地学前缘 ›› 2009, Vol. 16 ›› Issue (6): 55-65.

• 论文 • 上一篇    下一篇


太平洋海山成矿系统与成矿作用过程

石学法,任向文,刘季花   

  1. 海洋沉积与环境地质国家海洋局重点实验室, 国家海洋局第一海洋研究所, 山东 青岛 266061
  • 收稿日期:2009-11-24 修回日期:2009-11-25 出版日期:2009-12-16 发布日期:2009-12-10
  • 基金资助:

    科学技术部国际科技合作重大项目(2006DFB21620);国际海底区域研究开发“十一五”课题(DYXM1150121);国家自然科学基金项目(40806027)；“泰山学者”建设工程项目

Ferromanganese metallogenic system and oreforming processes of seamounts in the Pacific. 

 DAN Hua-Fa, LIN Xiang-Wen, LIU Ji-Hua   

  • Received:2009-11-24 Revised:2009-11-25 Online:2009-12-16 Published:2009-12-10

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摘要：

文中初步探讨了太平洋海山富钴结壳成矿系统的结构与成矿作用过程。海山成矿系统的控矿要素主要包括地质要素和海洋要素,地质要素主要包括海山的形成、迁移、沉降和水道的开合等,海洋要素主要包括大洋温盐环流、最低含氧带(OMZ)、文石溶跃面、碳酸盐补偿深度和海山周围海水的动力情况等。重点分析了海山漂移和沉降、水道开合、最低含氧带变化、大洋环流以及气候变化等要素对富钴结壳成矿的控制作用。海山为富钴结壳成矿提供了一个容矿空间,稳定的基岩,即长期稳定的容矿空间,是富钴结壳成矿的基本条件;海山的形成年龄、海山的迁移和水道的开合决定并改变了富钴结壳的成矿背景条件,促使海山成矿系统发生演化。最低含氧带作为富钴结壳成矿的地球化学障,是直接的矿源层;而海山周边的地形旋涡沟通了最低含氧带与富氧、富铁的深层和底层水,使得最低含氧带中的成矿金属离子得到氧化,进而发生胶体凝聚沉淀,形成富钴结壳。以西太平洋海山成矿系统为例,将该区白垩纪以来富钴结壳成矿作用过程划分为5个阶段:(1)白垩纪—始新世,(2)始新世末—晚渐新世,(3)晚渐新世—中中新世早期,(4)中中新世早期—晚中新世早期,(5)晚中新世早期—现代,其中(2)、(3)阶段有利于发育富钴结壳。

关键词: 关键词：海山成矿系统;富钴结壳;控矿要素;成矿过程和阶段;太平洋

Abstract:

 The structure of metallogenic system and oreforming processes are studied preliminarily in this essay for Corich MnFe crusts on the seamounts in the Pacific. Orecontrolling factors of ferromanganese metallogenic system on seamounts mainly include geological and oceanographic factors. The major geological factors are composed of the formation, migration and drowning of seamounts, as well as opening and closure of seaways. The major oceanographic factors are composed of thermohaline circulation, oxygen minimum zone (OMZ), aragonite lysocline, carbonate compensation depth, and hydrodynamic conditions around seamounts. This essay focuses on the orecontrolling factors on Corich FeMn crusts, which could be the migration and drowning of seamounts, opening and closure of seaways, evolution of OMZ, variation of ocean circulation and climate change. Seamounts provide an oreholding space for the precipitation of Corich FeMn crusts. Longterm stability of an oreholding space is the precondition for the precipitation of crusts; the age of seamounts, migration of seamounts, and the opening and closure of seaways constrained the evolution of oreforming background of seamount metallogenic system for Corich FeMn crusts. OMZ is the predominant geochemical barrier zone for the mineralization of crusts, and a major source for manganese; internal tide and eddies mixed the OMZ seawater and oxygen and Ferich deep and bottom water, which resulted in the oxidation of metal ions, aggregation and then the precipitation of colloid, and the formation of Corich FeMn crusts. Taking the Magellan Seamount Cluster and Marcuswake Seamount Cluster as an example, the oreforming process of Corich FeMn crusts since the late Cretaceous is divided into five stages: (1) the Cretaceousthe Eocene; (2) the Late Eocenethe Late Oligocene; (3) the Late Oligocenethe early Middle Miocene; (4) the early Middle Miocenethe early Late Miocene; (5) the early Late Miocenethe present. Stage 2 and 3 are favorable for the formation of Corich FeMn crusts.

Key words: Key words: seamount metallogenic system; Corich FeMn crusts; orecontrolling factors; oreforming processes and stages; the Pacific