Mélanges and mélange-forming processes: a historical overview and new concepts
Mélanges and mélange-forming processes: a historical overview and new concepts
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DOI：
10.1080/00206810903557704
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发表时间：
2010-02
影响因子：
2.6
通讯作者：
A. Festa;G. Pini;Y. Dilek;G. Codegone
中科院分区：
文献类型：
--
作者：
A. Festa;G. Pini;Y. Dilek;G. Codegone
混杂岩是碰撞和增生造山带的重要组成部分，广泛分布于世界各地。自其首次引入和使用以来，该术语已演变为涵盖混杂岩形成的构造过程（构造、沉积和底辟）和构造环境。各种术语的含义和意义，指的是“块在矩阵混沌岩石”的起源仍然受到争议。本研究对混杂岩概念的演变进行了历史回顾，并探讨了混杂岩类型与其形成构造环境之间的关系。我们调查的贡献，质量运输与收缩变形过程中的混杂岩形成的开始，并在整个不同的混杂岩类型的演变，和连续性的性质和过渡，从破碎的地层真正的构造混杂岩。混杂岩是一种可测绘的混杂岩石的混沌体，具有块状基质结构，其内部结构和演化与其起源的构造、沉积、岩浆和变质过程密切相关。在对比分析已发掘的古陆混杂岩与现代混杂岩形成的构造环境的基础上，将其划分为与伸展构造、被动边缘演化、走滑构造、俯冲带、碰撞构造和陆内变形有关的单元。在所有这些构造环境中，沉积作用和收缩变形对混杂岩的形成都有重要贡献，尽管矿床的内部结构受到单一构造环境中混杂岩形成最后阶段的主要过程的强烈控制和叠加。构造混杂岩通常从属于破碎的地层，并局限于狭窄的、拉长的、合并的断层带、大型断层带和板块边界。
Mélanges represent a significant component of collisional and accretionary orogenic belts and occur widely around the world. Since its first introduction and use, the term has evolved to cover both processes (tectonic, sedimentary, and diapiric) and tectonic settings of mélange formation. The meaning and significance of various terms referring to the origin of ‘block-in-matrix chaotic rocks’ are still subject to debate. This study presents a historical overview of the evolving mélange concept and investigates the relationships between mélange types and their tectonic settings of formation. We investigate the contribution of mass-transport versus contractional deformation processes at the onset of mélange formation and throughout the evolution of different mélange types, and the nature of the continuum and transition from broken formations to true tectonic mélanges. A mélange is a mappable chaotic body of mixed rocks with a block-in-matrix fabric whose internal structure and evolution are intimately linked to the structural, sedimentary, magmatic, and metamorphic processes attending its origin. On the basis of a comparative analysis of exhumed, ancient on-land mélanges and modern tectonic environments, where mélange-forming processes are at work, such units are classified into those related to extensional tectonics, passive margin evolution, strike-slip tectonics, subduction zones, collisional tectonics, and intracontinental deformation. Sedimentation and contractional deformation contribute significantly to mélange formation in all these tectonic environments, although the internal structure of deposits is strongly controlled and overprinted by processes that prevail during the last stages of mélange formation in a single tectonic setting. Tectonic mélanges are commonly subordinate to broken formations and are restricted to narrow, elongated-to-coalescent fault zones, large-scale fault zones, and plate boundaries.