Search

我国华南是世界上最重要的锡矿资源省之一，其锡矿成矿时代从新元古代、古生代、早中生代至晚中生代均有发育，其中以晚中生代锡矿成矿作用最为重要，成矿集中在中晚侏罗世（160~150Ma）和晚白垩世（100~80Ma）。然而，最近在东南沿海成矿带新识别出一期早白垩世锡（钨）（145~130Ma）成矿事件，改变了以往华南锡（钨）矿床时空分布格局。本文在详细介绍东南沿海早白垩世锡（钨）矿床地质特征基础上，系统总结了其成岩成矿时空分布，并与南岭板内锡（钨）成矿作用进行对比，浅析了早白垩世锡（钨）矿的成岩成矿背景和找矿潜力。研究显示，早白垩世锡（钨）成矿主要发生在东南沿海成矿带的粤东和赣州会昌地区，矿床类型以斑岩型和锡石硫化物型为主。与成矿有关的岩石为黑云母花岗岩和花岗斑岩，成因上属于高分异I型或A型，与南岭板内锡（钨）矿相比，具有较高的锆石eHf（t）值和较低δ18O值，以及较高成岩温度，表明成岩过程中有较多新生地壳或地幔物质加入。结合区内发育同时期基性岩脉，认为华南这期早白垩世锡（钨）矿形成于岩石圈伸展背景，与古太平洋板块俯冲后撤有关。最后指出覆盖大面积晚白垩世火山岩的东南沿海地区，火山岩盖层下部具有寻找该期锡（钨）矿床的找矿潜力。

Previous studies have obtained some petrogenetic and metallogenic chronological data with SHRIMP (sensitive high-resolution ion microprobe) zircon U-Pb, zircon LA-ICPMS (laser-ablation–inductively coupled plasma mass spectroscopy) U-Pb, molybdenite Re-Os isochron and muscovite Ar-Ar methods in southern Jiangxi Province and its adjacent areas. Based on these, the purpose of this paper is to study the petrogenetic and metallogenic ages and their time gap for different genetic types of W-Sn deposits, and thus to research their numerous episodes, zonal arrangement and their geodynamic background. The result shows that the large-scale W-Sn mineralization in southern Jiangxi Province occurred in the middle to late Jurassic (170–150 Ma), the skarn W-Sn-polymetallic deposits formed much earlier (170–161 Ma), and all of the wolframite – quartz vein type, greisen type, altered granite type and fractured zone type tungsten deposits formed in the late Jurassic (160–150 Ma). In one ore field or ore district, greisen type tungsten deposits formed earlier than quartz vein type ones hosted in the endo- or exo-contact zone; and quartz vein type hosted in the endocontact zone formed earlier than that of exocontact zone. There is no significant time difference between tungsten-tin mineralization and its intimately associated parent granite emplacement (1–6 Ma). They all formed in the same rock-forming and ore-forming system and under the same geodynamic setting. Regionally, rock-forming and ore-forming processes of the W-Sn deposits in the Nanling region (include southern Jiangxi Province, southern Hunan Province, northern Guangdong Province and eastern Guangxi Zhuang Autonomous Region) exhibit numerous episodes. The mineralization in the Nanling region mainly occurred at (240–210) Ma, (170–150) Ma and (130–90) Ma. The tungsten-tin deposits in this region are centered by the largest scale in southern Jiangxi Province and southern Hunan Province, and become small in the east, west, south and north directions. This displays a zonal arrangement and temporal and spatial distribution regularity. Integrated with the latest research results, it is concluded that the W-Sn mineralization in southern Jiangxi Province and its adjacent areas corresponds to the second large-scale mineralization in South China. The Indosinian W-Sn mineralization formed under the extensional tectonic regime between collisional compressional stages, while the Yanshanian large-scale petrogenetic and metallogenic processes occurred in the Jurassic intraplate extensional geodynamic setting of lithosphere extension.

The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma (n=11, MSWD=1.3). Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153±3 Ma and model ages of 150.2±2.1 Ma – 155.4±2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Huangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150–170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2–6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1–4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133∼135 Ma, 150–162 Ma, and 166–170 Ma, respectively. The 150–162 Ma-stage is in accordance with ages of large-scale W-Sn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.