The Shift from Subduction-initiation to True Subduction in Intra-oceanic Systems
The Shift from Subduction-initiation to True Subduction in Intra-oceanic Systems

Author: Lisard Torró i Abat

Publisher:

Published: 2017

Total Pages: 0

ISBN-13:

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"The Maimón and Los Ranchos formations in Central and Oriental Cordilleras, Dominican Republic, Hispaniola Island, are acknowledged to be representative of the most primitive tholeiitic magmatic series recorded in the Greater Antilles of the Caribbean. Besides their importance for the study of the early tectonic and magmatic evolution of the Caribbean island-arc, these formations are renowned for hosting the Cerro de Maimón VMS and the world-class Pueblo Viejo epithermal deposits, currently under production, and a series of smaller metallic deposits and occurrences. Therefore, the integrated study of the hosting volcanic suites, the hydrothermal alterations and the sulfide mineralization from petrographic, geochemical and geochronological perspectives stands out as an excellent opportunity to understand the metallogenic evolution associated to the early evolution of intra-oceanic subduction systems. In this Thesis, new whole rock major- and trace-element and radiogenic isotope data, detailed petrographic studies of the hosts, hydrothermal alterations and the sulfide mineralization and geochronological constraints by means of zircon U-Pb and molybdenite Re-Os dating are presented and discussed. Bottom to top, basalts and basaltic andesites of the Maimón Formation (metamorphosed in the greenschists-blueschists facies transition) and of the lower portion of the Los Ranchos Formation shift from LREE-depleted low-Ti tholeiites and boninites to LREE-richer (normal) low-Ti tholeiites. In addition, basaltic andesites, diorites, monzodiorites and andesites of the upper portion of the Los Ranchos Formation present island-arc tholeiitic and calc-alkaline affinities. These variations mirror the geochemical evolution from proto- to first-arc lavas documented in subduction-initiation ophiolites. The extrusion of the Maimón Formation volcanic rocks is here contextualized in the forearc segment, close to the subducting proto- Caribbean spreading ridge, in a hot-subduction scenario. On the other hand, the extrusion of the Los Ranchos Formation volcanic rocks is contextualized in the forearc-apical arc segment, and their volcanic and volcanosedimentary deposits evidence the progression from submarine to subaerial conditions of deposition. Plagiotonalite batholiths, plagiorhyolite stocks and plagiorhyolites from the Maimón and Los Ranchos formations have tholeiitic and M-type affinities. Volcanogenic massive sulfide (VMS) mineralization hosted in the Maimón Formation and the lower basaltic unit of the Los Ranchos Formation took place during the subduction-initiation stage of the Caribbean island-arc. Subsequently, porphyry Cu-(Mo) - high sulfidation epithermal mineralization took over in the Los Ranchos Formation at ca. 112 Ma, likely connected to a spread episode of acid magmatism during the steady-state or true- subduction regime."--TDX.

Intra-oceanic Subduction Systems
Intra-oceanic Subduction Systems

Author: Robert D. Larter

Publisher: Geological Society of London

Published: 2003

Total Pages: 362

ISBN-13: 9781862391475

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Recycling of oceanic plate back into the Earth's interior at subduction zones is one of the key processes in Earth evolution. Volcanic arcs, which form above subduction zones, are the most visible manifestations of plate tectonics, the convection mechanism by which the Earth loses excess heat. They are probably also the main location where new continental crust is formed, the so-called 'subduction factory' About 400f modern subduction zones on Earth are intra-oceanic. These subduction systems are generally simpler than those at continental margins as they commonly have a shorter history of subduction and their magmas are not contaminated by ancient sialic crust. They are therefore the optimum locations for studies of mantle processes and magmatic addition to the crust in subduction zones.

Subduction Zones Part II
Subduction Zones Part II

Author: Larry J. Ruff

Publisher: Birkhäuser

Published: 2012-12-06

Total Pages: 280

ISBN-13: 3034891407

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Subduction zones consume oceanic lithosphere and are an indispensible part of plate tectonics. Unlike the oceanic lithosphere production system which can be linked as a nearly continuous, albeit sinuous, strand around the earth, subduction zones are a rather dissociated group and are found in several isolated corners of the world. While plate tectonics can predict that subduction zones are required along certain plate boundaries, it does not stipulate how subduction zones initiate and develop. The preservation of newly created oceanic lithosphere and the propensity for spreading centers to fragment continents leaves a wealth of geological informa tion on the initiation and evolution of spreading. On the other hand, the subject of subduction initiation has little observational basis. To find such observations, we need to look at some muddled tectonic regimes. The Macquarie Ridge complex presents a natural laboratory for studies of subduction initiation. 2. Tectonics of the Macquarie Ridge Complex The Macquarie Ridge complex is a complicated physiographic feature that trends approximately north-south between South Island, New Zealand and the Pacific-Antarctica spreading center. This feature consists of a sequence of troughs and ridges, with Macquarie Island as the only exposed expression. The seismically active Macquarie Ridge complex (hereafter: MRC) is crudely continuous with the Tonga-Kermadec-New Zealand seismic activity. The basic physiographic features and seismicity of the MRC are shown in Figure I. The earthquake epicenters generally cluster about the bathymetric expression of the MRC.

Subduction
Subduction

Author: Alexander I. Shemenda

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 225

ISBN-13: 9401109524

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This book is devoted to the quantitative physical modeling of subduction and subduction-related processes. It presents a coherent description of the modeling method (including similarity criteria, and a novel applied experimental technique), results from model experiments, theoretical analysis of results on the basis of continuum mechanics, and their geodynamic interpretation. Subduction is modeled in general as well as applied to particular regions using both 2-D and 3-D approaches, with both slab-push and slab-pull driving forces. The modeling covers all stages from subduction initiation to `death', different regimes of subduction producing back arc extension and compression, blocking of subduction and jumps of subduction zone, arc-continent collision and continental subduction. This work is for geologists and geophysicists interested in geodynamics of the convergent plate boundaries and in mechanics of the lithosphere.

Deep Carbon
Deep Carbon

Author: Beth N. Orcutt

Publisher: Cambridge University Press

Published: 2019-10-17

Total Pages: 687

ISBN-13: 1108477496

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A comprehensive guide to carbon inside Earth - its quantities, movements, forms, origins, changes over time and impact on planetary processes. This title is also available as Open Access on Cambridge Core.

Ophiolites in Earth History
Ophiolites in Earth History

Author: Yildirim Dilek

Publisher: Geological Society of London

Published: 2003

Total Pages: 734

ISBN-13: 9781862391451

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The 32 papers in this volume examine the mode and nature of igneous, metamorphic, tectonic, sedimentological, and biological processes associated with the evolution of oceanic crust in different tectonic settings in Earth history as revealed in various ophiolites and ophiolite belts around the world, and the geodynamic significance of these ophiolites in the evolution of different orogenic systems. Divided into six thematic sections, the book presents a wealth of new data and syntheses from mainly Phanerozoic ophiolites around the world.

The Ordovician Earth System
The Ordovician Earth System

Author: Stanley Charles Finney

Publisher: Geological Society of America

Published: 2010-01-01

Total Pages: 204

ISBN-13: 081372466X

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"The Ordovician period is a significant chapter in Earth's history that included the great Mid-Ordovician biodiversification event, the Hirnantian glaciation, and long-term greenhouse conditions. Ordovician rocks are widespread on most continents and the recent finalization of a modern chronostratigraphic classification of the Ordovician system now facilitates high-resolution correlations that allow for integrated multidisciplinary research. The diverse papers comprising this volume address orogenesis, paleogeography, climate modeling, sedimentation, biodiversity, and isotopic excursions; together they promote an integrated view of the Ordovician earth system."--Publisher's description.

Tectonics of Sedimentary Basins
Tectonics of Sedimentary Basins

Author: Cathy Busby

Publisher: John Wiley & Sons

Published: 2011-12-07

Total Pages: 1034

ISBN-13: 1444347144

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Investigating the complex interplay between tectonics and sedimentation is a key endeavor in modern earth science. Many of the world's leading researchers in this field have been brought together in this volume to provide concise overviews of the current state of the subject. The plate tectonic revolution of the 1960's provided the framework for detailed models on the structure of orogens and basins, summarized in a 1995 textbook edited by Busby and Ingersoll. Tectonics of Sedimentary Basins: Recent Advances focuses on key topics or areas where the greatest strides forward have been made, while also providing on-line access to the comprehensive 1995 book. Breakthroughs in new techniques are described in Section 1, including detrital zircon geochronology, cosmogenic nuclide dating, magnetostratigraphy, 3-D seismic, and basin modelling. Section 2 presents the new models for rift, post-rift, transtensional and strike slip basin settings. Section 3 addresses the latest ideas in convergent margin tectonics, including the sedimentary record of subduction intiation and subduction, flat-slab subduction, and arc-continent collision; it then moves inboard to forearc basins and intra-arc basins, and ends with a series of papers formed under compessional strain regimes, as well as post-orogenic intramontane basins. Section 4 examines the origin of plate interior basins, and the sedimentary record of supercontinent formation. This book is required reading for any advanced student or professional interested in sedimentology, plate tectonics, or petroleum geoscience. Additional resources for this book can be found at: www.wiley.com/go/busby/sedimentarybasins.

Ophiolites and Oceanic Crust
Ophiolites and Oceanic Crust

Author: Yildirim Dilek

Publisher: Geological Society of America

Published: 2000-01-01

Total Pages: 570

ISBN-13: 9780813723495

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The proceedings from the September 1998 conference in Marshall, California contain 39 papers on the following topics: ophiolites, ocean crust, and global tectonics; oceanic lower crust and upper mantle; structure and physical properties of upper oceanic crust; hydrothermal processes; Pacific Rim ophiolites; and, Ophiolites from Iapetus, Rheic-Pleionic, Neotethyan, and Indian Oceans. Contributors include scientists with backgrounds in structural geology, tectonics, geophysics, petrology, and geochemistry. Numerous black and white illustrations (and one in color) are included. Annotation copyrighted by Book News Inc., Portland, OR