The Xitieshan volcanic sediment-hosted massive sulfide deposit, North Qaidam, China: Geology, structural deformation and geochronology
The Xitieshan volcanic sediment-hosted massive sulfide deposit, North Qaidam, China: Geology, structural deformation and geochronology
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中国柴北缘西铁山火山沉积物块状硫化物矿床：地质、构造变形和年代学
DOI：
10.1016/j.oregeorev.2016.08.027
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发表时间：
2017
影响因子：
3.3
通讯作者：
Dong Chaoge
中科院分区：
文献类型：
--
作者：
Fu Jiangang;Liang Xinquan;Wang Ce;Zhou Yun;Jiang Ying;Dong Chaoge
锡铁山存款（~ 64 Mt，含Zn 4.86%，Pb 4.16%，Ag 58 g/t，Au 0.68 g/t）产于柴北缘构造成矿带中-晚奥陶世滩间山群。该带以岛弧火山岩、超高压变质岩和蛇绿岩为特征。滩间山群是一套变质的双峰式火山岩和沉积岩系，形成于柴达木地块和祁连地块之间的弧后洋盆边缘，在其内部划分出4个地层单位。自北东向南西依次为：1）a单元，即下部火山-沉积岩，由双峰式火山岩组成（a-1单元）和沉积岩2）B单元，即中基性火山碎屑岩，以中基性火山碎屑岩夹层状碳质片岩和少量大理岩透镜体为特征;（3）c单元为紫红色桑迪砾岩，不整合地覆盖在B单元之上，代表早志留世前陆盆地沉积的产物; 4）d单元，即基性火山岩，自下而上包括下部基性火山岩（d-1单元）、中碎屑沉积岩（d-2单元）、上基性火山岩（d-3单元）和最上部基性火山岩（d-4单元）。块状硫化物以a-2单元为主，B单元次之，锡铁山存款以块状层状透镜体为主，半块状硫化物和不规则硫化物数量较多，细脉中硫化物数量较少。硫化物矿物以黄铁矿、方铅矿和闪锌矿为主，磁黄铁矿和黄铜矿次之。锆石U-Pb年代学研究表明，a-1单元下盘长英质火山岩、a-2单元沉积容矿岩和上盘B单元沉积容矿岩的年龄分别为454 Ma、452 Ma和451 Ma。锡铁山存款与滩间山群a-2单元和B单元的沉积时代相同。锡铁山存款经历了以韧性剪切为主和以韧脆性变形为主的两个阶段的强烈变形。韧性剪切带中糜棱岩化花岗质片麻岩中白云母的40 Ar-39 Ar年龄为~ 399 Ma，确定了锡铁山韧性剪切带的时代。锡铁山存款具有许多与加拿大巴瑟斯特地区相似的特征，西班牙的伊比利亚黄铁矿带，加拿大的金刚狼火山成因块状硫化物存款。锡铁山存款矿床在构造背景、赋矿岩石类型、局部地质背景、金属品位、年代学、成矿流体温度、盐度和硫源等方面具有类似于沉积喷流（SEDEX）和VMS矿床的特征，并与火山-沉积岩容矿块状硫化物（VSHMS）矿床相似。
The Xitieshan deposit (~ 64 Mt at 4.86% Zn, 4.16% Pb, 58 g/t Ag, and 0.68 g/t Au) is hosted by the Middle to Late Ordovician Tanjianshan Group of the North Qaidam tectonic metallogenic belt, NW China. This belt is characterized by island arc volcanic, ultra-high pressure (UHP) metamorphic and ophiolitic rocks. The Tanjianshan Group constitutes a succession of metamorphosed bimodal volcanic and sedimentary rocks, which are interpreted to have formed on the margin of a back-arc ocean basin between the Qaidam block and the Qilian block.Four stratigraphic units are identified within the Ordovician Tanjianshan Group. From northeast to southwest they are: 1) unit a, or the lower volcanic-sedimentary rocks, comprising bimodal volcanic rocks (unit a-1) and sedimentary rocks (unit a-2) ranging from carbonates to black carbonaceous schist; 2) unit b, or intermediate-mafic volcaniclastic rocks, characterized by intermediate to mafic volcaniclastic rocks intercalated with lamellar carbonaceous schist and minor marble lenses; 3) unit c, a purplish red sandy conglomerate that unconformably overlies unit b, representing the product of the foreland basin sedimentation during the Early Silurian; 4) unit d, or mafic volcanic rocks, from base to up, comprising the lower mafic volcaniclastic rocks (unit d-1), middle clastic sedimentary rocks (unit d-2), upper mafic volcaniclastic rocks (unit d-3), and uppermost mafic volcanic rocks (unit d-4). Unit a-2 hosts most of the massive sulfides whereas unit b contains subordinate amounts.The massive stratiform lenses constitute most of the Xitieshan deposit with significant amount of semi-massive and irregularly-shaped sulfides and minor amounts in stringer veins. Pyrite, galena and sphalerite are the dominant sulfide minerals, with subordinate pyrrhotite and chalcopyrite. Quartz is a dominant gangue mineral. Sericite, quartz, chlorite, and carbonate alteration of host rocks accompanies the mineralization.U-Pb zircon geochronology yields three ages of 454 Ma, 452 Ma and 451 Ma for the footwall felsic volcanic rocks in unit a-1, sedimentary host rocks in unit a-2 and hanging-wall unit b, respectively. The Xitieshan deposit is considered to be coeval with the sedimentation of unit a-2 and unit b of the Tanjianshan Group. The Xitieshan deposit has been intensely deformed during two phases (main ductile shear and minor ductile-brittle deformation). The main ductile shear deformation controls the general strike of the ore zones, whereas minor deformation controls the internal geometry of the ore bodies.40Ar-39Ar age of muscovite from mylonitized granitic gneisses in the ductile shear zone is ~ 399 Ma, which is interpreted to date the Xitieshan ductile shear zone, suggesting that Early Devonian metamorphism and deformation post-dated the Tanjianshan Group.The Xitieshan deposit has many features similar to that of the Bathurst district of Canada, the Iberian Pyrite Belt of Spain, the Wolverine volcanogenic massive sulfide deposit in Canada. Based on its tectonic setting, host-rock types, local geologic setting, metal grades, geochronology, temperatures and salinities of mineralizing fluid and source of sulfur, the Xitieshan deposit has features similar to sedimentary exhalative (SEDEX) and VMS deposits and is similar to volcanic and sediment-hosted massive sulfide (VSHMS) deposits.
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影响因子：
5.8
作者：
R. Large;S. Bull;P. McGoldrick;S. Walters;G. M. Derrick;G. Carr
通讯作者：
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影响因子：
3
作者：
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通讯作者：
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影响因子：
5.8
作者：
S. Piercey;J. Peter;J. Mortensen;S. Paradis;D. Murphy;T. L. Tucker
通讯作者：
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影响因子：
3.3
作者：
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通讯作者：
Changming Wang;Jun Deng;E. Carranza;Xiangru Lai
影响因子：
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作者：
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通讯作者：
Jingsui Yang;Cailai Wu;Jianxin Zhang;R. Shi;F. Meng;J. Wooden;Houng-Yi Yang