km, because molybdenite and scheelite in skarn, under thesphalerite, might have been mineralized.更多还原