| 华北克拉通北缘西段新元古代裂谷的确认与成矿 |
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| 引用本文： | 彭润民,王建平. 华北克拉通北缘西段新元古代裂谷的确认与成矿[J]. 地学前缘, 2020, 27(2): 420-441. DOI: 10.13745/j.esf.sf.2020.3.30 |
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| 作者姓名： | 彭润民 王建平 |
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| 作者单位： | 中国地质大学(北京) 地球科学与资源学院,北京 100083 |
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| 基金项目： | 中国地质调查局项目“中国北方两个重要成矿系统的形成、保存及评价”(1212011220923);国家重点基础研究发展计划“973”项目(2012CB416604);国家重点研发计划项目(2016YFC0600502) |
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| 摘 要： | 狼山-渣尔泰山是华北克拉通北缘西段元古宙伸展构造体制下被动陆缘的重要热水喷流成矿带,内产东升庙、炭窑口、霍各乞、甲生盘等大型-超大型矿床,其含矿建造是元古宇渣尔泰山群。该成矿带的主体在狼山山脉主峰地区,产有东升庙、炭窑口、霍各乞三大矿床。自2010年在狼山西南原渣尔泰山群阿古鲁沟组地层中发现新元古代酸性火山岩(锆石年龄816~805 Ma)以来,其东部狼山主峰地区的渣尔泰山群及产在其中的炭窑口、东升庙、霍各乞矿床是否也都可以归于新元古代形成是需要进一步研究的重要科学问题。本文依据的事实有:(1)狼山西南新元古界的碎屑锆石最小年龄为1 155 Ma与碳酸盐岩是方解石大理岩;(2)炭窑口矿区渣尔泰山群顶部刘鸿湾组地层的碎屑锆石年龄的两个年龄峰值分别为1 862~1 762 Ma(最小年龄为1 732 Ma)和2 448 Ma,所含碳酸盐岩全部是白云石大理岩类;(3)狼山北侧狼山群含矿岩组中发现年龄为887 Ma±的新元古代基性火山岩; (4)霍各乞矿床含重晶石与微晶长石的硅质层发育,多与黄铁矿层互层状产出,也有与闪锌矿+磁黄铁矿及方铅矿层互层,激光原位分析得到的黄铁矿、方铅矿、闪锌矿和磁黄铁矿的δ34S为17.60‰~21.97‰,显示喷流成矿的硫同位素组成特征。根据以上事实可以确认:(1)狼山西南含酸性火山岩与方解石大理岩的前寒武纪地层是与狼山南侧炭窑口矿区含白云石大理岩的渣尔泰山群在不同盆地中沉积而成;(2)狼山南侧是中元古代裂谷带,产有以炭窑口、东升庙矿床为代表的中元古代喷流-沉积成矿系统;(3)狼山北侧是新元古代裂谷带,产有以霍各乞矿田为代表的新元古代热水喷流成矿系统。产在新元古代狼山群中的霍各乞矿是介于SEDEX型与VMS型之间、但靠近SEDEX型一侧的热水喷流-沉积矿床。
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| 关 键 词： | 中元古代裂谷 新元古代裂谷 华北克拉通北缘西段 内蒙古狼山 |
| 收稿时间： | 2020-03-02 |
Confirmation and metallogenesis of the Neoproterozoic rift in the western section of the northern margin of the North China Craton |
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| PENG Runmin,WANG Jianping. Confirmation and metallogenesis of the Neoproterozoic rift in the western section of the northern margin of the North China Craton[J]. Earth Science Frontiers, 2020, 27(2): 420-441. DOI: 10.13745/j.esf.sf.2020.3.30 |
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| Authors: | PENG Runmin WANG Jianping |
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| Affiliation: | School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China |
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| Abstract: | The Langshan-Zha'ertaishan metallogenic belt, consisting of the Tanyaokou, Huogeqi, Dongshengmiao and Jiashengpan large-superlarge Zn-Pb-Cu-Fe sulphide deposits hosted in the Proterozoic Zha'ertaishan Group, is an important hydrothermal mineralization belt of the Proterozoic passive continental margin in an extensional structural regime in the western section of the northern margin of the North China Craton. Most areas of the mineralization belt distribute in the Langshan Mountain district. Three of the four typical deposits, the Huogeqi, Dongshengmiao and Tanyaokou deposits, occur in this region. It becomes an important scientific issue whether all the Mesoproterozoic Zha'ertaishan Group in the Langshan Mountain's core area and the three deposits hosted in the Zha'ertanshan Group be re-classified as the Neoproterozoic, after the 2010 discovery of acidic volcanic rocks with zircon ages of 816-805 Ma in the southwestern Langshan Mountain. Evidence includes (1) the minimum detrital zircon age of 1155 Ma for the meta-sedimentary rocks of the Precambrian strata with calcite marble from southern Langshan Mountain, (2) the detrital zircon age peaks at 1862-1762 (youngest age 1732 Ma) and 2448 Ma for the Liuhongwan Formation of the Zha'ertaishan Group with dolomate marble in the Tanyaokou district, (3) the occurrence of Neoproterozoic (887.4±9.1 Ma) meta-mafic volcanic rocks in the host formation of the Langshan Group in the north side of the Langshan Mountain, and (4) the “interbedding” of siliceous bands containing barite and microcrystal feldspar with pyrites, sometimes sphalerites and pyrrhotite and galena, with δ34S values of these four sulfide minerals varying between 17.60‰ and 21.97‰ and showing the characteristics of hydrothermal exhalation. Based on the evidence, we suggest the following: (1) the Zha'ertaishan Group hosting dolomite marble in the Tanyaokou district, and the Precambrian strata (formerly called the Zha'ertaishan Group) hosting acidic volcanic rocks and calcite marbles in southwest Langshan, were deposited in two different rift basins; (2) the Mesoproterozoic rifts and hydrothermal metallogenic systems in the south side of the Langshan Mountain developed the Tanyaokou and Dongshengmiao deposits in the Mesoproterozoic Zha'ertaishan Group; and (3) the Neoproterozoic rift and hydrothermal metallogenic system in the north side of the Langshan Mountain developed the Huogeqi orefield in the Neoproterozoic Langshan Group. The Huogeqi deposit hosted in the Neoproterozoic Langshan Group obviously appears to be a transitional type of mineral deposits between the SEDEX and VMS types with a bias towards SEDEX type. |
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| Keywords: | Mesoproterozoic rift Neoproterozoic rift the western section of the northern margin of the North China Craton Langshan Inner Mongolia |
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