New theory of the Earth

From time to time the phrase ＇Theory of the Earth＇ occurs among titles in Earth science history. It usually happens after times of changing major scientific paradigms. A first peak occurred in the Renaissance at the time of the origin of modern science with the introduction of the word geology by Ulisse Aldrovandi in 1603; and the phrase moved around in the controversy about the origin of marine fossils found in mountains, with works by Alessandro degli Alessandri （about 1500）, Girolamo Cardano （1550）, Gabriele Falloppio （1564）, Bernard Palissy （1580）, Andrea Cesalpino （1596）, and Simeone Maioli （1597）.     

The composition of the Earth

Compositional models of the Earth are critically dependent on three main sources of information: the seismic profile of the Earth and its interpretation, comparisons between primitive meteorites and the solar nebula composition, and chemical and petrological models of peridotite-basalt melting relationships. Whereas a family of compositional models for the Earth are permissible based on these methods, the model that is most consistent with the seismological and geodynamic structure of the Earth comprises an upper and lower mantle of similar composition, an Fe---Ni core having between 5% and 15% of a low-atomic-weight element, and a mantle which, when compared to CI carbonaceous chondrites, is depleted in Mg and Si relative to the refractory lithophile elements.The absolute and relative abundances of the refractory elements in carbonaceous, ordinary, and enstatite chondritic meteorites are compared. The bulk composition of an average CI carbonaceous chondrite is defined from previous compilations and from the refractory element compositions of different groups of chondrites. The absolute uncertainties in their refractory element compositions are evaluated by comparing ratios of these elements. These data are then used to evaluate existing models of the composition of the Silicate Earth.The systematic behavior of major and trace elements during differentiation of the mantle is used to constrain the Silicate Earth composition. Seemingly fertile peridotites have experienced a previous melting event that must be accounted for when developing these models. The approach taken here avoids unnecessary assumptions inherent in several existing models, and results in an internally consistent Silicate Earth composition having chondritic proportions of the refractory lithophile elements at 2.75 times that in CI carbonaceous chondrites. Element ratios in peridotites, komatiites, basalts and various crustal rocks are used to assess the abundances of both non-lithophile and non-refractory elements in the Silicate Earth. These data provide insights into the accretion processes of the Earth, the chemical evolution of the Earth's mantle, the effect of core formation, and indicate negligible exchange between the core and mantle throughout the geologic record (the last 3.5 Ga).The composition of the Earth's core is poorly constrained beyond its major constituents (i.e. an Fe---Ni alloy). Density contrasts between the inner and outer core boundary are used to suggest the presence ( 10 ± 5%) of a light element or a combination of elements (e.g., O, S, Si) in the outer core. The core is the dominant repository of siderophile elements in the Earth. The limits of our understanding of the core's composition (including the light-element component) depend on models of core formation and the class of chondritic meteorites we have chosen when constructing models of the bulk Earth's composition.The Earth has a bulk Fe/Al of 20 ± 2, established by assuming that the Earth's budget of Al is stored entirely within the Silicate Earth and Fe is partitioned between the Silicate Earth ( 14%) and the core ( 86%). Chondritic meteorites display a range of Fe/Al ratios, with many having a value close to 20. A comparison of the bulk composition of the Earth and chondritic meteorites reveals both similarities and differences, with the Earth being more strongly depleted in the more volatile elements. There is no group of meteorites that has a bulk composition matching that of the Earth's.     

Tectonic map of the Earth

The regions of continental and oceanic crust are marked on the tectonic map of the World compiled by the author. Within the limits of the former the author indicates the Alpine geosynclines; the Alpine platforms outside these regions are divided into parts according to the age of the folded basement.The platforms have anticlises and syneclises marked on them, as well as the regions of tectonic activisation. The author proceeds from the conception that the history of the Earth had two stages. The first one is the geosyncline-platform or the granite stage, and it is characterised by the formation of the granitic continental crust. The second or basalt stage is marked by the rise of overheated basalts from the deep layers of the mantle. On the surface it is manifested in tectonic activisation, in extrusions of plateau-basalts and in oceanisation, which is associated with the secondary transformation of the granite-basalt continental crust into the water-basalt oceanic crust.

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Zusammenfassung Auf der vom Verfasser aufgestellten tektonischen Karte der Welt sind die Gebiete mit Kontinental- und Ozeankruste angegeben. Im Rahmen der Gebiete mit Kontinentalkruste sind die alpidischen Geosynklinalen gezeigt; die außer diesen Gebieten liegenden alpidischen Plattformen sind nach dem Alter des gefalteten Grundgebirges aufgeteilt. Die Plattformen teilen sich in Antiklisen und Syneklisen; es sind auch die Gebiete der tektonischen Aktivierung gezeigt. Der Verfasser legt dabei die Vorstellung zugrunde, daß die Geschichte der Erdkugel in zwei Stadien zu teilen ist. Das erste Stadium, das als Geosynklinalen- und Plattform-Stadium oder Granitstadium bezeichnet werden kann, ist durch die Bildung der Kontinentalkruste aus Granit gekennzeichnet. Das zweite Stadium, das sog. Basaltstadium, besteht im Aufstieg überhitzter Basalte aus den tiefen Schichten des Mantels. Auf der Oberfläche kommt dieses Stadium in der tektonischen Aktivierung, im Erguß von Plateau-Basalten und in der Bildung der Ozeane zum Ausdruck, die die sekundäre Umwandlung von granit-basaltischer Kontinentalkruste in wasser-basaltische Ozeankruste begleiten.

     

Effects of instability of the Earth and celestial coordinate systems on Earth orientation parameters

Unknown secular and long-term changes in the Earth orientation parameters attributed to instability (possible rotation) of both the Earth and celestial coordinate systems (ECS and CCS) are studied. Rotation of the CCS due to changes in the coordinates of extragalactic sources resulting from gravitational lensing can lead to errors of the order of several microarcseconds in the orientation parameters. The rotation of the ECS due to the crust pressing on the mantle diminishes the tidal retardation of the Earth's rotation and produces long-term variations in the duration of the day (with a period of about 1500 years) and in the motion of the pole relative to the Earth's surface.     

Geochemistry of Rare Earth Metals in the Ore Eudialyte Complex of the Lovozero Rare Earth Deposit

Doklady Earth Sciences - Rare earth elements belong to the category of strategic metals. The largest deposits of these strategic raw materials are associated with alkali-carbonatite formations. The...     

Multisphere Tectonics of the Earth System

The fundamental theoretical framework of the Multisphere Tectonics of the Earth System is as follows: (1) It intends to extend the geotectonic studies from the crustal and lithospheric tectonics to the multisphere tectonics of the Earth system as a whole. (2) The global dynamics driven by both the Earth system and the cosmic celestial system: solar energy, multispheric interactions of the Earth system and the combined effects of the motions of celestial bodies in the cosmos system are the driving forces of various geological processes. (3) The Continent-Ocean transformation theory: the continent and ocean are two opposite yet unified geological units, which can be transformed into each other; neither continent nor ocean will survive forever; there is no one-way development of continental accretion or ocean extinction; the simple theory of one-way continental accretion is regarded as invalid. (4) The continental crust and mantle are characterized by multiple layers, with different layers liable to slide along the interfaces between them, but corroboration is needed that continents move as a whole or even drift freely. (5) The cyclic evolution theory: the development of Earth’s tectonics is not a uniform change, but a spiral forward evolution, characterized by a combination of non-uniform, non-linear, gradual and catastrophic changes; different evolutionary stages (tectonic cycles) of Earth have distinctive global tectonic patterns and characteristics, one tectonic model should not be applied to different tectonic cycles or evolutionary stages. (6) The structure and evolution of Earth are asymmetric and heterogeneous, thus one tectonic model cannot be applied to different areas of the world. (7) The polycyclic evolution of the continental crust: the continental crust is formed by polycyclic tectonics and magmatism, rather than simply lateral or vertical accretion. (8) The role of deep faults: the deep fault zones cutting through different layers of the crust and mantle usually play important roles in tectonic evolution. For example, the present-day mid-ocean ridge fault zones, transform fault zones and Benioff zones outline the global tectonic framework. Different tectonic cycles and stages of Earth’s evolution must have their own distinctive deep fault systems which control the global tectonic framework and evolutionary processes during different tectonic cycles and stages. Starting from the two mantle superplumes Jason (Pacific) and Tuzo (Africa), the study of the evolutionary process of the composition and structure of the crust and mantle during the great transformation and reorganization of the Meso-Cenozoic tectonic framework in China and the other regions of Asia is a good demonstration of theory of Multisphere Tectonics of the Earth System.     

Not so rare Earth? New developments in understanding the origin of the Earth and Moon

A widely accepted model for the origin of the Earth and Moon has been a somewhat specific giant impact scenario involving an impactor to proto-Earth mass ratio of 3:7, occurring 50-60 Ma after T₀, when the Earth was only half-accreted, with the majority of Earth's water then accreted after the main stage of growth, perhaps from comets. There have been many changes to this specific scenario, due to advances in isotopic and trace element geochemistry, more detailed, improved, and realistic giant impact and terrestrial planet accretion modeling, and consideration of terrestrial water sources other than high D/H comets. The current scenario is that the Earth accreted faster and differentiated quickly, the Moon-forming impact could have been mid- to late in the accretion process, and water may have been present during accretion. These new developments have broadened the range of conditions required to make an Earth-Moon system, and suggests there may be many new fruitful avenues of research. There are also some classic and unresolved problems such as the significance of the identical O isotopic composition of the Earth and Moon, the depletion of volatiles on the lunar mantle relative to Earth's, the relative contribution of the impactor and proto-Earth to the Moon's mass, and the timing of Earth's possible atmospheric loss relative to the giant impact.     

流体地球科学与地球系统科学

近年来,地球系统科学逐渐成为地球科学的新趋势,但固体地球科学尚难于融入其中。其根本原因在于地球系统科学属于系统科学或复杂科学的组成部分,而固体地球科学其本质上属于理想科学的范畴,以研究线性地球过程为主,或者以理想科学的手法研究非线性地球过程。流体地球科学不仅研究地球的流体系统,也研究流体系统与固体系统的强和弱相互作用,是固体地球科学融入地球系统科学的唯一途径。     

The impact environment of the Hadean Earth

Impact bombardment in the first billion years of solar system history determined in large part the initial physical and chemical states of the inner planets and their potential to host biospheres. The range of physical states and thermal consequences of the impact epoch, however, are not well quantified. Here, we assess these effects on the young Earth's crust as well as the likelihood that a record of such effects could be preserved in the oldest terrestrial minerals and rocks. We place special emphasis on modeling the thermal effects of the late heavy bombardment (LHB) – a putative spike in the number of impacts at about 3.9 Gyr ago – using several different numerical modeling and analytical techniques. A comprehensive array of impact-produced heat sources was evaluated which includes shock heating, impact melt generation, uplift, and ejecta heating. Results indicate that ∼1.5–2.5 vol.% of the upper 20 km of Earth's crust was melted in the LHB, with only ∼0.3–1.5 vol.% in a molten state at any given time. The model predicts that approximately 5–10% of the planet's surface area was covered by >1 km deep impact melt sheets. A global average of ∼600–800 m of ejecta and ∼800–1000 m of condensed rock vapor is predicted to have been deposited in the LHB, with most of the condensed rock vapor produced by the largest (>100-km) projectiles. To explore for a record of such catastrophic events, we created two- and three-dimensional models of post-impact cooling of ejecta and craters, coupled to diffusion models of radiogenic Pb*-loss in zircons. We used this to estimate what the cumulative effects of putative LHB-induced age resetting would be of Hadean zircons on a global scale. Zircons entrained in ejecta are projected to have the following average global distribution after the end of the LHB: ∼59% with no impact-induced Pb*-loss, ∼26% with partial Pb*-loss and ∼15% with complete Pb*-loss or destruction of the grain. In addition to the relatively high erodibility of ejecta, our results show that if discordant ca. 3.9 Gyr old zones in the Jack Hills zircons are a signature of the LHB, they were most likely sourced from impact ejecta.     

地球系统多圈层构造观

地球系统多圈层构造观的基本理论框架是:①把大地构造学从研究地球表层的地壳构造、岩石圈构造推进到研究地球整体多圈层构造的新阶段.②地球系统和宇宙天体系统共同作用下形成的全球动力学,太阳能、地球系统多圈层相互作用以及宇宙天体运行的联合作用是各种地质作用的动力来源.③洋陆转化论:陆与洋是对立统一、相互转化的.陆与洋都不会永存...     

Forecasting the polar motions of the deformable Earth

A mathematical model for the complicated phenomenon of the polar oscillations of the deformable Earth that adequately describes the astrometric data of the International Earth Rotation Service is constructed using celestial mechanics and asymptotic techniques. This model enables us to describe the observed phenomena (free nutation, annual oscillations, and trends) simply and with statistical reliability. The model contains a small number of parameters determined via a least-squares solution using well-known basis functions. Interpolations of the polar trajectory for intervals of 6 and 12 yrs and forecasts for 1–3 yrs are obtained using the theoretical curve. The calculated coordinates demonstrate a higher accuracy than those known earlier.     

地质遗产、地质公园及通过2008国际地球年促进地球科学

In the years 2000 and 2001 a few visionaries in IUGS under the lead of Ed de Mulder, at that time President of IUGS, started to think out loudly about an ＂ International Year of Planet Earth＂ （YEAR）. It was their feeling that globally the geosciences did not get that part of public recognition that geosciences should earn, compared to ecology, economy, sustainable development and environmental sciences at large.[第一段]     

文化视角下的地球科学

从文化视角来审视地球科学, 或将地球科学作为一种文化现象来研究, 地球科学至少包含三方面的内容: 一是地学研究方法或思维逻辑, 即“真”的问题; 二是人地关系或地学的价值理念, 即“善”的问题; 三是地球演化的平衡或人与地球的和谐, 即“美”的问题.文化视角下的地球科学是由“真”、“善”、“美”三者构成的统一体系.      

The oceans and the physics of the Earth

The Earth is the only terrestrial planet to have seas, by which it is covered to the extent of seventy percent. The oceans determine the climate of the Earth and it is through them that life and civilization have evolved, but they also have major influence on physical processes in the solid Earth. Tidal friction leads to the Earth's spin slowing down with a consequent recession of the Moon from the Earth, while the presence of the oceans controls the tectonic evolution of the Earth through the formation of oceanic crust, the erosion of land and the accumulation of sediment, the formation of mountains and the establishment of isostatic balance.     

Physical state of the very early Earth

The earliest surface environment of the Earth is reconstructed in accordance with the planetary formation theory. Formation of an atmosphere is an inevitable consequence of Earth's formation. The atmosphere near the close of accretion is composed of 200 300 bars of H₂ and H₂O, and several tens of bars of CO and CO₂. Either by the blanketing effect of the proto-atmosphere or heating by large planetesimal impacts a magma ocean is formed during accretion. We can distinguish three stages for the thermal evolution of the magma ocean and proto-crust. Stage 0 is characterized by a super-liquidus (or completely molten) regime near the surface. At this stage the surface of the Earth is covered by a super-liquidus magma ocean. No chemical differentiation is expected during this stage. Once the energy flux released by planet formation decreases to the 200 W/m² level the super-liquidus magma ocean then disappears within a time interval of 1 m.y. This is the transition from stage 0 to 1. Stage 1 is characterized by a partially molten magma ocean. In the magma ocean consisting of 20 30% partial melt, heat transport is controlled by melt-solid separation (a type of compositional convection) rather than thermal convection. Chemical differentiation of the mantle mainly occurs in this stage. Once the energy flux drops to the 160 W/m² level, more than 90% of water vapor in the proto-atmosphere condense to form the proto-oceans. Several tens of bars of CO and CO₂ remain in the atmosphere just after formation of the oceans. Water oceans are occasionally evaporated by large impacts. After each such event, recondensation of the ocean takes several hundred years. Although the surface is covered by a chilled proto-crust, it is short-lived because of extensive volcanic resurfacing activity as well as meteorite impacts resurfacing. This stage ends when the energy flux drops to 0.1 1 W/m² level. The duration time of stage 1 is estimated to be several hundred million years (the best estimate is about 400 m.y.). Stage 2 is characterized by solid state convection. This stage continues to the present day. One of the most important change on the proto-Earth is the transition from stage 1 to 2, which occurs several hundred million years after the Earth formation. Long-lived crust is formed only after this transition.     

Climate and the orbital parameters of the Earth

The discovery of glacial ages in the 19th century triggered the first scientific questions on the evolution of climate through time, and thus corresponds to the dawn of palaeoclimatology. Since then, scientists have attempted to reconstruct past climatic changes and to understand their physical basis. Two competing theories have been suggested to explain the sequence of glacial–interglacial epochs: either the variations of the Earth orbital elements, or the atmospheric composition in carbon dioxide. If the astronomical theory has been largely confirmed since the last 30 years, a physical modeling of the climatic processes at work is still in its infancy. Besides, the most recent results of palaeoclimatology are clearly demonstrating that, more than never, a synthesis of these two old hypotheses is needed.