scholarly journals Lithospheric plate tectonics and mass extinctions of biological species

2021 ◽  
Vol 946 (1) ◽  
pp. 012009
Author(s):  
V V Snakin
Keyword(s):  
Plate Tectonics ◽  
Biological Species ◽  
Lithospheric Plate ◽  
Mass Extinctions ◽  
Geographic Isolation ◽  
Interspecies Competition ◽  
Lithospheric Plates ◽  
Species Extinctions

Abstract The merging of lithospheric plates and the formation of supercontinents are considered to be the main causes of global species extinctions within the Earth’s biosphere. Under those conditions, the factor of geographic isolation is diminished and interspecies competition is accelerated, allowing for the survival of the best-adapted species. The divergence of lithospheric plates triggers a new spurt of speciation that surpasses the previous one, as it involves the participation of the winning species.

Climate modelling of mass-extinction events: a review

2009 ◽  
Vol 8 (3) ◽  
pp. 207-212 ◽  
Author(s):  
Georg Feulner
Keyword(s):  
Mass Extinction ◽  
Plate Tectonics ◽  
Large Scale ◽  
Volcanic Eruptions ◽  
Biological Species ◽  
Future Research ◽  
Climate Modelling ◽  
Mass Extinctions ◽  
Extinction Events ◽  
Mass Extinction Events

AbstractDespite tremendous interest in the topic and decades of research, the origins of the major losses of biodiversity in the history of life on Earth remain elusive. A variety of possible causes for these mass-extinction events have been investigated, including impacts of asteroids or comets, large-scale volcanic eruptions, effects from changes in the distribution of continents caused by plate tectonics, and biological factors, to name but a few. Many of these suggested drivers involve or indeed require changes of Earth's climate, which then affect the biosphere of our planet, causing a global reduction in the diversity of biological species. It can be argued, therefore, that a detailed understanding of these climatic variations and their effects on ecosystems are prerequisites for a solution to the enigma of biological extinctions. Apart from investigations of the paleoclimate data of the time periods of mass extinctions, climate-modelling experiments should be able to shed some light on these dramatic events. Somewhat surprisingly, however, only a few comprehensive modelling studies of the climate changes associated with extinction events have been undertaken. These studies will be reviewed in this paper. Furthermore, the role of modelling in extinction research in general and suggestions for future research are discussed.

scholarly journals Geological archive of the onset of plate tectonics

2018 ◽  
Vol 376 (2132) ◽  
pp. 20170405 ◽  
Author(s):  
Peter A. Cawood ◽  
Chris J. Hawkesworth ◽  
Sergei A. Pisarevsky ◽  
Bruno Dhuime ◽  
Fabio A. Capitanio ◽  
...  
Keyword(s):  
Plate Tectonics ◽  
Foreland Basin ◽  
Sea Floor ◽  
Palaeomagnetic Data ◽  
Peraluminous Granites ◽  
Lithospheric Plates ◽  
Crustal Reworking ◽  
Sea Floor Spreading ◽  
Back Arc ◽  
Earth Dynamics

Plate tectonics, involving a globally linked system of lateral motion of rigid surface plates, is a characteristic feature of our planet, but estimates of how long it has been the modus operandi of lithospheric formation and interactions range from the Hadean to the Neoproterozoic. In this paper, we review sedimentary, igneous and metamorphic proxies along with palaeomagnetic data to infer both the development of rigid lithospheric plates and their independent relative motion, and conclude that significant changes in Earth behaviour occurred in the mid- to late Archaean, between 3.2 Ga and 2.5 Ga. These data include: sedimentary rock associations inferred to have accumulated in passive continental margin settings, marking the onset of sea-floor spreading; the oldest foreland basin deposits associated with lithospheric convergence; a change from thin, new continental crust of mafic composition to thicker crust of intermediate composition, increased crustal reworking and the emplacement of potassic and peraluminous granites, indicating stabilization of the lithosphere; replacement of dome and keel structures in granite-greenstone terranes, which relate to vertical tectonics, by linear thrust imbricated belts; the commencement of temporally paired systems of intermediate and high dT/dP gradients, with the former interpreted to represent subduction to collisional settings and the latter representing possible hinterland back-arc settings or ocean plateau environments. Palaeomagnetic data from the Kaapvaal and Pilbara cratons for the interval 2780–2710 Ma and from the Superior, Kaapvaal and Kola-Karelia cratons for 2700–2440 Ma suggest significant relative movements. We consider these changes in the behaviour and character of the lithosphere to be consistent with a gestational transition from a non-plate tectonic mode, arguably with localized subduction, to the onset of sustained plate tectonics. This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics'.

The Geological Framework

2005 ◽  
Author(s):  
Charles S. Hutchison
Keyword(s):  
Indian Ocean ◽  
Southeast Asia ◽  
Deep Water ◽  
Plate Tectonics ◽  
Petroleum Industry ◽  
South Indian ◽  
Lithospheric Plates ◽  
Asean Countries ◽  
Convergent Plate Margin ◽  
Straits Of Malacca

This chapter outlines the principal geological features of the region, extending from Myanmar and Taiwan in the north, southwards to include all the ASEAN countries, and extending as far as northern Australia. The present-day lithospheric plates and plate margins are described, and the Cenozoic evolution of the region discussed. Within a general framework of convergent plate tectonics, Southeast Asia is also characterized by important extensional tectonics, resulting in the world’s greatest concentration of deep-water marginal basins and Cenozoic sedimentary basins, which have become the focus of the petroleum industry. The pre-Cenozoic geology is too complex for an adequate analysis in this chapter and the reader is referred to Hutchison (1989) for further details. A chronological account summarizing the major geological changes in Southeast Asia is given in Figure 1.2. The main geographical features of the region were established in the Triassic, when the large lithospheric plate of Sinoburmalaya (also known as Sibumasu), which had earlier rifted from the Australian part of Gondwanaland, and collided with and became sutured onto South China and Indochina, together named Cathaysia. The result was a great mountain-building event known as the Indosinian orogeny. Major granites were emplaced during this orogeny, with which the tin and tungsten mineral deposits were genetically related. The orogeny resulted in general uplift and the formation of major new landmasses, which have predominantly persisted as the present-day regional physical geography of Southeast Asia. The Indo-Australian Plate is converging at an average rate of 70 mm a−1 in a 003° direction, pushed from the active South Indian Ocean spreading axis. For the most part it is composed of the Indian Ocean, formed of oceanic sea-floor basalt overlain by deep water. It forms a convergent plate margin with the continental Eurasian Plate, beneath which it subducts at the Sunda or Java Trench. The Eurasian continental plate protrudes as a peninsular extension (Sundaland) southwards as far as Singapore, continuing beneath the shallow Straits of Malacca and the Sunda Shelf as the island of Sumatra and the northwestern part of Borneo.

On the forcing mechanism for the H2-driven deep biosphere

2008 ◽  
Vol 7 (2) ◽  
pp. 157-167 ◽  
Author(s):  
Helge Hellevang
Keyword(s):  
Hydrogen Production ◽  
Ferrous Iron ◽  
Plate Tectonics ◽  
Large Scale ◽  
Ocean Water ◽  
Deep Biosphere ◽  
The Earth ◽  
Hydrothermal Convection ◽  
Lithospheric Plates ◽  
Reduced State

AbstractHeat produced in the mantle and core of the Earth by the decay of radioactive elements and mineral fusion results in large-scale mantle convection. The outer shell of the Earth that floats on the convective mantle is divided into rigid lithospheric plates. Subduction of dense cold plates into the mantle leads to plate tectonics. At divergent plate margins, heat is dissipated through hydrothermal convection cells. As ocean water is entrained into hydrothermal cells it interacts with fresh magmatic rocks and liberates ferrous iron. This iron reduces the ocean water to such an extent that it decomposes and forms hydrogen. Molecular hydrogen, as the most reduced component in the system, forms a basal component to a deep dark biosphere powered by metastable redox gradients. In this paper we review the driving force behind a hydrogen-driven deep biosphere. We present abundant observations of hydrogen produced at natural hydrothermal settings as well as in laboratory experiments. The key mineral reactions responsible for the bulk of this hydrogen production are then presented. A division of the reaction progression into an oxidized state and a reduced state is suggested. The amount of hydrogen produced is insignificant in the oxidized state whereas it becomes proportional to the amount of ferrous iron oxidized in the reduced state. The bulk of basalt-hosted aquifers are expected to reside in the oxidized state because of the low content of ferrous minerals, whereas abundant olivine in ultramafic-hosted systems is responsible for large-scale hydrogen production. Today the majority of the seafloor is basaltic. The Archean seafloor on the other hand consisted of fewer ultramafic exposures, but was dominated by ultramafic magnesium-rich lavas with a higher potential for hydrogen production than the present seafloor.

scholarly journals The Subduction Dichotomy of Strong Plates and Weak Slabs

2016 ◽  
Author(s):  
Robert I. Petersen ◽  
Dave R. Stegman ◽  
Paul J. Tackley
Keyword(s):  
Lower Mantle ◽  
Plate Tectonics ◽  
Material Strength ◽  
Control Material ◽  
The Earth ◽  
Dynamic Forces ◽  
Lithospheric Plates ◽  
Geodynamic Models

Abstract. A key element of plate tectonics on Earth is that the lithosphere is subducting into the mantle. Subduction results from forces that bend and pull the lithosphere into the interior of the Earth. Once subducted, lithospheric slabs are further modified by dynamic forces in the mantle and their sinking is inhibited by the increase in viscosity of the lower mantle. These forces are resisted by the material strength of the lithosphere. Using geodynamic models we investigate several subduction models wherein we control material strength by setting a maximum viscosity for the surface plates and the subducted slabs independently. We find that the models which produce results most analogous to observations of subduction on Earth are characterized by a dichotomy of lithosphere strengths. These models have strong lithospheric plates at the surface which promotes Earth-like single-sided subduction. At the same time these models have weakened lithospheric subducted slabs which pile, bend or lie flat at the top of the lower mantle reproducing the spectrum of slab morphologies observed on Earth.

scholarly journals Conductive Channels in the Deep Oceanic Lithosphere Could Consist of Garnet Pyroxenites at the Fossilized Lithosphere–Asthenosphere Boundary

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1107
Author(s):  
Thomas P. Ferrand
Keyword(s):  
Plate Tectonics ◽  
Early Stage ◽  
Experimental Petrology ◽  
Oceanic Lithosphere ◽  
High Conductivity ◽  
Stability Field ◽  
Cocos Plate ◽  
Lithospheric Plates ◽  
Oceanic Plates ◽  
Garnet Stability Field

Magnetotelluric (MT) surveys have identified anisotropic conductive anomalies in the mantle of the Cocos and Nazca oceanic plates, respectively, offshore Nicaragua and in the eastern neighborhood of the East Pacific Rise (EPR). Both the origin and nature of these anomalies are controversial as well as their role in plate tectonics. The high electrical conductivity has been hypothesized to originate from partial melting and melt pooling at the lithosphere–asthenosphere boundary (LAB). The anisotropic nature of the anomaly likely highlights high-conductivity channels in the spreading direction, which could be further interpreted as the persistence of a stable liquid silicate throughout the whole oceanic cycle, on which the lithospheric plates would slide by shearing. However, considering minor hydration, some mantle minerals can be as conductive as silicate melts. Here I show that the observed electrical anomaly offshore Nicaragua does not correlate with the LAB but instead with the top of the garnet stability field and that garnet networks suffice to explain the reported conductivity values. I further propose that this anomaly actually corresponds to the fossilized trace of the early-stage LAB that formed near the EPR about 23 million years ago. Melt-bearing channels and/or pyroxenite underplating at the bottom of the young Cocos plate would transform into garnet-rich pyroxenites with decreasing temperature, forming solid-state high-conductivity channels between 40 and 65 km depth (1.25–1.9 GPa, 1000–1100 °C), consistently with experimental petrology.

scholarly journals Olivine anisotropy suggests Gutenberg discontinuity is not the base of the lithosphere

2016 ◽  
Vol 113 (38) ◽  
pp. 10503-10506 ◽  
Author(s):  
Lars N. Hansen ◽  
Chao Qi ◽  
Jessica M. Warren
Keyword(s):  
Upper Mantle ◽  
Plate Tectonics ◽  
Large Scale ◽  
Flow Model ◽  
Seismic Anisotropy ◽  
Current Debate ◽  
Tectonic Plates ◽  
Midocean Ridges ◽  
Wide Range ◽  
Lithospheric Plates

Tectonic plates are a key feature of Earth’s structure, and their behavior and dynamics are fundamental drivers in a wide range of large-scale processes. The operation of plate tectonics, in general, depends intimately on the manner in which lithospheric plates couple to the convecting interior. Current debate centers on whether the transition from rigid lithosphere to flowing asthenosphere relates to increases in temperature or to changes in composition such as the presence of a small amount of melt or an increase in water content below a specified depth. Thus, the manner in which the rigid lithosphere couples to the flowing asthenosphere is currently unclear. Here we present results from laboratory-based torsion experiments on olivine aggregates with and without melt, yielding an improved database describing the crystallographic alignment of olivine grains. We combine this database with a flow model for oceanic upper mantle to predict the structure of the seismic anisotropy beneath ocean basins. Agreement between our model and seismological observations supports the view that the base of the lithosphere is thermally controlled. This model additionally supports the idea that discontinuities in velocity and anisotropy, often assumed to be the base of the lithosphere, are, instead, intralithospheric features reflecting a compositional boundary established at midocean ridges, not a rheological boundary.

scholarly journals Are global hotspots of endemic richness shaped by plate tectonics?

2017 ◽  
Author(s):  
Pellissier Loïc ◽  
Christian Heine ◽  
Camille Albouy
Keyword(s):  
Plate Tectonics ◽  
Large Fraction ◽  
Spatial Models ◽  
Future Research ◽  
Deep Time ◽  
Current Location ◽  
Lithospheric Plates ◽  
Taxonomic Groups

AbstractSingular regions of the globe harbour a disproportionally large fraction of extant biodiversity. Spatial biodiversity gradients are frequently associated to extant ecological conditions using statistical models, but more rarely to paleo-environmental conditions, especially beyond the Quaternary. On one hand the role of plate tectonics in shaping the extant diversity of lineages is supported by numerous phylogenetic and fossil evidences, and on the other hand the spatial variation of biodiversity across the globe is rarely associated to geodynamic variables. In this study, we propose that plate tectonics explain the current location of hotspots of endemic richness across the globe. As an illustration, we used paleogeographies in a model, which quantifies through time and for each cell the potential dispersal across disconnected habitat patches. Rare events of dispersal across dynamic straits of unsuitable habitats allows species colonisation and that a subsequent absence of gene flow could lead to in-situ speciation. We evaluated whether this process could pinpoint the locations of hotspots of endemic richness computed from the ranges of 181,603 species across 14 taxonomic groups. The significant congruence between the regions highlighted by the model and the endemic richness provides evidences of the contribution of plate tectonics in shaping global biodiversity gradients. Places with high tectonic complexity, predominantly located at the confluence of major lithospheric plates such as the Mediterranean basin, Central America, Madagascar and South East Asia likely provided favourable circumstances for allopatric speciation and the emergence of new species across straits. While our illustration supports the role of plate tectonics, accounting for deep time geological events in spatial models of extant biodiversity is not straightforward. Future research should develop quantitative spatial models of biodiversity including the dynamic of ancient habitats.

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