Tectonics and Metallogeny of the Tethyan Orogenic Belt

The Tethyan orogenic belt stretches from the Alps, through the Carpathians and Balkans, Taurides and Caucasus, Zagros, Makran, and Himalayas, to Indochina and into the southwest Pacific Ocean. It represents a complete Wilson Cycle, from opening and closure of the Paleotethys Ocean in the mid-Paleozoic to the Late Triassic, opening of the Neotethys Ocean in the Permian-Early Triassic, and its progressive closure throughout the late Mesozoic and Cenozoic eras. The current state of the orogen includes all stages of convergence from active subduction beneath the Makran and eastern Mediterranean, through advanced continental collision in the Caucasus/Taurides and Zagros, to syn- to postcollisional readjustment in the Carpathians, Balkans, Himalayas, and Indochina (Richards, 2015).
The region has been the focus of significant recent attention from geologists interested both in its tectonic evolution and metallogeny, made possible by increased accessibility to many of the geographic sections of the orogen. Key breakthroughs in understanding its tectonic history have come through improved geochronological techniques and expansion of the database of samples and events dated, combined with more accurate paleogeographic and tectonic models. In parallel, an improved understanding of the subtle relationships between tectonomagmatic and metallogenic processes have refined interpretations that were once based on simplistic assumptions (e.g., that porphyry deposits only form above active subduction zones). Indeed, economic geologists have been among the key drivers of these advances by demanding more accurate and predictive tectonomagmatic models for ore formation that can reliably inform mineral exploration.
Consequently, the Tethyan orogen is now understood to be the best preserved global example of a collisional orogen, where all stages of convergence can be observed in real or recent geological time, and the detailed relationships to ore formation, commonly reflecting tectonic changes measured on submillion-year timescales, can be accurately documented and modeled.
In this volume, we present a selection of papers that showcase this advancement in knowledge, with examples from Eastern Europe to South Asia.Beginning in the Balkans, Knaak et al. (2016) describe the variety of mineral deposits that occur in the emergent worldclass Timok region of eastern Serbia. The origin of the Late Cretaceous Timok Magmatic Complex remains debated, but the authors propose that arc magmatism was focused by dextral transtensional structures, followed by complex structural rearrangement in the Cenozoic. Porphyry Cu-Au deposits, polymetallic replacement deposits, and sedimentary rockhosted Au deposits occur in close spatial, and possibly genetic, relationship to the Late Cretaceous arc rocks. A key contribution of this study is the detailed reconstruction of later Cenozoic fault movements that led to structural dislocation and oroclinal bending, complicating geologic and metallogenic correlations in the region.
Tectonic Processes and Metallogeny along the Tethyan Mountain Ranges of the Middle East and South Asia (Oman, Himalaya, Karakoram, Tibet, Myanmar, Thailand, Malaysia)
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Published:January 01, 2016
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CiteCitation
Michael P. Searle, Laurence J. Robb, Nicholas J. Gardiner, 2016. "Tectonic Processes and Metallogeny along the Tethyan Mountain Ranges of the Middle East and South Asia (Oman, Himalaya, Karakoram, Tibet, Myanmar, Thailand, Malaysia)", Tectonics and Metallogeny of the Tethyan Orogenic Belt, Jeremy P. Richards
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Abstract
The genesis of mineral deposits has been widely linked to specific tectonic settings, but has less frequently been linked to tectonic processes. Understanding processes of oceanic and continental collision tectonics is crucial to understanding key factors leading to the genesis of magmatic-, metamorphic-, hydrothermal-, and sedimentary-related mineral deposits. Geologic studies of most ore deposits typically focus on the final stages of concentration and emplacement. The ultimate source (mantle, lower crust, upper crust) of mineral deposits in many cases remains more cryptic. Uniquely, along the Tethyan collision zones of Asia, every stage of the convergence process can be studied from the initial oceanic settings where ophiolite complexes were formed, through subduction zone and island-arc settings with ultrahigh- to high-pressure metamorphism, to the continental collision settings of the Himalaya, and advanced, long-lived collisional settings such as Afghanistan, the Karakoram Ranges, and the Tibetan plateau. The India-Asia collision closed the intervening Neotethys ocean at ~50 Ma and resulted in the formation of the Himalayan mountain ranges, and increased crustal thickening, metamorphism, deformation, and uplift of the Karakoram-Hindu Kush ranges, Tibetan plateau, and older collision zones across central Asia. Metallogenesis in oceanic crust (hydrothermal Cu-Au; Fe, Mn nodules) and mantle (Cr, Ni, Pt) can be deduced from ophiolite complexes preserved around the Arabia/India-Asia collision (Oman, Ladakh, South Tibet, Myanmar, Andaman Islands). Tectonic-metallogenic processes in island arcs and ancient subduction complexes (VMS Cu-Zn-Pb) can be deduced from studies in the Dras-Kohistan arc (Pakistan) and the various arc complexes along the Myanmar-Andaman segment of the collision zone. Metallogenesis of Andean-type margins (Cu-Au-Mo porphyry; epithermal Au-Ag) can be seen along the Jurassic-Eocene Transhimalayan ranges of Pakistan, Ladakh, South Tibet, and Myanmar. Large porphyry Cu deposits in Tibet are related to both precollisional calc-alkaline granites and postcollisional alkaline adakite-like intrusions. Metallogenesis of continent-continent collision zones is prominent along the Myanmar-Thailand-Malaysia Sn-W granite belts, but less common along the Himalaya. The Mogok metamorphic belt of Myanmar is known for its gemstones associated with regional high-temperature metamorphism (ruby, spinel, sapphire, etc). In Myanmar it is likely that extensive alkaline magmatism has contributed extra heat during the formation of high-temperature metamorphism. This paper attempts to link metallogeny of the Himalaya-Karakoram-Tibet and Myanmar collision zone to tectonic processes derived from multidisciplinary geologic studies.
- Arabian Peninsula
- Asia
- Burma
- calc-alkalic composition
- continental margin
- copper ores
- epithermal processes
- Far East
- ferromanganese composition
- geodynamics
- gold
- gold ores
- Himalayas
- iron ores
- Karakoram
- Malaysia
- metal ores
- metallogeny
- metals
- Middle East
- mineral deposits, genesis
- molybdenum ores
- Neotethys
- Oman
- plate collision
- plate tectonics
- rifting
- Southeast Asia
- Tethys
- Thailand
- Tibetan Plateau