东南亚新生代两类埃达克岩的分布、成因和含矿性

DISTRIBUTION,ORIGIN AND MINERALIZATION OF TWO TYPES OF CENOZOIC ADAKITE AND ADAKITE-LIKE ROCKS IN SOUTHEASTERN ASIA

东南亚的巽他群岛-巴布亚新几内亚是新生代埃达克岩和类埃达克岩发育的地区。这些中酸性岩浆岩广泛见于印度尼西亚几内亚岛、苏拉威西和巴布亚新几内亚,零星见于苏门答腊、班达岛弧、西爪哇和中加里曼丹等地。本区埃达克岩和类埃达克岩岩石类型分别属于岛弧拉斑/钙碱性系列和高钾钙碱性系列,以重稀土元素Y,Yb含量低(分别为Y≤19×10-6和Yb≤1.8×10-6)和高Sr值(>355×10-6)为特征。微量元素蛛网图上有明显的Ba、K、Sr正异常峰和负的Th、Nb(Ta)异常谷。大离子亲石元素(LILE)和高场强元素(HFSE)相对富集。本区埃达克岩和类埃达克岩的构造位置为新生代缝合线附近的大洋岛弧和陆缘造山带,可划分为两种成因类型:第一种为岛弧拉斑/钙碱性系列,其REE配分模式属于大洋岛弧型,见于现代大洋岛弧,称为岛弧型(O-型)埃达克岩;另一种为高钾钙碱性系列,其REE配分模式属于大陆型,产于大陆板块边缘造山带,与弧-陆碰撞和后碰撞构造环境有成因联系,见于大陆边缘,称为大陆型(C-型)埃达克岩。研究结果表明:大陆型(C-型)埃达克岩和类埃达克岩分布区域与世界级斑岩铜-金矿分布相一致,而大洋岛弧型(O-型)主要与浅成热泉金矿和喷气型有成因联系。

The Sunda Islands of southeastern Asia is an area where Cenozoic adakite and adakite-like rocks are well developed. These intermediate-acid magmatic rocks are widespread in Guinea Island, Sulawesi （Indonesia）, Papua New Guinea, and scattered in Sumatra western Java, Banda island are and Central Kalimantan. The adakite and adakite-like rocks of the area belong respectively to island-arc tholeiitic/callc-alkaline series and high-potassium callc-alkaline series and are characterized by low HREE contents such as Y and Yb （Y≥ 19 ×10^-6 and Yb≤1.8 ×10^-6 respectively） and high Sr content （ 〉 355 ×10^-6）. The spider diagrams show strongly positive anomalies of Ba, K and Sr and relatively negative anomalies of Th and Nb. The adakite and adakite-like rocks show enrichments in large-ion lithophitic dement （LILE） and high-fidd strength dements （HFSE）. The adakite and adakite-like rocks of Sunda Islands are tectonically distributed near the Cenozoic sutures, and can be divided into two types of origin. The first one, called oceanic type （O-type） of adakites, belongs to tholeiitic/calcalkaline series with REE pattern of oceanic island arcs, and is seen at the oceanic island. The second type, named continental type （C-type） of adakites, belongs to high-potassium calc-alkaline series with REE patterns of continental type, often occurs in continental margin orogenic zone of continental plate and is originally related to are-continent collision zone or post-collision. Our result reveals that the our research works reveals that the continental-type （C-type） adakite and adakite-like rocks have a similar distribution to the world-class porphyry copper-gold deposits, whereas the oceanic island arc type （O- type） adakite and adakite-like rocks are related in origin with epithermal hot-spring gold zones and ehalation ore deposits.