CAJ | 학술논문

通过野外观察、光学显微镜、X射线衍射、扫描电镜及微区能谱分析、流体包裹体成分及盐度测定、稳定同位素(S、O、H)分析等手段,研究了广东凡口铅锌矿区闪锌矿的某些成因矿物学特征.结果表明,凡口矿区闪锌矿具有3个世代,分别形成于铅锌成矿期的3个成矿阶段.各世代闪锌矿在产出特征,表观颜色,结晶形态,解理发育程度,晶体常数,铁含量,流体包裹体的成分、盐度、氢氧同位素组成、硫同位素组成及同与其连生的方铅矿的平衡分馏温度等方面均存在规律性差别.从早期阶段到晚期阶段,成矿流体的演化特征是:成矿温度和成矿流体盐度从低到高再到低,流体包裹体成分从Na+-Ca+-Cl-型到K+-Ca+-Cl-型再到Na+-Ca+-Cl-型,δ18O、δD及δ34S均由高到低变化,但δ18O、δD及δ34S自中期阶段到晚期阶段降幅显著大于从早期阶段到中期阶段的降幅,反映晚期阶段至少有部分δ18O、δD及δ34S均显著较低的岩浆源流体参与成矿.认为凡口铅锌矿成矿流体主要为燕山早期区域岩浆热事件加热的中低温混合源循环热卤水,成矿中晚期有岩浆热液参与成矿.
통과야외관찰、광학현미경、X사선연사、소묘전경급미구능보분석、류체포과체성분급염도측정、은정동위소(S、O、H)분석등수단,연구료엄동범구연자광구섬자광적모사성인광물학특정.결과표명,범구광구섬자광구유3개세대,분별형성우연자성광기적3개성광계단.각세대섬자광재산출특정,표관안색,결정형태,해리발육정도,정체상수,철함량,류체포과체적성분、염도、경양동위소조성、류동위소조성급동여기련생적방연광적평형분류온도등방면균존재규률성차별.종조기계단도만기계단,성광류체적연화특정시:성광온도화성광류체염도종저도고재도저,류체포과체성분종Na+-Ca+-Cl-형도K+-Ca+-Cl-형재도Na+-Ca+-Cl-형,δ18O、δD급δ34S균유고도저변화,단δ18O、δD급δ34S자중기계단도만기계단강폭현저대우종조기계단도중기계단적강폭,반영만기계단지소유부분δ18O、δD급δ34S균현저교저적암장원류체삼여성광.인위범구연자광성광류체주요위연산조기구역암장열사건가열적중저온혼합원순배열서수,성광중만기유암장열액삼여성광.
Based on field investigation, microscopic and scanning electron microscopic observation, X-ray diffraction, microprobe analysis, salinity and composition measurement of fluid inclusions and isotopic composition measurement of S, O and H, the authors studied some genetic mineralogical properties of sphalerite from the Fankou Pb-Zn ore district in Guangdong Province. The results suggest that there are three generations of sphalerite in this ore district formed respectively at three stages of the hydrothermal Pb-Zn sulfide ore-forming period. These three generations of sphalerite show remarkable differences in such aspects as mode of occurrence, paragenesis, apparent color, morphology, cleavage development, unit cell parameter, Fe content, composition and salinity, δ18O‰ and δD‰ of fluid inclusions, δ34S‰ and fractionation equilibrium temperature with galena. The evolutional properties of the ore-forming fluid from the first stage to the third stage are as follows: the temperature and salinity varied from low through high to low again; the compositions of the ore-forming fluid changed from Na+-Ca+-Cl- through K+-Ca+-Cl- to Na+-Ca+-Cl- again. The values of δ18O, δD and δ34S decreased , but the decreasing was much more drastic from the second to the third stage than from the first to the second stage, implying that a portion of newly-produced solution with much lower values of δ18O, δD and δ34S participated in the ore-forming fluid during the third stage. It is thus held that the ore-forming fluid should be a kind of mixed-source hot brine heated by Yanshanian regional magmatic event, with a portion of magmatic-hydrothermal solution participating in the formation of the hot brine at the intermediate-late ore-forming stage.