大地构造与成矿学
大地構造與成礦學
대지구조여성광학
GETECTONICA ET METALLOGENIA
2014年
4期
908-918
,共11页
杨林%王庆飞%刘学飞%张尧%管涛%潘瑞广%冯跃文
楊林%王慶飛%劉學飛%張堯%管濤%潘瑞廣%馮躍文
양림%왕경비%류학비%장요%관도%반서엄%풍약문
新立金矿床%断层泥%XRD%粒度分布%胶东
新立金礦床%斷層泥%XRD%粒度分佈%膠東
신립금광상%단층니%XRD%립도분포%효동
Xinli gold deposit%fault gouge%XRD%particle size distribution%Jiaodong
胶东半岛中生代金矿床具有重要的经济价值,其蚀变和矿化均受北东向断裂控制。例如,位于胶东半岛西北部的新立金矿床受区域三山岛-仓上断裂(F1)和次级断裂(F2)控制,其中F1广泛地控制蚀变和矿化, F2仅分割黄铁绢英岩化蚀变和钾化蚀变。本文选取新立金矿床 F1和 F2的断层泥为研究对象,通过显微观察,矿物组成测定,激光粒度分析等多种手段,探讨断层泥物质组成、矿物成因、演化阶段及其在成矿过程中的作用。矿物学分析表明F1断层泥主要成分为高岭石和石英,含少量黄铁矿、伊利石和石膏； F2断层泥含有大量的石英和绢云母以及少量高岭石和伊蒙混层。根据矿物共生关系和相图分析得出,高岭石是绢云母反应形成的,伊利石由高岭石转化所致,伊蒙混层是高岭石转化为伊利石的中间产物,这些矿物之间的转化反映了 aK+或 aK+/aH+连续减小。F1断层泥中黄铁矿和 F2断层泥中石英和绢云母可能为围岩残留,石膏是次生风化的产物。F1断层泥的粒度分布曲线呈单峰型、复式双峰和三峰型,其粒度分布分维值为2.61~2.82；而F2断层泥仅呈简单双峰型,分维值为2.46~2.52,表明F1断层泥组份经历颗粒旋转磨蚀阶段, F2断层泥组份处于约束碾磨阶段。综上所述,水岩反应和构造磨蚀在断层泥的形成过程中扮演重要角色,两者在主断裂 F1中更强烈、复杂。鉴于F2产出位置和断层泥特征,我们推断F2为成矿后构造。断层泥中大量的黏土矿物、高度分化的颗粒粒度以及定向的显微构造导致低的横向渗透性,使断层作为障碍层阻隔成矿流体并形成差异的蚀变矿化带。
膠東半島中生代金礦床具有重要的經濟價值,其蝕變和礦化均受北東嚮斷裂控製。例如,位于膠東半島西北部的新立金礦床受區域三山島-倉上斷裂(F1)和次級斷裂(F2)控製,其中F1廣汎地控製蝕變和礦化, F2僅分割黃鐵絹英巖化蝕變和鉀化蝕變。本文選取新立金礦床 F1和 F2的斷層泥為研究對象,通過顯微觀察,礦物組成測定,激光粒度分析等多種手段,探討斷層泥物質組成、礦物成因、縯化階段及其在成礦過程中的作用。礦物學分析錶明F1斷層泥主要成分為高嶺石和石英,含少量黃鐵礦、伊利石和石膏； F2斷層泥含有大量的石英和絹雲母以及少量高嶺石和伊矇混層。根據礦物共生關繫和相圖分析得齣,高嶺石是絹雲母反應形成的,伊利石由高嶺石轉化所緻,伊矇混層是高嶺石轉化為伊利石的中間產物,這些礦物之間的轉化反映瞭 aK+或 aK+/aH+連續減小。F1斷層泥中黃鐵礦和 F2斷層泥中石英和絹雲母可能為圍巖殘留,石膏是次生風化的產物。F1斷層泥的粒度分佈麯線呈單峰型、複式雙峰和三峰型,其粒度分佈分維值為2.61~2.82；而F2斷層泥僅呈簡單雙峰型,分維值為2.46~2.52,錶明F1斷層泥組份經歷顆粒鏇轉磨蝕階段, F2斷層泥組份處于約束碾磨階段。綜上所述,水巖反應和構造磨蝕在斷層泥的形成過程中扮縯重要角色,兩者在主斷裂 F1中更彊烈、複雜。鑒于F2產齣位置和斷層泥特徵,我們推斷F2為成礦後構造。斷層泥中大量的黏土礦物、高度分化的顆粒粒度以及定嚮的顯微構造導緻低的橫嚮滲透性,使斷層作為障礙層阻隔成礦流體併形成差異的蝕變礦化帶。
효동반도중생대금광상구유중요적경제개치,기식변화광화균수북동향단렬공제。례여,위우효동반도서북부적신립금광상수구역삼산도-창상단렬(F1)화차급단렬(F2)공제,기중F1엄범지공제식변화광화, F2부분할황철견영암화식변화갑화식변。본문선취신립금광상 F1화 F2적단층니위연구대상,통과현미관찰,광물조성측정,격광립도분석등다충수단,탐토단층니물질조성、광물성인、연화계단급기재성광과정중적작용。광물학분석표명F1단층니주요성분위고령석화석영,함소량황철광、이리석화석고； F2단층니함유대량적석영화견운모이급소량고령석화이몽혼층。근거광물공생관계화상도분석득출,고령석시견운모반응형성적,이리석유고령석전화소치,이몽혼층시고령석전화위이리석적중간산물,저사광물지간적전화반영료 aK+혹 aK+/aH+련속감소。F1단층니중황철광화 F2단층니중석영화견운모가능위위암잔류,석고시차생풍화적산물。F1단층니적립도분포곡선정단봉형、복식쌍봉화삼봉형,기립도분포분유치위2.61~2.82；이F2단층니부정간단쌍봉형,분유치위2.46~2.52,표명F1단층니조빈경력과립선전마식계단, F2단층니조빈처우약속년마계단。종상소술,수암반응화구조마식재단층니적형성과정중분연중요각색,량자재주단렬 F1중경강렬、복잡。감우F2산출위치화단층니특정,아문추단F2위성광후구조。단층니중대량적점토광물、고도분화적과립립도이급정향적현미구조도치저적횡향삼투성,사단층작위장애층조격성광류체병형성차이적식변광화대。
The Mesozoic gold deposits in the Jiaodong Peninsula, eastern North China Craton, are economically significant. The mineralization and alteration are strictly controlled by the NE-trending faults. For instance, the Xinli gold deposit, located at northwestern margin of the Jiaodong Peninsula, is controlled by the regional Sansh-andao-Cangshang fault (F1) and the secondary fault (F2).The F1 divides the extensively altered and mineralized zones and the F2 merely separates the pyrite-sericite-quartz alteration and K-feldspathization alteration. The faults gouge from the two faults in the Xinli gold deposit have studied via the microscopic observation, mineral compositions determination and laser particle size analysis. Mineralogical analyses via XRD reveal that the kaolinite and quartz are the major components in the F1 fault gouge with small amounts of illite, pyrite and gypsum, while the F2 fault gouge contain large amounts of quartz and sericite with subordinate kaolinite and mixed-layer illite-smectite. Constraints from the mineral occurrence and genetic conditions, sericite was considered to transform into kaolinite, then into the illite-smectite mixed-layer acted as the intermediate product, and finally into illite. The mineral transformations reflect that theaK+, oraK+/aH+ (acid) is continuously decreased. Pyrite from the F1 fault gouge and quartz and sericite from the F2 fault gouge are probably the residue of the primary rocks. Gypsum is the result of the superficial weathering. The particle size distribution for the F1 fault gouge displays unimodal, composite bimodal and trimodal peaks. In contrast, the F2fault gouge shows merely bimodal peaks. The fractal dimension of particle size distribution in F1 and F2 are 2.61-2.82 and 2.46-2.52, respectively. It can interpret that the F1 fault gouge has undergone the process of rolling abrasion, while the F2fault gouge was in the status of constrained comminution. The characteristics of the fault gouge illustrate fluid-rock interaction and structural abrasion played a critical role in the formation of fault gouge and the F1 activities were more drastic and complicated than F2. Considered the location of the F2 fault and the characteristics of the gouge, the F2 fault likely formed after the gold mineralization. The dominant clay compositions, highly differentiated particle sizes and oriented microstructures induce a low lateral permeability, making the fault act as a “barrier layer” for the ore fluid and form the mineralization and alteration zonation.
