The investigation aims to understand how external forces influence tectonic plate movement, causing earthquakes and volcanic eruptions. Our emphasis was on calculating perigee forces at various moon-Earth distances. O...The investigation aims to understand how external forces influence tectonic plate movement, causing earthquakes and volcanic eruptions. Our emphasis was on calculating perigee forces at various moon-Earth distances. Our initial concern is the fluctuating perigee distance between the Moon and Earth. Later, we will cover Earth’s mass fluctuations caused by crustal inhomogeneity. Gravitational force depends on distance and Earth’s mass variations. Wobbling’s Earth and translation around Sun are additional factors. Tidal variations from the Moon trigger subduction zone earthquakes. Volcanoes in the Ring of Fire are influenced by plate movement on fractures and faults.展开更多
With the support of the National Natural Science Foundation of China,a collaborative study by Dr.Chen Lin(陈林)from the Institute of Geology and Geophysics,Chinese Academy of Sciences,Dr.Fabio Capitanio from Monash Un...With the support of the National Natural Science Foundation of China,a collaborative study by Dr.Chen Lin(陈林)from the Institute of Geology and Geophysics,Chinese Academy of Sciences,Dr.Fabio Capitanio from Monash University,Dr.Lijun Liu from the University of Illinois at Urbana-Champaign and Taras Gerya from Swiss Federal Institute of Technology Zurich demonstrates that the unique shape and complex deep structure of the Tibetan plateau may be controlled mostly by the strength heterogeneity展开更多
The past size and location of the hypothesized proto-South China Sea vanished ocean basin has important plate-tectonic implications for Southeast Asia since the Mesozoic. Here we present new details on proto-South Chi...The past size and location of the hypothesized proto-South China Sea vanished ocean basin has important plate-tectonic implications for Southeast Asia since the Mesozoic. Here we present new details on proto-South China Sea paleogeography using mapped and unfolded slabs from tomography. Mapped slabs included： the Eurasia-South China Sea slab subducting at the Manila trench; the northern Philippine Sea Plate slab subducting at the Ryukyu trench; and, a swath of detached, subhorizontal, slab-like tomographic anomalies directly under the South China Sea at 450 to 700 km depths that we show is subducted ‘northern proto-South China Sea’ lithosphere. Slab unfolding revealed that the South China Sea lay directly above the ‘northern Proto-South China Sea’ with both extending 400 to 500 km to the east of the present Manila trench prior to subduction. Our slab-based plate reconstruction indicated the proto-South China Sea was consumed by double-sided subduction, as follows：（1） The ‘northern proto-South China Sea’ subducted in the Oligo–Miocene under the Dangerous Grounds and southward expanding South China Sea by in-place ‘self subduction’ similar to the western Mediterranean basins;（2） limited southward subduction of the proto-South China Sea under Borneo occurred pre-Oligocene, represented by the 800–900 km deep ‘southern proto-South China Sea’ slab.展开更多
When plate tectonics began on the Earth has been long debated and here we argue this topic based on the records of Earth-Moon geology and asteroid belt to conclude that the onset of plate tectonics was during the midd...When plate tectonics began on the Earth has been long debated and here we argue this topic based on the records of Earth-Moon geology and asteroid belt to conclude that the onset of plate tectonics was during the middle Hadean（4.37-4.20 Ga）. The trigger of the initiation of plate tectonics is the ABEL Bombardment, which delivered oceanic and atmospheric components on a completely dry reductive Earth, originally comprised of enstatite chondrite-like materials. Through the accretion of volatiles, shock metamorphism processed with vaporization of both CI chondrite and supracrustal rocks at the bombarded location, and significant recrystallization went through under wet conditions, caused considerable eclogitization in the primordial continents composed of felsic upper crust of 21 km thick anorthosite, and 50 km or even thicker KREEP lower crust. Eclogitization must have yielded a powerful slab-pull force to initiate plate tectonics in the middle Hadean. Another important factor is the size of the bombardment. By creating Pacific Ocean class crater by 1000 km across impactor, rigid plate operating stagnant lid tectonics since the early Hadean was severely destroyed, and oceanic lithosphere was generated to have bi-modal lithosphere on the Earth to enable the operation of plate tectonics.Considering the importance of the ABEL Bombardment event which initiated plate tectonics including the appearance of ocean and atmosphere, we propose that the Hadean Eon can be subdivided into three periods：（1） early Hadean（4.57-4.37 Ga）,（2） middle Hadean（4.37-4.20 Ga）, and（3） late Hadean（4.20-4.00 Ga）.展开更多
Objective The North China Craton （NCC） is one of the oldest cratons in the world. The accretionary belt at its northern margin has been the focus of scholars both at home and abroad （Zhu Junbing and Ren Jishun, 2...Objective The North China Craton （NCC） is one of the oldest cratons in the world. The accretionary belt at its northern margin has been the focus of scholars both at home and abroad （Zhu Junbing and Ren Jishun, 2017）. In recent years, a series of Late Paleozoic-Mesozoic intrusions trending E-W have been discovered within the northern margin of the NCC, forming a magmatic belt. The study on the origin and tectonic setting of this magmatic belt not only has important significance for understanding the Late Paleozoic-Mesozoic tectonic evolution history of the northern margin of the NCC, but also can provide key constraints on the evolution of its surrounding Xing＇an- Mongolia orogenic belt and the Paleo-Asian Ocean. At present, no Devonian to early stage of Early Carboniferous intrusion has been reported within the northern margin of the NCC.展开更多
As the chronicle of plate motions through time, paleogeography is fundamental to our understanding of plate tectonics and its role in shaping the geology of the present-day. To properly appreciate the history of tecto...As the chronicle of plate motions through time, paleogeography is fundamental to our understanding of plate tectonics and its role in shaping the geology of the present-day. To properly appreciate the history of tectonics--and its influence on the deep Earth and climate-it is imperative to seek an accurate and global model of paleogeography. However, owing to the incessant loss of oceanic lithosphere through subduction, the paleogeographic reconstruction of ＇full-plates＇ （including oceanic lithosphere） becomes increasingly challenging with age. Prior to 150 Ma ~60% of the lithosphere is missing and re- constructions are developed without explicit regard for oceanic lithosphere or plate tectonic principles; in effect, reflecting the earlier mobilistic paradigm of continental drift. Although these ＇continental＇ re- constructions have been immensely useful, the next-generation of mantle models requires global plate kinematic descriptions with full-plate reconstructions. Moreover, in disregarding （or only loosely applying） plate tectonic rules, continental reconstructions fail to take advantage of a wealth of additional information in the form of practical constraints. Following a series of new developments, both in geo- dynamic theory and analytical tools, it is now feasible to construct full-plate models that lend themselves to testing by the wider Earth-science community. Such a model is presented here for the late Paleozoic （410-250 Ma） together with a review of the underlying data. Although we expect this model to be particularly useful for numerical mantle modeling, we hope that it will also serve as a general framework for understanding late Paleozoic tectonics, one on which future improvements can be built and further tested.展开更多
As we continue searching for exoplanets, we wonder if life and technological species capable of communicating with us exists on any of them. As geoscientists, we can also wonder how important is the presence or absenc...As we continue searching for exoplanets, we wonder if life and technological species capable of communicating with us exists on any of them. As geoscientists, we can also wonder how important is the presence or absence of plate tectonics for the evolution of technological species. This essay considers this question, focusing on tectonically active roclw （silicate） planets, like Earth, Venus, and Mars. The development of technological species on Earth provides key insights for understanding evolution on exoplanets, including the likely role that plate tectonics may play. An Earth-sized silicate planet is likely to experience several tectonic styles over its lifetime, as it cools and its lithosphere thickens, strengthens, and becomes denser. These include magma ocean, various styles of stagnant lid, and perhaps plate tectonics. Abundant liquid water favors both life and plate tectonics. Ocean is required for early evolution of diverse single-celled organisms, then colonies of cells which specialized further to form guts, ap- pendages, and sensory organisms up to the complexity of fish （central nervous system, appendages, eyes）. Large expanses of dry land also begin in the ocean, today produced above subduction zones in juvenile arcs and by their coalescence to form continents, although it is not clear that plate tectonics was required to create continental crust on Earth. Dry land of continents is required for further evolution of technological species, where modification of appendages for grasping and manipulating, and improve- ment of eyes and central nervous system could be perfected. These bioassets allowed intelligent crea- tures to examine the night sky and wonder, the beginning of abstract thinking, including religion and science. Technology arises from the exigencies of daily living such as tool-making, agriculture, clothing, and weapons, but the pace of innovation accelerates once it is allied with science. Finally, the importance of plate tectonics for developing a technological species is examined via a thought experiment using two otherwise identical planets： one with plate tectonics and the other without. A planet with oceans, continents, and plate tectonics maximizes opportunities for speciation and natural selection, whereas a similar planet without plate tectonics provides fewer such opportunities. Plate tectonics exerts envi- ronmental pressures that drive evolution without being capable of extinguishing all life. Plate tectonic processes such as the redistribution of continents, growth of mountain ranges, formation of land bridges, and opening and closing of oceans provide a continuous but moderate environmental pressure that stimulates populations to adapt and evolve. Plate tectonics may not be needed in order for life to begin, but evolution of technological species is favored on planets with oceans, continents, plate tectonics, and intermittently clear night sky.展开更多
In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to postArchean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram was obtained usi...In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to postArchean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram was obtained using 〉2000 known ophiolitic basalts and was tested using -560 modern rocks from known tectonic settings. Ten different basaltic varieties from worldwide ophiolitic complexes have been examined. They include two basaltic types that have never been considered before, which are： （1） medium-Ti basalts （MTB） generated at nascent forearc settings; （2） a type of mid-ocean ridge basalts showing garnet signature （G-MORB） that characterizes Alpine-type （i,e., non volcanic） rifted margins and ocean-continent transition zones （OCTZ）. In the Th-Nb diagram, basalts generated in oceanic subductionunrelated settings, rifted margins, and OCTZ can be distinguished from subduction-related basalts with a misclassification rate 〈 1%. This diagram highlights the chemical variation of oceanic, rifted margin, and OCTZ basalts from depleted compositions to progressively more enriched compositions reflecting, in turn, the variance of source composition and degree of melting within the MORB-OIB array. It also highlights the chemical contributions of enriched （OIB-type） components to mantle sources. Enrichment of Th relative to Nb is particularly effective for highlighting crustal input via subduction or crustal contamination. Basalts formed at continental margin arcs and island arc with a complex polygenetic crust can be distinguished from those generated in intra-oceanic arcs in supra-subducrion zones （SSZ） with a misclassification rate 〈1%. Within the SSZ group, two sub-settings can be recognized with a misclassification rate 〈0.5%. They are： （1） SSZ influenced by chemical contribution from subduction- derived components （forearc and intra-arc sub-settings） characterized by island arc tholeiitic （IAT） and boninitic basalts; （2） SSZ with no contribution from subduction-derived components （nascent forearc sub-settings） characterized by MTBs and depleted-MORBs. Two additional discrimination diagrams are proposed： （1） a Dy-Yb diagram is used for discriminating boninite and IAT basalts; （2） a Ce/Yb-Dy/Yb diagram is used for discriminating G-MORBs and normal MORBs. The proposed method may effectively assist in recovering the tectonic affinity of ancient ophiolites, which is fundamental for establishing the geodvnamic evolution of ancient oceanic and continental domains, as well as orogenic belts.展开更多
Accurately mapping plate boundary types and locations through time is essential for understanding the evolution of the plate-mantle system and the exchange of material between the solid Earth and surface environments....Accurately mapping plate boundary types and locations through time is essential for understanding the evolution of the plate-mantle system and the exchange of material between the solid Earth and surface environments.However,the complexity of the Earth system and the cryptic nature of the geological record make it difficult to discriminate tectonic environments through deep time.Here we present a new method for identifying tectonic paleo-environments on Earth through a data mining approach using global geochemical data.We first fingerprint a variety of present-day tectonic environments utilising up to 136 geochemical data attributes in any available combination.A total of 38301 geochemical analyses from basalts aged from 5-0 Ma together with a well-established plate reconstruction model are used to construct a suite of discriminatory models for the first order tectonic environments of subduction and mid-ocean ridge as distinct from intraplate hotspot oceanic environments,identifying 41,35,and 39 key discriminatory geochemical attributes,respectively.After training and validation,our model is applied to a global geochemical database of 1547 basalt samples of unknown tectonic origin aged between 1000-410 Ma,a relatively ill-constrained period of Earth’s evolution following the breakup of the Rodinia supercontinent,producing 56 unique global tectonic environment predictions throughout the Neoproterozoic and Early Paleozoic.Predictions are used to discriminate between three alternative published Rodinia configuration models,identifying the model demonstrating the closest spatio-temporal consistency with the basalt record,and emphasizing the importance of integrating geochemical data into plate reconstructions.Our approach offers an extensible framework for constructing full-plate,deeptime reconstructions capable of assimilating a broad range of geochemical and geological observations,enabling next generation Earth system models.展开更多
Based on analyses of the share of documents of structural geology and tectonics in the GeoRef system over 100 years in the last century, and the historical change of international （31 years） and domestic （16 years...Based on analyses of the share of documents of structural geology and tectonics in the GeoRef system over 100 years in the last century, and the historical change of international （31 years） and domestic （16 years） document counts of various topics in structural geology and tectonics, the position of structural geology and tectonics in the geosciences is evaluated and the major advaces in fields of plate tectonics, continental dynamics and global dynamics are reviewed. Our attention mainly focuses on the advances in studies of structural analysis, deformation mechanisms and rheology of rocks, contractional tectonics and late- and post-orogenic extensional collapse in orogens, large-scale strikeslip faults and indentation-extrusion tectonics, active tectonics and natural hazards. The relationships of structural geology and tectonics with petrology and geochronology are also discussed in terms of intersection of scientific disciplines. Finally, some suggestions are proposed for the further development of structural geology and tectonics in China.展开更多
The theory of plate tectonics came together in the 1960s,achieving wide acceptance after 1968.Since then it has been the most successful framework for investigations of Earth’s evolution.Subduction of the oceanic lit...The theory of plate tectonics came together in the 1960s,achieving wide acceptance after 1968.Since then it has been the most successful framework for investigations of Earth’s evolution.Subduction of the oceanic lithosphere,as the engine that drives plate tectonics,has played a key role in the theory.However,one of the biggest unanswered questions in Earth science is how the first subduction was initiated,and hence how plate tectonics began.The main challenge is how the strong lithosphere could break and bend if plate tectonics-related weakness and slab-pull force were both absent.In this work we review state-of-the-art subduction initiation(SI)models with a focus on their prerequisites and related driving mechanisms.We note that the plume-lithosphere-interaction and mantleconvection models do not rely on the operation of existing plate tectonics and thus may be capable of explaining the first SI.Reinvestigation of plate-driving mechanisms reveals that mantle drag may be the missing driving force for surface plates,capable of triggering initiation of the first subduction.We propose a composite driving mechanism,suggesting that plate tectonics may be driven by both subducting slabs and convection currents in the mantle.We also discuss and try to answer the following question:Why has plate tectonics been observed only on Earth?展开更多
Earth is the only planet known to be habitable,and is also unique with its liquid water,and the operation of plate tectonics.The geological record shows that the habitability of our planet can rapidly recover from maj...Earth is the only planet known to be habitable,and is also unique with its liquid water,and the operation of plate tectonics.The geological record shows that the habitability of our planet can rapidly recover from major disasters or catastrophes,even those that cause mass extinctions.We suggest that plate tectonics,which acts as a link between the shallow and deep,is pivotal for the formation,evolution,and long-term stability of the hydrosphere,atmosphere,lithosphere,and thus life.Plate tectonics links the surface environment with the deep interior of high viscosity,low Reynolds number,low entropy,and low chaos,able to produce a strong healing effect to neutralize catastrophic events.It can transfer the bio-essential elements from the deep interior to the near-surface environment and can recycle toxic elements to the deep.This unique planetary energy and material transfer process of Earth is a continuous,slow-release,and bidirectional cycle,where a change in the surface is slowly buffered by a reaction from the deep,shaping a long-term and stable habitable environment.Therefore,it is considered that plate tectonics is the basic condition for the long-term stable evolution of the Earth’s biosphere and the stabilizer of the Earth’s habitability.展开更多
The possibility of a net rotation of the lithosphere with respect to the mantle is generally overlooked since it depends on the adopted mantle reference frames, which are arbitrary. We review the geological and geophy...The possibility of a net rotation of the lithosphere with respect to the mantle is generally overlooked since it depends on the adopted mantle reference frames, which are arbitrary. We review the geological and geophysical signatures of plate boundaries, and show that they are markedly asymmetric worldwide. Then we compare available reference frames of plate motions relative to the mantle and discuss which is at best able to fit global tectonic data. Different assumptions about the depths of hotspot sources （below or within the asthenosphere, which decouples the lithosphere from the deep mantle） predict different rates of net rotation of the lithosphere relative to the mantle. The widely used no-net-rotation （NNR） reference frame, and low （〈0.2°-0.4°/Ma） net rotation rates （deep hotspots source） predict an average net rotation in which some plates move eastward relative to the mantle （e.g., Nazca）. With fast （〉1°/Ma） net rotation （shallow hotspots source）, all plates, albeit at different velocity, move westerly along a curved trajectory, with a tectonic equator tilted about 30° relative to the geographic equator. This is consistent with the observed global tectonic asymmetries.展开更多
The global geological volatile cycle(H,C,N)plays an important role in the long term self-regulation of the Earth system.However,the complex interaction between its deep,solid Earth components(i.e.crust and mantle),Ea...The global geological volatile cycle(H,C,N)plays an important role in the long term self-regulation of the Earth system.However,the complex interaction between its deep,solid Earth components(i.e.crust and mantle),Earth’s fluid envelopes(i.e.atmosphere and hydrosphere)and plate tectonic processes is a subject of ongoing debate.In this study we want to draw attention to how the presence of primary melt(MI)and fluid(FI)inclusions in high-grade metamorphic minerals could help constrain the crustal component of the volatile cycle.To that end,we review the distribution of MI and FI throughout Earth’s history,from ca.3.0 Ga ago up to the present day.We argue that the lower crust might constitute an important,longterm,volatile storage unit,capable to influence the composition of the surface envelopes through the mean of weathering,crustal thickening,partial melting and crustal assimilation during volcanic activity.Combined with thermodynamic modelling,our compilation indicates that periods of well-established plate tectonic regimes at<0.85 Ga and 1.7-2.1 Ga,might be more prone to the reworking of supracrustal lithologies and the storage of volatiles in the lower crust.Such hypothesis has implication beyond the scope of metamorphic petrology as it potentially links geodynamic mechanisms to habitable surface conditions.MI and FI in metamorphic crustal rocks then represent an invaluable archive to assess and quantify the co-joint evolution of plate tectonics and Earth’s external processes.展开更多
An emerging view is that Earth’s geodynamic regime witnessed a fundamental transition towards plate tectonics around 3.0 Ga(billion years).However,the manifestations of this change may have been diachronous and crato...An emerging view is that Earth’s geodynamic regime witnessed a fundamental transition towards plate tectonics around 3.0 Ga(billion years).However,the manifestations of this change may have been diachronous and craton-specific.展开更多
Although the Indo-Australian plate near the Ninetyeast Ridge is important for understanding the formation of new plate boundaries, its tectonic problems are complex and most of them are poorly known. This paper made a...Although the Indo-Australian plate near the Ninetyeast Ridge is important for understanding the formation of new plate boundaries, its tectonic problems are complex and most of them are poorly known. This paper made a detailed tectonic analysis based on the data of bathymetry, gravity and magnetics. Bathymetry and gravity maps show morphological features of many folds, which are related to the intraplate deformation of the Indo-Australian plate due to the collision between the Indian and Asian plates. Gravity anomalies show the structure of fracture zones, which are caused by the seafloor spreading and transform faulting. The characteristics of the folds and fracture zones are consistent with the hypothesis that diffuse plate boundaries and redefined plate components would occur within the Indo-Australian plate. In addition, compiled magnetic data demonstrate magnetic lineations, abandoned spreading centers, southward ridge jumps and plate motions. These features provide useful information for rebuilding the tectonic evolution history of the study area. Magnetic anomalies suggest that an additional plate boundary of transform fault type is developing.展开更多
The statistical testing models of the plate tectonic units and the hypothesis of their rigidity is presented by using the dense geodetic data, and to a certain extent the established statistic value c...The statistical testing models of the plate tectonic units and the hypothesis of their rigidity is presented by using the dense geodetic data, and to a certain extent the established statistic value can be regarded as a quantitative index to compare the rigidity degrees of different blocks. The several conclusions about the global megaplates and the regional tectonics of China are tested and verified by actual calculations, which testifies the effectiveness of this method in testing the rigidity degree and delineating their boundaries.展开更多
This paper reviews briefly the progresses made during the last four years (1999~2002) in study of seismotectonics in China, especially appraises the achievements in the fields of the crustal and upper mantles structur...This paper reviews briefly the progresses made during the last four years (1999~2002) in study of seismotectonics in China, especially appraises the achievements in the fields of the crustal and upper mantles structure, the active faults and tectonic setting of large earthquakes, the crustal deformation, and the numerical simulation. Most earthquakes occurred in China belong to continental earthquakes. Therefore, Chinese seismologists pay more attention to the continental earthquakes. Based on improvements of the observation systems in China during the ninth Five-Year Plan, the studies on seismotectonics have achieved great progresses.展开更多
About three decades after the establishment of the plate tec- tonics theory in the late 1960s, Maruyama （1994） proposed the ＂plume tectonics＂ theory based on whole-mantle seismic tomogra- phy image （Fukao, 1992; ...About three decades after the establishment of the plate tec- tonics theory in the late 1960s, Maruyama （1994） proposed the ＂plume tectonics＂ theory based on whole-mantle seismic tomogra- phy image （Fukao, 1992; Fukao et al., 1994）. According to this the- ory, the earth＇s interior is divided into three regimes： the earth＇s surface region governed by lateral motions of tectonic plates, the mantle governed by vertical motions of ＂superplumes＂ （i.e., large- scale mantle upwelling/downwelling plumes）, and the core, whose convection style is probably controlled by superplumes in the mantle. With the rapid progress in earth science after the birth of the plume tectonics theory, it is now widely accepted that various geological phenomena observed in the earth＇s surface are closely linked to the fluid motion in the deep mantle （e.g., Davies, 2011）.展开更多
Subduction plays a fundamental role in plate tectonics and is a significant factor in modifying the structure and topography of the Earth. It is driven by convection forces that change over a >100 Myr time scale. H...Subduction plays a fundamental role in plate tectonics and is a significant factor in modifying the structure and topography of the Earth. It is driven by convection forces that change over a >100 Myr time scale. However, when an oceanic plateau approaches, it plugs the subduction, and causes slab necking and tearing. This abrupt change may trigger a series of geodynamic (tectonic, volcanic) and sedimentary responses recorded across the convergence boundary and its surrounding regions by synchronous structural modifications. We suggest that a large enough triggering event may lead to a ripple tectonic effect that propagates outwards while speeding up the yielding of localized stress states that otherwise would not reach their threshold. The ripple effect facilitates tectonic, volcanic, and structural events worldwide that are seemingly unrelated. When the world’s largest oceanic plateau, Ontong Java Plateau (OJP), choked the Pacific-Australian convergence zone at ~6 Myr ago, it induced kinematic modifications throughout the Pacific region and along its plate margins. Other, seemingly unrelated, short-lived modifications were recorded worldwide during that time window. These modifications changed the rotation of the entire Pacific plate, which occupies ~20% of the Earth’s surface. In addition, the Scotia Sea spreading stopped, global volcanism increased, the Strait of Gibraltar closed, and the Mediterranean Sea dried up and induced the Messinian salinity crisis. In this paper, we attribute these and many other synchronous events to a new “ripple tectonics” mechanism. We suggest that the OJPincipient collision triggered the Miocene-Pliocene transition. Similarly, we suggest that innovative GPS-based studies conducted today may seek the connectivity between tectonic, seismic, and volcanic events worldwide.展开更多
文摘The investigation aims to understand how external forces influence tectonic plate movement, causing earthquakes and volcanic eruptions. Our emphasis was on calculating perigee forces at various moon-Earth distances. Our initial concern is the fluctuating perigee distance between the Moon and Earth. Later, we will cover Earth’s mass fluctuations caused by crustal inhomogeneity. Gravitational force depends on distance and Earth’s mass variations. Wobbling’s Earth and translation around Sun are additional factors. Tidal variations from the Moon trigger subduction zone earthquakes. Volcanoes in the Ring of Fire are influenced by plate movement on fractures and faults.
文摘With the support of the National Natural Science Foundation of China,a collaborative study by Dr.Chen Lin(陈林)from the Institute of Geology and Geophysics,Chinese Academy of Sciences,Dr.Fabio Capitanio from Monash University,Dr.Lijun Liu from the University of Illinois at Urbana-Champaign and Taras Gerya from Swiss Federal Institute of Technology Zurich demonstrates that the unique shape and complex deep structure of the Tibetan plateau may be controlled mostly by the strength heterogeneity
文摘The past size and location of the hypothesized proto-South China Sea vanished ocean basin has important plate-tectonic implications for Southeast Asia since the Mesozoic. Here we present new details on proto-South China Sea paleogeography using mapped and unfolded slabs from tomography. Mapped slabs included： the Eurasia-South China Sea slab subducting at the Manila trench; the northern Philippine Sea Plate slab subducting at the Ryukyu trench; and, a swath of detached, subhorizontal, slab-like tomographic anomalies directly under the South China Sea at 450 to 700 km depths that we show is subducted ‘northern proto-South China Sea’ lithosphere. Slab unfolding revealed that the South China Sea lay directly above the ‘northern Proto-South China Sea’ with both extending 400 to 500 km to the east of the present Manila trench prior to subduction. Our slab-based plate reconstruction indicated the proto-South China Sea was consumed by double-sided subduction, as follows：（1） The ‘northern proto-South China Sea’ subducted in the Oligo–Miocene under the Dangerous Grounds and southward expanding South China Sea by in-place ‘self subduction’ similar to the western Mediterranean basins;（2） limited southward subduction of the proto-South China Sea under Borneo occurred pre-Oligocene, represented by the 800–900 km deep ‘southern proto-South China Sea’ slab.
基金supported by Grant-in-Aid for Scientific Research on Innovative Areas Grant Number 26106002
文摘When plate tectonics began on the Earth has been long debated and here we argue this topic based on the records of Earth-Moon geology and asteroid belt to conclude that the onset of plate tectonics was during the middle Hadean（4.37-4.20 Ga）. The trigger of the initiation of plate tectonics is the ABEL Bombardment, which delivered oceanic and atmospheric components on a completely dry reductive Earth, originally comprised of enstatite chondrite-like materials. Through the accretion of volatiles, shock metamorphism processed with vaporization of both CI chondrite and supracrustal rocks at the bombarded location, and significant recrystallization went through under wet conditions, caused considerable eclogitization in the primordial continents composed of felsic upper crust of 21 km thick anorthosite, and 50 km or even thicker KREEP lower crust. Eclogitization must have yielded a powerful slab-pull force to initiate plate tectonics in the middle Hadean. Another important factor is the size of the bombardment. By creating Pacific Ocean class crater by 1000 km across impactor, rigid plate operating stagnant lid tectonics since the early Hadean was severely destroyed, and oceanic lithosphere was generated to have bi-modal lithosphere on the Earth to enable the operation of plate tectonics.Considering the importance of the ABEL Bombardment event which initiated plate tectonics including the appearance of ocean and atmosphere, we propose that the Hadean Eon can be subdivided into three periods：（1） early Hadean（4.57-4.37 Ga）,（2） middle Hadean（4.37-4.20 Ga）, and（3） late Hadean（4.20-4.00 Ga）.
基金financially supported by the China Geological Survey(grants No.DD20160048-05,12120113053400 and 12120114055501)
文摘Objective The North China Craton （NCC） is one of the oldest cratons in the world. The accretionary belt at its northern margin has been the focus of scholars both at home and abroad （Zhu Junbing and Ren Jishun, 2017）. In recent years, a series of Late Paleozoic-Mesozoic intrusions trending E-W have been discovered within the northern margin of the NCC, forming a magmatic belt. The study on the origin and tectonic setting of this magmatic belt not only has important significance for understanding the Late Paleozoic-Mesozoic tectonic evolution history of the northern margin of the NCC, but also can provide key constraints on the evolution of its surrounding Xing＇an- Mongolia orogenic belt and the Paleo-Asian Ocean. At present, no Devonian to early stage of Early Carboniferous intrusion has been reported within the northern margin of the NCC.
基金The European Research Council under the Euro-pean Union's Seventh Framework Programme(FP7/2007-2013)/ERC Advanced Grant Agreement Number 267631(Beyond Plate Tectonics)the Research Council of Norway through its Centres of Excellence funding scheme,project number 223272(CEED)are acknowledged for financial support
文摘As the chronicle of plate motions through time, paleogeography is fundamental to our understanding of plate tectonics and its role in shaping the geology of the present-day. To properly appreciate the history of tectonics--and its influence on the deep Earth and climate-it is imperative to seek an accurate and global model of paleogeography. However, owing to the incessant loss of oceanic lithosphere through subduction, the paleogeographic reconstruction of ＇full-plates＇ （including oceanic lithosphere） becomes increasingly challenging with age. Prior to 150 Ma ~60% of the lithosphere is missing and re- constructions are developed without explicit regard for oceanic lithosphere or plate tectonic principles; in effect, reflecting the earlier mobilistic paradigm of continental drift. Although these ＇continental＇ re- constructions have been immensely useful, the next-generation of mantle models requires global plate kinematic descriptions with full-plate reconstructions. Moreover, in disregarding （or only loosely applying） plate tectonic rules, continental reconstructions fail to take advantage of a wealth of additional information in the form of practical constraints. Following a series of new developments, both in geo- dynamic theory and analytical tools, it is now feasible to construct full-plate models that lend themselves to testing by the wider Earth-science community. Such a model is presented here for the late Paleozoic （410-250 Ma） together with a review of the underlying data. Although we expect this model to be particularly useful for numerical mantle modeling, we hope that it will also serve as a general framework for understanding late Paleozoic tectonics, one on which future improvements can be built and further tested.
基金supported by a generous grant from the Gordon and Betty Moore Foundation
文摘As we continue searching for exoplanets, we wonder if life and technological species capable of communicating with us exists on any of them. As geoscientists, we can also wonder how important is the presence or absence of plate tectonics for the evolution of technological species. This essay considers this question, focusing on tectonically active roclw （silicate） planets, like Earth, Venus, and Mars. The development of technological species on Earth provides key insights for understanding evolution on exoplanets, including the likely role that plate tectonics may play. An Earth-sized silicate planet is likely to experience several tectonic styles over its lifetime, as it cools and its lithosphere thickens, strengthens, and becomes denser. These include magma ocean, various styles of stagnant lid, and perhaps plate tectonics. Abundant liquid water favors both life and plate tectonics. Ocean is required for early evolution of diverse single-celled organisms, then colonies of cells which specialized further to form guts, ap- pendages, and sensory organisms up to the complexity of fish （central nervous system, appendages, eyes）. Large expanses of dry land also begin in the ocean, today produced above subduction zones in juvenile arcs and by their coalescence to form continents, although it is not clear that plate tectonics was required to create continental crust on Earth. Dry land of continents is required for further evolution of technological species, where modification of appendages for grasping and manipulating, and improve- ment of eyes and central nervous system could be perfected. These bioassets allowed intelligent crea- tures to examine the night sky and wonder, the beginning of abstract thinking, including religion and science. Technology arises from the exigencies of daily living such as tool-making, agriculture, clothing, and weapons, but the pace of innovation accelerates once it is allied with science. Finally, the importance of plate tectonics for developing a technological species is examined via a thought experiment using two otherwise identical planets： one with plate tectonics and the other without. A planet with oceans, continents, and plate tectonics maximizes opportunities for speciation and natural selection, whereas a similar planet without plate tectonics provides fewer such opportunities. Plate tectonics exerts envi- ronmental pressures that drive evolution without being capable of extinguishing all life. Plate tectonic processes such as the redistribution of continents, growth of mountain ranges, formation of land bridges, and opening and closing of oceans provide a continuous but moderate environmental pressure that stimulates populations to adapt and evolve. Plate tectonics may not be needed in order for life to begin, but evolution of technological species is favored on planets with oceans, continents, plate tectonics, and intermittently clear night sky.
文摘In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to postArchean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram was obtained using 〉2000 known ophiolitic basalts and was tested using -560 modern rocks from known tectonic settings. Ten different basaltic varieties from worldwide ophiolitic complexes have been examined. They include two basaltic types that have never been considered before, which are： （1） medium-Ti basalts （MTB） generated at nascent forearc settings; （2） a type of mid-ocean ridge basalts showing garnet signature （G-MORB） that characterizes Alpine-type （i,e., non volcanic） rifted margins and ocean-continent transition zones （OCTZ）. In the Th-Nb diagram, basalts generated in oceanic subductionunrelated settings, rifted margins, and OCTZ can be distinguished from subduction-related basalts with a misclassification rate 〈 1%. This diagram highlights the chemical variation of oceanic, rifted margin, and OCTZ basalts from depleted compositions to progressively more enriched compositions reflecting, in turn, the variance of source composition and degree of melting within the MORB-OIB array. It also highlights the chemical contributions of enriched （OIB-type） components to mantle sources. Enrichment of Th relative to Nb is particularly effective for highlighting crustal input via subduction or crustal contamination. Basalts formed at continental margin arcs and island arc with a complex polygenetic crust can be distinguished from those generated in intra-oceanic arcs in supra-subducrion zones （SSZ） with a misclassification rate 〈1%. Within the SSZ group, two sub-settings can be recognized with a misclassification rate 〈0.5%. They are： （1） SSZ influenced by chemical contribution from subduction- derived components （forearc and intra-arc sub-settings） characterized by island arc tholeiitic （IAT） and boninitic basalts; （2） SSZ with no contribution from subduction-derived components （nascent forearc sub-settings） characterized by MTBs and depleted-MORBs. Two additional discrimination diagrams are proposed： （1） a Dy-Yb diagram is used for discriminating boninite and IAT basalts; （2） a Ce/Yb-Dy/Yb diagram is used for discriminating G-MORBs and normal MORBs. The proposed method may effectively assist in recovering the tectonic affinity of ancient ophiolites, which is fundamental for establishing the geodvnamic evolution of ancient oceanic and continental domains, as well as orogenic belts.
基金supported by the Science Industry Endowment Fund (RP 04-174) Big Data Knowledge Discovery Projectsupport from a CSIRO-Data61 Postgraduate Scholarshipsupport of the Australian Research Council through a Laureate Fellowship grant (FL150100133)
文摘Accurately mapping plate boundary types and locations through time is essential for understanding the evolution of the plate-mantle system and the exchange of material between the solid Earth and surface environments.However,the complexity of the Earth system and the cryptic nature of the geological record make it difficult to discriminate tectonic environments through deep time.Here we present a new method for identifying tectonic paleo-environments on Earth through a data mining approach using global geochemical data.We first fingerprint a variety of present-day tectonic environments utilising up to 136 geochemical data attributes in any available combination.A total of 38301 geochemical analyses from basalts aged from 5-0 Ma together with a well-established plate reconstruction model are used to construct a suite of discriminatory models for the first order tectonic environments of subduction and mid-ocean ridge as distinct from intraplate hotspot oceanic environments,identifying 41,35,and 39 key discriminatory geochemical attributes,respectively.After training and validation,our model is applied to a global geochemical database of 1547 basalt samples of unknown tectonic origin aged between 1000-410 Ma,a relatively ill-constrained period of Earth’s evolution following the breakup of the Rodinia supercontinent,producing 56 unique global tectonic environment predictions throughout the Neoproterozoic and Early Paleozoic.Predictions are used to discriminate between three alternative published Rodinia configuration models,identifying the model demonstrating the closest spatio-temporal consistency with the basalt record,and emphasizing the importance of integrating geochemical data into plate reconstructions.Our approach offers an extensible framework for constructing full-plate,deeptime reconstructions capable of assimilating a broad range of geochemical and geological observations,enabling next generation Earth system models.
文摘Based on analyses of the share of documents of structural geology and tectonics in the GeoRef system over 100 years in the last century, and the historical change of international （31 years） and domestic （16 years） document counts of various topics in structural geology and tectonics, the position of structural geology and tectonics in the geosciences is evaluated and the major advaces in fields of plate tectonics, continental dynamics and global dynamics are reviewed. Our attention mainly focuses on the advances in studies of structural analysis, deformation mechanisms and rheology of rocks, contractional tectonics and late- and post-orogenic extensional collapse in orogens, large-scale strikeslip faults and indentation-extrusion tectonics, active tectonics and natural hazards. The relationships of structural geology and tectonics with petrology and geochronology are also discussed in terms of intersection of scientific disciplines. Finally, some suggestions are proposed for the further development of structural geology and tectonics in China.
基金sponsored by the National Key R&D Program of China(grant No.2017YFC0601206)National Natural Science Foundation of China(grant No.41774112).
文摘The theory of plate tectonics came together in the 1960s,achieving wide acceptance after 1968.Since then it has been the most successful framework for investigations of Earth’s evolution.Subduction of the oceanic lithosphere,as the engine that drives plate tectonics,has played a key role in the theory.However,one of the biggest unanswered questions in Earth science is how the first subduction was initiated,and hence how plate tectonics began.The main challenge is how the strong lithosphere could break and bend if plate tectonics-related weakness and slab-pull force were both absent.In this work we review state-of-the-art subduction initiation(SI)models with a focus on their prerequisites and related driving mechanisms.We note that the plume-lithosphere-interaction and mantleconvection models do not rely on the operation of existing plate tectonics and thus may be capable of explaining the first SI.Reinvestigation of plate-driving mechanisms reveals that mantle drag may be the missing driving force for surface plates,capable of triggering initiation of the first subduction.We propose a composite driving mechanism,suggesting that plate tectonics may be driven by both subducting slabs and convection currents in the mantle.We also discuss and try to answer the following question:Why has plate tectonics been observed only on Earth?
基金supported by the National Natural Science Foundation of China(Nos.42272243,41802217,41888101,41890834,and 41961144020)the MOST Special Fund(No.MSFGPMR2022-7).
文摘Earth is the only planet known to be habitable,and is also unique with its liquid water,and the operation of plate tectonics.The geological record shows that the habitability of our planet can rapidly recover from major disasters or catastrophes,even those that cause mass extinctions.We suggest that plate tectonics,which acts as a link between the shallow and deep,is pivotal for the formation,evolution,and long-term stability of the hydrosphere,atmosphere,lithosphere,and thus life.Plate tectonics links the surface environment with the deep interior of high viscosity,low Reynolds number,low entropy,and low chaos,able to produce a strong healing effect to neutralize catastrophic events.It can transfer the bio-essential elements from the deep interior to the near-surface environment and can recycle toxic elements to the deep.This unique planetary energy and material transfer process of Earth is a continuous,slow-release,and bidirectional cycle,where a change in the surface is slowly buffered by a reaction from the deep,shaping a long-term and stable habitable environment.Therefore,it is considered that plate tectonics is the basic condition for the long-term stable evolution of the Earth’s biosphere and the stabilizer of the Earth’s habitability.
基金Research supported by Sapienza University of Rome and Miur-Prin2011
文摘The possibility of a net rotation of the lithosphere with respect to the mantle is generally overlooked since it depends on the adopted mantle reference frames, which are arbitrary. We review the geological and geophysical signatures of plate boundaries, and show that they are markedly asymmetric worldwide. Then we compare available reference frames of plate motions relative to the mantle and discuss which is at best able to fit global tectonic data. Different assumptions about the depths of hotspot sources （below or within the asthenosphere, which decouples the lithosphere from the deep mantle） predict different rates of net rotation of the lithosphere relative to the mantle. The widely used no-net-rotation （NNR） reference frame, and low （〈0.2°-0.4°/Ma） net rotation rates （deep hotspots source） predict an average net rotation in which some plates move eastward relative to the mantle （e.g., Nazca）. With fast （〉1°/Ma） net rotation （shallow hotspots source）, all plates, albeit at different velocity, move westerly along a curved trajectory, with a tectonic equator tilted about 30° relative to the geographic equator. This is consistent with the observed global tectonic asymmetries.
文摘The global geological volatile cycle(H,C,N)plays an important role in the long term self-regulation of the Earth system.However,the complex interaction between its deep,solid Earth components(i.e.crust and mantle),Earth’s fluid envelopes(i.e.atmosphere and hydrosphere)and plate tectonic processes is a subject of ongoing debate.In this study we want to draw attention to how the presence of primary melt(MI)and fluid(FI)inclusions in high-grade metamorphic minerals could help constrain the crustal component of the volatile cycle.To that end,we review the distribution of MI and FI throughout Earth’s history,from ca.3.0 Ga ago up to the present day.We argue that the lower crust might constitute an important,longterm,volatile storage unit,capable to influence the composition of the surface envelopes through the mean of weathering,crustal thickening,partial melting and crustal assimilation during volcanic activity.Combined with thermodynamic modelling,our compilation indicates that periods of well-established plate tectonic regimes at<0.85 Ga and 1.7-2.1 Ga,might be more prone to the reworking of supracrustal lithologies and the storage of volatiles in the lower crust.Such hypothesis has implication beyond the scope of metamorphic petrology as it potentially links geodynamic mechanisms to habitable surface conditions.MI and FI in metamorphic crustal rocks then represent an invaluable archive to assess and quantify the co-joint evolution of plate tectonics and Earth’s external processes.
基金support from projects:CSIR-GeoMet(No.MLP-0002-FBR-2-EVB)Ministry of Earth Sciences(No.MoES P.O.(Geo)/99(i)/2017).
文摘An emerging view is that Earth’s geodynamic regime witnessed a fundamental transition towards plate tectonics around 3.0 Ga(billion years).However,the manifestations of this change may have been diachronous and craton-specific.
基金supported by the National Natural Science Foundation of China (Nos. 41606069 and 31500411)the Key Laboratory of Marginal Sea Geology, Chinese Academy of Sciences (MSGL15-04)+6 种基金the Key Laboratory of Marine Mineral Resources, Ministry of Land and Resources of China (No. KLMMR-2014-B-06)the Natural Science Foundation of Guangdong Province in China (No. 2015A030310374)the Director Grant for Oceanic technology of South China Sea Branch, State Oceanic Administration (1501)the Ministry of Human Resources and Social Security of China (50603-54)the Key Laboratory of Integrated Marine Monitoring and Applied Technologies for Harmful Algal Blooms, State Oceanic Administration (No. MATHAB201501)the Key Laboratory for Ecological Environment in Coastal Areas, State Oceanic Administration (201504)the Mariana Trench Project of the South China Sea Institute of Oceanology, Chinese Academy of Sciences
文摘Although the Indo-Australian plate near the Ninetyeast Ridge is important for understanding the formation of new plate boundaries, its tectonic problems are complex and most of them are poorly known. This paper made a detailed tectonic analysis based on the data of bathymetry, gravity and magnetics. Bathymetry and gravity maps show morphological features of many folds, which are related to the intraplate deformation of the Indo-Australian plate due to the collision between the Indian and Asian plates. Gravity anomalies show the structure of fracture zones, which are caused by the seafloor spreading and transform faulting. The characteristics of the folds and fracture zones are consistent with the hypothesis that diffuse plate boundaries and redefined plate components would occur within the Indo-Australian plate. In addition, compiled magnetic data demonstrate magnetic lineations, abandoned spreading centers, southward ridge jumps and plate motions. These features provide useful information for rebuilding the tectonic evolution history of the study area. Magnetic anomalies suggest that an additional plate boundary of transform fault type is developing.
文摘The statistical testing models of the plate tectonic units and the hypothesis of their rigidity is presented by using the dense geodetic data, and to a certain extent the established statistic value can be regarded as a quantitative index to compare the rigidity degrees of different blocks. The several conclusions about the global megaplates and the regional tectonics of China are tested and verified by actual calculations, which testifies the effectiveness of this method in testing the rigidity degree and delineating their boundaries.
基金Climbing Project Continental Dynamics of East Asia (95-S-05) from Ministry of Science and Technology China and key project Digital Crustal and Upper Mantles Structure in Chinese Mainland from China Seismological Bureau.
文摘This paper reviews briefly the progresses made during the last four years (1999~2002) in study of seismotectonics in China, especially appraises the achievements in the fields of the crustal and upper mantles structure, the active faults and tectonic setting of large earthquakes, the crustal deformation, and the numerical simulation. Most earthquakes occurred in China belong to continental earthquakes. Therefore, Chinese seismologists pay more attention to the continental earthquakes. Based on improvements of the observation systems in China during the ninth Five-Year Plan, the studies on seismotectonics have achieved great progresses.
文摘About three decades after the establishment of the plate tec- tonics theory in the late 1960s, Maruyama （1994） proposed the ＂plume tectonics＂ theory based on whole-mantle seismic tomogra- phy image （Fukao, 1992; Fukao et al., 1994）. According to this the- ory, the earth＇s interior is divided into three regimes： the earth＇s surface region governed by lateral motions of tectonic plates, the mantle governed by vertical motions of ＂superplumes＂ （i.e., large- scale mantle upwelling/downwelling plumes）, and the core, whose convection style is probably controlled by superplumes in the mantle. With the rapid progress in earth science after the birth of the plume tectonics theory, it is now widely accepted that various geological phenomena observed in the earth＇s surface are closely linked to the fluid motion in the deep mantle （e.g., Davies, 2011）.
文摘Subduction plays a fundamental role in plate tectonics and is a significant factor in modifying the structure and topography of the Earth. It is driven by convection forces that change over a >100 Myr time scale. However, when an oceanic plateau approaches, it plugs the subduction, and causes slab necking and tearing. This abrupt change may trigger a series of geodynamic (tectonic, volcanic) and sedimentary responses recorded across the convergence boundary and its surrounding regions by synchronous structural modifications. We suggest that a large enough triggering event may lead to a ripple tectonic effect that propagates outwards while speeding up the yielding of localized stress states that otherwise would not reach their threshold. The ripple effect facilitates tectonic, volcanic, and structural events worldwide that are seemingly unrelated. When the world’s largest oceanic plateau, Ontong Java Plateau (OJP), choked the Pacific-Australian convergence zone at ~6 Myr ago, it induced kinematic modifications throughout the Pacific region and along its plate margins. Other, seemingly unrelated, short-lived modifications were recorded worldwide during that time window. These modifications changed the rotation of the entire Pacific plate, which occupies ~20% of the Earth’s surface. In addition, the Scotia Sea spreading stopped, global volcanism increased, the Strait of Gibraltar closed, and the Mediterranean Sea dried up and induced the Messinian salinity crisis. In this paper, we attribute these and many other synchronous events to a new “ripple tectonics” mechanism. We suggest that the OJPincipient collision triggered the Miocene-Pliocene transition. Similarly, we suggest that innovative GPS-based studies conducted today may seek the connectivity between tectonic, seismic, and volcanic events worldwide.
