CAJ | 학술논문

花牛山金矿床位于北山造山带柳园地区,是一处矽卡岩型矿床。矿体产在花牛山钾长花岗岩与蓟县系平头山组大理岩的接触带上。获得矽卡岩型矿石中辉钼矿Re-Os模式年龄为221.0±3.4 Ma,成岩-成矿时间误差范围内一致,暗示成矿作用发生在晚三叠世。石英-硫化物期早阶段石英中发育四类流体包裹体：富液两相包裹体(Ⅰ型)、富气两相包裹体(Ⅱ型)、三相包裹体(Ⅲ型)和纯液相包裹体(Ⅳ型)。Ⅰ型包裹体均一温度范围为170~430℃,多数集中在300~370℃,盐度介于6.59%~14.04% NaCleq；Ⅱ型包裹体均一温度范围为330~415℃,盐度为12.62%~16.14% NaCleq；Ⅲ型包裹体完全均一温度范围为300~436℃。晚阶段方解石中仅发育富液两相包裹体(Ⅰ型),均一温度范围为121~182℃,相应盐度4.34%~8.01%NaCleq。主成矿阶段(即早阶段)流体具高温、中等盐度、富CO2、CH4流体特征,并在300~415℃温度区间发生了流体沸腾作用。从早阶段到晚阶段,流体温度和盐度逐渐降低,密度有增大趋势。流体系统演化过程中,可能发生了岩浆水与大气降水的混合作用。石英中流体包裹体的δ18O和δD值分别为-0.01‰~0.29‰和-116‰~-109‰,暗示成矿流体是岩浆水与大气降水的混合热液。矿石金属硫化物δ34S值范围为4.21‰~6.53‰,均一化程度较高,矿石硫主要来自花牛山钾长花岗岩浆。结合区域地质,认为该矿床形成于造山后伸展环境,幔源岩浆底侵诱发地壳物质的部分熔融,继而导致构造-岩浆活动和金成矿作用发生。
화우산금광상위우북산조산대류완지구,시일처석잡암형광상。광체산재화우산갑장화강암여계현계평두산조대리암적접촉대상。획득석잡암형광석중휘목광Re-Os모식년령위221.0±3.4 Ma,성암-성광시간오차범위내일치,암시성광작용발생재만삼첩세。석영-류화물기조계단석영중발육사류류체포과체：부액량상포과체(Ⅰ형)、부기량상포과체(Ⅱ형)、삼상포과체(Ⅲ형)화순액상포과체(Ⅳ형)。Ⅰ형포과체균일온도범위위170~430℃,다수집중재300~370℃,염도개우6.59%~14.04% NaCleq；Ⅱ형포과체균일온도범위위330~415℃,염도위12.62%~16.14% NaCleq；Ⅲ형포과체완전균일온도범위위300~436℃。만계단방해석중부발육부액량상포과체(Ⅰ형),균일온도범위위121~182℃,상응염도4.34%~8.01%NaCleq。주성광계단(즉조계단)류체구고온、중등염도、부CO2、CH4류체특정,병재300~415℃온도구간발생료류체비등작용。종조계단도만계단,류체온도화염도축점강저,밀도유증대추세。류체계통연화과정중,가능발생료암장수여대기강수적혼합작용。석영중류체포과체적δ18O화δD치분별위-0.01‰~0.29‰화-116‰~-109‰,암시성광류체시암장수여대기강수적혼합열액。광석금속류화물δ34S치범위위4.21‰~6.53‰,균일화정도교고,광석류주요래자화우산갑장화강암장。결합구역지질,인위해광상형성우조산후신전배경,만원암장저침유발지각물질적부분용융,계이도치구조-암장활동화금성광작용발생。
The Huaniushan skarn-type gold deposit is located in the southern Beishan area. The ore bodies occur in the contact zone between the Huaniushan granite and the marble. Re-Os dating of a molybdenite sample yields a model age of 221.0±3.4 Ma, which is consistent with the zircon U-Pb age of the granite (225.6±2.2 Ma) within errors. The gold mineralization is therefore considered to be genetically related to the Huaniushan granite. Four main types of fluid inclusions are recognized: (1) two-phase liquid-rich inclusions, (2) two-phase gas-rich inclusions, (3) three-phase CH4-CO2-H2O inclusions, and (4) monophase vapor inclusions. Fluids associated with Au-bearing quartz veins (the early stage) have medium-high temperatures (285℃ to 436℃) and moderate salinities (6.59% to 16.14% NaCl equivalent);whereas fluids associated with calcite veins (the late stage) have low temperatures of 121℃ to 182℃ and low salinities of about 4.34%to 8.01%NaCl equivalent. The temperature and salinity of the ore-forming fluids decrease progressively. Fluid boiling happened during the main Au mineralization period at the temperature of about 300℃ to 415℃. Oxygen and hydrogen isotopic compositions of the ore fluids range from -0.01‰ to 0.29‰ and -116‰ to-109‰, respectively, which is compatible with mixing between the magmatic and meteoric components. Measuredδ34S values for sulfide minerals are 4.21‰to 6.53‰, indicating a magmatic sulfur origin. Considering the regional geology, we further propose that the Huaniushan skarn-type gold deposit was probably formed in the post-orogenic extensional setting.