郑勇+黄文海+周义+赵振刚+郭新成+陈郑辉

基金项目：中国地质调查局地质大调查项目(12120113078200，1212011120494，1212010633903)；

摘要：新疆备战铁矿是西天山阿吾拉勒铁铜金成矿带上重要的铁矿床之一，矿区南部出露有钾长花岗岩和钾长花岗斑岩，两者之间呈脉动侵入接触关系。岩石地球化学研究表明，分析样品均属于高硅、富钾钙碱性系列，富集大离子亲石元素 Rb、K，亏损高场强元素，具有明显的Ba、Sr、P、Ti负异常，轻、重稀土元素分馏明显。LAICPMS锆石UPb测年结果表明，钾长花岗岩和钾长花岗斑岩形成时代分别为(320.5±1.9)Ma和(306.8±1.6)Ma。依据岩石地球化学、年代学，结合区域地质资料，矿区出露的钾长花岗岩和钾长花岗斑岩为同源岩浆产物，可能形成于早石炭世末—晚石炭世时期的南天山洋俯冲结束向陆内碰撞造山带转换阶段中。

关键词：铁矿；地球化学；侵入岩；锆石；钾长花岗岩；钾长花岗斑岩；西天山；新疆

中图分类号：P588.12；P597+.3文献标志码：A

Geochemistry, Geochronology and Geological Implication of

Intrusive Rock from Beizhan Iron Deposit of Xinjiang

ZHENG Yong1, HUANG Wenhai1, ZHOU Yi2, ZHAO Zhengang1,

GUO Xincheng1, CHEN Zhenghui3

(1. No.11 Geological Team, Xinjiang Bureau of Geology and Mineral Resources, Changji 830011, Xinjiang, China;

2. School of Earth Science and Resources, Changan University, Xian 710054, Shaanxi, China;

3. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China)

Abstract: Beizhan iron deposit in Xinjiang is one of the important deposits of Awulale ironcoppergold metallogenic belt in the western Tianshan.Kfeldspar granite and Kfeldspar granite porphyry, which have pulsating intrusive contact relationship, are exposed in the southern of iron district. Geochemical characteristics show that the rocks are high potassium calcalkaline, enriched in large iron lithophile element (Rb and K), and relatively depleted in high field strength elements, and Ba, Sr, P and Ti are significantly negative anomaly; fractionation of light and heavy rare earth elements is obvious. Ages of Kfeldspar granite and Kfeldspar granite porphyry from Beizhan iron deposit are respectively (320.5±1.9)Ma and (306.8±1.6)Ma by the method of LAICPMS zircon UPb dating. Combined with regional geological data, the geochemical and geochronological results show that Kfeldpar granite and Kfeldspar granite porphyry exposed have the same magma source, and probably form in the tectonic setting transformed from the subduction of southern Tianshan oceans to the continental collision orogeny from Early Carboniferous to Late Carboniferous.

Key words: iron deposit; geochemistry; intrusive rock; zircon; Kfeldpar granite; Kfeldspar granite porphyry; western Tianshan; Xinjiang

0引言

新疆西天山阿吾拉勒成矿带是中国重要的铁铜金成矿带之一，近年来铁矿勘查工作取得重大进展，相继勘查发现了查岗诺尔、备战、智博、敦德、松湖、雾岭及尼新塔格—阿克萨依等多个铁矿床，已经成为新疆重要的铁矿开发基地。伴随铁矿的勘查，该地矿床研究也取得了大量的研究成果［113］，但对矿床成矿环境和成矿机制、成矿规律认识还存在分歧和争议，前人对矿床形成提出了火山岩型［1］、火山喷气沉积改造型［2］、矽卡岩型［3］、以安山质(玄武质)岩浆为母岩浆的岩浆矿床和热液的复合型［45,11］、与火山活动和岩浆热液交代有关［6,910］等不同认识。……