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Multi-source and multi-stage metal mobilization during the tectonic evolution of the Central Lapland Greenstone Belt, Finland: implications for the formation of orogenic Au deposits
Mineralium Deposita ( IF 4.4 ) Pub Date : 2022-09-11 , DOI: 10.1007/s00126-022-01133-z
C. G. C. Patten , F. Molnár , I. K. Pitcairn , J. Kolb , S. Mertanen , S. Hector

Precambrian greenstone belts are prospective terrains for orogenic Au deposits worldwide, but the sources of Au, base metals, metalloids, and ligands enriched within the deposits are still debated. Metamorphic devolatilization is a key mechanism for generating Au-rich hydrothermal fluids, but the respective role of the metavolcanic and metasedimentary rocks present within these belts in releasing ore-forming elements is still not fully understood. The Central Lapland Greenstone Belt (CLGB), Finland, one of the largest Paleoproterozoic greenstone belts, hosts numerous orogenic Au deposits and is composed of variably metamorphosed volcanic and sedimentary rocks. Characterization of element behavior during prograde metamorphism highlights that (1) metavolcanic rocks release significant Au, As, Sn, Te, and possibly S; (2) metasedimentary rocks release significant S, C, Cu, As, Se, Mo, Sn, Sb, Te, and U, but limited Au; and (3) metakomatiite releases C and possibly Au. Throughout the CLGB metamorphic evolution, two main stages are identified for metal mobilization: (1) prograde metamorphism at ~ 1.92–1.86 Ga, promoting the formation of typical orogenic Au deposits and (2) late orogenic evolution between ~ 1.83 and 1.76 Ga, promoting the formation of both typical and atypical orogenic Au deposits. The complex lithologic diversity, tectonic evolution, and metamorphic history of the CLGB highlight that metal mobilization can occur at different stages of an orogenic cycle and from different sources, stressing the necessity to consider the complete dynamic and long-lasting evolution of orogenic belts when investigating the source of Au, ligands, metals, and metalloids in orogenic Au deposits.



中文翻译:

芬兰中拉普兰绿岩带构造演化过程中的多源多阶段金属迁移:对造山带金矿床形成的影响

前寒武纪绿岩带是全球造山金矿床的潜在地形,但矿床中富集的金、贱金属、准金属和配体的来源仍存在争议。变质脱挥发分是产生富金热液的关键机制,但这些带内变质火山岩和变沉积岩在释放成矿元素中的作用尚不完全清楚。芬兰中央拉普兰绿岩带 (CLGB) 是最大的古元古代绿岩带之一,拥有大量造山带金矿床,由变质的火山岩和沉积岩组成。推进变质作用过程中元素行为的特征突出表明(1)变质火山岩释放出大量的金、砷、锡、碲,可能还有硫;(2) 变沉积岩释放大量的S、C、Cu、As、Se、Mo、Sn、Sb、Te、U,但少量的Au;(3) metakomatiite 释放 C 和可能的 Au。在整个 CLGB 变质演化过程中,确定了金属迁移的两个主要阶段:(1) 约 1.92-1.86 Ga 的推进变质作用,促进典型造山金矿床的形成;(2) 约 1.83 和 1.76 Ga 之间的晚期造山演化,促进典型和非典型造山金矿床的形成。CLGB复杂的岩性多样性、构造演化和变质历史突出表明,金属活动可能发生在造山旋回的不同阶段和不同来源,强调在调查时必须考虑造山带的完整动态和长期演化Au、配体、金属的来源,

更新日期:2022-09-12
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