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赣东北塔前—赋春成矿带岩浆岩时代限定与序列划分及其意义

Northeast Jiangxi Taqian-Fuchun Metallogenic Belt Magmatite Time Limit and Sequence Division and Its Significance

  • 摘要: 赣东北地区朱溪超大型铜钨矿床的发现,突破了江西境内“南钨北铜”的传统认识,引起了我国同行对朱溪铜钨矿区所在塔前—赋春成矿带的关注,重新研究塔前—赋春成矿带的地质特征是解释“南钨北扩”现象的关键所在。塔前—赋春成矿带成矿类型复杂,矿种多样,富集铜、钨、钼、金等多金属,但多与各类岩浆岩成岩作用相关。本文利用激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)锆石U-Pb法对岩浆岩进行定年,探讨 “南钨北扩”的构造演化背景和物质来源的地质科学问题。系统分析表明:塔前—朱溪—赋春成矿带上至少有3期岩浆岩活动、2期成矿作用。3期岩浆岩活动分别是850 Ma的花岗闪长岩和煌斑岩脉、160 Ma花岗闪长岩和煌斑岩以及146 Ma的花岗岩;2期成矿作用分别是与160 Ma岩浆岩有关的塔前矽卡岩型钨钼矿床和月形矽卡岩型铜多金属矿床、与146 Ma花岗岩有关的朱溪矽卡岩型铜钨矿床。在收集区域已有资料的基础上,依据本次的同位素年代学研究,分析认为塔前—赋春成矿带上晋宁期的岩浆岩和燕山期成矿岩浆岩的成岩源岩一致,燕山期成矿岩浆岩是继承于晋宁期岩浆岩作用而成,而形成于145 Ma的花岗斑岩脉及细晶岩脉是勘查铜钨矿的标志。

     

    Abstract: It is a fatal challenge to the traditional cognition, which the W and Cu deposits distribute in the south and north regions of Jiangxi Province respectively, when the super Cu-W deposit in Zhuxi area was discovered recently, which attracts domestic researchers' attention and their interests in restudying geology of Taqian-Fuchun metallogenic belt in Zhuxi area that provides pivotal proofs for phenomenon of the south W deposit extends to the north region of the area. The recent discovery of the super Cu-W deposit in the Zhuxi area of northeast Jiangxi has challenged the belief that W and Cu deposits are distributed in the south and north regions of the province respectively and has led to a renewed interest in analyzing these areas again. The metallogenesis types in the Taqian-Fuchun metallogenic belt are complicated with multiple ores. For instance, Cu, W, Mo and Au are related to various igneous rocks, with some diagenesis. To address geological issues, such as the tectonic evolutional setting and ore material origins, which need to be solved urgently, the zircon U-Pb isotopic method of LA-ICP-MS was utilized and is reported in this paper in order to date the ore-related magmatic rocks. The results show that there were at least three periods of magmatism and two stages of metallogenesis in the belt. The three periods of magmatism include 850 Ma and 160 Ma granodiorites and for the lamprophyre veins, 146 Ma granites. Two stages of metallogenesis are the Taqian skarn-type W-Mo deposit and the Yuexing skarn-type Cu polymetallic deposit related to the 160 Ma granites, and the Zhuxi skarn-type Cu-W deposit related to the 146 Ma granites. Thus, considering previous regional data, the hypothesis from this study is that the ore-related magmas of Neoproterozoic and Jurassic in the belt were derived from the same magma chamber and the latter was inherited from the former. The porphyry granite and aplite veins formed in 145 Ma are the indicators of Cu-W deposit.

     

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