reconstruction of northeast asian deformation integrated with western pacific plate subduction since 200 ma abstract the configuration and kinematics of continental deformation and its marginal plate tectonics on the earth s surface are intrinsic manifestations of plate mantle coupling the complex interactions of plate boundary forces result in plate motions that are dominated by slab pull and ridge push forces and the effects of mantle drag these interactions also result in continental deformation with a complex basin mountain architecture and evolution the kinematics and evolution of the western pacific subduction and northeast asian continental margin deformation represent a first order tectonic process whose nature and chronology remains controversial this paper implements a deep time reconstruction of the western pacific subduction continental accretion or collision and basin mountain deformation in northeast asia since 200 ma based on a newly revised global plate model we use gplates software to examine strain recovery geological and seismic tomography constraints for the western pacific plate subduction and sequentially backward rotations of deforming features the results indicate a nw se oriented shortening from 200 to 137 ma a nww see oriented extension from 136 to 101 ma a nearly n s oriented extension and uplift with a short term nww see oriented compressional inversion in northeast china from 100 to 67 ma and a nw se and nearly n s oriented extension from 66 ma to the present day the western pacific oceanic plate subducted forward under east asia along mudanjiang honshu island during the jurassic and the trenches retreated to the sikhote alin north shimanto and south shimanto zones from ca 137 128 ma ca 130 90 ma and in ca 60 ma respectively our time dependent analysis of plate motion and continental deformation coupling suggests that the multi plate convergent motion and ocean continent convergent orogeny were induced by advance subduction during the jurassic and earliest cretaceous our analysis also indicates that intra continent rifting and back arc extension were triggered by trench retreat during the cretaceous and that the subduction of the oceanic ridge and arc were triggered by trench retreat during the cenozoic therefore reconstructing the history of plate motion and subduction and tracing the geological and deformation records in continents play a significant role in revealing the effects of complex plate motions and the interactions of plate boundary forces on plate mantle coupling and plate motion intracontinental deformation coupling

formation and evolution of the tancheng lujiang wrench fault system a major shear system to the northwest of the pacific ocean abstract in the northwestern peri pacific tectonic belt on the continental margin of east asia there is a series of major faults trending ne nne i e the tancheng lujiang wrench fault system this fault system extends more than 5000 km with a width of 800 1000 km in the continent and a general strike of n30 e on the basis of the results of special research on the major faults and a lot of new information about the fault system the authors discuss early mesozoic triassic jurassic period sinistral transcurrent faulting in the different regions it is suggested that in the eastern continent of east asia the e w trending tectonic pattern of the paleozoic and beginning of the mesozoic appear in the nuclei of the sino korean continent massif and the yangtze continent massif these ancient continent massifs accreted both southwards and northwards which finally led to their collision and suturing to the angura continent massif later this tectonic framework was changed greatly by the tancheng lujiang wrench fault system along which left lateral horizontal displacement of 1000 1500 km took place since the mesozoic the dislocation and deformation of horizontal displacement of the tancheng lujiang fault system produced a series of structures trending ne nne in the continental margin which have greatly transformed the ancient structures of the preceding mesozoic this is an important diktyogenese in the continent of east asia during the horizontal displacement motion of these faults the folds nappes and decollement structures pull apart basins and subductions within the continent occurred in the continent at the same time some large sinistral ductile shear zones of horizontal displacement appeared the depth of the deformed horizon of ductile shear which belongs to simple shear was controlled by the tectonic element and distance away from the continental margin whilst the ductile shear deformation occurred the fault dynamo thermal metamorphism and the fault remelting took place and magma activity appeared within the continent in the mesozoic the fault zones used to be high energy zones and recently became the seismic belts within the continent formation of the tan lu fault system was due to the collision between the southern and northern blocks its large sinistral horizontal displacement in the mesozoic was closely related to the kula plate moving northwards therefore the continent disintegrated by shearing which produced some new terranes the shear edge belt was formed between the continent and ocean the change of relative motion between the continent and pacific ocean plate transformed the tan lu fault system into first extension and then compression clarifying the characteristics of the tan lu fault system is an important key in understanding the evolution of the east asia continent since the mesozoic

coupling of strike slip faulting and lacustrine basin evolution sequence stratigraphy structure and sedimentation in the north yellow sea basin west bay basin offshore north korea eastern china abstract the north yellow sea basin in offshore areas of eastern china provides a unique opportunity to document the interaction between the paleo eurasian and circum pacific tectonic domains and the coupled relationship between tanlu fault strike slip activity intrabasinal tectonics and sedimentation this study combines well data three dimensional 3 d and two dimensional 2 d seismic data to make regional tectonics interpretations and delineate the sequence stratigraphy geological structure and sedimentary history of the basin s eastern depression particularly focusing on the influence of tanlu fault strike slip activity on basin evolution the eastern depression data record the development of five second order stratigraphic sequences both the mesozoic and the cenozoic fault systems with basement f1 f2 and f3 faults and the deposition of various deltaic fan delta lacustrine and subaqueous fan facies associations the f1 and f3 faults controlled the nw and ne trending secondary faults and associated mesozoic sedimentation within the depression while the f1 and f2 faults jointly controlled the development of ne and near e w trending secondary faults and associated cenozoic sedimentation the results indicate that the plate movements and tanlu episodic strike slip faulting generated a left lateral stress field in the early cretaceous that switched to a right lateral stress field during the middle eocene to oligocene this transformation produced secondary shear stress fields in the north yellow sea basin and generated ne trending rifting superimposed on the previous nw trending rift generation and controlled the related structural geology and sedimentation in the eastern depression of the basin this proposed explanation of a tectonic regime transformation model coupled with tanlu strike slip movements could also provide new insights into the differences in gaps that occur in the stratigraphic record for the north yellow sea basin and adjacent areas in eastern china

identifying marine incursions into the paleogene bohai bay basin lake system in northeastern china abstract the extent of marine influence on the paleogene bohai bay basin in northeastern china which accumulated mainly continental e g fluvial and lacustrine facies remains under debate evidence from geochemical paleontological and lithological data have documented several marine incursions but no systematic study has been conducted to investigate their timing and frequency and their significance for understanding the paleogene tectonic evolution of northeastern china in order to address the marine influence on sediment accumulation and to identify variations in paleosalinity during deposition of the mid eocene lower es3 es3l member of the shahejie formation this study analyzed multiple paleosalinity proxies b ga sr ba and s toc in fine grained siliciclastic argillaceous sediments of the luo 69 drillcore from the dongying depression all three proxies yielded similar paleosalinity interpretations with peak salinity and marine influence i e maximum b ga sr ba and s toc values occurring at the base of the es3l member and progressively declining salinities representing a shift toward brackish conditions upsection over an interval of 185 5 m representing 2 2 myr of sedimentation this paleosalinity record suggests gradual long term variations that were probably due to changes in tectonically controlled gateways linking the bohai bay basin to the yellow sea in addition to analysis of the mid eocene es3l member published data on the stratigraphic distribution of marine fossils glauconite and elemental paleosalinity proxies are applied to evaluate the history of marine incursions into the bohai bay lake system throughout the mid to late paleogene 50 24 ma this analysis revealed four intervals of probable major marine incursions dating to the early eocene the middle eocene the early oligocene and the late oligocene

destruction of ancient lower crust through magma underplating beneath jiaodong peninsula north china craton u pb and hf isotopic evidence from granulite xenoliths abstract zircons from granulite xenoliths entrained in a late cretaceous mafic dike in the jiaodong peninsula north china craton ncc show three distinct u pb age populations part of the old zircon grains yield discordant data that project to ages of about 2 4 to 2 5 ga a few grains indicate growth at about 2 0 ga and a third group yield cretaceous ages with peaks at 120 and 90 ma the oldest zircons give hf t dm model ages of 2 6 2 8 ga these results demonstrate the existence of original archean lower crust in the jiaodong region zircons of 2 0 ga have similar hf t dm model ages as the neoarchean paleoproterozoic grains suggesting that these zircons were products of metamorphic recrystallization due to thermal event without juvenile input early cretaceous zircons yield ehf t values of 21 to 12 and late cretaceous zircons large variable ehf t from 4 to 50 these data suggest that magmatic underplating occurred in the neoarchean to earliest proterozoic lower crust of the ncc both in the early and late cretaceous it is suggested that the mesozoic magma underplating which also provided the heat source for the voluminous mesozoic magmatism in the ncc significantly modified the composition of the archean to paleoproterozoic lower crust of the ncc

lithospheric thinning in the eastern indian craton evidence for lithospheric delamination below the archean singhbhum craton abstract we herein present shear velocity structure extending down to 300 km depth below the archean singhbhum odisha craton soc and proterozoic chotanagpur granitic gneissic terrain cggt which has been obtained through the inversion modeling of p receiver functions we use three component broadband recordings of 200 teleseismic earthquakes 30 90 from a 15 station seismic network that has been operational in the eastern indian shield since february 2013 we obtain the thinnest crust of 35 km overlying a thin lithosphere of 78 km below the region near south singhbhum shear zone which could be attributed to the 1 6 ga plume activity associated with dalma volcanic however the thickest crust of 47 km overlying a thin lithosphere of 81 km is noticed below the region near the singhbhum granite of 3 6 ga this thinning of lithosphere could be attributed to the delamination of lithospheric root due to the himalayan orogeny with a shortening rate of 2 cm year this delamination model in soc gets further support from the densification of the lower crust which could result from repeated episodes of basaltic underplating associated with episodes related to dalma 1 6 ga and rajmahal 117 ma volcanisms this led to relatively more mafic heterogeneous and deformed crustal structure in soc as well as egmb with an average crustal vs of 4 0 km s in comparison to that in cggt with an average crustal vs of 3 9 km s as seen through our modeling results the thickest lithosphere of 100 km is observed in the southwestern soc as well as northeastern cggt we also notice that a sharp and flat moho in cggt which could be attributed to thermal reactivation and large volume melting of the mafic cratonic crust during the late archean subduction process and associated volcanism episodes this model gets further support from the estimated 169 km thick lower vs zone in the upper mantle below cggt our modeling results also support a northward subduction of archean soc under the proterozoic cggt during 1 0 1 6 ga as earlier proposed by the geological age data from the region

mesozoic large scale lateral extrusion rotation and uplift of the tongbai dabie shan belt in east china the tectonic convergence between the south china block and qinling belt that occurred in mesozoic time was not homogeneous along strike it was mainly concentrated in the shengnongjia and hannan domes which formed a pair of indentors along which the south china block penetrated the qinling belt as a consequence the tongbai dabie shan belt the eastern part of the qinling orogenic belt may have undergone large scale eastward extrusion clockwise rotation and uplift as indicated by its boundary deformation features it was originally located beneath the narrowest part of the qinling belt where it underwent ultrahigh pressure metamorphism in the early triassic

lower cretaceous stratigraphic characteristics and tectonic control of the eastern depression north yellow sea basin north china the lower cretaceous of the eastern depression in the north yellow sea basin is a set of residual strata that can be divided into k1sq1 and k1sq2 sequences there are four lithology lithofacies arc

experimental study and active tectonics on the zhangjiakou penglai fault zone across north china abstract the zhangjiakou penglai fault zone zpfz as a large scale wnw trending active fault zone with frequent seismic activity is an area prone to moderate to intense earthquakes across north china a detailed analysis of the zpfz has been carried out based on earthquake activity deep structural response dynamic mechanism and physical simulation by conducting an en echelon fault model experiment the results show that the zpfz is a lithospheric active fault zone that has controlled some small en echelon quaternary pull apart basins and has triggered many earthquakes as seismogenic structures the earthquake location and intensity distribution by the experimental simulation fit well with those of actual earthquakes the earthquake distribution is controlled obviously by the en echelon structural properties the intensity of seismic activity is strong in the middle and weak at the western and eastern ends of the fault zone migrating from the southeast to the northwest along the entire fault zone this wnw trending fault zone in north china is closely related to the surrounding plate activities the zpfz is not only dominated by the collision of the indian plate to the eurasian plate but is also influenced by the subduction of the pacific plate it depends on the comprehensive reflection of two geodynamic settings from the western collision of the indian to the eurasian plates and the eastern subduction of the pacific ocean plate to the eurasian plate

cyclostratigraphy and astronomical tuning during the oligocene in the jizhong depression bohai bay basin northeastern china abstract the dongying formation ed and the first member of the shahejie formation es1 in the central raoyang sag cover about 1705 m long sedimentary series of terrestrial lacustrine infill we employed the gamma ray gr log data as a paleoclimatic and paleoenvironmental proxy to conduct the high resolution cyclostratigraphy research in well w33 and w62 prominent sedimentary cycles in decameters and meters were revealed by multi taper mtm power spectra evolutionary fast flourier transformation fft and correlation coefficient analyses in the es1 and ed intervals the 405 kyr long eccentricity 125 kyr and 100 kyr short eccentricity 40 kyr obliquity and 23 kyr precession can be recognized with a wavelength ratio of approximately 20 5 2 1 respectively by tuning the 405 kyr filter output in well w33 to the orbital target curve of la2010d astronomical solution we established an astronomical time scale ats that provided absolute age controls during the oligocene and shed light on the event correlation among isolated depressions in the bohai bay basin sediment accumulation rates sars were derived from the extracted 405 kyr long eccentricity and were tested with an average of 17 cm kyr age boundaries of ng ed1 ed1 ed2 ed2 ed3 ed3 es1 and es1 es2 are 23 03 ma 24 34 ma 25 53 ma 29 05 ma and 33 10 ma respectively based on the ats and sars we discussed the depositional evolution within age boundaries cause of high sars and origin of formation overpressure after the largest lake transgression shallow water deltas and fluvial plains transitionally dominate the central raoyang sag with shallowing water depth thin interlayers of mudstones and sandstones originate from shallow water deltaic systems with low sand to mud ratios under high sars enhanced by mountain uplift and low sand to mud ratios formation overpressure results mainly from high porosities in under compacted mudstone intervals

geodynamic mechanism and classification of basins in the earth system abstract the sedimentary basin is a basic geological unit in the earth system its formation and evolution are controlled mainly by plate tectonics and geodynamics which have produced a variety of basin types the development and evolution of various basins depend not only on the tectonic effect of lithospheric plate but also on sublithospheric and earth surface actions basin classification schemes based on the theories of platform geosyncline or plate tectonics could neither include all basin types nor reflect the complex processes of basin formation and evolution from the viewpoint of earth system we proposed a new basin classification scheme based on geodynamic mechanism that is lithospheric plate sublithospheric and earth surface actions in our geodynamic classification we employed a series of geodynamic settings of basin formation and evolution including the lithospheric plate sublithospheric and earth surface environments the dynamic regimes of basin formation and evolution such as tectonic setting extension compression and shearing the thermal processes and gravity effects the various natures of basin basement and crustal types continental oceanic or transitional crust and the history of basin sedimentary filling and tectonic paleogeography successively as the controlling factors for basin classification this new geodynamic classification scheme highlights both the role of the lithosphere and the effects of the sublithospheric and the earth surface actions on controlling the basin formation and evolution the basic dynamic types of basin classification include the prototype basin forming under a single tectonic thermal or gravity regime and the superimposed basin as well as residual basin forming under multistage thermal and or tectonic regimes thus this classification scheme could provide an evolving understanding of lithosphere crust mantle interaction and geodynamic processes as well as of hydrocarbon accumulation and metallogenic mechanisms in sedimentary basins and would help in the synthetic exploration of various resources

deep shallow coupling response of the cenozoic bohai bay basin to plate interactions around the eurasian plate abstract the bohai bay basin bbb is a meso cenozoic intracontinental petroliferous basin where four pre existing continental scale fault zones intersect in east china the bbb has experienced complex deformational and evolutionary history that records significant information about how the lithosphere there has responded to the coeval plate interactions around the eurasian plate and or their resulting deep crust mantle processes in the cenozoic now both deep and shallow deformational and evolutionary processes of the bbb have been well studied but many geodynamic mechanisms previously proposed for those processes are too general to explain them well based on various data and principles we first summarized both deep and shallow responses and processes of the bbb in the cenozoic and then matched reasonable geodynamic mechanisms for each of them the results show as follows the cenozoic differential reactivation of pre existing continental scale weak zones controlled the coeval deep shallow differential coupling evolution of the bbb the paleogene extension in the bbb was mainly caused by crust mantle processes triggered by the stagnant izanagi slab the cenozoic strike slip faulting was influenced by various plate interactions in which the oblique subduction and anticlockwise rotation of young pacific plate resulted in the complex pre oligocene strike slip history of the tan lu fault zone to the south of the zhang peng fault zone while the india eurasia collision has caused the intense and synchronous strike slip faulting of various faults there since 35 ma which was then weakened by the oblique subduction and clockwise rotation of young philippine sea plate in the neogene the compression resulting from both the india eurasia collision and the philippine sea plate s subduction contributed to the latest paleogene tectonic inversion in the bbb the arrival of mantle flow triggered by both the india eurasia collision and the stagnant slab of the pacific plate resulted in the tectonic reactivation there in the late neogene

multi chronometric dating of the huarong granitoids from the middle yangtze craton implications for the tectonic evolution of eastern china abstract the tectonic thermal history of the huarong granitoids is used to clarify the tectonic evolution of the middle yangtze craton and eastern china the huarong granitoids include the xiaomoshan and taohuashan plutons and form a northeast trending belt in the middle yangtze craton eastern china multi method geochronology reveals the thermal history of the huarong granitoids from their emplacement to near surface conditions la icp ms u pb zircon dating suggests granitoid emplacement at ca 117 ma a cluster of zircons at ca 127 ma is likely inherited from an earlier intrusion phase the granitoids formed in an extensional setting which was almost certainly associated with pacific plate subduction in the late early cretaceous biotite 40ar 39ar ages at ca 96 ma record regional post magmatic cooling apatite fission track aft and apatite u th sm he ahe thermochronology and thermal history modeling indicate cooling in three stages enhanced cooling at 96 60 ma is interpreted to reflect cooling from the late early cretaceous regional magmatism tertiary ca 60 20 ma very slow cooling stagnation or even re heating suggests insignificant exhumation and peneplanation this interval correlates with late cretaceous eocene red bed deposition and rifting throughout eastern china causes for speculative accelerated cooling after ca 20 ma may be a far field effect of the india asia collision or pacific plate subduction this study demonstrates that the middle yangtze craton was involved in the cretaceous extension widely occurring in the eastern china continent and suggests that the formation of the jianghan basin a major depocenter in the middle yangtze craton may have initiated at ca 120 ma

multiple fluvial styles in late miocene post rift successions of the offshore bohai bay basin china evidence from a seismic geomorphological study abstract during the late miocene river systems exhibiting different planform styles caused accumulation in the post rift offshore bohai bay basin in china these changes in the fluvial style have profound implications for the evolution of the bohai sea shelf and the late miocene monsoon controlled climate using three dimensional 3d seismic data and well and mud logging data seismic and well based fluvial sequence stratigraphic analyses have been untaken the lower minghuazhen member can be subdivided into four fourth order sequences sqm1 to sqm4 each of which contains low and high accommodation systems tracts five fluvial styles including wide trunk incised valleys narrow medium incised tributary valleys medium trunk channels narrow medium low sinuosity channels and narrow high sinuosity channels are recognized based on seismic expressions and well log patterns the seismic geomorphological study of selected stratal slices indicates the temporal change in the fluvial styles from low to high sinuosity channels between last and hast as shift in drainage direction from ssw to see occurs between sqm1 and sqm2 which may be attributed to the lateral migration of the late miocene paleo luan river and the paleo qinglong river that originated from yanshan mountain to the north the development of wide incised braided trunk channels together with some narrow medium incised tributary systems at the base of sqm3 and sqm4 can be interpreted as a response to climate induced enhanced sediment supply in addition the paleoclimate reconstruction based on the palynological analysis reveals that the late miocene fluvial transition from a meandering river to a braided river occurring at sqm3 and sqm4 could be linked to multiple periods of short lived intensification of the east asian summer monsoon easm during the late late miocene within an overall declining trend this might have been conducive to triggering seasonal braided rivers under the higher monsoon rainfall

geochemistry and mineralogy of quaternary sediments in the northern bohai bay basin north china implications for provenance and climate change the bohai bay basin located in the eastern north china block is an important sedimentary basin for studying the quaternary climate and environment of northern china although sporo pollen analyse

crustal structure of bohai sea and adjacent area north china from two onshore offshore wide angle seismic survey lines abstract in 2010 and 2011 onshore offshore surveys along two lines in the bohai area were carried out this paper presents the deep structure from wide angle seismic data along the two lines and try to improve the reliability of deep interfaces by using of the cmp prospecting method the result is as follows 1 the environmental noise of records from obss in shallow water area is stronger than that from deep waters 2 the cmp stacking method is potential for high density obs surveys 3 the thickness of sedimentary layer in bohai sea and surrounding area is 3 5 km the velocity increases with depth from about 2 km s at the seafloor to about 4 5 km s on the sedimentary basement 4 the upper crust thins toward the sea area from the land area the middle and lower crust also vary insignificantly the middle crust is about 4 km and the lower crust is about 15 km the velocities of the middle and lower crust shows gentle variation in vertical but obvious in lateral due to the impact of fault zones 5 the velocity contours nearby the tancheng lujiang tlfz and zhangjiakou penglai zpfz fault zones are u shaped where the velocity changes laterally and the interface undulates significantly velocity disturbances exist in the crust mantle transition zone at the fault zones the tlfz and zpfz could be the upwelling channels of deep material 6 in the eastern part of north china craton ncc the moho gently ranges at the depth of about 30 km with local rises lithosphere thinning occurred predominantly at the top of upper mantle the east boundary of lithosphere thinning is inferred to be on the east of bohai sea

new evidence from seismic imaging for subduction during assembly of the north china craton comment the frozen in information in the crust plays an important role in improving our understanding of cratonic formation and evolution and plate tectonics in the precambrian the trans north china orogen is a continent continent collision belt generated by the assembly of the north china craton the mechanism and modality of the collision are disputed here we present a seismic image of the western block and the trans north china orogen of the north china craton derived using receiver function analysis of the teleseismic records from a dense array a low velocity zone extending from the middle crust to the moho is interpreted as a remnant of upper middle crustal material associated with westward dipping subduction beneath the western block of the north china craton crustal uplift and magmatic underplating resulting from subsequent tectonic events were responsible for modifying the remaining subduction architecture the western boundary of the trans north china orogen is located west of the boundary earlier identified by surface investigation the results combined with previous seismic imaging in the eastern north china craton provide insight into the amalgamation of the eastern and western blocks and the subsequent tectonic deformation of the north china craton

microplate tectonics new insights from micro blocks in the global oceans continental margins and deep mantle abstract any plate has a growth process from small to large the micro blocks or micro plates are sometimes the precursors of large plates the origin growth aborting extinction and residual process of micro blocks are of great significance for the study of plate tectonics and pre plate tectonics the micro block can be divided into continental oceanic and mantle micro blocks according to their compositions in this paper the micro blocks in the global oceans have been summarized according to the following five environments mid ocean ridge system subduction system transform fault system deep sea intraplate system and extension rift system we first propose a genetic classification of micro blocks comprising detachment derived rifting derived transform derived propagation derived ridge jumping derived subduction derived accretion derived collision derived and delamination derived micro blocks the different types of micro block boundaries such as active or fossil detachment fault subduction zone mid ocean ridge transform fault fracture zone transfer fault accommodation zone lithosphere scale strike slip fault pseudofault intra oceanic convergent zone overlapping spreading centre non transform offset rheological crustal or mantle discontinuity are systematically discussed for different micro blocks thus the number of triple junctions will be more than the 16 in the traditional plate tectonic theory a stability analysis of these triple junctions is the key to understanding the causes of micro blocks however the micro block has no ultimate cause so it is unnecessary to pursue one ultimate cause or initiation of plate tectonics these micro blocks within oceanic basins along oceanic margins or within the deep mantle can not only be used to develop deep ocean fine structural analysis and plate tectonic reconstruction but also to explain the causes of micro blocks in some orogens this will enrich the research of more detailed pre orogenic or syn orogenic evolution of orogenic belts and even extend to the study of early precambrian pre plate tectonic mechanisms the micro block can be a transition among microplate plate and terrane under a plate tectonic regime it can also be formed in inter sphere tectonic processes it helps better our understanding of regimes of cratonic basin formation and intra continental deformation which are the difficulties faced by the plate tectonics theory we speculate that the micro block tectonics theory is a unified tectonic theory of cross layer cross phase cross space time scale and cross planet

holocene development of the yellow river s subaqueous delta north yellow sea high resolution seismic profiles from the north yellow sea reveal a 20 40 m thick subaqueous clinoform delta that wraps around the eastern end of the shandong peninsula extending into the south yellow sea this complex sigmoidal oblique clinoform containing an estimated 400 km 3 of sediment overlies prominent relict transgressive surfaces the nearshore topset of the clinoform 50 m contain less than 1 m of holocene sediment with low sedimentation rates 1 mm year in contrast to other clinoforms the shandong clinoform appears to be a compound subaqueous deltaic system with what we interpret to be proximal and distal phases of clinoform development the underlying proximal sequence formed proximally between f11 and 9 2 ka in response to a temporary pause in the rapid postglacial sea level rise after the meltwater pulse 1b mwp 1b and increased discharge from the yellow river to the north yellow sea due to intensification of the summer monsoon a flooding surface appears to separate the proximal and distal phases corresponding to the next rapid sea level rise 9 5 9 2 ka bp mwp 1c since 9 2 ka bp an overlying distal sedimentary sequence has accumulated reflecting the backstepping and shifting river mouth westward to the gulf of bohai some inputs from coastal erosion and nearby small streams may be locally important along shore transport cross shelf advection and upwelling in the north yellow sea have reworked post lgm sediment and have helped maintain the morphology of the clinoform in the shandong mud wedge d 2004 elsevier b v all rights reserved

how the continents deform the evidence from tectonic geodesy space geodesy now provides quantitative maps of the surface velocity field within tectonically active regions supplying constraints on the spatial distribution of deformation the forces that drive it and the brittle and ductile properties of continental lithosphere deformation is usefully described as relative motions among elastic blocks and is block like because major faults are weaker than adjacent intact crust despite similarities continental block kinematics differs from global plate tectonics blocks are much smaller typically 100 1000 km in size departures from block rigidity are sometimes measurable and blocks evolve over 1 10 ma timescales particularly near their often geometrically irregular boundaries quantitatively relating deformation to the forces that drive it requires simplifying assumptions about the strength distribution in the lithosphere if brittle elastic crust is strongest interactions among blocks control the deformation if ductile lithosphere is the stronger its fl

early cenozoic two phase extension and late cenozoic thermal subsidence and inversion of the bohai basin northern china abstract the bohai basin is one of a family of early cenozoic extensional basins that lie along the eastern margin of asia from russia to vietnam initial extension was probably triggered by subduction roll back of the oceanic pacific plate from the asian continent there were two phases in the bohai basin s rift history the earlier paleocene early eocene phase resulted in the deposition of the kongdian formation and the fourth lowest member of the shahejie formation in a series of elongate half grabens these half grabens have master faults with a nne ssw orientation secondary normal faults are typically clockwise oblique to the master faults indicating a component of dextral transtension deposition was focused in the west and south of the present basin these rocks are mainly alluvial fan and fluvial red beds the architecture of the basin underwent an important change at ca 43 45 ma middle eocene beginning with the deposition of the third member of the shahejie formation in part these sediments were deposited in the same half grabens as the kongdian formation but the bozhong depression in the central part of the basin originated at this time and became the major depocentre the bozhong depression superficially resembles a pull apart basin it formed when continued transtension of the earlier tertiary fault systems to the east and west created an extensional overlap between them during this phase the basin as a whole had a geometry with elements typical of both pull apart and transtensional basins regional extension in many east asian basins ended at the end of the oligocene probably because of the onset of transpression within eastern asia caused by the collision of australia with the philippine sea plate dextral transpression caused minor inversion of some of the earlier normal faults in bohai but as a whole the basin began to subside in a post rift phase of thermal subsidence that has lasted until the present day

structural deformation and evolution of right lateral strike slip tectonics of the liaohe western depression during the early cenozoic abstract the tan lu fault zone tlfz traverses the liaohe western depression lhwd affords an exceptional opportunity to reveal the structural deformation and evolution of a major strike slip fault of the lhwd using three dimensional seismic data and well data in this paper based on structural interpretations of the 3 d seismic data of the lhwd combined with depth slice and seismic coherency a variety of structural features in relation to right lateral strike slip fault the western branch of the tan lu fault have been revealed presence in the depression such as thrust faults xinlongtai taian dawa and chenjia faults structural wedges positive flower structures and en echelon normal faults fault cutoffs growth strata and the neogene unconformity developed in the lhwd verify that the activity of right lateral strike slip from the late eocene to neogene ca 43 23 ma the study indicates that the right lateral strike slip played an important role in controlling the structural deformation and evolution of the lhwd in the early cenozoic moreover the front structural wedge generated the gross morphology of the xinlongtai anticline and developed the lengdong faulted anticline during the late eocene and the back structural wedge refolded the lengdong faulted anticline zone in the late eocene to the early oligocene wrench related structures the chenjia thrust fault and the en echelon normal faults were developed during the late oligocene uniform subsidence in the neogene to quaternary furthermore the driving force of the right lateral strike slip deformation was originated from n s extension stress related to the opening of the japan sea and ne sw compression as the far field effect of india eurasia convergence

mirror symmetry of the crust in the oil gas region of shengli china abstract the concept of mirror image symmetry describes the correlation between the bottom of a sedimentary basin and the top of the underlying mantle the degree of mirror symmetry is analyzed here using thickness data from mesozoic cenozoic sedimentary basins and the moho depth with the purpose of investigating the implications for tectonics and exploratory practices in oil gas bearing basins our attention is focused on different tectonic elements of a multi scale tectonic partition in the oil gas region of shengli southeast of bohai bay china by applying standard least squares analysis methods to both datasets we obtained the average thickness h of the consolidated crust and the mirror symmetry factor a for every tectonic unit thereby allowing us to explore the correlation between the bottom depth of a sedimentary basin and the top of the underlying mantle a detailed analysis of data uncertainties and their potential effects led to small fluctuations of h and a within a narrow band around the mean values of 33 26 km and 1 43 respectively thus the results can be considered valid if they are constrained by these error bounds the issues of crust mantle interaction and the deviation of the crust from isostatic equilibrium are also addressed for their tectonic implications other structural parameters related to the deep rooted crust beneath the tectonic elements that make up the study region such as the ratio r of the thickness of the consolidated crust to the absolute value of the symmetry factor the ratio k of the maximum sediment thickness to the maximum uplift of the mantle and the product kh are also evaluated for their implications in geophysical prospecting the symmetry signature of the crust is compared to the symmetry of other sedimentary basins in china and in the world suggesting symmetry as a feasible prognostic tool in exploration for oil gas reservoirs the key result is that those locations where oil gas reservoirs have been found to date are basins in which the crust mantle interaction is active and the crust is isostatically compensated both of those parameters can be quantitatively constrained conversely oil and gas reserves are poor or nonexistent in regions where the crust mantle interaction is inactive and the crust is far from isostatic equilibrium however an intermediate case between these two extreme scenarios wherein the crust mantle interaction is rather moderate but the crust is in a state close to isostasy cannot be entirely ruled out

uplift history of the jiaodong peninsula eastern north china craton implications for lithosphere thinning and gold mineralization the link between lithosphere thinning and formation of world class gold deposits is well established in the jiaodong peninsula within the eastern north china craton ncc however the timing of initiation and duration of the lithospheric thinning process as well as the depth of formation of the mineralization remain uncertain since these parameters are fundamental to formulate exploration strategies in this study we perform fission track ft analysis on zircon and apatite grains in late mesozoic granitoid samples from the jiaodong peninsula and provide new constraints for the mode and duration of lithospheric evolution and mineralization depth the zircon ft ages range from 64 3 to 90 9 ma and those of apatite show a range of 32 8 50 9 ma the data collectively display age peaks at 60 80 and 30 50 ma reverse modelling of the apatite ft results indicates rapid crustal uplift during 30 80 ma in the jiaodong peninsula this period coincides with the timing of maximal sedimentation in the neighboring basins and voluminous basaltic eruptions in the eastern ncc we suggest that the jiaodong peninsula has experienced two stages of crust uplift in the late cretaceous and paleogene as a consequence of the continuing lithosphere thinning together with the surrounding basins forming the horst graben system in the eastern ncc the late mesozoic granitoids are the main wall rocks for gold deposits in jiaodong and thus the crust denudation history gathered from the ft data suggest that the gold mineralization formed at depths of c 6 11 km

anatomy of a lacustrine stratigraphic sequence within the fourth member of the eocene shahejie formation along the steep margin of the dongying depression eastern china a comprehensive study on rift stratigraphy requires a solid understanding of sequence architecture along the steep margins of rift basins this study analyzes an eocene lacustrine sequence along the steep margin of the dongying depression in eastern china through integrated core well log and three dimensional seismic analyses the lacustrine sequence is bounded by unconformities and their correlative conformities at the base and top and consists of three systems tracts namely an early expansion systems tract eest late expansion early contraction systems tract leecst and late contraction systems tract lcst which record a lake expansion contraction cycle these systems tracts differ in thickness and development of depositional systems the eest is the thickest and contains well developed marginal and basinal fan systems with an overall retrogradational stacking pattern the well developed fan systems are the most striking features within the sequence the leecst is the most widespread and contains dominantly profundal sublittoral deposits the lcst is the thinnest with poorly developed fan systems and is characterized by significant erosion by fluvial incision the variable thickness and development of depositional systems in the three systems tracts are the responses to the interplay of sediment supply and accommodation space accommodation space establishes the framework for sedimentary infill and sediment supply determines spatial distribution and temporal evolution of depositional systems within each systems tract this study provides a lake expansion contraction scheme to divide a lacustrine stratigraphic sequence into systems tracts and highlights the feasibility of applying this approach in studying sequence stratigraphy along the steep margin of a lacustrine rift basin the results also provide understandings for the development distribution and evolution of depositional systems and their controlling factors along the steep margin of other rift basins in the world

tectonic evolution of the penglai 7 6 structure and its implications for petroleum exploration in a releasing bend of a strike slip fault system tan lu fault zone east china abstract the penglai 7 6 pl7 6 structure is located on the tan lu fault zone a huge fault zone in east asia tectonism of the tan lu fault zone produced complex structural deformation and was an important factor in petroleum accumulation three dimensional seismic data were employed to document the structural geometry and evolutionary process of the pl7 6 structure and implications for petroleum exploration in a releasing bend of a strike slip fault system were discussed systematic analysis of the seismic data indicates that the main fault the bd2 fault of the tan lu fault system slipped right laterally during the cenozoic strike slip movement of the bd2 fault peaked during deposition of e 1 2 k to e 3 d 3 and decreased largely in intensity during e 3 d 1 2 deposition in the neogene and quaternary the bd2 fault was reactivated formation of the bodongnan low uplift is related to the connection between the bodongnan low uplift n and bodongnan low uplift s the bodongnan low uplift n is represented by an anticline produced by strike slip movement of the bd2 fault and the bodongnan low uplift s is represented by the relatively uplifted strata in the vicinity of an extensional fault the bd3 fault the pl7 6 structure developed above a releasing bend formed by the subsequent strike slip movement of the curved bd3 fault orientations of the shallow faults in the pl7 6 structure are not only associated with the lower bd3 fault but also controlled by the basement high unlike traditional releasing bends that are generally disadvantage to petroleum accumulation due to the lower structural elevation in the center the releasing bend in the pl7 6 structure is favorable for petroleum accumulation because of the three reasons 1 adjacent to generative kitchens 2 located on a regional structural high and 3 served by the releasing bend related faults acting as conduits for vertical petroleum migration

quaternary activity along the tan lu fault zone in the bohai bay east china evidence from seismic profiles abstract the middle segment of the nne ssw striking tan lu fault zone tlfz crosses the bohai bay in east china this fault zone is a large seismically active belt that was responsible for the 1969 m magnitude 7 4 bohai earthquake however the geometry kinematics and detailed characteristics of the most recent quaternary seismic activity along the tlfz in the bohai bay area are debated primarily as the fault crops out below sea level in this area here we present the results of a series of seismic profiles that enable the identification of quaternary activity along the tlfz within the bohai bay area these data indicate that the quaternary tlfz crops out over a wide area of the bohai bay and is dominated by two main faults both of which dip steeply to the west each of these two main faults consists of several left stepping en echelon faults quaternary activity along the tlfz was generally focused along pre existing paleogene neogene faults the seismic profiles combined with the distribution of earthquakes in this area demonstrate that the tlfz in the southern and central areas of the bohai bay was last active during the holocene whereas the last movements along the faults in the northern bohai bay area range from late pleistocene in the south to early middle pleistocene and the end of the neogene in the north the seismic profiles show both normal and reverse offset of the base of the quaternary sediments by the tan lu faults although the normal offset predominates anticlines developed in quaternary sediments occur close to the quaternary tan lu faults and the tlfz is also associated with an angular unconformity between holocene and pleistocene sediments it is likely that the tlfz was dominated by reverse dextral slip during the holocene whereas all of the quaternary faulting before this involved alternating reverse and normal dextral slip oblique extension is most likely responsible for the normal dextral slip along the tlfz whereas focal mechanisms gps global positioning system data and in situ stress measurements all suggest that ene wsw compression led to the reverse dextral faulting associated with numerous recent earthquakes in the bohai bay area

spatial variations of current tectonic stress field and its relationship to the structure and rheology of lithosphere around the bohai sea north china abstract the tectonic stress field in the middle upper crust is closely related to the structure and rheology of the lithosphere to determine the stress field in the deep crust we inversed the focal mechanism solutions fmss of 62 earthquakes that occurred between 2009 and 2015 in the bohai sea and its surrounding areas using broadband seismic waveforms collected from 140 stations we then derived the tectonic stress field using the software satsi spatial and temporal stress inversion based on the damped linear inversion method the inversion results show that both the maximum 1 and minimum 3 principle stress axes throughout the entire region are nearly horizontal except in the tangshan and haicheng areas suggesting that the study area is predominantly under a strike slip faulting stress regime the 1 and 3 axes are found to be oriented in the nee sww or nearly e w and nnw sse or nearly s n directions respectively these results indicate that the stress field in the north china craton is controlled by the combined effects of the pacific plate westward subduction and the india eurasia plate collision however localized normal faulting stress regimes where the vertical stress v 1 are observed in the tangshan and haicheng areas where low viscosity bodies lvbs were identified using geophysical data based on the analysis of focal mechanism solutions active faults and lithosphere rheology characteristics in the tangshan and haicheng areas we speculate that the anomalous stress regime is caused by the local extension resulting from the movement of strike slip faults under the action of the regional stress field the existence of lvb may indicate weakness in the crust that favors the accumulation of tectonic stress and triggers large earthquakes

assembling north china craton within the columbia supercontinent the role of double sided subduction abstract an evaluation of recent s wave receiver functions s wave velocities and two versions of p wave tomographic images along various transects in the north china craton provides some clues on the subduction collision history of the different crustal blocks and their final amalgamation within the paleoproterozoic columbia supercontinent interpretation of a n s seismic section of the craton suggests thick slab debris sinking to various depths in the mantle the w e seismic corridors show the preservation of a thick 200 km lithospheric root tectosphere beneath the ordos block and its variable and extensive erosion towards the yanliao block eastern block this zone is characterized by layers with marked velocity contrast and suggests repeated stacking of the remnants of underplated and accreted paleoproterozoic oceanic lithosphere the present day lithosphere asthenosphere boundary beneath this region probably marks the erosional plane along which decratonization occurred through subduction erosion from the east and thermal and material erosion by upwelling asthenosphere from below resulting in the partial destruction of the tectosphere and its thinning towards the east within the asthenosphere below the yanliao block younger and thinner slabs predominate in the absence of any prominent thick high velocity layers these younger slabs define a westward polarity and constitute a mega scale duplex formed by underplating through phanerozoic subduction process particularly the pacific plate subduction from the east the lithologic associations within the inner mongolia suture zone dividing the yinshan block to the north and ordos block to the south correspond to an accreted ocean plate stratigraphic sequence with the tonalite trondhjemite granodiorite ttg gneisses charnockites and calc alkaline granites representing a continental arc built up through subduction from the north the seismic transects bring out a contrasting polarity in the subduction regime with an oblique east to southward subduction of the yinshan block and a westward subduction of the yanliao block here i propose a double sided subduction history for the ncc similar to the ongoing subduction process in the western pacific such double sided subduction is considered to promote rapid amalgamation of continental fragments within supercontinents and the subduction polarities and mantle dynamics of ncc are therefore considered to be critical in evaluating the final assembly of the paleoproterozoic supercontinent columbia

numerical modeling of late miocene tectonic inversion in the xihu sag east china sea shelf basin china abstract the east china sea shelf basin is an important oil and gas bearing basin in the west pacific continental margin this region was affected by subduction of the pacific plate and the philippine plate in cenozoic and experienced multi stage tectonic inversions this paper presents results from a numerical simulation by finite element method to the xihu sag in the east china sea shelf basin and neighboring areas in an attempt to evaluate the wnw directed compression on the sag during late miocene based on comprehensive structural analysis of a large number of seismic profiles we determine the structural geometry of the sag including the basement of the basin the sedimentary cover and 29 major faults in the xihu sag simulation results show that under continuous wnw directed compression tectonic inversion occurred firstly in the longjing and yuquan tectonic zones in the sag based on quantitative analysis of vertical displacement field of the xihu sag and peripheral areas and its stress intensity evolution we identify a compressional regime in the longjing anticline zone with a gradually propagated uplifting from south to north whereas the propagation of uplifting in the yuquan anticline zone is from north to south the inversion intensity decreases from north to south the formation of the tectonic inversion zone in the xihu sag is not only correlated to the direction of compression and fault patterns in the basin but also closely related to the spatial configuration of fault surfaces of the xihu jilong fault in the xihu sag

gold metallogeny associated with craton destruction a geophysical perspective from the north china craton abstract currently ranking as the largest producer of gold in the world china s gold reserves are spread over 200 major gold deposits and several minor deposits a large part of these belong to the late mesozoic gold deposits in the north china craton ncc that occur along craton margins as well as within the cratonic interior in reactivated paleo sutures and show a close spatio temporal relationship with zones of lithospheric thinning and craton destruction here we integrate and evaluate geophysical information from the ncc through an analysis of receiver function and tomography that suggest mantle upwelling accompanied by lower crustal or lithospheric delamination our results identify that the major gold belts in the ncc are largely located above zones of mantle upwelling and craton destruction the faults and paleo sutures provided the pathways for migration of ore bearing fluids with the granitoids offering favorable conditions for gold deposition

mesozoic basins in eastern china and their bearing on the deconstruction of the north china craton abstract mesozoic basins occur widely in the eastern block and the neighboring area of the north china craton including the bohai bay the jiaolai the hefei and the north yellow sea in the north and the jianghan and the subei south yellow sea basins to the south their spatial temporal framework is the consequence of the indosinian and yanshanian tectonic regimes in eastern china and record the events related to mesozoic deconstruction of the north china craton our results demonstrate that the mesozoic tectonic evolution of the eastern north china craton was related to both sub crustal delamination and intra crustal extrusion or escape tectonics thus we propose that the mechanism of uplift of the yanshanian north china plateau and related lithosphere thinning in the eastern north china craton were related to sub crustal delamination at depth however the different distribution patterns of the basins on both sides of the tan lu fault system as well as the co existence of both compressional and extensional basins in the mesozoic indicate that these were controlled by escape tectonics in different tectonic parts of the crust

cenozoic tectonic jumping and implications for hydrocarbon accumulation in basins in the east asia continental margin abstract tectonic migration is a common geological process of basin formation and evolution however little is known about tectonic migration in the western pacific margins this paper focuses on the representative cenozoic basins of east china and its surrounding seas in the western pacific domain to discuss the phenomenon of tectonic jumping in cenozoic basins based on structural data from the bohai bay basin the south yellow sea basin the east china sea shelf basin and the south china sea continental shelf basin the western pacific active continental margin is the eastern margin of a global convergent system involving the eurasian plate the pacific plate and the indian plate under the combined effects of the india eurasia collision and retrogressive or roll back subduction of the pacific plate the western pacific active continental margin had a wide basin arc trench system which migrated or jumped eastward and further oceanward this migration and jumping is characterized by progressive eastward younging of faulting sedimentation and subsidence within the basins owing to the tectonic migration the geological conditions associated with hydrocarbon and gashydrate accumulation in the cenozoic basins of east china and its adjacent seas also become progressively younger from west to east showing eastward younging in the generation time of reservoirs seals traps accumulations and preservation of hydrocarbon and gashydrate such a spatio temporal distribution of cenozoic hydrocarbon and gashydrate is significant for the oil gas and gashydrate exploration in the east asian continental margin finally this study discusses the mechanism of cenozoic intrabasinal and interbasinal tectonic migration in terms of interplate intraplate and underplating processes the migration or jumping regimes of three separate or interrelated events 1 tectonism magmatism 2 basin formation and 3 hydrocarbon gashydrate accumulation are the combined effects of the late mesozoic extrusion tectonics the cenozoic nw directed crustal extension and the regional far field eastward flow of the western asthenosphere due to the india eurasia plate collision accompanied by eastward jumping and roll back of subduction zones of the pacific plate

post triassic multiple exhumation of the taihang mountains revealed via low t thermochronology implications for the paleo geomorphologic reconstruction of the north china craton abstract to better define the uplift and denudation process of the taihang mountains and its uplift subsidence coupling with the western bohai bay basin the zircon and apatite u th he thermochronology and apatite fission track thermochronology of samples from the taihang mountains trans north china orogen were examined in this study the weighted averages of single grain zircon and apatite u th he ages were 70 3 79 9 ma and 15 1 26 8 ma respectively the apatite fission track ages ranged from 41 8 ma to 51 9 ma with mean track lengths of 11 68 13 3 m three distinct episodes of cooling at 100 45 ma at 38 30 ma and after 20 ma revealed via joint inverse modeling were related to compression from the subduction of the kula plate during the late cretaceous the rapidly changing differential elevation and subsidence between the taihang mountains and the western bohai bay basin from the late eocene to early oligocene and the combined distant effects of the collision of the indian and eurasian plates and the rollback of the subducting pacific plate during late cenozoic respectively this paper presents the cooling histories of the shallow crust below 200 c in the taihang mountains and provides new insights into the geodynamic mechanism of the uplift events that occurred in the different areas of the north china craton understanding these events is very important to comprehend the differential uplift in the north china craton basin mountain coupling and its tectonic morphological evolution since the mesozoic

numerical modelling of stress fields and earthquakes jointly controlled by ne and nw trending fault zones in the central north china block abstract the stress field of the central north china block cncb has been affected by the interaction among the indian eurasian and pacific ocean plates and the effect is manifested by the occurrence of large earthquakes in this region here using numerical simulation of the finite element method attempts were made to evaluate ese directed compression on three tectonic zones namely the shanxi graben zone the zhangjiakou penglai fault zone and the taihangshan fault zone in these zones the structural geometry and viscoelastic property of the model were determined as well as 49 main faults identified by means of a comprehensive structural analysis of seismic profiles gravity data and tomography this study shows that the stress concentration areas in the three zones are all located in the transition zone between ne trending and nw trending faults numerical simulation analysis of the xingtai and tangshan earthquakes revealed that the ne and nw trending faults had played an important role in controlling the distribution of the stress field triggering aftershocks and or stopping stress propagation during earthquakes the differences of the stress fields and earthquake distributions among the three tectonic zones resulted from not only the fault combination patterns but also the geometry of the main faults

paleochannel controlled earth fissures in daming north china plain and their implication for underground paleogeomorphology abstract earth fissures are a geologic phenomenon that mainly affects the medium with shallow surface soil and mainly developed in the quaternary sediment cover in the yellow river qinghe river zhanghe river shallow buried paleochannel band hqz qh2 ii band on the north china plain 93 earth fissures are developed among them 29 fissures are evolved in the daming zone in the upper reaches of the paleochannel band thus the zone belongs to a densely grouped fissure area this study through a series of field trenching and surveying revealed that these earth fissures have unique plane distribution rules and profile structure features of short length several meters to several hundred meters shallow depth smaller than 10 m and good correspondence to daming paleochannels these basic characteristics reveal that unlike other tectonic earth fissures daming earth fissures are a new and unknown type of fissures i e paleochannel controlled earth fissures theoretical analysis of their features showed that they were formed due to the actions of gravity primary joint factors and groundwater pumping activities and controlled by ancient river factors including paleochannels sediments and groundwater among them the process of mode i can be summed up as self gravity action tensile cracks surface water scouring earth fissures the process of mode ii is primary join surface water infiltration piping cave in earth fissures the process of mode iii is groundwater extraction aquifer compression inhomogeneous ground subsidence earth fissures these formation mechanisms of paleochannel induced earth fissures can be used to predict the fine distribution of shallow buried paleochannels and the overall migration process of the rivers thus this kind of earth fissures is of great significance for understanding the underground paleogeomorphology buried paleochannel of the north china plain and other alluvial plains of the world

late mesozoic compressional to extensional tectonics in the yiwulushan massif ne china and its bearing on the evolution of the yinshan yanshan orogenic belt part i structural analyses and geochronological constraints abstract with a cratonic nucleus the north china craton ncc experienced a complex tectonic evolution with multiphase compressional and extensional events during mesozoic times along the northern part of the ncc the yinshan yanshan fold and thrust belt was a typical intraplate orogen jurassic and cretaceous continental sedimentation magmatism widespread intraplate characterize the yinshan yanshan orogenic belt the geodynamic significance of these tectonic events is still in dispute in the western part of the liaoning province the yiwulushan massif crops out at the eastern end of the yinshan yanshan orogenic belt the yiwulushan massif presents an elliptical domal shape with a ne sw striking long axis the structural evolution of this massif brings new insights for the understanding of the mesozoic plutonic tectonic history of the ncc a multidisciplinary study involving structural geology geochronology anisotropy of magnetic susceptibility ams and gravity modeling have been carried out the presentation of the new results splits into two parts part i this paper deals with field and laboratory structural observations and presents the main geochronological results the ams gravity modeling data will be provided in a companion paper part ii the early compressional deformation d1 corresponds to a late jurassic to early cretaceous southward thrusting the subsequent deformation is related to the early cretaceous exhumation of the yiwulushan massif a detailed structural analysis allows us to distinguish several deformation events d2 d3 and d4 the cretaceous extensional structures such as syntectonic plutons bounded by ductile normal faults metamorphic core complexes and half graben basins are recognized in many places in east asia these new data from the yiwulushan massif constitute a link between transbaikalia mongolia north china and south china indicating that nw se extensional mesozoic tectonics occurred throughout the entire region

collision leading to multiple stage large scale extrusion in the qinling orogen insights from the mianlue suture abstract the geologic framework of the phanerozoic qinling dabie orogen was built up through two major suturing events of three blocks from north to south these include the north china craton including the north qinling block the qinling dabie microblock and the south china craton including the bikou block separated by the shangdan and mianlue sutures the mianlue suture zone contains evidence for mesozoic extrusion tectonics in the form of major strike slip border faults surrounding basement blocks a late paleozoic ophiolite and a ca 240 200 ma thrust belt that reformed by 200 150 ma thrusts during a type intracontinental subduction the regional map pattern shows that the blocks are surrounded by complexly deformed devonian to early triassic metasandstones and metapelites forming a regional scale block in matrix melange fabric five distinct tectonic units have been recognized in the belt 1 basement blocks including two types of precambrian basement crystalline and transitional 2 continental margin slices including early paleozoic strata and late paleozoic fluviodeltaic sedimentary rocks proximal and distal fan clastics reflecting the development of a north facing rift margin on the edge of the south china plate 3 out of sequence oceanic crustal slices including strongly deformed postrift deep water sedimentary rocks sheeted dikes basalts and mafic ultramafic cumulates of a late paleozoic ophiolite suite developing independent of the rift margin in a separate basin 4 out of sequence island arc slices 5 accretionary wedge slices all the tectonic units were deformed during three geometrically distinct deformation episodes d 1 d 2 and d 3 during 240 200 ma units 2 4 involved southward thrusting and vertical then southward extrusion of about 20 km of horizontal displacement above the autochthonous basement during the d 1 episode thrust slices 20 km south of the mianlue suture are related to this vertical extrusion due to the same rock assemblages ages and kinematics the d 2 and d 3 episodes folded all the units in a thick skinned style about east west d 2 and west northwest d 3 axes in the mianlue suture zone an early foreland propagating sequence of accretion of late paleozoic rocks deposited above the yangtze craton is not involved in d 1 deformation but is temporally equivalent to the d 2 and d 3 deformation in the mianlue suture two stages of strike slip faulting mainly occurred at the end of d 2 and d 3 respectively during d 2 deformation the bikou block was obliquely indented to the ese into the mianlue suture rather than being thrust over the mianlue suture from the north as a part of the qinling dabie microblock during d 3 deformation however the bikou block was bounded by the south boundary fault of the mianlue suture and the yangpingguan fault on the south these faults are coeval strike slip faults but of opposite senses and accommodated minor southwestward extrusion of the bikou block into songpan ganze orogen the other basement blocks north of the mianlue suture were extruded eastward by about 20 km of lateral displacement based on the offset of the wudang dome during the d 3 episode due to the northeastward indentation of the hannan complex of the south china craton post d 3 emplacement of granite cutting across the strike slip faults such as the mianlue suture provides a minimum age of 200 ma for d 3 deformation therefore based on insights from the evolution of the mianlue suture the d 2 and d 3 episodes in the mianlue suture and its neighbors are not responsible for and associated with the two stage extrusion of the dabie uhp hp terranes from the foping dome to the present erosional surface more than 350 km

cenozoic faulting of the bohai bay basin and its bearing on the destruction of the eastern north china craton abstract the cenozoic bohai bay basin is located at the center of the eastern block of the north china craton the structural architecture of this basin provides important clues on the deep seated lithosphere thinning of the north china craton the cenozoic regional stress field is characterized by nw oriented extension however the various cenozoic structural patterns of normal faulting and related transverse folding in the bohai bay basin are controlled not only by cenozoic stress field but also by strain field and mesozoic basement fault assemblages in this area regionally the cenozoic tectonic features and the dynamic evolution of the eastern north china craton are dominated by two lithosphere penetrating fault systems including the sinistral tan lu fault system and the dextral lan liao fault system to the west of the lan liao fault system cenozoic extensional tectonics includes nne trending listric normal faults that controlled half grabens however between these two fault systems are wnw trending half grabens which show basement involved faulting in the north and overlapping relations between sedimentary cover and basement in the south to the east of the tan lu fault the north yellow sea basin is a wnw trending fault depression with faulting in the south and overlapping relations in the north these structural features are inherited from the mesozoic tectonic framework of this area whose tectonic characteristics were completely controlled by two opposite strike slipping faults the trans extensional or oblique rifting in the paleogene followed by extensional faulting and subsequent subsidence furthermore the culmination of the decratonization of the north china craton was also related to an eastward jump of cenozoic subduction of the pacific plate and the far field effect of eastward extrusion of cenozoic subduction of the indian plate and was not essentially restricted to the early mesozoic processes therefore the cenozoic especially 25 ma marks the time of cessation of the processes that led to lithosphere thinning and destruction of the eastern block of the north china craton

mesozoic to cenozoic tectonic transition process in zhanhua sag bohai bay basin east china abstract the zhanhua sag is part of the bohai bay intracontinental basin system that has developed since the mesozoic in east china the timing of this basin system coincides with the final assembly of east asia and the development of western pacific type plate margin here we use 3 d seismic and core log data to investigate the evolution of this basin and discuss its broad tectonic settings our new structural study of zhanhua sag suggests that there are four major tectonic transitions occurred in the bohai bay basin during mesozoic and cenozoic 1 the first tectonic transition was from stable craton to thrusting during the triassic mainly caused by the south china block s subduction northward beneath the north china block which induced the formation of the nw striking thrust faults 2 the second tectonic transition was mainly characterized by a change from compression to extension which can be further divided into two stages at the first stage two episodes of nw se shortening occurred in east asia during early middle jurassic and late jurassic earliest cretaceous respectively at the second stage the extension and left lateral shearing took place during early cretaceous while compression occurred during late cretaceous the nw striking thrust faults changed to normal faults and the nne striking left lateral strike slip faults started to influence the eastern part of the basin 3 the third transition occurred when the nw se extension and nne striking right lateral shearing started to form during paleogene and the peak deformation happen around 40 ma due to the change of the subduction direction of pacific plate relative to eurasia plate the ne striking normal faults are the main structure and the pre existing nne striking strike slip faults changed from left lateral to right lateral 4 the fourth transition saw the regional subsidence during neogene which was probably caused by the india asia hard collision between 25 and 20 ma

neogene residual subsidence and its response to a sinking slab in the deep mantle of eastern china abstract mantle convection could have a significant effect on basin evolution however research quantifying this relationship is controversial to understand the formation mechanism and evolution of the cenozoic rift basins in eastern china we applied the back stripping technique and strain rate inversion modeling to 119 wells from sangjiang basin bohai bay basin north yellow sea basin south yellow sea basin east china sea shelf basin and four basins within the northern south china sea margin the modeled results can be used to reconstruct the tectonic subsidence history and further assess the potential subsidence mechanisms of eastern china residual subsidence is defined as the difference between the theoretical and observed tectonic subsidences our results show that the residual subsidence since 20 ma in eastern china generally increases from 100 to 300 m in terrestrial areas to 1 2 1 8 km on the continental shelf our observed residual subsidence is generally consistent with the present day dynamic topography that is predicted from mantle flow models and it is associated with a stagnant slab within the mantle that has been observed by seismic tomography the migration pathway of the residual subsidence since 20 ma is consistent with the movement direction of the pacific and philippine plates therefore we suggest that the residual subsidence might be a dynamic subsidence induced by a negative buoyancy of the sinking slab in the deep mantle beneath eastern china

cenozoic tectonic evolution of liaodong dome northeast liaodong bay bohai offshore china constraints from seismic stratigraphy vitrinite reflectance and apatite fission track data abstract the liaodong dome is a region of localized uplift and deformation within the liaodong bay bohai offshore china 3 d seismic dataset vitrinite reflectance and apatite fission track data provide an exceptional opportunity to document the evolution of the liaodong dome which developed coeval with the tan lu strike slip fault zone with a rift system the 3 d seismic data demonstrates that the dome formed before the deposition stage of esm sequence 40 ma and it uplifted again during or after the depositional stage of ed sequence 32 24 ma apatite fission track and vitrinite reflectance data indicate that the dome experienced two stages of cooling episodes paleocene to early middle eocene 65 40 ma and late oligocene to late miocene 30 11 5 ma usually indicating uplifting both the seismic stratigraphy and thermal history analysis show that 1 the liaodong dome is part of the jiaoliao terrane 2 regional continental rifting climaxed during 65 40 ma as it did the rift shoulder uplift of the dome 3 the reactivation of the tan lu fault caused a second uplift processes of the liaodong dome during 30 11 5 ma 4 the liaodong dome uplifted independently and separated from the jiaoliao terrane our results also suggest that it is important to take uplifting evolution into consideration to target a potential petroleum reservoir

continental dynamics of eastern china insights from tectonic history and receiver function analysis east asia records a complex sequence of tectonic processes with the mosaic of cratonic blocks and orogenic belts in china preserving evidence for multiple episodes of amalgamation and reworking from the archean to cenozoic the prolonged subduction of the pacific plate from the east has been invoked to explain the volcanic activities in the ne china region and in the songliao basin as well as the extensive destruction of the sub continental lithospheric mantle of the north china craton ncc the collision between the ncc and the yangtze craton involved deep subduction and exhumation of ultrahigh pressure metamorphic orogen in the south china craton the yangtze and cathaysia blocks collided along the shaoxing jiangshan pingxiang suture here we present an overview of the results from multidisciplinary studies on the major tectonic events in the eastern china region and evaluate the geodynamics of these in the light of our recent work based on receiver function analysis the compression induced by the westward subduction of the pacific plate in the ncc and south china appears to have triggered lower crustal and lithospheric delamination we also identify mantle upwelling as a dominant trigger for the major tectonic process in this region

diachronous onset and polyphase cooling of the taili yiwulushan metamorphic core complex corridor ne china and its relationships to the formation of adjacent extensional basins abstract the aim of the study to investigate the cooling and exhumation history of deep crustal rocks along the taili yiwulushan metamorphic core complex mcc corridor and correlate these with volcanic clastic deposition in the late jurassic to early cretaceous supra detachment fuxin yixian basin in the west and the mostly eocene liaohe basin in the east this corridor exposes low to medium grade metamorphic neoarchean rocks and late triassic late jurassic and early cretaceous granitic rocks which exhumed from the middle to shallow crustal levels new 40ar 39ar ages of muscovite biotite k feldspar and apatite u th sm he ages in combination with compiled published geochronological data from the granitic rocks constrain three major stages of cooling exhumation and deformation from late jurassic through early cretaceous to eocene interrupted by late cretaceous tectonic quiescence the onset of activity and exhumation and cooling is diachronous along the mcc corridor at taili in the south the main activity of the sinistral shear zone is constrained between 160 and 140 ma with major cooling from crystallization temperatures of granitoids from 700 750 c to 160 c first stage along the waziyu ductile detachment at the western border of the yiwulushan mcc major cooling and exhumation is bracketed between 130 ma and 100 ma second stage and thus indicates a northward progradation of deformation and exhumation activity however cooling ages as old as 159 ma along the eastern margin of the yiwulushan mcc indicate an earlier initiation of cooling and westward rolling hinge type propagation first stage late cretaceous and paleogene times are characterized by a tectonically quiet period with only minor cooling and exhumation stage three the fourth and final stage of exhumation and cooling to very low temperatures occurred during late paleocene to earliest eocene times and is associated with the transtensional or extensional opening of the liaohe basin

quaternary deformation at the southeastern margin of the ordos block north china inferred from structural analysis of basin bounding faults abstract the southeastern margin of the ordos block semob is located at the juncture of the north china block the ordos block and the qinling orogen a series of faulted basins has developed in this area since the cenozoic the latest focal mechanism solution and stress field analyses indicate that the semob is located at the adjacent regions of present different stress field although the structural activity and internal mechanisms of this changing remain unclear in this paper we describe the results of a study into the fault systems and quaternary deformation between the linfen and weihe basins on the semob based on the deformation sequences kinematic analyses and activity timing we found that the strain field in semob underwent three evolutionary stages during the quaternary nw se extension in the early pleistocene ne sw extension in the middle pleistocene and ca n s oblique extension from the late pleistocene to the holocene this evolution of the strain field affected both the geomorphic patterns and the activity of paleo earthquake events along the semob during the quaternary quaternary extensional deformation in the upper crust along the semob possibly resulted from crust mantle decoupling which may be related to eastward expansion of the tibetan plateau and subduction of the pacific and philippine sea plates

late paleogene sinistral strike slip system along east qinling and in southern north china implications for interaction between collision related block trans rotation and subduction related back arc extension in east china abstract we present in this paper a compilation of paleogene rift and strike slip structures in east qinling and southern north china based on a synthesis of published stratigraphic structural and thermochronological data which aids in delineating a broad 500 km wide kinematically interlinked eocene oligocene transtensional system this transtensional system was bifurcated from two discrete strike slip fault zones in ne tibetan plateau the overall fault patterns indicate a clockwise rotation of south china relative to north china during the cenozoic possibly driven by dextral shearing along the eastern tibetan margin this collision related trans rotation of south china occurred coevally with late paleogene intracontinental rifting and volcanism in east china in a subduction related back arc extensional setting these two tectonic processes interacted with each other giving birth to cenozoic rift systems and contrasting morpho structural features in east asia

terrigenous plant wax inputs to the arabian sea implications for the reconstruction of winds associated with the indian monsoon author posting the authors 2005 this is the author s version of the work it is posted here by permission of elsevier b v for personal use not for redistribution the definitive version was published in geochimica et cosmochimica acta 69 2005 2547 2558 doi 10 1016 j gca 2005 01 001

mesozoic cenozoic evolution and mechanism of tectonic geomorphology in the central north china block constraint from apatite fission track thermochronology abstract during the mesozoic cenozoic the central north china block underwent complex tectonic transition and significant changes of tectonic geomorphology this apatite fission track study shows that the west part of the taihang mountains experienced a rapid event which commenced before 160 ma and lasted until 135 ma together with the extensive development of folds and thrusts indicating this area experienced intense compression and uplift combined with the petrological and geological characteristics the exhumation event represents the uplift of the yanshanian north china plateau and the taihang mountains inside it during the cenozoic two episodes of rapid cooling events took place during 65 55 ma and after 25 ma respectively the former one corresponds with the formation of the bohai bay basin bbb which led to the extensional denudation of the taihang mountains the formation of the bohai bay basin disrupted the yanshanian north china plateau caused the negative inversion of the tectonic geomorphology in the central north china block the thermal models indicates that the formation of north and south parts of the bbb commenced simultaneously in the south and north parts of the taihang mountains implying the dynamics should be derived from the west or the east rather than the north or the south the latter cooling event took place earlier in the north part of the taihang mountains than the south part corresponding with the miocene thermal subsidence of the bbb

crustal structure and continental dynamics of central china a receiver function study and implications for ultrahigh pressure metamorphism abstract the qinling tongbai hong an dabie sulu orogenic belt records the tectonic history of paleozoic convergence between the south china and north china blocks in this study the distribution of crustal thickness and p and s wave velocity ratio vp vs is obtained by using the h k stacking technique from the dabie sulu belt in central china our results show marked differences in the crustal structure between the dabie and sulu segments of the ultrahigh pressure uhp orogen the lower crust in the dabie orogenic belt is dominantly of felsic intermediate composition whereas the crust beneath the sulu segment is largely intermediate mafic the crust of the dabie orogenic belt is thicker by ca 3 5 km as compared to that of the surrounding region with the presence of an orogenic root the crustal thickness is nearly uniform in the dabie orogenic belt with a generally smooth crust mantle boundary a symmetrically thickened crust in the absence of any deep structural features similar to that of the yangtze block suggests no supportive evidence for the proposed northward subduction of the yangtze continental block beneath the north china block we propose that the collision between the yangtze and north china blocks and extrusion caused crustal shortening and thickening as well as delamination of the lower crust resulting in asthenospheric upwelling and lower crustal uhp metamorphism along the dabie orogen our results also reveal the presence of a se to nw dipping moho in the north china block beneath the tran north china orogen and eastern block suggesting the fossil architecture of the northwestward subduction of the kula plate

the structural and tectonic relationships of the major fault systems of the tan lu fault zone with a focus on the segments within the north china region abstract the jiashan lujiang yishu and bohai segments have been the most tectonically active parts of the tan lu fault system since the mesozoic any analysis of faulting processes in the tan lu system is highly dependent on the relationships among the three segments here we divide the tan lu system into three styles of faulting strike slip faulting regional extensional faulting and listric normal faulting on the basis of emap data seismic profiles and geological evidence we suggest that 1 the strike slip faults which formed in the late jurassic include mainly the jiashan lujiang fault the deep parts of the chihe taihu fault and the guhe sanbing fault these three faults have had the most dramatic effect on the jiashan lujiang segment the strike slip style of faulting produced a huge positive flower structure that extends between the deep section of the chihe taihu fault and the guhe sanbing fault and overlaps with the position of the zhangbaling ductile shear zone 2 the regional extensional style of faulting whose characteristics are reflected best in the yishu fault zone is composed of the changyi dadian anqiu quxian yishui yangtou and tangwu gegou faults all of which were active during the early cretaceous these extension dominated faults extend southwards to the jiashan and hefei basins and die out in front of the dabie mountains to the north the faults penetrate the deeper parts of the weibei depression where they controlled cretaceous deposition in graben horst graben structures 3 the listric normal faults which were initiated in the paleogene generally occur around the bohai bay basin and include a series of ne trending faults in the weibei depression such as the tandong and tanxi faults these listric faults differ from the regional extensional faults in their localized occurrence and association with basin formation our study indicates that these three styles of faulting varied not only in timing and mechanical properties but developed at different levels at different locations resulting in different tectonic relationships and the formation of different geologic features in the different segments of the tan lu master system

cenozoic evolution of the yilan yitong graben in ne china an example of graben formation controlled by pre existing structures abstract the ne trending yilan yitong graben yyg occurs along the yilan yitong fault zone in the northern segment of the tan lu fault zone northeastern china it shows an unusually narrow straight shape in map view with a length of ca 600 km and width of

evolution of the cenozoic thermal lithosphere of the jiyang sub basin bohai bay basin implications for the lithospheric thinning mechanism abstract the jiyang sub basin is an important sub tectonic unit of the bohai bay basin bbb which thinned by over 100 km during the meso cenozoic changes in the thermal lithospheric thickness of the jiyang sub basin in the cenozoic were assessed using data from 131 single boreholes together with the thermal history and layered crustal structure from these basement subsidence stretching factor and strain rate were calculated for each borehole the results show that the jiyang sub basin experienced a peak of lithospheric thinning during the cenozoic in the early cenozoic the thickness of the lithosphere was about 80 100 km and the strain rate was mostly low 10 16 10 22 s 1 indicating a weak extensional environment at the peak of the lithospheric thinning 50 ma to 35 ma the thermal lithosphere thickness was 70 55 km the tectonic subsidence was about 1000 m the lithospheric strain rate was higher about 10 15 10 16 s 1 the stretching factor had also increased rapidly to 1 1 1 2 the thinning of the lithosphere in the eocene is interpreted as a product of collective movements of the indian pacific and the philippine sea plates although the effect of the pacific plate was small as the izanagi pacific mid ocean ridge is still young age 0 10 ma knowledge of the history of the cenozoic lithosphere in the jiyang sub basin is of great significance for understanding the tectonic evolution of the bbb and of the north china craton

initiation and origin of dextral deformation at mid eocene in the western bohai bay basin east china abstract the cenozoic back arc rift basins along the continental margin of east asia are featured by both extensional and dextral deformation systems here we investigate the timing and interaction of these two types of systems based on seismic data stratigraphic isopach maps and drilling data in the jizhong depression in the northwestern bohai bay basin bbb east china the results show the rifting was initiated as early as the eocene while the dextral deformation did not occur until ca 42 ma the jizhong depression changed from a simple rift basin with boundary faults to the west to a geometrically more complex dextral transtensional basin at ca 42 ma this event was roughly concordant with the initial dextral slip on the tan lu fault lying at the eastern bbb and together they transformed the bbb into a complex pull apart rift basin the tectonic reorganization of the bbb was probably the response to the change from an orthogonal to an oblique subduction of the pacific plate beneath east asia at that time

holocene intracontinental deformation of the northern north china plain evidence of tectonic ground fissures abstract following the collecting and analyzing of field data on the geometry and kinematics characteristics of ground fissures in the northern north china plain nncp this paper shows that en echelon ground fissures or tectonic ground fissures with a length of several meters to tens of kilometers extending along active faults are possibly controlled by underlying active faults there are two groups of tectonic ground fissures developed in the nncp one group consists of ene trending right stepping ground fissures some of which have a component of sinistral motion the other group is nne trending left stepping ground fissures with dextral motion a large amount of data from trenches boreholes and seismic exploration reflect that they are active faulting related the nnw trending regional extensional stress field and the reactivation of pre existing faults are the major factors controlling ground fissures data from the quaternary sedimentary records deep incised valleys the distribution of earthquakes and ground fissures and our field work show that the holocene intracontinental deformation of the nncp is characterized by intense faulting and northwestward tilting which may be related to a nnw sse oriented tensional stress field in the shallow crust and asthenospheric upwelling in the mantle

structural architecture and tectonic evolution of the cenozoic zhanhua sag along the tan lu fault zone in the eastern north china reconciliation of tectonic models on the origin of the bohai bay basin abstract the zhanhua sag a major depocenter within the larger bohai bay basin bbb along the tan lu fault zone tlfz in the eastern north china developed through two successive phases with different stress regimes during the paleogene the kinematics and the slip history of the nw se and n s striking normal fault systems strongly controlled the internal structure and stratigraphy of the paleocene lower eocene strata in the zhanhua sag during phase 1 isopach maps of the paleocene lower eocene stratigraphy show 4000 m thick clastic rock sequences in these structurally controlled depocenters the average dip slip rates of the nw se and n s striking faults were 78 96 and 50 82 m m y respectively in the paleocene early eocene but decreased to 45 87 and 35 81 m m y in the middle late oligocene the ne sw striking fault systems and their slip history controlled the development of the middle eocene oligocene depocenters and their strata during phase 2 the average dip slip rate of the ne sw striking faults was 10 47 m m y in the paleocene early eocene but increased to 93 49 m m y in the middle late oligocene the ne sw oriented faults cut across and displace the nw se striking faults indicating their relatively younger ages these fault patterns and kinematics recorded in the zhanhua sag reflect an abrupt change in extension directions from ene wsw to nw se before and after the middle eocene that was related to a reversal in the slip direction from sinistral to dextral along the tlfz this slip reversal was in turn a result of a major change in the subduction direction of the pacific plate beneath eastern asia and in the mode of strain partitioning across the tlfz in the continental upper plate

lithospheric structure variations between the eastern and central north china craton from s and p receiver function migration abstract i imaged the lithospheric structure beneath the bohai bay basin bbb in the eastern north china craton ncc and the taihang mountains tm and areas further to the west in the central ncc by applying the wave equation migration technique to both the s and p receiver functions rfs collected in this region the data images and synthetic modeling results indicate that s rf imaging is more appropriate than p rf imaging for mapping lithospheric discontinuities especially the lithosphere asthenosphere boundary lab in various types of regions even directly applicable to basin areas that are covered by thick sediments the constructed s rf images show that the lithospheric thickness of the study region is highly variable the imaged lab is on average 80 km beneath the bbb and displays obvious undulations from 120 km under the tm to 40 km under the mountain areas in the central ncc consistent with previous p rf imaging results the observed structural differences between the eastern and central ncc are likely associated with different lithospheric tectonics in these two regions while widespread lithosphere reactivation and extension in the eastern ncc during the late mesozoic time was plausibly responsible for both the thinned crust and lithosphere in the bbb lithospheric thinning in the central ncc may be equally heterogeneous but less significant and probably occurred mainly in cenozoic such a process may have given rise to the highly variable present day lithospheric thickness in this region however it probably did not noticeably affect the overlying crust that was reported to have thickened in response to the early magmatic underplating in the mesozoic time the different tectonic processes in the eastern and central ncc may have induced the formation of the nsgl which likely serves as a major tectonic boundary separating the two regions of contrasting lithospheric structures at present

temporal and spatial variations of mesozoic magmatism and deformation in the north china craton implications for lithospheric thinning and decratonization abstract mesozoic triassic cretaceous magmatic rocks and structural deformation are widely distributed in the north china craton ncc and are crucial to understanding the timing location and geodynamic mechanisms of lithospheric thinning and decratonization of the ncc our new geochronological geochemical and structural data combined with previously published results on mesozoic magmatic rocks and deformational structures in the ncc indicate a temporal and spatial migration of magmatism and deformation from its margins to its cratonal interior triassic and early jurassic igneous rocks are only distributed along the northern southern and eastern margins of the ncc in contrast cretaceous magmatic rocks are widely distributed in whole eastern and central parts of the ncc there is a younging trend for mesozoic magmatic rocks from the northern and eastern parts yanshan jiaodong peninsula and liaodong to the central part of the ncc taihangshan mesozoic deformation in the ncc exhibits a similar migration trend from craton margins to its inland areas triassic early jurassic deformation mainly occurred in the margins of the ncc and transformed from compression during the early middle triassic to extension during the late triassic to early jurassic in its northern margin middle late jurassic to earliest cretaceous deformation is widely distributed in the ncc and exhibited non unique contractional directions usually perpendicular to boundaries of the ncc and its ordos block indicating that it was likely controlled by multiple tectonic regimes during the middle late jurassic to earliest cretaceous early cretaceous deformation was characterized by near unique nw se extension that was likely controlled by unique geodynamic regime that probably related to the far field effect of cretaceous paleo pacific plate subduction the above mentioned temporal and spatial migrations of mesozoic magmatic rocks and deformation indicate that lithospheric thinning and decratonization of the ncc was diachronous and complex the lithospheric thinning and decratonization of the ncc initially started from its northern and eastern margins as a result of post collisional post orogenic lithospheric delamination during the middle late triassic and then spread to the interior of the craton during the late mesozoic interactions of the surrounding orogenesis and the small size of the ncc may have played important roles on its late mesozoic lithospheric thinning and decratonization

teleseismic p wave crustal tomography of the weifang segment on the tanlu fault zone a case study based on short period dense seismic array experiment abstract the 1896 high quality relative travel time residuals are collected by applying the multi channel cross correlation technique to the waveform data of teleseismic events recorded by a short period dense seismic array consisting of 302 stations in the weifang segment of the tanlu fault zone using the fast marching teleseismic tomography technique these residuals are inverted for a fine p wave crustal velocity model under the study region down to 30 km depth with the resolution of 20 km in horizontal directions and 30 km in depth we image obvious high velocity anomalies to the west of the fault zone from the surface down to a depth of 30 km and striking low velocity anomalies appear within the fault zone around 36 5 n where the changle volcano exists on the surface whilst to the east velocity anomalies exhibit a complicated pattern meanwhile our tomographic images roughly show a boundary between the fault zone and its surrounding areas we infer that the fault zone provides a plausible channel for continuous upwelling of hot and wet materials from the mantle to the surface when it intruded into the crust the process of upwelling of hot and wet materials from the mantle could be associated with mantle dynamics of the big mantle wedge due to the stagnation and dehydration of the subducted pacific slab in the mantle transition zone under the region our present study demonstrates that it is possible that a fine crustal velocity structure can be obtained by teleseismic tomography with a short period dense seismic array

mineralogy and oxygen isotope systematics of magnetite grains and a magnetite dolomite assemblage in hydrated fine grained antarctic micrometeorites

tan lu fault system and its significance in oil accumulation in the central liaodong bay subbasin bohai bay basin china the tan lu fault system in the central liaodong bay subbasin bohai bay basin has complex structural characteristics and its tectonism during the cenozoic is an important factor in oil accumulation three dimensional seismic data were used to document the structural features and evolution of the system variations in source rock occurrence oil catchment area and faulting intensity were comprehensively evaluated to discuss the heterogeneity of oil occurrence along the system detailed analysis of the seismic data indicates a right lateral slip for the tan lu fault system transpression and transtension occur on two branches of the tan lu fault with different orientations indicating a likely slip azimuth that is between the two orientations i e 30 35 the strike slip began at the middle stage of deposition of the shahejie formation and reached its climax during deposition of the first and second members of the dongying formation to date the slip is still continuing in the transpressional system the lower strata on opposite sides of the strike slip fault were shortened and folded whereby the upper strata were stretched and normal faulted as a result a negative flower structure developed immediately above a positive flower structure strain distribution in this system is similar to that in a classic fold moderate tectonic deformation could enlarge the oil catchment area benefiting oil accumulation weak or intense deformation is unfavorable for commercial oil accumulation because of a small oil catchment area and poor oil preservation respectively

cenozoic rifting and volcanism in eastern china a mantle dynamic link to the indo asian collision abstract the indo asian continental collision is known to have had a great impact on crustal deformation in south central asia but its effects on the sublithospheric mantle remain uncertain studies of seismic anisotropy and volcanism have suggested that the collision may have driven significant lateral mantle flow under the asian continent similar to the observed lateral extrusion of asian crustal blocks here we present supporting evidence from p wave travel time seismic tomography and numerical modeling the tomography shows continuous low velocity asthenospheric mantle structures extending from the tibetan plateau to eastern china consistent with the notion of a collision driven lateral mantle extrusion numerical simulations suggest that at the presence of a low viscosity asthenosphere continued mass injection under the indo asian collision zone over the past 50 my could have driven significant lateral extrusion of the asthenospheric mantle leading to diffuse asthenospheric upwelling rifting and widespread cenozoic volcanism in eastern china

plume or no plume emeishan large igneous province in southwest china revisited from receiver function analysis the late permian emeishan large igneous province at the western margin of the yangtze craton and eastern tibet is popularly regarded as the signature of mantle plume impingement onto the lithosphere in this study we investigate the crustal structure and upper mantle discontinuities of this region by employing h k stacking of receiver function and depth domain receiver function our results image the mantle transition zone however no vestiges of any mantle plume upwelling in this area are recorded in our results and the region is characterized by a largely cold domain in contrast our data reveal a region of lower crustal delamination that coincides with the cold mantle transition zone we therefore suggest that the delaminated lower crustal material was recycled into the upper mantle or the mantle transition zone turning the latter into a cold domain the delamination of the lower crust might have also led to asthenospheric upwelling and plume like upwelling from the mantle transition zone that generated the basalts in the emeishan large igneous province

upper miocene quaternary magnetostratigraphy and magnetic susceptibility from the bohai bay basin eastern china and implications for regional volcanic and basinal subsidence history abstract the thick cenozoic sequence of alluvial lacustrine volcaniclastic and marine sediments in the bohai bay basin bbb of eastern china is an important sedimentary archive for studying the regional late cenozoic history of volcanism tectonism and paleoclimate changes as well as the evolution of the east asian monsoon system however well dated deep drillcores are sparse in this region which has prevented a comprehensive analysis of these issues here we present the results of a detailed magnetostratigraphic and magnetic susceptibility study of two deep drillcores g2 and g3 from the huanghua depression with the aims of 1 refining the upper miocene to recent chronostratigraphic framework and subsidence history of the bbb and 2 investigating its relationship to regional volcanic and tectonic events the observed pattern of paleomagnetic polarity zones in core g3 can be correlated well to the geomagnetic polarity time scale gpts quaternary age peaks in the magnetic susceptibility profiles of cores g2 and g3 may record large volcanic eruptions they can be matched to similar peaks in other bbb drillcores demonstrating their potential utility as regional marker horizons increased sedimentation rates in the study cores at 8 0 6 4 ma and 3 6 3 0 ma reflect late miocene uplift of the taihang and lvliang mountains and late pliocene bbb subsidence respectively integrated into a regional framework for the upper miocene to recent our magnetostratigraphic data show that subsidence of the huanghua depression increased from southwest to northeast

mesozoic cenozoic basin inversion and geodynamics in east china a review abstract east china experienced alternating tectonic extension and compression with ambiguous tectonic settings in the mesozoic cenozoic interval long term extensional episodes associated with the subduction retreat of the paleo pacific and pacific slabs have been widely studied the compressional events of which basin inversion is a typical case are less concerned but important in understanding the tectonic evolution and geodynamics in east china we made a systematic study involving tectonics sedimentation apatite fission track and dynamic topography on the mesozoic cenozoic basin inversion in east china four phases of basin inversion were concluded 1 early late cretaceous inversion occurred at 115 100 ma in southeast china and at 100 89 ma in northeast china showing a northward migration due to the diachronous collision of the northward moving okhotomorsk block with east asia 2 the latest cretaceous early paleogene inversion was widely developed throughout east china it is associated with the increasingly younger subducted oceanic crust of the izanagi plate which caused the progressively increasing buoyancy beneath east china and an uplift in dynamic topography cenozoic inversion showed an eastward migration from 3 the western part of each basin at the late paleogene to 4 the eastern part at the neogene due to the subduction retreat of the pacific plate