Crustal movement determined from repeat surveying — results from southeastern and southwestern Australia

First order geodetic measurements show that strain rates in southeastern New South Wales are about 50 × 10‐⁸ y‐¹. These strain rates are much greater than those suggested by seismicity. The direction of the principal axis of compression varies with position, but it is consistent with compression axis directions of the earthquake focal mechanisms in the Bowning area, and with the pattern of late Cainozoic vertical displacements suggested by geomorphology. In southwestern Western Australia strain identified from geodetic measurements is patchy in distribution, and is irregular in magnitude and direction. It is found close to areas of historic faulting, in areas of high measured stress, and across the Darling Fault line of weakness separating the Perth Basin from the Yilgarn Craton.     

Rheological Strength of UHP Eclogite from Dabieshan: Evidences from High p-T Experiments

ＴｈｅｈｙｐｏｔｈｅｓｉｓｏｆｔｒａｎｓｆｏｒｍａｔｉｏｎｏｆｂａｓａｌｔｔｏｅｃｌｏｇｉｔｅａｔｔｈｅｃｏｎｔｉｎｅｎｔａｌＭｏｈｏｄｉｓｃｏｎｔｉｎｕｉｔｙｉｎ 196 0ｓｅｖｅｒｂｒｏｕｇｈｔｂｒｏａｄｉｎｔｅｒｅｓｔｓｔｏｇｅｏｓｃｉｅｎｃｅｃｏｍｍｕｎｉｔｙ (ＲｉｎｇｗｏｏｄａｎｄＧｒｅｅｎ ,1996 ;ＧｒｅｅｎａｎｄＲｉｎｇｗｏｏｄ ,1972 ;ＩｔｏａｎｄＫｅｎｎｅｄｙ ,1971;ＫｕｓｈｉｒｏａｎｄＡｏｋｉ,196 8) .Ｔｈｉｒｔｙｙｅａｒｓｌａｔｅｒ ,ｗｉｔｈｔｈｅｄｉｓｃｏｖ ｅｒｉｅｓｏｆｃｏｅｓ…     

Oil geochemistry derived from the Qinjiatun–Qikeshu oilfields: insight from light hydrocarbons

A suite of 27 oils from the Qinjiatun–Qikeshu oilfields in the Lishu Fault Depression of the Songliao Basin was analyzed using whole oil gas chromatography. In combination with the relative distribution of C₂₇, C₂₈, and C₂₉ regular steranes, detailed geochemical analyses of light hydrocarbons in oil samples revealed crude oils characterized by the dual input of lower aquatic organisms and higher terrestrial plants. Several light hydrocarbon indicators suggest that the liquid hydrocarbons have maturities equivalent to vitrinite reflectances of around 0.78%–0.93%. This is consistent with the maturity determination of steranes C₂₉ 20S/(20S + 20R) and C₂₉ ααβ/(ααα + αββ). Crude oils derived from the two distinct oilfields likely both have source rocks deposited in a lacustrine environment based on light hydrocarbon parameters and on higher molecular weight hydrocarbon parameters. The results show that light hydrocarbon data in crude oils can provide important information for understanding the geochemical characteristics of the Qinjiatun–Qikeshu oils during geologic evolution.     

OneGeology： from concept to reality

In the March 2007 edition of Episodes, an article described the origins of OneGeology and progress during its first 12 months. Since March 2007, the project has moved forward dramatically and in August 2008, at the 33rd International Geological Congress in Oslo, it was launched to the world.     

Application of U-Pb-systems from detrital Zircons for palaeogeographic reconstructions a – case-study from the Rhenohercynian

Abstract

U-Pb. systematics of detrital zircons carry a mineral-specific information summarizing important geologic events during the preelastic slate of the minerals. Comparisons with U/Pb isotope rati of zircons from potential provenances reveal relationships between source areas of the zircons and their final location of deposition in a sedimentary basin. The Palaeozoic zircon detritus accumulated in sedimentary basins on the Rhenohercynian crustal segment is taken as an example to elucidate the plate-tectonical induced changes of the source areas by significant changes of the ²⁰⁶Pb/²³⁸ vs. ²⁰⁷Pb/²³⁵ratios in the zircons.

The U-Pb systematic of detrital zircon- from the Cambrian sediments deposited in the Brabant Massif and in the Ardennes indicale two source areas. Part of the detritus derived from an area. where strong Cadomian-Panafrican events influenced the U-Pb systems of the zircons. The oilier part reflects a source, in which the U-Pb systems were able to preserve their Arehaean to Early Proterozoic age information. Zircons of the latter source record the most ancient ages so far observed in detrital zircons of the later Rhenohercynian crustal seg ment. The similarities with the U/Pb isotope ratios of zircons from the Armorican Massif, the Bohemian Massif. and certain regions of the Mps indicate a geotectonic position of the sedimentar) basin during Cambrian times in the periphery of the Condwana mega-continent.

The detrital zircons accumulated in the Variscan Rhenish basin during the Lower Devonian show a completely different summarizing age information. The majority of the zircons reflect a Laurussian-type origin. which suggests a palaeogeographic position of the Variscan Rhenohercynian basin close to Laurussia. Euhedral zircons crystallized during Caledonian times document the erosion of Caledonian granitoids from structural highs in the Mid European Caledonides.

Zircons of the Lower Carboniferous flysch sediments of todays Eastern Rhenish Massif originate from two source areas characterised by very different geologic histories. Euhedral zircons represent a rather young component of about 410 Ma in the detritus, whereas. in contrast. the well rounded crystals show a summarizing age-information identical to that of the zircons found in the Cambrian sandstones. The low ages resemble intrusion ages as recorded from the Mid-German-Crystalline-Rise, the high age reflect a Gondwana-type input into the Rhenohercynian sedimentary basin during Lower Carboniferous times. The detritus thus documents the Variscan collision and a renewed coherence of the Rhenohercynian crustal segment to Cnndwana.

The zircon population from Upper Carboniferous molasse deposits is comprised of Condwana-tуpc material and of mate rial with similar U/Pb ratios as recorded in the Lower Devonian zircons. In parts the Variscan molasse must have been derived from sediments once deposited in a southern part of the Rhenohercynian basin and in the Saxothurìngian basin. U/Pb ratios of euhedral and round diamond-like lustrous zircons indicate a major geologic event at the Namurian/Westphalian boundary (310-315 Ma). These zircons thus reflect an influx of detritus into the molasse from other source rocks, probably synsedimentary volcanics.     

P -T paths from anatectic pelites

A relatively simple petrogenetic grid for partial melting of pelitic rocks in the NCKFMASH system is presented based on the assumption that the only H₂O available for melting is through dehydration reactions. The grid includes both discontinuous and continuous Fe-Mg reactions; contours of Fe/(Fe+Mg) for continuous reactions define P-T vectors along which continuous melting will occur. For biotite-bearing assemblages (garnet+biotite + sillimanite + K-feldspar + liquid and garnet + biotite + cordierite + K-feldspar + liquid), Fe/(Fe+Mg) contours have negative slopes and melting will occur with increasing temperature or pressure. For biotite-absent assemblages (garnet + cordierite + sillimanite + K-feldspar + liquid or garnet + cordierite + orthopyroxene + K-feldspar + liquid) Fe/(Fe + Mg) contours have flat slopes and melting will occur only with increasing pressure. The grid predicts that abundant matrix K-feldspar should only be observed if rocks are heated at P < 3.8 kbar, that abundant retrograde muscovite should only be observed if rocks are cooled at P > 3.8 kbar, and that generation of late biotite + sillimanite replacing garnet, cordierite, or as selvages around leu- cosomes should be common in rocks in which melt is not removed. There is also a predicted field for dehydration melting of staurolite between 5 and 12 kbar. Textures in migmatites from New Hampshire, USA, suggest that prograde dehydration melting reactions are very nearly completely reversible during cooling and crystallization in rocks in which melt is not removed. Therefore, many reaction textures in “low grade” migmatites may represent retrograde rather than prograde reactions. Received: 5 March 1998 / Accepted: 7 August 1998     

First Record of the Belemnite Genus Hibolithes from Late Jurassic–Early Cretaceous Turbidites from Malaysia

Discovery of the remains of belemnites referred to the Hibolithes sp. from the Jurassic–Cretaceous Pedawan Formation in Sarawak, on the island of Borneo(Malaysia) comprises four fragments of belemnite rostra. The specimens are characterized by multiple fractures and vein filling. Two fragments measuring about 130 mm are relatively intact, with only part of the alveolar region missing; a third piece represents the middle part of a rostrum, and the fourth specimen is too fragmentary to be assigned to any specific part of the rostrum. Based on specimen characteristics, a Tithonian–Hauterivian age is plausible. The sedimentary succession that yielded the belemnite material comprises thick shale that reflects the Te division of Bouma sequence. The occurrence of a Hibolithes taxon in the uppermost Jurassic to lowermost Cretaceous Pedawan Formation sediments in Borneo reflects a near to global palaeobiogeographic distribution of this genus.     

Early Cooling History of Eciogites from the Dabie-Sulu Orogen： Constraints from Diffusion Kinetics of Garnet

Abstract For the first time, we apply different geospeedometric models to garnet zoning patterns that were obtained in this study from detailed EMP analyses for garnets from eclogites and granulite in the Dabie‐Sulu orogen. Various zonings of cation diffusion were preserved in the garnets, enabling the acquirement of average cooling rates for the high‐to ultrahigh‐pressure rocks without using geochronological approaches. The coesite‐bearing hot eclogites yield fast cooling rates of about 20 to 30°C/Ma subsequent to peak metamorphic temperatures, whereas the cold eclogite gives a relatively slow cooling rate of 8°C/Ma at its initial exhumation. A very slow cooling rate of <0.3°C/Ma is obtained for the granulite at Huangtuling, suggesting that the granulite may not be involved in the continental deep subduction.     

Spherules from the Tunguska event site: Could they originate from the Tunguska Cosmic Body?

Soil layers at the Tunguska event site may have accumulated infalling extraterrestrial matter derived from the Tunguska Cosmic Body (TCB). Using mineralogical, textural, and chemical criteria, a set of metal and silicate spherules of probably cosmic origin was identified in the collection of spherules and rounded particles recovered from sites with high concentrations of magnetic spherules on a terrace above the floodplain of the Chunya River. The metal spherules consist of Ni(Cr)-bearing wüstite and magnetite with Ni-rich metal inclusions. The silicate spherules are glassy, cryptocrystalline, barred, and porphyritic melted micrometeorites, some of which contain metal droplets. The number of spherules counted in our samples is higher than the background level, indicating the possible presence of the TCB material.     

Groundwater supply and demand from southern Africa’s crystalline basement aquifer: evidence from Malawi

Failure of borehole sources in weathered and fractured crystalline basement aquifers in Malawi in southern Africa has been linked with poor borehole design, mechanical failure and badly sited boreholes. However, recent work in Malawi indicates that demand may now exceed long-term resource potential in some places and that this is also a cause of water point failure. An 11-year climate cycle (including a wet and dry period) necessitates overdraft from groundwater storage during the dry-cycle years before episodic rainfall events in the wetter part of the cycle again recharge the aquifers. Data, particularly groundwater hydrograph data, are sparse, but sufficient to evaluate the long-term renewable groundwater potential for both fractured and weathered basement-aquifer types in each of the 15 management areas in Malawi. The groundwater potential or long-term renewable resource (recharge) is given by the sum of Darcian throughflow and dry-season depletion of storage. Estimated rural demand exceeds the renewable resource in the fractured-rock aquifer in two management units and in the weathered-rock aquifer in two other units. Although there is inherent uncertainty in the water-balance estimates, the likelihood that rural demand is exceeding long-term average recharge in some areas is cause for concern.     

Diamond in Oceanic Peridotites and Chromitites: Evidence for Deep Recycled Mantle in the Global Ophiolite Record

Diamonds have been discovered in mantle peridotites and chromitites of six ophiolitic massifs along the 1300 km‐long Yarlung‐Zangbo suture (Bai et al., 1993; Yang et al., 2014; Xu et al., 2015), and in the Dongqiao and Dingqing mantle peridotites of the Bangong‐Nujiang suture in the eastern Tethyan zone (Robinson et al., 2004; Xiong et al., 2018). Recently, in‐situ diamond, coesite and other UHP mineral have also been reported in the Nidar ophiolite of the western Yarlung‐Zangbo suture (Das et al., 2015, 2017). The above‐mentioned diamond‐bearing ophiolites represent remnants of the eastern Mesozoic Tethyan oceanic lithosphere. New publications show that diamonds also occur in chromitites in the Pozanti‐Karsanti ophiolite of Turkey, and in the Mirdita ophiolite of Albania in the western Tethyan zone (Lian et al., 2017; Xiong et al., 2017; Wu et al., 2018). Similar diamonds and associated minerals have also reported from Paleozoic ophiolitic chromitites of Central Asian Orogenic Belt of China and the Ray‐Iz ophiolite in the Polar Urals, Russia (Yang et al., 2015a, b; Tian et al., 2015; Huang et al, 2015). Importantly, in‐situ diamonds have been recovered in chromitites of both the Luobusa ophiolite in Tbet and the Ray‐Iz ophiolite in Russia (Yang et al., 2014, 2015a). The extensive occurrences of such ultra‐high pressure (UHP) minerals in many ophiolites suggest formation by similar geological events in different oceans and orogenic belts of different ages. Compared to diamonds from kimberlites and UHP metamorphic belts, micro‐diamonds from ophiolites present a new occurrence of diamond that requires significantly different physical and chemical conditions of formation in Earth's mantle. The forms of chromite and qingsongites (BN) indicate that ophiolitic chromitite may form at depths of >150‐380 km or even deeper in the mantle (Yang et al., 2007; Dobrthinetskaya et al., 2009). The very light C isotope composition (δ13C ‐18 to ‐28‰) of these ophiolitic diamonds and their Mn‐bearing mineral inclusions, as well as coesite and clinopyroxene lamallae in chromite grains all indicate recycling of ancient continental or oceanic crustal materials into the deep mantle (>300 km) or down to the mantle transition zone via subduction (Yang et al., 2014, 2015a; Robinson et al., 2015; Moe et al., 2018). These new observations and new data strongly suggest that micro‐diamonds and their host podiform chromitite may have formed near the transition zone in the deep mantle, and that they were then transported upward into shallow mantle depths by convection processes. The in‐situ occurrence of micro‐diamonds has been well‐demonstrated by different groups of international researchers, along with other UHP minerals in podiform chromitites and ophiolitic peridotites clearly indicate their deep mantle origin and effectively address questions of possible contamination during sample processing and analytical work. The widespread occurrence of ophiolite‐hosted diamonds and associated UHP mineral groups suggests that they may be a common feature of in‐situ oceanic mantle. The fundamental scientific question to address here is how and where these micro‐diamonds and UHP minerals first crystallized, how they were incorporated into ophiolitic chromitites and peridotites and how they were preserved during transport to the surface. Thus, diamonds and UHP minerals in ophiolites have raised new scientific problems and opened a new window for geologists to study recycling from crust to deep mantle and back to the surface.     

Thermo-mechanical modeling of the obduction process based on the Oman Ophiolite case

Obduction emplaces regional-scale fragments of oceanic lithosphere (ophiolites) over continental lithosphere margins of much lower density. For this reason, the mechanisms responsible for obduction remain enigmatic in the framework of plate tectonics. We present two-dimensional (2D) thermo-mechanical models of obduction and investigate the possible dynamics and physical controls of this process. Model geometry and boundary conditions are based on available geological and geochronological data and numerical modeling results are validated against petrological and structural observations of the Oman (Semail) Ophiolite. Our model reproduces the stages of oceanic subduction initiation away from the Arabian margin, the emplacement of the Oman Ophiolite on top of it, and the domal exhumation of the metamorphosed margin through the ophiolitic nappe. A systematic study indicates that 350–400 km of bulk shortening provides the best fit for both maximum pressure–temperature conditions of the metamorphosed margin (1.5–2.5 GPa/450–600 °C) and the dimension of the ophiolitic nappe (~ 170 km width). Our results confirm that a thermal anomaly located close to the Arabian margin (~ 100 km) is needed to initiate obduction. We further suggest that a strong continental basement rheology is a prerequisite for ophiolite emplacement.     

中国板块构造研究的某些新进展

<正> 1972年尹赞勋综合大量国外资料,在我国首次较系统地介绍了板块构造理论,接着李春昱、傅承义等又著文进一步介绍板块构造的基本理论,在我国广大地质工作者中引起了强烈的反响。由于当时还处在十年动乱时期,板块构造这一新兴学说得不到应有的重视,研究工作未能广泛开展,只有局部地区的探索。李春昱先生不顾古稀之年,带领西北地质研究所少数几人,首先开展了祁连山—秦岭地区的板块构造研究工作,这对我国板块构造研究起了先锋作用。     

Stratigraphy and tectonics of a time-transgressive ophiolite obduction onto the eastern margin of the Pelagonian platform from Late Bathonian until Valanginian time,exemplified in northern Evvoia,Greece

The obduction of an ophiolite sheet onto the eastern Pelagonian carbonate platform complex of the Hellenides began during the Late Bathonian and ended with the final emplacement of the ophiolite during Valanginian time. The early stages of obduction caused subaerial exposure of the platform, recorded by an unconformity of Callovian age, which is marked by laterites overlying folded and faulted, karstic substrates. The laterites have distinct ophiolitic geochemical signatures, indicating that emergent ophiolite had been undergoing lateritic weathering. This unconformity coincides with widespread western Tethyan, Callovian gaps, indicating that the obduction in the Hellenides was probably related to far-reaching plate tectonic processes. Resumed gravitational pull and rollback of the subducted, oceanic leading edge of the temporarily exposed ophiolite. Platform drowning continued into Tithonian–Valanginian time, documented initially by reefal carbonates and then by below-CCD, carbonate-free radiolarian cherts and shales. Subsequently, siliciclastic turbidites, which apparently originated from uplifted Variscan basement, were deposited together with and over the radiolarite as the ophiolite nappe sheet advanced. The nappe substrate underwent tectonic deformations of varying intensity, while polymictic mélange and syntectonic sedimentary debris accreted beneath the ophiolite and at the nappe front. The provenience of the ophiolite nappe complexes of northern Evvoia most probably has to be looked for in the Vardar ocean.     

Earliest Eocene (53 Ma) convergence in the Southwest Pacific: evidence from pre‐obduction dikes in the ophiolite of New Caledonia

Uncertainty about the timing and location of the initiation of convergence in the western and south‐western Pacific greatly hinders accurate plate tectonic reconstructions of subduction systems in that area. The chemistry and age of dikes intruding mantle peridotite in the ophiolite of New Caledonia infer that subduction‐related magmatism began before 53 Ma. These new results infer that obduction in the south‐west Pacific is unrelated to the reorientation of the Pacific plate motion that occurred c. 43 Ma and confirm new interpretations showing that changes in mantle flow, hotspot and plate motion may have occurred as soon as late Paleocene or early Eocene.     

Modélisation magnétique de la suture ophiolitique de Bou Azzer–El Graara (Anti-Atlas central,Maroc). Implications sur la reconstitution géodynamique panafricaine

Aeromagnetic data of the Anti-Atlas Mountains show an important magnetic anomaly along the ‘Major Anti-Atlas Fault’, produced by different mafic and ultramafic rocks of a Neoproterozoic ophiolite complex. The magnetic modelling of Bou Azzer–El Graara ophiolitic suture shows a deep-seated anomaly through the upper continental crust corresponding to a north-dipping subduction. The polarity of the Pan-African subduction in the Anti-Atlas is therefore compatible with the contemporaneous Pan-African orogenic belts, where polarity of subduction dipped away from the West African Craton during the amalgamation of Western Gondwana. To cite this article: A. Soulaimani et al., C. R. Geoscience 338 (2006).     

Trace and Minor Elements in Smithsonite from Huoshaoyun Nonsulfide Zinc Deposits in Southwest China: A LA–ICP–MS Study

The geodynamic setting of the Xigaze ophiolite has long been debated. Structural and geochemical evidence suggest the Xigaze ophiolite was formed at a slow‐spreading ridge (Nicolas et al., 1981; Liu et al., 2016). Based on incompatible element concentrations, the Xigaze ophiolite volcanics are consistent with the ubiquitous subduction signature in suprasubduction zone (Bedard et al., 2009; Hebert et al., 2012; Dai et al., 2013). It is noteworthy that the Xigaze ophiolite is different from the Geotimes and Lasail and Velly units from Oman ophiolite, respectively. The mafic rocks of the Xigaze ophiolite generally resemble typical N‐MORB and Geotimes volcanics in composition except for slight depletions of Th and Nb (Fig.1a). Although the Xigaze rocks have similar Th and Nb concentrations to Lasail and Velly rocks, most incompatible elements in the Xigaze rocks are comparable to N‐MORB. Petrography in gabbro of Xigaze ophiolite shows that euhedral plagioclases are enclosed by clinopyroxenes suggesting that these minerals have crystallized from an anhydrous magma (Sisson and Grove, 1993). Although the Xigaze volcanic rocks are slightly depleted in Th and Nb, they have MORB‐like trace element characteristics implying that they are derived from an anhydrous MORB magma at spreading centre. Godard et al. (2006) suggested that the mantle source of the Oman ophiolite have element and isotopic characteristics similar to Indian Ocean MORB, where the mantle preserved some older slab materials. A negative Nb anomaly of Oman Geotimes volcanic rocks may be resulted from contamination of the slab materials via decompression melting of the convecting mantle. Moreover, the Xigaze rocks have 1.27–3.18 of (Th/Nb)_N ratios similar with those of Geotimes volcanics ((Th/Nb)_N =0.51–2.77) and lower than those of Lasail and Velly units ((Th/Nb)_N =2.12–6.35). These features suggest that the Xigaze ophiolite may have formed at the spreading centre.     

87Sr/86Sr in Precambrian carbonates as an index of crustal evolution

The Sr isotopic composition of ‘seawater’, as measured on carbonate rocks, shows a composite pattern during geologic history. All known Archaean data are compatible with contemporaneous upper mantle ⁸⁷Sr/⁸⁶Sr values. This is followed by a strong increase in the radiogenic component during the 2.5–2.1 b.y. period, a less pronounced increase during the remaining portion of the Proterozoic and a decrease during the Phanerozoic. The trend closely resembles the K₂O/Na₂O secular variations in composition of igneous and sedimentary rocks (Engelet al, Bull. Geol. Soc. Amer. 85, 843–858, 1974) and probably reflects the fractionation state of the contemporary crust. The data are compatible with recent suggestions of three major tectonic regimes during geologic history: greenstone belts during the Archaean, mobile belts during the Proterozoic and plate tectonics during the Phanerozoic. They also indicate that continental crust during the Archaean contributed only subordinate Sr into the meteoric cycle.     

The mafic–ultramafic complex of Sikhoran (central Iran): a polygenetic ophiolite complexLe massif basique-ultrabasique de Sikhoran (Iran central) : un complexe ophiolitique polygénétique

The mafic–ultramafic complex of Sikhoran presents a long geological history, marked out by various magmatic, metamorphic and tectonic events. This history is much more complex than a simple ophiolite obduction over a continental margin. As early as the Upper Permian, following a mantle uprise in a Tethysian supra-subduction zone, the opening of a (back-arc?) basin in extensional/transtensional conditions provoked the intrusion of multiple gabbroic dykes, veins and plutons charged with fluids, through a mafic/ultramafic complex and its metamorphic cover. Several basins, characterised by abundant submarine basaltic volcanism developed during Jurassic, whose feeding dykes may be represented by the diabase dyke swarms intruding the whole Sikhoran complex and its metamorphic cover. To cite this article: H. Ghasemi et al., C. R. Geoscience 334 (2002) 431–438.     

月球东海盆地综合解析与撞击初始条件的研究

东海是月球上最年轻的多环撞击盆地,关于其形成机制的研究很多,但成果大都基于正撞击的机制提出的,虽然有部分学者提出东海是斜撞击的,但缺乏具体撞击参数。本文通过多源数据融合,综合分析LRO影像数据、LOLA地形数据、M~3高光谱数据和IIM高光谱数据,对东海地区的地貌特征、物质成分进行了较为系统的解译,发现在东海中央熔融区存在一条与东海撞击方向垂直的中央隆起区域(中央隆起线),其也是中央熔融区粗糙部分与光滑部分的分界线,结合撞击坑成坑理论,认为其可能是撞击过程冲击波作用引起的堆叠作用形成的。同时利用GRAIL数据及对该地区的重力异常的成因进行了分析,认为异常是由于压强、温度及岩石粘度的改变引起局部莫霍面抬升和中央熔融物的形成而出现的,进而估算出熔融物占盆地内物质的25%,约为1.1×10~6km~3。同时,对GRAIL数据的剖面分析结果也支持了本文的斜撞击理论。最后,综合多方面的信息和撞击理论获取东海盆地构造分布图,并根据中央隆起线、溅射物及线性构造的分布特征等,提出东海盆地理论上是由一直径在50~100km的撞击体以10~30km/s的速度自东偏北约20°~30°方向以20°~30°的角度斜撞击月表而形成的。这可为研究更早期的月球撞击坑提供理论参考。