Geodynamics of the South Balkan and Northern Aegean Regions Driven by the Westward Escape of Anatolia

The Plio-Quaternary deformation pattern of the northern Aegean and south Balkan regions is interpreted as an effect of the interaction between the Anatolian-Aegean-Pelagonian system (Tethyan belt), undergoing westward extrusion and strong deformation, and the surrounding plates (Nubia, Europe and Adriatic). Since the middle-late Miocene, the collision of the Tethyan belt with the continental Adriatic domain has caused strong E-W shortening in the outer Hellenides and Albanides, also involving the southward extrusion of the Peloponnesus wedge, at the expense of the Ionian oceanic domain. The roughly E-W extension recognized in the western South Balkan zones (Macedonia and eastern Albania) is related to the divergence between the Pelagonian belt (Albanides and Hellenides) and the Rhodope-Moesia domain. Stressed by the westward displacement of the central Anatolian plateau and by the southward bowing of the Cycladic Arc, the northern Aegean zone has contemporaneously undergone E-W compression and N-S extension, which has generated a series of dextral shear faults, delimiting a number of slats. The westward displacement and deformation of such slats can explain the morphological features of the northern Aegean zone. During this phase, the push of the central Anatolian plateau also caused the separation of the Rhodope massif from the Moesian European domain, with the consequent formation of the upper Thrace basin. This hypothesis can explain the Plio-Quaternary compressional deformations recognized in a sector of the North Anatolian fault system, the Ganos-Gelibolu zone. The proposed geodynamic/tectonic interpretation may help to explain some features of the time-space distribution of major earthquakes in the study area.

Implementation of a particle-in-cell method for the energy solver in 3D spherical geodynamic modeling

The thermal evolution of the Earth’s interior and its dynamic effects are the focus of Earth sciences.However,the commonly adopted grid-based temperature solver is usually prone to numerical oscillations,especially in the presence of sharp thermal gradients,such as when modeling subducting slabs and rising plumes.This phenomenon prohibits the correct representation of thermal evolution and may cause incorrect implications of geodynamic processes.After examining several approaches for removing these numerical oscillations,we show that the Lagrangian method provides an ideal way to solve this problem.In this study,we propose a particle-in-cell method as a strategy for improving the solution to the energy equation and demonstrate its effectiveness in both one-dimensional and three-dimensional thermal problems,as well as in a global spherical simulation with data assimilation.We have implemented this method in the open-source finite-element code CitcomS,which features a spherical coordinate system,distributed memory parallel computing,and data assimilation algorithms.

Interrelationships between Length of the Day, Moon Distance, Phanerozoic Geodynamic Cycles, Tidal Dissipation and Earth’s Core: Review and Analysis

The rotation of the Earth and the related length of the day (LOD) are predominantly affected by tidal dissipation through the Moon and the growth of the Earth’s core. Due to the increased concentration of mass around the rotation axis of the spinning Earth during the growth of the core the rotation should have been accelerated. Controversially the tidal dissipation by the Moon, which is mainly dependent on the availability of open shallow seas and the kind of Moon escape from a nearby position, acts towards a deceleration of the rotating Earth. Measurements of LOD for Phanerozoic and Precambrian times open ways to solve questions concerning the geodynamical history of the Earth. These measurements encompass investigations of growth patterns in fossils and depositional patterns in sediments (Cyclostratigraphy, Tidalites, Stromatolites, Rhythmites). These patterns contain information on the LOD and on the changing distance between Earth and Moon and can be used as well for a discussion about the growth of the Earth’s core. By updating an older paper with its simple approach as well as incorporating newly published results provided by the geoscientific community, a moderate to fast growth of the core in a hot early Earth will be favored controversially to the assumption of a delayed development of the core in an originally cold Earth. Core development with acceleration of Earth’s rotation and the contemporaneous slowing down due to tidal dissipation during the filling of the ocean may significantly interrelate.

A new cache of Eoarchaean detrital zircons from the Singhbhum craton,eastern India and constraints on early Earth geodynamics

The dominant geodynamic processes that underpin the formation and evolution of Earth’s early crust remain enigmatic calling for new information from less studied ancient cratonic nuclei.Here,we present U-Pb ages and Hf isotopic compositions of detrital zircon grains from^2.9 Ga old quartzites and magmatic zircon from a 3.505 Ga old dacite from the Iron Ore Group of the Singhbhum craton,eastern India.The detrital zircon grains range in age between 3.95 Ga and 2.91 Ga.Together with the recently reported Hadean,Eoarchean xenocrystic(up to 4.24 Ga)and modem detritus zircon grains from the Singhbhum craton,our results suggest that the Eoarchean detrital zircons represent crust generated by recycling of Hadean felsic crust formed at^4.3-4.2 Ga and^3.95 Ga.We observe a prominent shift in Hf isotope compositions at^3.6-3.5 Ga towards super-chondritic values,which signify an increased role for depleted mantle and the relevance of plate tectonics.The Paleo-,Mesoarchean zircon Hf isotopic record in the craton indicates crust generation involving the role of both depleted and enriched mantle sources.We infer a short-lived suprasubduction setting around^3.6-3.5 Ga followed by mantle plume activity during the Paleo-,Mesoarchean crust formation in the Singhbhum craton.The Singhbhum craton provides an additional repository for Earth’s oldest materials.

Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in： contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes fiat subduction above the plume, resulting in a ＂bowed＂ shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau ~ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the over- riding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen （Altiads）, which are characterised by accreted ophiolite complexes with diverse geochemical affinities, and a protracted evolution of accretion of exotic terranes includinu oceanic Dlateau and terranes with nlume origins.

The deforming and rotating Earth——A review of the 18th International Symposium on Geodynamics and Earth Tide,Trieste 2016

The 18th International Symposium on Geodynamics and Earth Tides 2016 covered phenomena that generate temporal variations in geodetic and geophysical observations. In calculating the stress field for Earth tides, the observed geodetic response is used for defining the Earth＇s theology, the Earth internal structure, ＇Earth rotation parameters, and the functioning of the sophisticated instrumentation mounted on Earth and satellites. The instrumentation capable of observing Earth tides, measures changes generated by lithospheric plate movements, as the earthquake cycle and volcanism. Hydrology, tem- perature, and pressure, either of natural or anthropogenic origin, affect the high precision observations, and therefore must be included in this study-realm.

Early Mesozoic Basin-Mountain Coupling Mechanism and Basin Geodynamics of East China

arly Mesozoic flexural basins developed in East China include flexural basin with foredeep, compressive flexural basin, transpressional flexural basin and so on. Late Triassic collision between Gondwana and Eurasian continents led to the formation of large flexural basins with foredeep. Jurassic Tethys geotectonic domain and western Pacific active continental margin activated, resulting in the formation of Early-Middle Jurassic large flexural basins and Late Jurassic small foreland basins. These basins and their marginal orogenic belts were arranged as weakly constrained lateral extrusion structures and constrained lateral extrusion structures, which show a genetic coupling relationship between the orogenic belts and the basins.

Complexity and Geodynamics of Ore-accumulating Basins in the Qinling Orogenic Belt,China

Researches were made of different continental-margin and intraplate basin systems in the Qinling microplate in terms of hydrothermal deposition, geodynamics of basin formation, hydrothermal sedimentary rock facies, syntectonics in the basins, and the styles of ore accumulation in the basins.

Deep geodynamics of far field interconti- nental back-arc extension: Formation of Cenozoic volcanoes in northeastern China

There are three cases of variation of trench location possible to occur during subduction: trench fixed, trench ad- vancing, and trench retreating. Retreat of trench may lead to back-arc extension. The Pacific plate subducts at low angle beneath the Eurasia plate, tomographic results indicate that the subducted Pacific slab does not penetrate the 670 km discontinuity, instead, it is lying flat above the interface. The flattening occurred about 28 Ma ago. Geo- dynamic computation suggests: when the frontier of the subducted slab reaches the phase boundary of lower and upper mantle, it may be hindered and turn flat lying above the boundary, facilitates the retreat of trench and back-arc extension. Volcanism in northeastern China is likely a product of such retreat of subduction, far field back-arc extension, and melting due to reduce of pressure while mantle upwelling.

Some Fundamental Problems of Geodynamics and Application of Earth Observations by Space-Based Measurements

Although great-progress has been made in the earth sciences,some fundamental problems of geodynamics remain unsolved.They are concerned with the whole earth as well as regional tectonics,such as the west Pacific and Qinghai-Xizhang plateau.The new generation of earth observation by space-based measurement will contribute to solving these problems of geodynamics.In this regard,some specific plans about application of these techniques are suggested in this paper.

Stress Transfer and the Impact of the India-Eurasia Collision and the Western Pacific Subduction on the Geodynamics of the Asian Continent

The interaction between the India-Eurasia collision and the Western Pacific subduction and their contribution to recent geodynamics of the Asian continent are discussed. We perform a comparative analysis of the data available from world literature and new data on the slow strain and earthquake migration from the India-Eurasia collision and the Western Pacific subduction zones. Based on the concepts of wave dynamics of the deformation processes, a localization scheme is constructed illustrating the migration of slow strain fronts in central and eastern Asia, and the wave geodynamic impact of collision and subduction on the Asian continent is shown.

GEODYNAMICS OF SUPERLARGE DEPOSITS IN CHINSES YUNNAN-GUIZHOU-GUANGXI ON THE EASTERN MARGIN OF THE QINGZANG PLEAUTAN

Interest in the ore\|forming histories of basins has grown rapid since 1960 and is now intensive. The main reason behind the acceleration is the increasing awareness that the natural processes responsible for generating metal deposits in the sedimentary basin from the source rocks of the beneath the basin and intensively hydrothermal activity in the basin. Observations made in different continental margin basin systems and superlarge deposits in Chinese Yunnan\|Guizhou\|Guangxi Province on the eastern margin of the Qingzang (Himalaya—Karakoram—Tibet) were investigated in terms of geodynamics of basin formation. Geotectonically, the area is situated in the conjoint between the Tethys—Himalaya and the Marginal\|Pacific tectonic domain, characterized by very complex geological structure, typical basin\|mountain tectonics, abundant Superlarge deposits.

An Introduction on Basin Geodynamics of Eastern China

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GEODYNAMICS OF THE PAMIRS—HIMALAYA REGION

The Pamirs—Himalaya region possessing a complex tectonic structure and high seismic activity is located at the central part of the Alpine—Himalayan fold belt. During long\|term geodynamical studies we revealed new features of its modern structural plan steadily traced at different deep levels. The reconstruction of paleostresses by analyzing fracture patterns of Mesozoic—Cenozoic sedimentary rocks has been carried out in order to establish geodynamic regularities of the region under study and to propose a model of its development. Unlike traditional approaches to the problem of paleostress reconstruction from orientation of systems of rock joints, approaches which are based usually on the local strength criteria, we consider the formation of joint sets as a rheological instability manifesting in localized form. The systems of layers of localized plastic deformation are formed during lithification of sedimentary rocks and evolve with time into joint sets. The corresponding method of reconstruction of paleostress axes was developed. It was tested for some tectonically active regions: Central Asia, the Caucasus, the Crimea, Cuba, Iran, and others. The method was found to be useful for reconstruction of both history and spatial distribution of paleostress axes in active crustal blocks and near large geological structures. In the Pamirs—Himalaya region the fracturing of rocks has been investigated in about 1000 outcrops. By analyzing the Mesozoic—Cenozoic paleostress history it was confirmed that the structural features of the region (including an arc\|like shape of the Pamirs—Tian Shan junction zone) are caused by movement of the Hindustan mobile plate towards the rather stable Eurasian plate during the Alpine cycle of development.

DEEP GEODYNAMICS OF THE HIMALAYA OROGENY

The Himalaya is a frontal part of an intracontinental collision system connected with an approach of Asia and Hindustan. This approach takes place in the “cold” sector of the Earth (global seismic tomography data) expressed by the geoid surface’s depression. This depression is limited from east and west by lineaments (linear slopes the geoid surface) penetrated up to the core\|mantle boundary. It consists of an Asian low step and the Indian ocean minimum of the geoid surface stipulated by gigantic “cold” crust\|mantle blocks. The Indian ocean crust\|mantle block has 1500km vertical sizes and moves northward, and displaces the Tibet—Himalaya fragment of the Mediterranean mobile belt to the same direction more than 1000km. The Himalaya is on the contact of the Asian and the Indian ocean crust\|mantle blocks. The lithospheric plates’ displacements add the approach of gigantic “cold” crust\|mantle blocks.

Petrological geodynamics of mantle melting Ⅲ.AlphaMELTS+multiphase flow:The effect of water

The influence of water is evaluated in this last contribution of a series aiming to study the petrological and dynamic evolution of mantle melting.Water is considered to be either a chemical component in the melt or solid assemblage but it can also be present as a pure water phase in a oversaturated environment.A three-phase-flow model was developed for this purpose.Only a limited set of conditions has been applied to the 1-D upwelling mantle column.A range of fixed temperatures(1150-1450℃) and water contents in the solid mantle(0,0.02 wt.%,0.2 wt.%) have been imposed at the entry point(120 km deep) for the two melting models introduced in the previous installments,dynamic equilibrium melting(DEM) and dynamic fractional melting(DFM) model.As expected,for a given temperature at the base of the mantle column,the depth of the first melt formation increases with higher water content in the mantle.After the first melt is created,very negligible amount of melt is formed over a certain depth interval which approximately ends at the depth where the first melting of the dry mantle would take place.However melt is present as a dynamic phase thorough the entire region regardless whether the DEM or DFM model has been applied.Under a quasi-steady state regime,the melt and residual mantle compositions vary significantly over depth,depending on the conditions imposed to the model(DEM,DFM,bottom temperature and water content).Several distinctions can be made at the extraction point(top of the mantle column=15 km deep).For DEM and DFM models at this lowest depth,the most influential factor affecting the melt composition after the quasi-steady state condition has been reached is the temperature at the base of the column.In general,for a high temperature model,the input water in the mantle does not seem to play a significant role on the bulk composition of the melt(except for the water content in melt).But at low temperature water does have some noticeable influence on the variation of some chemical components in melt(SiO2,Fe2 O3,CaO,Na2 O at T=1250℃ or lower).A similar conclusion can be made also for the residual mantle composition.The presence of a dynamic free water phase is detected only in absence of melt or in coexistence with a melt phase when the mantle is relatively cold(bottom temperature≤1250℃) and the input water content at the base of the model is relatively high(0.2 wt.%).Complete output data for several numerical simulations and six animations illustrating various melting models are available following the instructions in the supplementary material.

Geodynamics on Formation and Evolution of Bohaiwan Basin,China

he Bohaiwan basin is a Cenozoic lacustrine fault basin, which was composed of many subbasins in Eogene. The subbasins can be classified into three types,such as extension subbasin,shove subbasin and transform subbasin, and five subtypes. In the light of the structural styles and distributions of the subbasins, regional dynamic setting and basalt data in the Bohaiwan basin, this paper proposes an inland transformextension model.

Lithospheric structure and continental geodynamics

This paper briefly reviews main progress in the research on lithospheric structure and continental geodynamics made by Chinese geophysicists during last 4 years since 22nd IUGG general assembly in July 1999. The research mainly covers the following fields: investigations on regional lithospheric structure, DSS survey of crust and upper mantle velocity structure, study on present-day inner movement and deformation of Chinese mainland by analyzing GPS observations, geodynamics of Qingzang plateau, geophysical survey of the Dabie-Sulu ultra-high pressure metamorphic belt and probing into its formation mechanism, geophysical observations in sedimentary basins and study on their evolution process, and plate dynamics, etc.

Tibetan Plateau:Geodynamics and Environmental Evolution——The cooperative projects based upon the memorandum of CAS and DFG

The Tibetan Plateau （TP） plays a unique role in Earth System Sciences. It represents a key area to understand not only basic geodynamic processes linked with the formation and uplift of mountains and plateaus, but also the interaction between plateau uplift and environmental changes. Over the last 50 million years the formation of the TP has considerably influenced the global climate and monsoon system. Moreover, the TP proves to be extremely sensitive to present-day global change phenomena. Based upon the foundation of the new Institute of Tibetan Plateau Research （1TP） by the Chinese Academy of Sciences （CAS） and through the Memorandum signed by the CAS and DFG （Deutschen Forschungsgemeinschaft）, both CAS and DFG provide opportunities to intensify TP research and to develop coordinated research programs. ＂The Tibetan Plateau - Geodynamics and Environmental Evolution＂ consisting of one big projects funded by CAS and five projects funded by DFG that cover the pre- and early-collision history of the TP, the Palaeogene/Neogene uplift and climatic dynamics as well as the Late Quaternary and recent environmental and climatic changes on the TP. The projects are linked through several levels of interactions.

Petrogenesis,Geodynamics and Radioactivity of the Granitic Rocks of the Nugrus Weakness Zone,South Eastern Desert,Egypt

The studied granitic bodies belong to the south Eastern Desert of Egypt.They extend in a NNW–SSE trend along the same strike of the Nugrus weakness zone by which they are structurally controlled.These rocks are composed of biotite and biotite-muscovite monzogranites to syenogranites.Geochemically,a higher abundance of Ba and Rb in biotite granites with a relatively low abundance in biotite-muscovite granites as well as the diversity of Th,U,Nb,Ta,Zr,and REE reflects their origin from different sources and geodynamic settings.The biotite granites are predominantly metaluminous to low peraluminous whereas the biotite-muscovite granites have a peraluminous nature.Potassium enrichment at the expense of calcium in these rocks reflects a derivation from crustal sources by partial melting in the presence of a volatile system.Radiometric investigation showed high abundances of U(up to 38 ppm)and Th(up to 26 ppm)in biotite-muscovite granites relative to biotite granites(up to 5 ppm U and 18 ppm Th).Radioactive anomalies furthermore have been recorded in parts of biotite-muscovite granites that were affected by the faults(up to 116 ppm eU and 97 ppm eTh).Consequently,biotite-muscovite granites form a potentially fertile source for uranium mineralization.