Devonian integrative stratigraphy and timescale of China

The Global Boundary Stratotype Sections and Points(GSSPs) for the bases of all seven international Devonian stages have been formally defined and ratified by IUGS till 1996, and nowadays, the main tasks for Devonian stratigraphers include further subdivision of these standard stages, strictly constrained absolute ages for the boundaries, and precise neritic-pelagic and marine-terrestrial correlations using multidisciplinary stratigraphy methods. Establishment of high-resolution Devonian integrative stratigraphy framework and timescale of China would play an important role in improving regional and international correlation, facilitating the recognition of important stratigraphic levels in different paleogeographic settings, and understanding the evolution pattern of biota, paleoclimate and paleoenvironment during this critical interval. Based on well-studied bio-and chronostratigraphy of Devonian in South China and adjacent areas, in combination with recent achievements in carbon isotope stratigraphy, event stratigraphy and radioactive isotope ages, this paper briefly summarize the research history and current status of Devonian chronostratigraphy of China, and for the first time introduce Devonian integrative stratigraphy framework of China.Up to date, few studies have been conducted on the astronomical cyclostratigraphy and high-resolution radioactive isotope dating in Devonian of China, which should be our main focuses in the near future.     

Silurian integrative stratigraphy and timescale of China

Silurian is a period with the shortest duration in Phanerozoic except for the Neogene and Quaternary. It represents an important and unique interval when the biotic diversity recovered quickly after the end-Ordovician mass extinction, different paleoplates or terranes conjoined, big oceans disappeared or narrowed, climate and sea level changed frequently, global biotic provincialism became weaker, some primitive plants started to occupy the land. Silurian is also the first system of which all the chronostratigraphic stratotypes(i.e. the GSSPs) including four series and seven stages were established by the International Subcommission on Silurian Stratigraphy(ISSS). Nonetheless, during the post-GSSP studies conducted by ISSS in the middle1980 s, some Silurian GSSPs were found to have some congenital defects such as no index fossils available that hinder the high resolution subdivision and correlation on a regional or global scale. In this paper, based on the latest development of Silurian study in China, the progress in biostratigraphy, chronostratigraphy, event stratigraphy(such as facies differentiation, heterochrony of black shales, marine red beds, carbonate rocks and reefs), chemostratigraphy, and tectonic stratigraphy(e.g., widespread of the late Silurian rocks in South China and its tectonic implication) are systematically summarized. Some existing problems and the areas to be focused in future work are also discussed. It is suitable for chronostratigraphic study to concentrate not only on the boundary but also doing multidisciplinary analysis on the biotic, chemical, magnetic, environmental, and chronologic aspects, in order to enhance the reliability and the potential for regional and global correlation of a certain GSSP.Some important achievements are expected in these areas in the Silurian study in China:(1) ecostratigraphy and basin analysis of the Llandovery, and the correlation of integrative stratigraphy with a high resolution;(2) establishment of the Wenlock to Pridoli chronostratigraphic framework;(3) the chemo-and magnetic stratigraphy and the age of some key intervals and horizons;(4)further investigation on paleogeography and plate tectonics; and(5) origin and early evolution of the terrestrial ecosystem. Some new breakthroughs might occur in the restudy on some of those problematic GSSPs of some particular series and stages.     

Triassic integrative stratigraphy and timescale of China

The Triassic rocks are widespread in China, and both marine and terrestrial strata are well developed. The Triassic stratigraphic architecture of China is very complex in both spatial variation of the so-called "South Marine and North Continental", i.e. the southern areas of China occupied mostly by marine facies while the northern China by terrestrial facies during the Triassic Period, and temporal transition of the "Lower Marine and Upper Continental", i.e. the lower part of the Triassic System composed mainly of marine facies and the upper part of terrestrial strata especially in South China. Although the Global Stratotype Section and Point(GSSP) of the Permian-Triassic boundary is located in South China, the Triassic of China except for some marine Lower-Middle Triassic depositions shows significantly local characteristics and is hardly correlated with the global chronostratigraphic chart. Consequently, the Triassic of China contains not only the international research hotspots but also difficult points in stratigraphic study. This paper aims to present a brief review of the Triassic in China, including chronostratigraphy, biostratigraphy, magnetostratigraphy and chemostratigraphy, and summarize an integrated Triassic stratigraphic framework of China. Accordingly, a stratigraphic correlation is proposed for the lithostratigraphic sequences among the three tectono-paleogeographic stratigraphic regions. The comprehensive study indicates that ammonoids are the classic index fossils in Triassic biostratigraphy but conodonts are more advantageous in the study and definition of the Triassic chronostratigraphic boundaries. China still has the potential to optimize the GSSPs of the Induan-Olenekian boundary and Olenekian-Anisian boundary. The correlation of the Permian-Triassic boundary between marine and terrestrial facies might be achieved with the help of the Permian-Triassic "transitional bed" and its related biotic and environmental events in association with the biostratigraphic study of conchostracan, vertebrate and plant fossils. In addition, the carbon isotopes have been proved to be one of the powerful methods in marine Triassic stratigraphic study, whereas the oxygen and strontium isotopes may be additional important bridges to establish the correlation between the marine and terrestrial strata, but as yet lacking of relevant studies in terrestrial strata. Considering the most stratigraphic intervals of the Triassic and the terrestrial Triassic in China are difficult to be correlated to the global chart, the proposed Chinese(regional) Triassic chronostratigraphic chart of marine and terrestrial stages would be of importance to the study of Chinese Triassic stratigraphy and related aspects, but the stages must be conceptually in line with international standards and studied as soon as possible in order to finalize the definition.     

Cambrian integrative stratigraphy and timescale of China

The Cambrian Period is the first period of the Phanerozoic Eon and witnessed the explosive appearance of the metazoans, representing the beginning of the modern earth-life system characterized by animals in contrary to the Precambrian earth-life system dominated by microbial life. However, understanding Cambrian earth-life system evolution is hampered by regional and global stratigraphic correlations due to an incomplete chronostratigraphy and consequent absence of a highresolution timescale. Here we briefly review the historical narrative of the present international chronostratigraphic framework of the Cambrian System and summarize recent advances and problems of the undefined Cambrian stage GSSPs, in particular we challenge the global correlation of the GSSP for the Cambrian base, in addition to Cambrian chemostratigraphy and geochronology. Based on the recent advances of the international Cambrian chronostratigraphy, revisions to the Cambrian chronostratigraphy of China, which are largely based on the stratigraphic record of South China, are suggested, and the Xiaotanian Stage is newly proposed for the Cambrian Stage 2 of China. We further summarize the integrative stratigraphy of South China, North China and Tarim platforms respectively with an emphasis on the facies variations of the Precambrian-Cambrian boundary successions and problems for identification of the Cambrian base in the different facies and areas of China. Moreover, we discuss stratigraphic complications that are introduced by poorly fossiliferous dolomite successions in the upper Cambrian System which are widespread in South China, North China and Tarim platforms.     

Cambrian-Ordovician sequence stratigraphy on the northern Tarim Platform and its correlation with Yangtze Platform and North China Platform

The Cambrian and Ordovician on the northern Tarim Platform are mainly composed of carbonates. On the basis of detailed outcrop analysis, the sequence stratigraphic system of the Cambrian-Ordovician in the northern Tarim Platform is outlined in this paper. Altogether 35 third-order sequences, 12 supersequences, 4 supersequence sets and 2 megasequences are recognized. The characteristics of the major sequence boundaries have been documented with an integrated examination of outcrop, seismic and borehole data, and the ages of these sequence boundaries have been calibrated through the combination of sequence stratigraphy with biostratigraphy. It is discovered that there is good correlation of the sequence stratigraphy of the Cambrian-Ordovician among Tarim, Yangtze and North China platforms. This may illustrate that the development of the Cambrian-Ordovician carbonate sequences in these three platforms is mainly controlled by regional or global sea level changes. This forms the theoretical basis for the construction of high-resolution chronostratigraphic system of the Cambrian-Ordovician in the three platforms in China.     

Quaternary integrative stratigraphy and timescale of China

Quaternary strata in China mainly comprise continental deposits in a variety of depositional settings. The continental Quaternary in temperate northern China consists mainly of eolian and fluvio-lacustrine deposits; that in subtropical southern China, mainly of vermiculated red soils, cave/fissure deposits, and fluvio-lacustrine deposits; and that in the alpine Tibetan Plateau, mainly of fluvio-lacustrine and piedmont deposits. The marine Quaternary in China consists of detrital deposits and biogenic reef deposits. The integration of biostratigraphy, magnetostratigraphy, climatostratigraphy and an astronomically calibrated chronology has led to the establishment of high-precision climatochronostratigraphic timescales for the detrital marine Quaternary in the South China Sea and the loess-paleosol sequence in the Chinese Loess Plateau. Extremely high-precision230 Th dating has provided a high-precision absolute age model for cave stalagmites over the past 640000 years as well as highresolution oxygen isotope records representing orbital-to suborbital-scale climate changes. By combining magnetic stratigraphy and biostratigraphy, robust chronostratigraphic frameworks for non-eolian continental Quaternary deposits on the scale of Quaternary geomagnetic polarities have been established. The continental Pleistocene Series consists, from oldest to youngest,of the Nihewanian Stage of the Lower Pleistocene, the Zhoukoudianian Stage of the Middle Pleistocene, and the Salawusuan Stage of the Upper Pleistocene. Stages of the continental Holocene Series have not yet been established. This review summarizes recent developments in the Quaternary chronostratigraphy of representative Quaternary strata and associated faunas, and then proposes an integrative chronostratigraphic framework and a stratigraphic correlation scheme for Quaternary continental strata in China. In the near-future, it is hoped to establish not only a Chinese continental Quaternary climatochronostratigraphic chart on the scale of glacial-interglacial cycles but also a Quaternary integrative chronostratigraphic chart including both continental and marine strata in China.     

Middle Miocene to Pleistocene magneto-biostratigraphy of ODP Sites 1150 and 1151, northwest Pacific: Sedimentation rate and updated regional geological timescale

Abstract Shipboard and shore‐based investigation on siliceous and calcareous microfossil biostratigraphy, magneto‐stratigraphy and tephrostratigraphy identified numerous datum events from the sedimentary sequences of Sites 1150 and 1151 drilled on the forearc basin of northern Japan by the Ocean Drilling Program Leg 186. Some 83 datum events were selected to construct new age–depth models for the sites. Based on the reliable magneto‐stratigraphy from the Pleistocene to the Upper Miocene, which were correlated to the standard geomagnetic polarity timescale, and on excellent records of diatom and radiolarian biostratigraphy throughout the sequences, the shipboard age model was revised. Major revisions referred to stratigraphic position of the Miocene–Pliocene boundary that has been shifted more than 200 m downward in each sequence. The age–depth relations of the forearc sites represent drastic changes in the sedimentation rate—extremely high (40 cm/k.y. on average) in the Early Pliocene and low (less than 2 cm/k.y. on average) in the Middle Miocene—and several hiatuses exist throughout the sequence. The drastic changes can be related mostly to changes in diatom sedimentation and the tectonics of the Japanese Island Arc. Local ages for some foraminiferal, calcareous nannofossil and radiolarian bioevents are estimated from the age–depth models at each site. These newly calibrated bioevents and biozones as well as established diatom biostratigraphy are incorporated into the updated magneto‐biochronologic timescale, which will contribute to an improvement in biochronologic accuracy of Neogene sediments in northern Japan and adjacent areas.     

Pacific Miocene carbon isotope stratigraphy using benthic foraminifera

Seven Miocene Pacific Ocean Deep Sea Drilling Project sites from four different water masses (planktonic foraminiferal biogeographic regions) have been correlated using 18 prominent carbon isotopic events defined in the benthic foraminiferal δ¹³C records in DSDP Site 289. The correlations are based on the assumption that there are global or at least Pacific-wide controls on the δ¹³C of deep-water HCO₃^?. Each of the individual δ¹³C records is correlated to Site 289 based on the shape of the curves in a manner analogous to that used to correlate sea-floor magnetic anomaly patterns.The results of this correlation experiment confirm that planktonic foraminiferal biostratigraphy and carbon isotopic stratigraphy are consistent within the tropical surface water mass and precise to ±100,000 years. Correlations between surface water masses suggest that the precision of foraminiferal biostratigraphy is on the average less than ±200,000 years due to the lack of cosmopolitan marker species and diachronism of species occurrences. Carbon isotope stratigraphy used in conjunction with biostratigraphy has the potential to provide an easily utilized, globally applicable, correlation tool (with an interregional precision of ±100,000 years or better) as more continuous and undisturbed deep-sea sections become available as a result of the Hydraulic Piston Coring Program.     

Tephrostratigraphy of the Pliocene to Middle Pleistocene Series in Honshu and Kyushu Islands,Japan

The Pliocene to Pleistocene Series in each sedimentary basin or area of Japan has been investigated and described; however, their stratigraphic correlation is difficult because of complex geological structures. Regional stratigraphy has therefore been established using many intercalated tephra beds, i.e. by correlating tephra beds between distant areas. A standardized stratigraphic model of the Pliocene to Middle Pleistocene Series in Japan is put forward in this paper on the basis of tephrostratigraphy, magnetostratigraphy, and biostratigraphy. This stratigraphic model is important for studies of environmental changes and explosive volcanism in this period around the Japanese island‐arc.     

Spatio-temporal carbon isotope variation during the Ediacaran period in South China and its impact on bio-evolution

The Ediacaran period is characterized by the extremely negative carbon isotope anomalies and great biotic evolution in Earth history. At least four negative carbon isotope anomalies have been reported from this interval in South China so far. It is traditionally argued that the isotope variations can be used as a useful tool for global correlation of Ediacaran succession; however, more and more researches argued against this idea. We reviewed the previously published carbon isotope data in South China, and ...     

Some fundamental problems in outcrop sequence stratigraphy

Some fundamental problems in outcrop sequence stratigraphy are discussed, and the following ideas are obtained: (i) Detailed sedimentary facies analysis and study on stacking pattern of parasequences, careful and accurate study of biostratigraphy, and stratigraphical correlation of different facies areas are the essential conditions for proper identification of sequences. (ii) The first flooding surface may be an ideal sequence boundary in outcrop sequence stratigraphy, where the most distinct palaeontological and sedimentary changes take place and make the surface readily recognizable in outcmp. (iii) The distribution in space, specially in different facies belts, is regarded as an important criterion for defining and recognizing the various orders of sequences. The third-order sequence is probably global in nature, which may be discerned in various depositional facies belts at least on one continental margin, and can be correlated over long distances, sometimes worldwide. (iv) The first flooding surface may be used as a useful reference marker in optimizing chronostratigraphic boundaries. Project jointly supported by the SSER, the Ministry of Science and Technology of China, and the Ministry of Land and Natural Resources of China.     

Cambrian-Ordovician sequence stratigraphy on the

The Cambrian and Ordovician on the northern Tarim Platform are mainly composed of carbonates. On the basis of detailed outcrop analysis, the sequence stratigraphic system of the Cambrian-Ordovician in the northern Tarim Platform is outlined in this paper. Altogether 35 third-order sequences, 12 supersequences, 4 supersequence sets and 2 megasequences are recognized. The characteristics of the major sequence boundaries have been documented with an integrated examination of outcrop, seismic and borehole data, and the ages of these sequence boundaries have been calibrated through the combination of sequence stratigraphy with biostrati-graphy. It is discovered that there is good correlation of the sequence stratigraphy of the Cambrian-Ordovician among Tarim, Yangtze and North China platforms. This may illustrate that the development of the Cambrian-Ordovician carbonate sequences in these three platforms is mainly controlled by regional or global sea level changes. This forms the theoretical basis for the construction of high-resolution chronostratigraphic system of the Cambrian-Ordovician in the three platforms in China.     

Neogene integrative stratigraphy and timescale of China

The widely exposed Chinese Neogene terrestrial deposits provide the best circumstance for the establishment of an accurate chronostratigraphic system of Eurasia, and the rapidly evolved mammalian fossils contribute efficiently to the division and correlation of Asian Neogene strata. A uniform Neogene biostratigraphic framework for China has already been established,with seven mammalian ages named. With a developed stratigraphic basis for the geochronologic "ages", seven chronostratigraphic "stage" have been established for the Chinese Neogene terrestrial strata, namely the Miocene Xiejian, Shanwangian,Tunggurian, Bahean, and Baodean stages, and the Pliocene Gaozhuangian and Mazegouan stages. Based on a series of research achievements, refined biostratigraphic, paleomagnetic and isotopic methods were combined and applied to continuous sections,and a Chinese Neogene chronostratigraphic sequence with accurate geological ages was established and improved in recent years. The lower boundaries of most of the stages could be correlated with those of the marine stages in the International Chronostratigraphic Chart, except the Tunggurian Stage, which is correlated with the European land mammal age. The biostratigraphic markers of the Chinese Neogene stages are usually first appearance of a single taxon, some representing regional species replacement, others indicating intercontinental migration of certain taxa. Candidate stratotype sections have been proposed for all the Chinese Neogene stages according to the principle and rule of modern stratigraphy, and other Chinese Neogene strata in different regions are comprehensively correlated.     

Pyrite morphology and episodic euxinia of the Ediacaran Doushantuo Formation in South China

The Ediacaran Doushantuo Formation with well-preserved fossil record in South China provides a rare window for our understanding of biological evolution,global carbon cycle,and oceanic redox states.Prominent negativeδ~(13)C anomalies(i.e.,the Shuram excursion)in Ediacaran successions worldwide fundamentally challenge the traditional models of isotopic mass balance.Additionally,conflicting opinions of both oxic and anoxic conditions have been proposed for the deep waters during this period.Here,we present a detailed study of pyrite morphology and carbonate carbon isotope data documented from drill core samples at Songtao County,northeastern Guizhou.Framboid aggregates are the dominant pyrite form in black shale and they can transfer to euhedral crystals through continuous growth of the constituent microcrystals.A positive correlation between microcrystal sizes(d)and framboid diameters(D)is observed,while the different D/d ratios of framboids in argillaceous dolostone and black shale reflect different substrate availability.Electron microprobe analyses reveal no consistent compositional patterns between framboidal and euhedral pyrites.Framboid size distributions of the investigated drill core,in combination with previously published redox data from the intra-shelf Jiulongwan section,shelf margin Zhongling section,and lower slope Wuhe section,suggest that three episodes of marine euxinia have been established throughout the deposition of the Doushantuo Formation.The time lag between the uppermost euxinic interval and the Shuram excursion may arise from the depression of sulfate reduction maintained by other oxidants.     

Carbonate deposits on submerged seamounts in the northwestern Pacific Ocean

Abstract   The lithology of shallow-water carbonates collected from 19 sites on 16 seamounts in six areas of the northwestern Pacific Ocean using the Deep-sea Boring Machine System are described. The areas include the Amami Plateau, Daito Ridge, Oki-Daito Ridge, Urdaneta Plateau, Kyushu-Palau Ridge and Ogasawara Plateau. Chronological constraint is provided by calcareous nannofossil biostratigraphy, planktonic foraminiferal biostratigraphy, larger foraminiferal biostratigraphy and strontium (Sr) isotope stratigraphy. Large amounts of shallow-water carbonates accumulated on the seamounts during the Oligocene, a relatively cool period, whereas limited carbonate deposits formed during the Early Miocene, a relatively warm period. This might indicate that deposition of shallow-water carbonates on seamounts in the northwestern Pacific Ocean was not necessarily controlled by climatic conditions, but was related to volcanism and tectonics that served as foundations for reef/carbonate-platform formation. Remarkable differences in biotic composition exist between Cretaceous and Cenozoic shallow-water carbonates. Late Cretaceous shallow-water carbonates are distinguished by the occurrence of rudists, solenoporacean algae and microencrusters. Middle Eocene to Early Oligocene shallow-water carbonates are dominated by Halimeda or nummulitid and discocyclinid larger foraminifers. Scleractinian corals became common from the Oligocene onward. Nongeniculate coralline algae and larger foraminifers were common to abundant throughout the Eocene to the Pleistocene. The replacement of major carbonate producers in the shallow-water carbonate factory during post-Cretaceous time is in accordance with previous studies and is considered to reflect a shift in seawater chemistry.     

Application of ecostratigraphy to sequences tratigraphy

The results of ecostratigraphy can directly serve sequence stratigraphy. The habitat type curve is useful not only in the analysis of sequences and parasequences, but also in demonstration of the process of regional sea level change. The various biological surfaces usually coincide with or relate to the boundaries of sequences or system tracts. The ecostratigraphic framework composed of coenozones, community sequences and ecotracts with good timing completely corresponds to the sequence stratigraphic framework of the sedimentary basin. Therefore, through establishment of the habitat type curve in individual section, recognition of the various biological surfaces, regional ecostratigraphic correlation and the formation of an ecostratigraphic framework of the sedimentary basin, ecostratigraphy plays an important role in the study of sequence stratigraphy and the reconstruction of regional and even global sea level changes.     

Jurassic integrative stratigraphy and timescale of China

The Jurassic stratigraphy in China is dominated by continental sediments. Marine facies and marine-terrigenous facies sediment have developed locally in the Qinghai-Tibet area, southern South China, and northeast China. The division of terrestrial Jurassic strata has been argued, and the conclusions of biostratigraphy and isotope chronology have been inconsistent.During the Jurassic period, the North China Plate, South China Plate, and Tarim Plate were spliced and formed the prototype of ancient China. The Yanshan Movement has had a profound influence on the eastern and northern regions of China and has formed an important regional unconformity. The Triassic-Jurassic boundary(201.3 Ma) is located roughly between the Haojiagou Formation and the Badaowan Formation in the Junggar Basin, and between the Xujiahe Formation and the Ziliujing Formation in the Sichuan Basin. The early Early Jurassic sediments generally were lacking in the eastern and central regions north of the ancient Dabie Mountains, suggesting that a clear uplift occurred in the eastern part of China during the Late Triassic period when it formed vast mountains and plateaus. A series of molasse-volcanic rock-coal strata developed in the northern margin of North China Craton in the Early Jurassic and are found in the Xingshikou Formation, Nandailing Formation, and Yaopo Formation in the West Beijing Basin. The geological age and markers of the boundary between the Yongfeng Stage and Liuhuanggou Stage are unclear. About 170 Ma ago, the Yanshan Movement began to affect China. The structural system of China changed from the near east-west Tethys or the Ancient Asia Ocean tectonic domain to the north-north-east Pacific tectonic domain since 170–135 Ma. A set of syngenetic conglomerate at the bottom of the Haifanggou or Longmen Fms. represented another set of molasse-volcanic rock-coal strata formed in the Yanliao region during the Middle Jurassic Yanshan Movement(Curtain A1). The bottom of the conglomerate is approximately equivalent to the boundary of the Shihezi Stage and Liuhuanggou Stage. The bottom of the Manas Stage creates a regional unconformity in northern China(about 161 Ma, Volcanic Curtain of the Yanshan Movement, Curtain A2). The Jurassic Yanshan Movement is likely related to the southward subduction of the Siberian Plate to the closure of the Mongolia-Okhotsk Ocean. A large-scale volcanic activity occurred in the Tiaojishan period around 161–153 Ma. Note that 153 Ma is the age of the bottom Tuchengzi Formation, and the bottom boundary of the Fifth Stage of the Jurassic terrestrial stage in China should have occurred earlier than this. This activity was marked by a warming event at the top of the Toutunhe Formation, and the change in the biological assembly is estimated to be 155 Ma. The terrestrial Jurassic-Cretaceous boundary(ca. 145.0 Ma) in the Yanliao region should be located in the upper part of Member 1 of the Tuchengzi Formation, the Ordos Basin in the upper part of the Anding Formation, the Junggar Basin in the upper part of the Qigu Formation, and the Sichuan Basin in the upper part of the Suining Formation The general characteristics of terrestrial Jurassic of China changed from the warm and humid coal-forming environment of the Early-Middle Jurassic to the hot, dry, red layers in the Late Jurassic. With the origin and development of the Coniopteris-Phoenicopsis flora, the Yanliao biota was developed and spread widely in the area north of the ancient Kunlun Mountains, ancient Qinling Mountains, and ancient Dabie Mountain ranges in the Middle Jurassic, and reached its great prosperity in the Early Late Jurassic and gradually declined and disappeared and moved southward with the arrival of a dry and hot climate.     

Regional characteristics of the effects of the El Niño-Southern Oscillation on the sea level in the China Sea

Based on coastal tide level, satellite altimetry, and sea surface temperature (SST) data of offshore areas of China’s coast and the equatorial Pacific Ocean, the regional characteristics of the effects of the El Niño-Southern Oscillation (ENSO) on the sea level in the China Sea were investigated. Singular value decomposition results show a significant teleconnection between the sea level in the China Sea and the SST of the tropical Pacific Ocean; the correlation coefficient decreases from south to north. Data from tide gauges along China’s coast show that the seasonal sea-level variations are significantly correlated with the ENSO. In addition, China’s coast was divided into three regions based on distinctive regional characteristics. Results obtained show that the annual amplitude of sea level was low during El Niño developing years, and especially so during the El Niño year. The ENSO intensity determined the response intensity of the annual amplitude of the sea level. The response region (amplitude) was relatively large for strong ENSO intensities. Significant oscillation periods at a timescale of 4–7 years existed in the sea level of the three regions. The largest amplitude of oscillation was 1.5 cm, which was the fluctuation with the 7-year period in the South China Sea. The largest amplitude of oscillation in the East China Sea was about 1.3 cm. The amplitude of oscillation with the 6-year period in the Bohai Sea and Yellow Sea was the smallest (less than 1 cm).     

Quantitative biostratigraphy and species evolutionary sequence

Introduction of species evolutionary sequence into the quantitative biostratigraphy is a significant work, either for studying biologic evolution or for making stratigraphic correlation and reconstructing geologic history. The quantitative biostratigraphy is to determine biostratigraphic event sequences by using probabilistic analysis. The evolutionary sequence systematics can efficiently ascertain species evolutionary sequences. Two methods have been proposed to determine the sequence of species-disappearance events: (1) species extinction events can be closed by last occurrence events using quantitative biostratigraphic analysis; (2) the duration of a species may be approximately replaced by the duration of its parent species. To combine these two methods for determining the sequence of species disappearance is the best way up to now. A consulting standard sequence that consists of the speciation sequence of Permian waagenophylloid corals and the biostratigraphic event sequence of other important fossils in Permian is used as an example. The group spearman rank-correlation test is used to test the consulting standard sequence by comparing four types of calculations and two kinds of sequences and to find abnormal events. Based on the found abnormal events in the test, the consulting standard sequence is revised to deal with different conditions. Sequences of speciation and species-disappearance, and species duration are determined. Application of species evolutionary sequence to quantitative biostratigraphy can largely improve the quality of biostratigraphic event sequence. In stratigraphic correlation, furthermore, event sequences have higher precision than range biozones.     

Sedimentary environment and development controls of the hydrocarbon source beds:Middle and Upper Proterozoic in northern North China

Problem on development control of marine source bed hold in Chinese petroleum industry progression. The Hongshuizhuang Formation,Tieling Formation and Xiamaling Formation in the Middle and Upper Proterozoic are important hydrocarbon source beds in northern North China, and investigation of their sedimentary environments and the controls has great significance for petroleum exploration in North China. Based on sedimentology (sequence stratigraphy), palaeoecology, sedimentary geochemistry, and sedimentary palaeogeography, their development pattern is discussed. All these studies indicate that the development controls of the hydrocarbon source beds include a favorite palaeogeographic location, exceeding propagation of biomes in low and middle latitudes, anoxic environments, enrichment of phosphorus element and the adsorption of clay minerals during the preservation of organic matter in the marine carbonates.