http://www.sciencedirect.com/science/article/pii/S1674987111000867

By applying the ‘theory of synchronization’ from the science of complexity to studying the regional regularity of ore formation within the Nanling region of South China, a characteristic target-pattern regional ore zonality has been discovered. During the early and late Yanshanian epoch (corresponding respectively to the Jurassic and Cretaceous periods), two centers of ore formation emerged successively in the Nanling region; the former is mainly for rare metals (W, Sn, Mo, Bi, Nb) and one rareearth element (La) and was generated in the Jurassic period; whereas the latter is mainly for base metals (Cu, Pb, Zn, Sb, Hg), noble metals (Au, Ag), and one radioactive element (U) and was generated in the Cretaceous period. Centers of ore formation were brought about by interface dynamics respectively at the Qitianling and Jiuyishan districts in southern Hunan Province. The characteristic giant nonlinear targetpattern regional ore zonality was generated respectively from the two centers of ore formation by the spatio-temporal synchronization process of the Nanling complex metallogenic system. It induced the collective dynamics and cooperative behavior of the system and displayed the configuration of the regional ore zonality. Then dynamical clustering transformed the configuration into rudimentary ordered coherent structures. Phase dynamics eventually defined the spatio-temporal structures of the target-pattern regional ore zonality and determined their localization and distribution. The integral successive processes of synchronization-dynamical clustering-phase dynamics accomplished the regional ore zonality by way of “multiple field dynamics” of spatio-temporal superposition of multiple coupled pulsatory solitary wave trains of the zonal sequences of different ores. A new methodology for revealing regional ore zonality is developed, which will encourage further investigation of the formation of deep-seated ore resources and the onset of large-scale mineralization.     

http://www.sciencedirect.com/science/article/pii/S1674987111000223

By applying the ‘theory of synchronization’ from the science of complexity to studying the regional regularity of ore formation within the Nanling region of southern China, a characteristic targetpattern regional ore zonality has been discovered. During the early and late Yanshanian epoch (corresponding respectively to the Jurassic and Cretaceous periods), two centers of ore formation emerged successively in the Nanling region; the former is mainly for rare metals (W, Sn,Mo, Bi, Nb) and one rare-earth element (La) and was generated in the Jurassic period; whereas the latter is mainly for base metals (Cu, Pb, Zn, Sb, Hg), noble metals (Au, Ag), and one radioactive element (U) and was generated in the Cretaceous period. Centers of ore formation were brought about by interface dynamics respectively at the Qitianling and Jiuyishan districts in southernHunan province. The characteristic giant nonlinear target-pattern regional ore zonality was generated by spatio-temporal synchronization process of the Nanling complex metallogenic system. It induced the collective dynamics and cooperative behavior of the system and displayed the configuration of the regional ore zonality. Then dynamical clustering transformed the configuration into rudimentary ordered coherent structures. Phase dynamics eventually defined the spatio-temporal structures of the target-pattern regional ore zonality and determined their localization and distribution. A new methodology for revealing regional ore zonality is developed, which will encourage further investigation of the formation of deep-seated ore resources and the onset of large-scale mineralization.     

http://www.sciencedirect.com/science/article/pii/S1674987114000929

Global sea-level has changed in a cyclic manner through geologic history, but the regularities of these changes are yet to be fully understood. Despite certain (and sometimes significant) differences, ...     

http://www.sciencedirect.com/science/article/pii/S1674987110000022

<正>The Early Cretaceous Hohhot metamorphic core complex(mcc) of the Daqing Shan(Mtns.) of central Inner Mongolia is among the best exposed and most spectacular of the spatially isolated mcc's that developed within the northern edge of the North China "craton".All of these mcc's were formed within the basement of a Late Paleozoic Andean-style arc and across older Mesozoic fold-and-thrust belts of variable age and tectonic vergence.The master Hohhot detachment fault roots southwards within the southern margin of the Daqing Shan for an along-strike distance of at least 120 km.Its geometry in the range to the north is complicated by interference patterns between(1) primary,large-scale NW-SE-trend-ing convex and concave fault corrugations and(2) secondary ENE-WSW-trending antiforms and synforms that folded the detachment in its late kinematic history.As in the Whipple Mtns.of California, the Hohhot master detachment is not of the Wernicke(1981) simple rooted type:instead,it was spawned from a mid-crustal shear zone,the top of which is preserved as a mylonitic front within Carboniferous metasedimentary rocks in its exhumed lower plate.~(40)Ar—~(39)Ar dating of siliceous volcanic rocks in basal sections of now isolated supradetachment basins suggest that crustal extension began at ca.127 Ma, although lower-plate mylonitic rocks were not exposed to erosion until after ca.119 Ma.Essentially synchronous cooling of hornblende,biotite.and muscovite in footwall mylonitic gneisses indicates very rapid exhumation and at ca.122—120 Ma.Contrary to several recent reports,the master detachment clearly cuts across and dismembers older,north-directed thrust sheets of the Daqing Shan foreland fold-and-thrust belt.Folded and thrust-faulted basalts within its foredeep strata are as young as 132.6±2.4 Ma,thus defining within 5—6 Ma the regional tectonic transition between crustal contraction and profound crustal extension.     

http://www.sciencedirect.com/science/article/pii/S1674987112000035

The well SK-I in the Songliao Basin is the first scientific borehole targeting the continental Cretaceous strata in China.Oval concretions,thin laminae and beds of dolostone are found intercalated within mudstone and organic-rich black shale in the Nenjiang Formation of Campanian age.Low ordered ferruginous dolomite is composed of euhedral-subhedral rhombs with cloudy nucleus and light rims formed during the diagenesis.which are typical features of replacement.The heavy carbon isotopes (δ¹³C_PDB-1.16-16.0) are results of both the fermentation of organic matter by microbes and degassing of carbon dioxide during the period of diagenesis,and the presence of light oxygen isotopes(δ¹⁸O_Pdb- 18.53～-5.1) is a characteristic feature of fresh water influence which means the carbonate may have been altered by ground water or rainwater in the late diagenesis.Marine water incursions into the normally lacustrine basin have been proved by both the salinity of Z value and the occurrence of foraminifera in the same strata where dolomite occurs.Pyrite framboids observed by SEM are usually enclosed in the dolomite crystals or in the mudstones,supporting the sulfate reducing bacteria（SRB）.The formation of both dolomite and pyrite are associated with marine water incursions,which not only supply magnesium ion for dolomite,but also result in limited carbonate precipitation in the basin.The presence of pyrite tramboids indicates the development of an anoxic environment associated with salinity stratification in the lake.The dolomite in the Nenjiang Formation is the results of marine water incursions,diagenetic replacement of calcareous carbonate and sulfate reducing bacteria（SRB）.     

http://www.sciencedirect.com/science/article/pii/S1674987111000879

Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin,northwestern China.The huge reserves of this high quality coal have a high commercial value.We studied the coal’s petrologic characteristics and its maceral distribution to determine the maceral’s contribution to generation of oil and gas.The results show that the Jurassic coals in the Ordos Basin have special penological features because of the Basin’s unique depositional environment which was mainly a series of high-stand swamps in the upper fluvial system.These petrographic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers.After burial,the peat continued to undergo oxidizing conditions,this process generated extensive higher inertinile contents in the coals and the vitrinite components were altered to semi-vitrinite.The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal,dull coal,semilustrous and lustrous coal.The proportions of semi-dull coal and dull coal are higher in the basin margins,especially in the area near the northern margin.The numbers of semilustrous and lustrous coals increase southwards and towards the central basin.This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components.Another observation is that in the Ordos" coal sequences,especially in the lower part,some sandstone beds are thick,up to 20 m with a coarse grain size.The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure.The fusinite structure is clear and well preserved.After burial,the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology.The sand bodies in the roof and floor exhibit good physical conditions so that pore water can maintain a long-term state of oxidation,circulation and connection to the coal.So coal components remain in an oxidation environment for a long time.Conversely,in the basin center,lacustrine facies developed and peat was rapidly covered by mudstone after burial and subsequent coal beds rapidly entered a reducing environment.As a result,abundant gelatification occurred and the vitrinite content increased.Exinite often accumulated in a specific position in the coal bed.Although the average exinite content is not high on the whole,it does significantly contribute to the total hydrocarbon generation. The exinite content has been underestimated,especially the amorphous bituminous fluid and its importance is emphasized here.The reason is that the fluid flows easily into fusinite which has strong rigidity,or flows into some fissures,where it is commonly neglected.     

http://www.sciencedirect.com/science/article/pii/S1674987113000856

Sulphide inclusions, which represent melts trapped in the minerals of magmatic rocks and xenoliths, provide important clues to the behaviour of immiscible sulphide liquids during the evolution of magmas and the formation of NieCueFe deposits. We describe sulphide inclusions from unique ultramafic clots within mafic xenoliths, from the mafic xenoliths themselves, and from the three silica-rich host plutons in Tongling, China. For the first time, we are able to propose a general framework model for the evolution of sulphide melts during the evolution of mafic to felsic magmas from the upper mantle to the upper crust. The model improves our understanding of the sulphide melt evolution in upper mantle to upper crust magmas, and provides insight into the formation of stratabound skarn-type FeeCu polymetallic deposits associated with felsic magmatism, thus promising to play an important role during prospecting for such deposits.     

Were Late Cretaceous extinctions of gastropods selective by generic longevity?

Many gastropod taxa went extinct during the Late Cretaceous.The stratigraphic ranges of 268 genera permit to establish the longevity of extinction victims for each stage of this epoch."Young" taxa (originated within 3 epochs before the extinction) prevailed among victims of the extinctions in all stages.The proportion of "old" taxa(originated before the Cretaceous) that went extinct was the highest in the Cenomanian,and it was the lowest in the Coniacian and the Maastrichtian.It appears that the end-Cretaceous mass extinction affected chiefly "young" taxa.However,the comparison with the earlier time intervals suggests that this pattern of selectivity by generic longevity was not specific for the noted catastrophe,but,in contrast,it was typical for the entire Late Cretaceous.The latest Cenomanian environmental perturbation(OAE2) caused a stronger extinction of "old" taxa,and thus,this biotic crisis was less selective by generic longevity.This hypothesis,however,is not proven by the statistical test.     

http://www.sciencedirect.com/science/article/pii/S1674987111001150

The Erlangmiao granite intrusion is located in the eastern part of the East Qinling Orogen.The granite contains almost 99 vol.％ felsic minerals with accessory garnet,muscovite,biotite,zircon,and Fe-Ti ...     

http://www.sciencedirect.com/science/article/pii/S1674987114000565

During granulite-facies metamorphism of metasedimentary rocks by the infiltration of carbonic fluids, the disappearance of hydrated minerals leads to the liberation of aqueous fluids. These fluids are strongly enriched in F and C1, and a series of Large-lon-Lithophile （LIL） elements and rare metals, resulting in their depletion in granulites. To sum up the fate of these elements, we focus on three domains representing different crustal levels and showing distinct behaviours with respect to these elements. The Lapland metasedimentary granulites illustrate the behaviour of the LILE and rare metals during lower crustal metamorphism. There is no change in Ba, moderate loss in Rb, and extreme depletion in Cs, Li, and Sn. F and CI contents are also very low compared to the protoliths or average upper continental crust. Biotite and amphibole breakdown leads to the incorporation of their partitioning into a fluid or a melt. The Tranomaro metasomatized marbles recrystallizing under granulite-facies conditions represent a demonstrative example of fluid transfer from granulite-facies supracrustals to traps represented by regional scale skarns. Such fluids may be at the origin of the incompatible element enrichment detected in leucosomes of migmatites from St Malo in Brittany （France） and Black Hills in South Dakota, The northern French Massif Central provides us with an example of a potential association between incompatible element enrichment of granitic melts and granulite-facies metamorphism. U- and F- enriched fine-grained granites are emplaced along a crustal scale shear zone active during the emplacement within the St Sylvestre peraluminous leucogranitic complex, We propose that during granulite-facies metamorphism dominated by carbonic waves in a deep segment of the continental crust, these shear zones control： （i） the percolation of F-, LILE-, rare metal-rich fluids liberated primarily by the breakdown of biotite; （ii） the enhancement of partial melting by F-rich fluids at intermediate crustal lev     

http://www.sciencedirect.com/science/article/pii/S1674987111000570

Mid-Cretaceous strata within the Tintina Trench.3 km west of the community of Ross River, contain evidence of deposition in two distinct,alternating,fluvial settings.Coal-bearing,mud-dominated strata are commonly associated with high-constructive sandy channel systems,with extensive overbank. levee and splay deposits.Channels are between 3 and 30 m wide and 0.4-7 m thick.They show repetitive development of side and in-channel bar-forms,as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits.Levees extended for several hundred metres away from the channels.In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams.The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata,inter-bedded with,and overlying coal-bearing units,are interpreted as deposits of wandering gravel-bed rivers,with sinuosity approaching 1.4.In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates,which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan.Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures.In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1-5.5 m.These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2-12 m.Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhone River system.Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion.Minimum channel width is from 70 to 450 m.     

http://www.sciencedirect.com/science/article/pii/S1674987114001133

A chronological study of seamount rocks in the South China Sea basin provides a great opportunity to understand the expansion and evolution history of the sea basin. In this paper, we analyzed the 40Ar...     

http://www.sciencedirect.com/science/article/pii/S1674987113000030

The Dabashan orocline is situated in the northwestern margin of the central Yangtze block,central China.Previous studies have defined the orthogonal superposed folds growing in its central-western segment thereby confirming its two-stage tectonic evolution history.Geological mapping has revealed that more types of superposed folds have developed in the eastern segment of the orocline,which probably provides more clues for probing the structure and tectonic history of the Dabashan orocline.In this paper,based on geological mapping,structural measurements and analyses of deformation,we have identified three groups of folds with different trends （e.g.NW-,NE-and nearly E-trending folds） and three types of structural patterns of superposed folds in the eastern Dabashan foreland （e.g.syn-axial,oblique,and conjunctional superposed folds）.In combination with geochronological data,we propose that the synaxial superposed folds are due to two stages of ～N-S shortening in the west and north of the Shennongjia massif,and that oblique superposed folds have been resulted from the superposition of the NW-and NE-trending folds onto the early ～ E-W folds in the east of the Shennongjia massif in the late Jurassic to early Cretaceous.The conjunctional folds are composed of the NW-and NE-trending folds,corresponding to the regional-scale dual-orocline in the eastern Sichuan as a result of the southwestward expansion of the Dabashan foreland during late Jurassic to early Cretaceous,coeval with the northwestward propagation of the Xuefengshan foreland.Integration of the structure and geochronology of the belt shows that the Dabashan orocline is a combined deformation belt primarily experiencing a twostage tectonic evolution history in Mesozoic,initiation of the Dabashan orocline as a foreland basin along the front of the Qinling orogen in late Triassic to early Jurassic due to collisional orogeny,and the final formation of the Dabashan orocline owing to the southwestward propagation of the Qinling orogen during late Jurassic to early Cretaceous intra-continental orogeny.Our studies provide some evidences for understanding the structure and deformation of the Dabashan orocline.     

http://www.sciencedirect.com/science/article/pii/S1674987113000832

The Sinus Iridum region, the first choice for China＇s＂Lunar Exploration Project＂is located at the center of the lunar LQ-4 area and is the site of Chang＇e-3 （CE-3）＇s soft landing. To make the scientific exploration of Chang＇e-3 more targeted and scientific, and to obtain a better macro-level understanding of the geotectonic environment of the Sinus Iridum region, the tectonic elements in LQ-4 region have been studied and the typical structures were analyzed statistically using data from CE-1, Clementine, LRO and Lunar Prospector missions. Also, the mineral components and periods of mare basalt activities in the study area have been ascertained. The present study divides the tectonic units and establishes the major tectonic events and sequence of evolution in the study area based on morphology, mineral constituents, and tectonic element distribution.     

http://www.sciencedirect.com/science/article/pii/S1674987110000095

<正>Bauxite deposits are studied because of their economic value and because they play an important role in the study of paleoclimate and paleogeography of continents.They provide a rare record of the weathering and evolution of continental surfaces.Geomicrobiological analysis makes it possible to verify that microorganisms have played a critical role during the formation of bauxite with the possibility already intimated in previous studies.Ambient temperature,abundance of water,organic carbon and bioavailable iron and other metal substrates provide a suitable environment for microbes to inhabit.Thio-bacillus, Leptospirilum,Thermophilic bacteria and Heterotrophs have been shown to be able to oxidize ferrous iron and to reduce sulfate-generating sulfuric acid,which can accelerate the weathering of alumi-nosilicates and precipitation of iron oxyhydroxides.Microorganisms referred to the genus Bacillus can mediate the release of alkaline metals.Although the dissimilatory iron-reducing and sulfate-reducing bacteria in bauxites have not yet been identified,some recorded authigenic carbonates and "bacteriopyrites" that appear to be unique in morphology and grain size might record microbial activity.Typical bauxite minerals such as gibbsite,kaolinite,covellite,galena,pyrite,zircon,calcium plagioclase,orthoclase, and albite have been investigated as part of an analysis of microbial mediation.The paleoecology of such bauxitic microorganisms inhabiting continental(sub) surfaces,revealed through geomicrobiolo-gical analysis,will add a further dimension to paleoclimatic and paleoenvironmental studies.     

http://www.sciencedirect.com/science/article/pii/S1674987114000401

In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to post-Archean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram ...     

http://www.sciencedirect.com/science/article/pii/S1674987113001357

A diverse suite of Archaean gneisses at Huangbaiyu village in the North China Craton, includes rare fuchsite-bearing （Cr-muscovite） siliceous rocks - known as the Caozhuang quartzite. The Caozhuang quartzite is strongly deformed and locally mylonitic, with silica penetration and pegmatite veining common. It contains abundant 3880-3600 Ma and some Palaeoarchaean zircons. Because of its siliceous nature, the presence of fuchsite and its complex zircon age distribution, it has until now been accepted as a （mature） quartzite. However, the Caozhuang quartzite sample studied here is feldspathic. The shape and cathodoluminescence petrography of the Caozhuang quartzite zircons show they resemble those found in immature detrital sedimentary rocks of local provenance or in Eoarchaean polyphase orthog- neisses, and not those in mature quartzites. The Caozhuang quartzite intra-zircon mineral inclusions are dominated by quartz,     

http://www.sciencedirect.com/science/article/pii/S1674987111000405

This study has focused on the processes of soil degradation and chemical element concentration in tea-growing regions of Rwanda, Africa. Soil degradation accelerated by erosion is caused not only by topography but also by human activities. This soil degradation involves both the physical loss and reduction in the amount of topsoil associated with nutrient decline. Soil samples were collected from eleven tropical zones in Rwanda and from variable depth within each collecting site. Of these, Samples from three locations in each zone were analyzed in the laboratory, with the result that the pH of all soil samples is shown to be less than 5 (pH < 5) with a general average of 4.4. The elements such as iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn) are present in high concentration levels. In contrast calcium (Ca) and sodium (Na) are present at low-level concentrations and carbon (C) was found in minimal concentrations. In addition, elements derived from fertilizers, such as nitrogen (N), phosphorous (P), and potassium (K) which is also from minerals such as feldspar, are also present in low-level concentrations. The results indicate that the soil in certain Rwandan tea plantations is acidic and that this level of pH may help explain, in addition to natural factors, the deficiency of some elements such as Ca, Mg, P and N. The use of chemical fertilizers, land use system and the location of fields relative to household plots are also considered to help explain why tea plantation soils are typically degraded.     

http://www.sciencedirect.com/science/article/pii/S1674987110000071

<正>The lithospheric structure of China and its adjacent area is very complex and is marked by several prominent characteristics.Firstly,China's continental crust is thick in the west but thins to the east,and thick in the south but thins to the north.Secondly,the continental crust of the Qinghai—Tibet Plateau has an average thickness of 60—65 km with a maximum thickness of 80 km,whereas in eastern China the average thickness is 30—35 km,with a minimum thickness of only 5 km in the center of the South China Sea.The average thickness of continental crust in China is 47.6 km,which greatly exceeds the global average thickness of 39.2 km.Thirdly,as with the crust,the lithosphere of China and its adjacent areas shows a general pattern of thicker in the west and south,and thinner in the east and north.The lithosphere of the Qinghai—Tibet Plateau and northwestern China has an average thickness of 165 km, with a maximum thickness of 180—200 km in the central and eastern parts of the Tarim Basin,Pamir, and Changdu areas.In contrast,the vast areas to the east of the Da Hinggan Ling—Taihang—Wuling Mountains,including the marginal seas,are characterized by lithospheric thicknesses of only 50—85 km.Fourthly,in western China the lithosphere and asthenosphere behave as a "layered structure", reflecting their dynamic background of plate collision and convergence.The lithosphere and asthenosphere in eastern China display a "block mosaic structure",where the lithosphere is thin and the asthenosphere is very thick,a pattern reflecting the consequences of crustal extension and an upsurge of asthenospheric materials.The latter is responsible for a huge low velocity anomaly at a depth of 85—250 km beneath East Asia and the western Pacific Ocean.Finally,in China there is an age structure of "older in the upper layers and younger in the lower layers" between both the upper and lower crusts and between the crust and the lithospheric mantle.     

The dilemma of the Jiaodong gold deposits: Are they unique?

The ca. 126e120 Ma Au deposits of the Jiaodong Peninsula, eastern China, define the country＇s largest gold province with an overall endowment estimated as＆gt;3000 t Au. The vein and disseminated ores are hosted by NE-to NNE-trending brittle normal faults that parallel the margins of ca. 165e150 Ma, deeply emplaced, lower crustal melt granites. The deposits are sited along the faults for many tens of kilometers and the larger orebodies are associated with dilatational jogs. Country rocks to the granites are Pre-cambrian high-grade metamorphic rocks located on both sides of a Triassic suture between the North and South China blocks. During early Mesozoic convergent deformation, the ore-hosting structures developed as ductile thrust faults that were subsequently reactivated during Early Cretaceous ＂Yan-shanian＂intracontinental extensional deformation and associated gold formation. 〈br〉 Classification of the gold deposits remains problematic. Many features resemble those typical of orogenic Au including the linear structural distribution of the deposits, mineralization style, ore and alteration assemblages, and ore fluid chemistry. However, Phanerozoic orogenic Au deposits are formed by prograde metamorphism of accreted oceanic rocks in Cordilleran-style orogens. The Jiaodong de-posits, in contrast, formed within two Precambrian blocks approximately 2 billion years after devolati-lization of the country rocks, and thus require a model that involves alternative fluid and metal sources for the ores. A widespread suite of ca. 130e123 Ma granodiorites overlaps temporally with the ores, but shows a poor spatial association with the deposits. Furthermore, the deposit distribution and mineral-ization style is atypical of ores formed from nearby magmas. The ore concentration requires fluid focusing during some type of sub-crustal thermal event, which could be broadly related to a combination of coeval lithospheric thinning, asthenospheric upwelling, paleo-Pacific plate subduction, and seismicity along the continental-scale Tan-Lu fault. Possible ore genesis scenarios include those where ore fluids were produced directly by the metamorphism of oceanic lithosphere and overlying sediment on the subducting paleo-Pacific slab, or by devolatilization of an enriched mantle wedge above the slab. Both the sulfur and gold could be sourced from either the oceanic sediments or the serpentinized mantle. A better understanding of the architecture of the paleo-Pacific slab during Early Cretaceous below the eastern margin of China is essential to determination of the validity of possible models.