The Age of the Latest Thermal Overprint of Tin and Polymetallic Deposits in the Erzgebirge, Germany: Constraints from Fluorite (U-Th-Sm)/He Thermochronology
The Age of the Latest Thermal Overprint of Tin and Polymetallic Deposits in the Erzgebirge, Germany: Constraints from Fluorite (U-Th-Sm)/He Thermochronology
复制标题
DOI：
10.2113/econgeo.110.8.2025
复制
发表时间：
2015-12
期刊：
影响因子：
5.8
通讯作者：
R. Wolff;I. Dunkl;U. Kempe;H. Eynatten
中科院分区：
文献类型：
--
作者：
R. Wolff;I. Dunkl;U. Kempe;H. Eynatten
德国的Erzgebirge地区记录了两个主要的热液活动事件，其中包括晚石炭世至早二叠世事件，与华力西晚期花岗岩岩浆活动有关的显著的锡-钨成矿作用，以及中生代多金属脉成矿作用。与第一次事件相反，较年轻的热液活动的年龄受到很大的限制。对于后者，各种地质年代学方法产生了广泛的年龄范围从二叠纪到早第三纪。在这里，我们将萤石（U-Th-Sm）/He热年代学（FHe）应用于两种类型的矿化，具有双重目标：（1）研究新的FHe方法的灵敏度和适用性（Evans等人，2005），和（2）限制热历史的矿床在Erzgebirge地区。已对7个矿化地点的233份样品进行了年代测定。六个矿床的萤石FHe年龄在112 ~ 79 Ma之间，与它们的共生关系无关。相比之下，来自Sadisdorf Sn-W存款的萤石的年龄为234 Ma。较年轻的年龄被解释为冷却年龄，表明最后一次热叠加的时间，包括可能的热液活动，在厄尔士山脉。最古老的，三叠纪FHe年龄在Sadisdorf表明，中生代的热叠加只有部分重置（U-Th-Sm）/He系统的华力西晚期矿化。热模拟的基础上FHe年龄和他在萤石中的扩散参数的结果在热历史相媲美的结果，从完善的磷灰石为基础的热模拟。本研究强调了萤石（U-Th-Sm）/He热年代学的适用性，特别适用于缺乏磷灰石的矿床。
The Erzgebirge region of Germany records two major episodes of hydrothermal activity, which includes a Late Carboniferous to Early Permian event associated with significant Sn-W mineralization that is related to late Variscan granite magmatism, and a Mesozoic episode of polymetallic vein mineralization. In contrast to the first event, the age of the younger hydrothermal activity is poorly constrained. For the latter, various geochronological methods yielded a wide age range from Permian to early Tertiary. Here we apply fluorite (U-Th-Sm)/He thermochronology (FHe) on both types of mineralization with a twofold goal: (1) to investigate the sensitivity and applicability of the new FHe method (Evans et al., 2005), and (2) to constrain the thermal history of ore deposits in the Erzgebirge region. Two hundred and thirty-three aliquots from seven mineralization localities have been dated. Fluorite from six deposits yielded Cretaceous FHe ages between 112 to 79 Ma, which are independent of their paragenesis. In contrast, fluorite from the Sadisdorf Sn-W deposit yielded an age of 234 Ma. The younger ages are interpreted as cooling ages indicating the time of the last thermal overprint, including possible hydrothermal activity, in the Erzgebirge. The oldest, Triassic FHe ages at Sadisdorf indicate that the Mesozoic thermal overprint only partially reset the (U-Th-Sm)/He system of the late Variscan mineralization. Thermal modeling based on FHe ages and He diffusion parameters in fluorite results in thermal histories comparable to the results from the well-established apatite-based thermal modeling. This study emphasizes the applicability of fluorite (U-Th-Sm)/He thermochronology, which is especially suited for ore deposits where apatite is lacking.