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古地理学报（英文版）
古地理学报（英文版）

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古地理学报（英文版）/Journal Journal of PalaeogeographyCSCDSCI
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    Circum-Indian Holocene sea-level database:A repository of distinct relative sea-level plots across the Indian Peninsula

    Shradha MenonPankaj KhannaSantanu Banerjee
    1-17页
    查看更多>>摘要：The Indian Peninsula is one of the most well-studied regions for Holocene sea-level fluctuations in the world,however,standardized relative sea-level datasets are missing.This study provides an archive of sea-level indicators(n=162,20 locations)along the western and the eastern sides of the peninsula,that have been used to develop Relative Sea Level(RSL)plots.Each dated sea-level indicator is recalibrated for its elevation based on tidal and tectonic correction,as well as age with reservoir correction,and have been separated into six zones based on coastal geomorphology and number of datasets.The database spans throughout the Holocene and covers sea-level depth/elevations from-45 m to+5 m from mean sea-level(MSL).Approximately 90％of the dataset range from 8 ka to the present day.The first transgression is highly variable and identified between 8.5-8 ka BP in Gujarat(Zone 1),～5.5 ka BP in Maharashtra(Zone 2),between 8 and 7 ka BP in Tamil Nadu(Zone 4)and between 8 and 7.5 ka BP in the Bengal coasts(Zone 6).No trans-gression above present sea-level is observed along Andhra Pradesh(Zone 5)(no data for Kerala-Zone 3).Further,Zones 1,2,4 and 6 show a strong uplift component(tectonic),whereas Zone 5 exhibits subsidence during the Holocene(Zone 3-insufficient data).Based on these findings,and given the region's coastal topography and tidal components,Zones 6 and 1 will likely undergo the largest coastal inundation,followed by Zones 5,4,2,and 3.These insights are critical in planning future coastal inundation measures across the Indian Peninsula.
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    Interpreting siliciclastic sedimentation in the upper Paleozoic Mulargia-Escalaplano Basin(Sardinia,Italy):influence of tectonics on provenance

    Luca G.CostamagnaSara Criniti
    18-34页
    查看更多>>摘要：Late to post-Variscan molassic basins of Late Pennsylvanian-Permian age are exposed in Sar-dinia(Italy).Here,the compositional and stratigraphic evolution of the Mulargia-Escalaplano sedimentary basin(central Sardinia)has been investigated to highlight how the tectono-magmatic processes have influenced the sedimentation.Ruditic and arenitic samples were collected along well-characterized stratigraphic sections to provide a new insight into the impact of the tectono-magmatic processes on siliciclastic sedimentation.As a result,the conglomerates are mainly clast-supported,petromictic,and thus immature,with no defined maturity trend upwards.Nevertheless,pebble composition changes in times from Variscan basement pebble-rich to volcanic rock-rich,as a consequence of the basin widening and the dismantling and reworking of the coeval volcanic activity.The sandstone composition clearly changes from quartzolithic to feldspatholithic upwards,as a response to the same change of feeding and reworking of the volcanic rocks.Occasionally,interbedded quartzolithic arenites suggest exceptional floods carrying debris from the far borders of the basin.Also,the immature sandstone composition has been interpreted as being controlled by a continuous supply of fresh debris and to a rapid burial rate.In addition,the disappearance of metaradiolarite(lydite AA)Paleozoic grains in the sandstone mineral suite could represent a distinctive marker of a progressive unroofing of the Variscan chain and a clastic supply from deeper tectonic units.
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    Evolution of Cenozoic sedimentary architecture in Central and Southern South China Sea basins

    Wu TangXiao-Jun XieYi-Bo WangLian-Qiao Xiong...
    35-53页
    查看更多>>摘要：The Central and Southern South China Sea(CSSCS)has a complex tectonic dynamic background and abundant oil and gas resources,which has always been a hot topic of academic and industrial attention.However,systematic analyses are still lacking regarding its sediment filling structure and evolution,mostly due to limited borehole penetration and poor quality of seismic reflection data for deeply buried sequences.No consensus has been reached yet on the sedimentary infilling processes,which impeded the reconstruction of the palaeogeography of Southeast Asia and the oil-and-gas exploration undertakings.Here,we illustrate the Cenozoic sedimentary evolution of the CSSCS region by synthesizing relevant data from previous literature and our own observations and displaying the evolution of depositional systems in sequential reconstructions.Be-sides,the controlling factors of preferred sedimentary scenarios in the CSSCS incorporate the latest in-terpretations of the spreading of South China Sea(SCS)as well as the demise of the hypothetical Proto-South China Sea(PSCS).The results show that there are three types of sedimentary basins in the CSSCS(foreland,strike-slip,and rift basins)with different sedimentary filling structures.The foreland basins formed a depo-sitional pattern of'transition from deep water to shallow water environments',dominated by deep-water depositional systems which were formed before the Early Oligocene with submarine fans developed.Later,the foreland basins were gradually dominated by shallow-water depositional systems with deltas and shallow marine facies.The strike-slip basins showed the depositional architecture of'transition from lake to marine environments',i.e.the basins were dominated by lacustrine deposits during the Eocene and evolved into the marine depositional environment since Oligocene with delta developed in the western part of the basin.The depositional evolution of rift basins illustrated the characteristics of'transition from clastic to carbonate deposits',i.e.,the rift basins were dominated by Eocene-Oligocene shallow marine clastic depositional systems,while carbonate platforms started to develop since the Early Oligocene from east to west.The above-mentioned differences of depositional architecture in the CSSCS were controlled by the scissor-style closure of the PSCS and the progressive-style expansion of the SCS.Specifically,the early-period deep-water sedimentary environment of CSSCS basins was controlled by the distribution of PSCS in the Eocene.As the scissor-style closure of PSCS progressed from west to east during the Oligocene to Early Miocene,the northwest of Bor-neo continued to rise,providing a great number of clastic materials to the basins and gradually developing large-scale deltas from west to east.The distribution of early-period lacustrine sedimentation of strike-slip basins was affected by paleo uplift,and the basins transgressed from the northeast and gradually evolved into marine sedimentary environment due to the expansion of SCS.The expansion of SCS also controlled the sedimentary filling evolution of the rift basins,which broke away from the South China continent and drifted southward.Thus,the rift basins lacked the supply of terrigenous clastic sediments which hindered the development of large-scale deltas and formed a clear water environment conducive to the development of carbonate platforms from east to west.
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    Stratigraphy of the Alveolina elliptica group from the Middle Eocene of Iran:Calibration with calcareous nannofossils biozones and description of Alveolina ozcani n.sp.

    Mehdi HadiLorenzo ConsortiAli BahramiMohammad Parandavar...
    54-79页
    查看更多>>摘要：Precise taxonomy and the chronostratigraphic calibration of the Middle Eocene Alveolina from Central Iran is here undertaken from the Chah-Talkh section of the southern Sabzevar region(Central Iran).We have identified Alveolina kieli,Alveolina stercusmuris and Alveolina nuttalli along with the new species Alveolina ozcani n.sp.that we include into the Alveolina elliptica group.We have also found Nummulites uroniensis,Nummulites obesus and Nummulites cf.verneuili and associated calcareous nannofossils that look reliable to make thoughtful correlations with the Shallow Benthic Zones(SBZ).The foraminiferal biostratig-raphy suggests an assignment to the upper part of the lower Lutetian-lower part of the middle Lutetian,SBZ13(Middle Eocene),further strengthened through the identification of the calcareous nannofossil NP14b-NP15b or CNE8-CNE10 biozones,providing a solid correlation with the global stratigraphic standards.
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    On the occurrence of Neoplanorbulinella Matsumaru,1976(Foraminifera)from the late Oligocene of Central Iran(Qom Formation):Palaeobiogeographic implications

    Mehdi SarfiMohsen Yazdi-Moghadam
    80-91页
    查看更多>>摘要：The shallow marine carbonates of the upper Oligocene Qom Formation yielded several occur-rences of the foraminiferan genus Neoplanorbulinella Matsumaru.Neoplanorbulinella saipanensis Matsumaru has so far been recorded from the late Eocene-early Miocene of Japan and late Oligocene of NE Italy whereas N.malatyaensis Gedik is only reported from the Oligocene from its type locality in the Malatya Basin,eastern Turkey.The new records reported here from the Qom Formation indicate that both species occur in the Dobaradar section,ca.10 km south of the city of Qom in North-Central Iran.The palaeogeographic distri-bution of these two species therefore has to be extended as far as the palaeolongitude of current Central Iran.The accompanying larger benthic foraminifers,including Miogypsinoides complanatus(Schlumberger),M.formosensis Yabe and Hanzawa,Spiroclypeus margaritatus(Schlumberger),Operculina complanata(Defrance),and Risananeiza pustulosa Boukhary et al.,indicate the upper Chattian SBZ 23 Zone.The co-existence of the N.saipanensis and N.malatyaensis points to suitable palaeobiogeographic conditions of Central Iran to host Western and Eastern Tethyan taxa.
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    Biological sources,paleoenvironment,and organic matter enrichment in source rocks of the Ordovician Majiagou Formation,Ordos Basin,China:Evidence from biomarkers,microfossils,and inorganic geochemical analyses

    Jing-Jing CaoWen-Zhe GangShang-Ru Yang
    92-115页
    查看更多>>摘要：Carbonate deposits in the Ordovivian Majiagou Formation are significant source rocks for natural gas generation in the Ordos Basin,northwestern China.Previous studies mainly focused on the organic matter enrichment mechanism of shales rather than carbonate rocks.The biological sources and paleoenvironment of carbonate source rocks,and the main controlling factors of organic matter enrichment in the carbonate source rocks were studied in this paper in combination with evidence from biomarkers,microfossils and inorganic geochemistry analysis.The results show that four types of microfacies were identified in the Majiagou For-mation,respectively as:mud flat microfacies,mud-dolomite flat microfacies,dolomite flat microfacies,and open marine microfacies.The biological sources of organic matter are chiefly planktonic algae,followed by bacteria.The mud flat and mud-dolomite flat contain a high abundance of terrigenous detrital inputs,as indicated by the high content of Al2O3,TiO2,Th,and Zr.The low Sr/Cu and high Rb/Sr values reveal warm and humid paleoclimate conditions in the mud flat and mud-dolomite flat,whereas the dolomite flat and open marine were likely formed in hot and arid paleoclimate conditions.The mud flat and mud-dolomite flat deposits were characterized by high paleoproductivity of the Majiagou Formation.Low Sr/Ba values were found in the mud flat samples,indicating fresh to brackish water condition,whereas samples of other facies have a relatively high degree of salinity.Based on Uauth,Moauth,Crauth,Coauth,δCe,and δEu values,the mud flat microfacies was formed in a suboxic and anoxic environment,whereas the mud-dolomite flat,dolomite flat and open marine microfacies were within dysoxic to oxic conditions.A model of organic matter enrich-ment in the Majiagou Formation is thus established.The level of terrigenous detrital inputs is the principal factor of organic matter enrichment in the Majiagou Formation,secondly are redox condition and then paleoproductivity.The mud flat and mud-dolomite flat microfacies show abundant terrestrial detrital inputs and nutrient elements,indicative of warm and humid climate that facilitated biotic productivity,including an abundance of planktonic algae(microfossils).The suboxic and anoxic environments promoted the preservation of organic matter,as evidenced by the relatively high TOC content.The mud flat as well as the mud-dolomite flat of the Majiagou Formation is prospecting for forming source rocks.
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    Power-law patterns in the Phanerozoic sedimentary records of carbon,oxygen,sulfur,and strontium isotopes

    Haitao Shang
    116-126页
    查看更多>>摘要：Power-law patterns appear in a variety of natural systems on the modern Earth;nevertheless,whether such behaviors appeared in the deep-time environment has rarely been studied.Isotopic records in sedimentary rocks,which are widely used to reconstruct the geological/geochemical conditions in paleo-environments and the evolutionary trajectories of biogeochemical cycles,offer an opportunity to investigate power laws in ancient geological systems.In this study,I focus on the Phanerozoic sedimentary records of carbon,oxygen,sulfur,and strontium isotopes,which have well documented and extraordinarily compre-hensive datasets.I perform statistical analyses on these datasets and show that the variations in the sedi-mentary records of the four isotopes exhibit power-law behaviors.The exponents of these power laws range between 2.2 and 2.9;this narrow interval indicates that the variations in carbon,oxygen,sulfur,and strontium isotopes likely belong to the same universality class,suggesting that these systematic power-law patterns are governed by universal,scale-free mechanisms.I then derive a general form for these power laws from a minimalistic model based on basic physical principles and geosystem-specific assumptions,which provides an interpretation for the power-law patterns from the perspective of thermodynamics.The fundamental mechanisms regulating such patterns might have been ubiquitous in paleoenvironments,implying that similar power-law behaviors may exist in the sedimentary records of other isotopes.
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    The reservoir characteristics and their controlling factors of the sublacustrine fan in the Paleogene Dongying Formation,Bohai Sea,China

    Xiao-Jun PangGuan-Min WangMeng ZhaoQing-Bin Wang...
    127-148页
    查看更多>>摘要：Sublacustrine fan is an important element in continental lacustrine basins and is significant for reservoir exploration.Oil and gas resources have been found in the sublacustrine fan sandstone reservoirs of the Paleogene Dongying Formation in the Bohai Sea.In this study,the characteristics of the sublacustrine fan reservoirs and the controlling factors are studied using information from logging,cores,physical properties,casting thin sections,X-ray diffraction of clay minerals,vitrinite reflectance,rock pyrolysis,manometry data,and 3D seismic data.The sublacustrine fans of the Dongying Formation in the LD10,QHD34,and BZ21 struc-tures show high-quality reservoirs with porosity＞15％and permeability＞5 mD.The main controlling factors of the high-quality reservoirs are attributed to the favorable sedimentary facies type and negligible compaction,and cementation,substantial dissolution of K-feldspar,overpressure,and the development of faults and fractures.A high-quality sublacustrine fan reservoir model has been established to explain how these factors affected the physical properties.The favorable targets for oil and gas exploration in the Dongying Formation of Bohai Sea include undercompacted sandy debris flow reservoirs showing the dissolution of K-feldspar,and the reservoirs which are connected to the source rocks by faults.This study provides insights to establish the relationship between sedimentology,diagenesis and reservoir quality.The results of this study are significant for the exploration and development of the sublacustrine fan sandstone reservoirs in the Bohai Sea and analogous sandstone reservoirs elsewhere.
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    A synthesis of the Cretaceous wildfire record related to atmospheric oxvgen levels?

    Da-Wei LüWen-Xu DuZhi-Hui ZhangYuan Gao...
    149-164页
    查看更多>>摘要：The Cretaceous was a significant greenhouse period in Earth's history with higher atmospheric CO2 levels and temperatures than today.Although evidence of combustion has been widely described from the Cretaceous deposits,our understanding of the spatiotemporal diversification pattern and process of the Cretaceous wildfires is still limited.In this study,we comprehensively synthesize a total of 271 published Cretaceous wildfire occurrences based on the by-products of burning,including fossil charcoal,pyrogenic inertinite(fossil charcoal in coal),and pyrogenic polycyclic aromatic hydrocarbons(PAHs).Spatially,the dataset shows a distinctive distribution of reported wildfire evidence characterized by high concentration in the middle latitudinal areas of the Northern Hemisphere(30°N-60°N)over the Cretaceous.Temporally,an overall increasing trend of the reported wildfire data from the Early Cretaceous to the Late Cretaceous is coincident with higher atmospheric O2 levels.However,the spatial and temporal patterns may result from many types of factors,such as taphonomy,preservation,and researcher biases,instead of a real picture of the Cretaceous wildfire evolution.To better understand the spatiotemporal diversification of the Cretaceous wildfire,more investigations on the record of wildfire occurrences during this period would be necessary in the future.
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    Trace fossil evidences of an Early Miocene paleoseismic event and depositional regime change from the Kutch(Kachchh)Basin

    Ayush SrivastavaSudipta DasguptaKrishanu ChatterjeeMohuli Das...
    165-180页
    查看更多>>摘要：Unconsolidated siliciclastic sediments can undergo post-burial deformation,which leads to the formation of distinctive sedimentary structures,known as soft-sediment deformation structures(SSDS).The presence of a series of sand volcanoes confined to a particular lithostratigraphic horizon can represent a paleoseismic activity and,thereby,exemplifies the concept of"seismite".The Kutch Basin has been a tectonically active region since the initiation of eastern Gondwana rifting followed by a tectonic inversion during the Cenozoic due to the collision of the Indian and Eurasian plates.A stratum-bound series of sand volcanoes belonging to the Khari Nadi Formation(KNF)is exposed along the banks of Khari River.They separate the shallow marine deposits below and non-marine deposits above with their characteristic marine and paleosol trace fossil suites,respectively.Although a seismogenic origin has been much debated for the SSDS,the ichnofabric analysis of the sand-volcano-bearing stratum unequivocally points toward such an origin under a shallow seafloor condition.In addition to the sedimentary regime change from an open shallow-marine setting to a continental depositional environment concomitant with basinal uplift,the behavior of the bur-rowing crustaceans testifies to a syn-depositional development of a fault network associated with the fluid-ization,sand volcanism,and the resilience of the trace-producers in surviving those processes until the sedimentary regime change in the overlying strata.Although the ichno-sedimentological evidence apparently differs from the previous works that proposed a continuous base-level rise from the beginning of deposition of the Khari Nadi Formation up to the middle part of the overlying Chhasra Formation,the paleoseismic activity,its ichnologic signature,and the depositional regime change refer to a higher-resolution(i.e.,lower-order)sequence-stratigraphic change causing a short-duration regression within a longer-duration cycle of base-level rise.
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