Carbon Isotopic Evolution Characteristics and the Geological Significance of the Permian Carbonate Stratotype Section in the Northern Upper-Yangtze Region, Southern China

The Permian global mass extinction events and the eruption of the Emeishan flood basalts in the Upper Yangtze region should display certain responses during the evolution of carbon isotope. In this paper, the Permian carbon isotopic evolution in the Upper Yangtze region is examined through systematic stratotype section sampling and determination of 13C in the northern Upper-Yangtze regions and Southern China. Additionally, the carbon isotopic evolution response characteristics of the geological events in the region are evaluated, comparing the sea-level changes in the Upper Yangtze region and the global sea-level change curves. Results of this study indicated that the carbon isotopic curves of the Permian in the Upper Yangtze region are characterized by higher background carbon-isotope baseline values, with three distinct negative excursions, which are located at the Middle–Late Permian boundary and the late period and end of the Late Permian. The three distinct negative excursions provide an insightful record of the global Permian mass extinction events and the eruption of the Emeishan flood basalts in the Upper Yangtze region. The first negative excursion at the Middle–Late Permian boundary reflected the eruption of the Emeishan flood basalts, a decrease in sea level, and biological extinction events of different genera in varying degrees. The second negative excursion in the Late Permian included a decrease in sea level and large-scale biological replacement events. The third negative excursion of the carbon isotope at the end of the Permian corresponded unusually to a rise rather than a decrease in sea level, and it revealed the largest biological mass extinction event in history.     

Geographic Distribution and Evolution of Changxingian Ammonoid Faunas of South China

Changxingian ammonoids are well developed in South China, including 154 species, 33 genera and 11 families. They are mainly distributed in the southern and northern subprovinces of the South China province but are rare in the middle. According to the development of the ammonoid zone and lithologic characteristics, the two subprovinces are subdivided into six endemic areas. The above-mentioneddistribution is controlled by such factors as palaeogeographic environment and sedimentary facies.The evolution of Changxingian ammonoids of South China is characterized by distinct evolutionary stages, and the whole evolutionary history of ammonites consists of alternate episodes of"explosive" radiation, slow and steady evolution and mass extinction. The alternation of mass extinction and"explosive" radiation usually occur at the boundaries of stages(or substages)."Explosive" radiation refers to rapid proliferation of new species(or genera) within a very short geologically negligeable period of time. The origin of species can be well explained by the concept of punctuated equilibria--a new concept of evolution. Mass extinction refers to rapid, large-scale demise of taxa within a very short period of time. The cause of such an extinction might be due to the inevitable replacement of the old forms by rapidly developing new ones and the environmental changes, in addition to the global sea-level changes, extraterrestrial impacts and geomagnetic reversal.     

Xinjiangoxylon Gen.Nov., a New Gymnosperm from the Latest Permian of China

Following the greatest known end-Permian mass extinction plants have low diversity. Lycopsids and conifers dominated on land. A new gymnosperm Xinjiangoxylon gen. nov. is proposed based on a woody stem specimen collected from the Upper Permian （latest, Changhsingian） Upper Guodikeng Formation of the Taoshuyuan section, Turpan, Xinjiang Uygur Autonomous Region, Northwest China. The decorticated stem is characterized by a complex pith, endarch primary xylem and a thick secondary xylem cylinder. Numerous petrified woods were found in the Changhsingian at this section. However, there are rare wood fossils in the Early Triassic. The abrupt decrease of fossil woods worldwide relates to the crisis at the end of the Permian. Xinjiangoxylon turpanense gen et. sp. nov. appears to represents one gymnosperm that existed in the latest Permian.     

Characteristics of Albaillella （ Albaillellarian ,Radiolarian） Fauna from Guadalupian to Lopingian Series in Permian, South China

On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy,a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a pelagic chert section in southeast Guangxi, South China. Radiolarian Albaillella is one of the most sensitive biology to the transitional environment. The Albaillella fauna shows an ecological evolutionary process from Guadalupian to Lopingian: declined stage-recovery stage-flourishing stage. The study of characteristics of the Albaillella fauna in the transitional environment may provide more information, not only for the subdivision and correlation of a high-resolution biostratigraphy, but also for influence of radiolarian Albaillella fauna on the pre-Lopingian mass extinction.     

Uneven Distribution of Pseudotormentus De Wever et Caridroit (Radiolaria, Protozoa): Provincialism of a Permian Planktonic Microorganism

The Permian planktonic distribution is not well known, in contrast to other fossil distributions of nekton and benthos. Radiolaria are representative microfossils of plankton in the Permian palaeocean. This study compares both correlated radiolarian occurrences (Pseudotormentus De Wever et Caridroit and Quadriremis Nazarov et Ormiston) in literature data from the Pacific Rim and quantitative data from the Liuhuang and Gujingling sections in South China. Pseudotormentus distributions are concentrated in the Panthalassa, whereas Quadriremis occurrences are distributed over both the Panthalassa and the Palaeotethys. The uneven distribution of Pseudotormentus seems to have been controlled by a difference in the oceanic basins, indicating the presence of faunal differences in Permian planktonic microorganisms between the Panthalassa and the Palaeotethys. In other words, this study infers the provincialism of Permian planktonic microorganisms. The uneven distribution is explainable by a hypothesis that Pseudotormentus was strongly affected by a Panthalassan equatorial current.     

http://www.sciencedirect.com/science/article/pii/S167498711200028X

Most Phanerozoic oolites are marked by ooids with a diameter less than 2 mm.Observations on a Neoproterozoic oolite have resulted in a change of concept.The term "pisolite" that traditionally referred to oolites with a grain size of more than 2 mm,is now restricted to those coated carbonate grains formed by meteoritic freshwater diagenesis;oolites with a grain size of more than 2 mm are now defined as "giant".Particular unusual giant oolites within a set of oolitic-bank limestones with thicknesses of more than 40 m in the top part of the Lower Triassic(Induan) Daye(Ruiping) Formation at the Lichuan section in the western part of Hubei Province in South China,represent an important sedimentological phenomenon in both the specific geological period and the geological setting that is related to the end-Permian biological mass extinction.Like the giant oolites of the Neoproterozoic that represent deposits where oolites formed in a vast low-angle carbonate ramp at that special geological period,the Triassic Daye Formation at the study section are significant because they provide a comparative example to help understand the evolving carbonate world reflected by oolites,the origin of which is still uncertain. and they give insight into the sedimentation pattern of the desolate sea floor,which resulted from the mass extinction at the turn of the Permian into the Tnassic.     

Effective Elastic Thickness of Southeast Part of Arctic Ocean—Eurasia Continent—Pacific Ocean Geoscience Transect

The effective lithospheric elastic thickness of the continent is an important parameter for examination of the large-scale structure and analyses of the mechanism of isostatic compensation within the plate, and a parameter standing for the strength of the lithosphere.The Te values along Quanzhou-Heishui,the southeast section of the Arctic Ocean-Eurasian Continent-Pacific Ocean geoscience transect, are estimated by using the coherence technique developed by Forsyth.Studies of the feature of the coher-ence between gravity and topography suggest that at short wavelengths(6.6-100km)for each data box that is used to estimate Te,the plate is strong enough to support topographic loads and gravity and topog-raphy are uncorrelated.At long wavelengths where the plate is deflected by surface and subsurface loads are compensated by the flexure model.Sichuan land-stone with low heat-flow values has high Te values whereas in Ninghua,Datian,land-stone with high heat-flow values has low Te values,which reflects a correlation,low heat-flow values corresponding to high Te values and high heat-flow values corresponding to low Te values.Te values can be divided into two sections:northwest high section and southeast low sec-tion.There is roughly a positive correlation between crustal thickness and effective elastic thickness of the lithosphere.     

Atrypid Brachiopods from the Upper Devonian Wangchengpo Formation (Frasnian) of southern Guizhou, China — Extinction Patterns in the Frasnian of South China

The Wangchengpo Frasnian section of Dushan County contains two atrypid brachiopod assemblages. The lower is characterized by the Atryparia （Costatrypa） dushanensis fauna that appears at the base of the Hejiazhai Member approximately in the falsiovalis to transitans conodont zones： the upper is characterized by the Radiatrypa yangi fauna, which appears in the Lujiazhai Member approximately correspondent with the hassi to Upper rhenana conodont zones. Atrypid brachiopods, together with other brachiopods from the Dushan section show that the Hejiazhai Member is of Frasnian age. Preliminary analyses of Frasnian atrypid brachiopods from sections of South China indicate that there are nine genera and subgenera including Atryparia （Costatrypa）, Kyrtatrypa, Spinatrypa, lsospinatrypa, Spinatrypina, lowatrypa, Desquamatia （Desquamatia）. Desquamatia （Seratrypa）, and Radiatr）pa. Atrypid species diversity did not change much through the Frasnian. On a regional scale in South China, most atrypid species went extinct prior to the Frasnian/Famennian boundary. At any specific locality or section, these atrypids became extinct about 20-40 m below the Frasnian/Famennian （F/F） boundary, within the linguiformis conodont Zone, marking this as the major extinction level. Three new atrypid species are described： Atryparia （Costatrypa） dushanensis, lowatrypa pseudobodini, and Radiatrypa yangi.     

Carbon and Strontium Isotopes of Late Palaeozoic Marine Carbonates in the Upper Yangtze Platform,Southwest China

238 marine carbonate samples were collected from seven sedimentary sections ofthe entire late Palaeozoic (Permian, Carboniferous and Devonian) in the Upper Yangtze Plat-form, southwest China. Based on the absence of cathodoluminescence and very low Mn (gener-ally<50 ppm) contents of the samples, it is thought that they contain information on the orig-inal sea water geochemistry. The results of isotopic analyses of these samples are presented interms of δ~(13)C and ~(87)Sr/~(86)Sr ratios versus geological time. The strontium data, consistent withother similar data based on samples from North America, Europe, Africa and other areas inAsia, support the notion of a global consistency in strontium isotope composition of marinecarbonates. The strontium data exhibit three intervals of relatively low ~(87)Sr/~(86)Sr ratios in thelate Middle Devonian to early Late Devonian, Early Carboniferous and Early Permian, corre-sponding to global eustatic high sea level stands. The lowest ~(87)Sr/~(86)Sr ratio recorded in theLate Permian was probably caused by substantial basalt eruptions in the Upper Yangtze Plat-form at the time. Three corresponding periods of relatively high δ~(13)C values at roughly the samethe intervals were caused by a relatively high rate of accumulation of organic carbon duringsea level rises at these times. The deposition of coal was probably responsible for the increaseof sea water δ~(13)C at other times. The δ~(13)C values drop dramatically near theDevonian/Carboniferous, Carboniferous/Permian and Permian/Triassic boundaries, con-sistent with other similar data, which further support the notion that geological time boundariesare associated with mass extinction and subsequent rejuvenation.     

A New Understanding on South China Permian Coal-bearing Strata and Coal Accumulation Regularity

The Longtan Formation was originally thought to belong to the Late Permian, but this study reveals that the lower part of this formation belongs to the Middle Permian. The study proposes the corresponding chro-nostratigraphic boundary and new schemes for the correlation of geological sections. Based on these schemes a new understanding on the accumulation regularity of Permian coal measures in South China is reached.     

NOTE ON A PHASE OF THE HERCYNIAN MOVEMENT IN SOUTHERN ANHUEI.

The Hercynian Movement is a well known and almost world-wide orogenetic movement. It embraces all the movements which took place in between the time limits of the beginning of the Carboniferous and the end of the Permian. In China the Kuenlun and Tsinling Ranges are generally supposed to have     

Late Olenekian Radiolarians from Bedded Chert of Ashio Terrane, Northeast Japan,and Faunal Turnovers in Western Panthalassa during Early Triassic

Late Olenekian assemblages in the western Panthalassa have been recovered from bedded radiolarian chert sequences of an accretionary complex, the Ashio belt. These faunas are documented and considered in terms of radiolarian diversity and faunal turnover during the latest Permian to Middle Triassic time. The fauna includes 30 radiolarians belonging to Spumellaria or Entactinaria, with two relicts from the Late Permian. This late Olenekian fauna is markedly different from Permian and Asisian faunas, respectively, and is herein named the Minowa fauna. Study of the literaure indicates that radiolarian provinces were significantly disconnected between the western Panthalassa and eastern Tethys during late Olenekian time. Furthermore, 121 of 143 species disappeared during late Olenekian time, and in turn 118 new species appeared in the western Panthalassa around the Olenekian-Anisian boundary. It is concluded that faunal turnover occurred at least three times between the latest Permian and Middle Triassic.The first turnover is the Poalaozoie-type radiolarian extinction at the Permain-Triassic boundary,the second is the diversification of spheroidal Spumellaria and Entactinaria between early and late Olenekian time, and the third is a faunal turnover from the Minowa fauna to the true Mesozoic-type radiolarian famas that are characterized by mulit0segmented Nassellaria.     

Boundary Between Upper Cretaceous and Lower Paleocene in the Zagros Mountain Ranges of Southwestern Iran

In the present study, over 3000?m of Upper Cretaceous sediments (Tarbur Formation) in seven stratigraphic, columnar sections were studied. The area is located in the Zagros mountain ranges of southwestern Iran, attributed to the converging continental Arabian Shield, and is interpreted as the result of subduction and collision. Based on foraminiferal studies of the Tarbur Formation in the sections, we have established many new biozones in the stratigraphic sections. However, investigations of the biozones indicate that there is no lithostratigraphic variation between the Upper Cretaceous and Lower Paleocene sediments in some of the studied sections. The concept of widespread formations and lithologic correlations is not applicable in this area, probably as a result of the tectonic unrest at that time. The biostratigraphic boundary between the Cretaceous and the Lower Paleocene is nevertheless well defined by the intraformational boundary in the sections.     

Early cambrian carbon isotope stratigraphy in the tarim basin and a correlation with the yangtze platform

Carbon isotope chemostratigraphy has been used worldwide for stratigraphic correlation.In this study,δ13Ccarb values are estimated for the Early Cambrian Sugaitebulake section in the Tarim Basin,Xinjiang Autonomous Region,China.As a result,one positive and two negative carbon isotope excursions in the studied section were iden-tified.The δ13Ccarb values reached the maximum negative excursion(N1:-12.39‰) at the basal of the Yuertusi For-mation,and then increased to P1.After P1,δ13Ccarb values sharply decreased to about-7.06‰(N2) in the studied section.The pattern of δ13Ccarb in the Early Cambrian is comparable to the synchronous records of other sections,such as the Laolin section,the Xiaotan section and the Anjiahe section of the Yangtze Platform.It is concluded that the Early Cambrian Yuertusi Formation from the Tarim Basin is within the Nemakit-Daldynian stage,and the lower strata of the Yuertusi Formation may belong to the Zhujiaqing Formation(Meishucun Formation) of the Yangtze Platform.The Ediacaran/Cambrian boundary of the Tarim Block should be located in cherts and phosphorites suc-cessions at the basal of the Yuertusi Formation.The δ13Ccarb negative excursion N1 is just across the PC/C boundary,and may be related to certain biomass extinction due to anoxic sedimentary environment,transgression and/or the oceanic overturn.The second δ13Ccarb negative excursion N2 may account for the sea-level falling in the Early Cam-brian.     

The Most Complete Sequence of Telychian Graptolite Zones in the World

This paper divides the Telychian into 7 graptolite zones, 12 subzones and 4 chitinoans in the Ziyangregion, China. The zones and subzones of England are almost totally suitable for the case of Ziyang in China, though they are 10000 km apart. All the above-mentioned biozones are found only in a unitary continuous section in Ziyang. It has been proved that the Ziyang section is the one with the most complete sequence of Telychian graptolite biozones in the world.     

Devonian–Carboniferous Hangenberg Crisis in South China: Variations in Trace Elements, Strontium and Carbon Isotope Chemostratigraphy in the Nanbiancun Carbonate Section

The global Hangenberg Crisis or Hangenberg Extinction is a mass extinction near the Devonian–Carboniferous boundary. Comprehensive research of petrology and geochemistry on the Devonian–Carboniferous boundary, as exposed in the Nanbiancun auxiliary stratotype section, South China, elucidates paleoenvironmental changes and controls on marine strontium (87Sr/86Sr) and carbonate carbon (δ13Ccarb) isotopes during the Hangenberg Crisis. The new 87Sr/86Sr data reveal a regression in the Middle Siphonodella praesulcata Zone, while the Hangenberg Extinction was occurring in South China. Moreover, the δ13Ccarb data records a negative excursion near the base of the Middle Siphonodella praesulcata Zone that may have been connected with the Hangenberg Extinction. A positive δ13Ccarb excursion, corresponding with the Upper Siphonodella praesulcata Zone, may reflect the effects of a vigorous biological pump. The magnitude of the Hangenberg Carbon Isotopic Excursion in peak δ13carb values and δ13Ccarb gradient in carbonate Devonian–Carboniferous boundary sections of the South China Craton during the Hangenberg Crisis, are a function of depositional water depth and distance from the shore. The carbon cycling during the Hangenberg Carbon Isotopic Excursion had a much stronger impact on oceanic surface waters than on the deep ocean and the δ13Ccarb gradient of local seawater was likely caused by enhanced marine productivity, associated with biological recovery in platform sediments during the Hangenberg Crisis.     

SHRIMP zircon U-Pb ages from coal beds across the Permian-Triassic boundary,eastern Yunnan,southwestern China

The first SHRIMP zircon U e Pb ages from coal beds close to the end-Permian mass extinction are reported from the C_1 coal seam in the Yantang Mine in Laibin Town, Xuanwei County, eastern Yunnan Province.Zircons were extracted from kaolinite claystone layers, defined as tonsteins(volcanic ash deposits), in the subseam B_1 and B_3 of the coal seam C_1.The U-Pb ages are 252.0 ± 2.3 Ma and 250.3 ± 2.1 Ma for the sub-seam B_1 and B_3, respectively. Within analytical uncertainties, these U-Pb ages include the time period of the onset of the mass extinction at 251.941 ± 0.037 Ma, which was obtained from the marine Meishan section in Zhejiang Province, ~1600 km away from the Yantang Mine. These new ages represent not only the first and closest ages to the PTB mass extinction in terrestrial coal beds, but also ages from the nearest site to the Emeishan volcanoes investigated so far. Therefore these new data provide the most accurate stratigraphic horizon of terrestrial facies of the end-Permian extinction in South China. The Emeishan volcanoes were likely the source of volcanic ash in the coal seams at the Xuanwei County and broader areas in South China. Furthermore, the minerals and geochemistry characteristics of the C_1 coal seam also implied the influences of contemporaneous volcanic activities.     

Geochemistry of the trace elements and rare-earth elements at the boundary between Cambrian Series 2 and Series 3 at Jianshan, South China: Paleoenvironmental and stratigraphic implications

The Jianshan section in Jianhe County,Guizhou Province,is a very important auxiliary section to the candidate stratotype at the boundary between Cambrian Series 2 and Series 3.Twenty four samples collected from the Jianshan section of the Kaili Formation were analyzed for the concentrations of trace element and rare-earth elements(REEs) by inductively coupled plasma mass spectrometry.The trace element and REE geochemical characteristics of the Kaili Formation at the Jianshan section show that trace element composition and REE distribution patterns across the section are covariant.Notably,at 44 m above the base of the Kaili Formation,most trace element contents and REEs concentrations are lower than those values observed below 44 m.Above 44 m,an increasing trend in the concentration of both trace elements and REEs is observed.These geochemical data indicate important,but subtle,changes at the 44 m horizon.If this is,in fact,verified by work in progress,geochemical criteria can provide additional supports for defining the top surface of Cambrian Series 2,especially in sections where Oryctocephalus indicus is absent.Trace element ratios,specifically Ni/Co,V/Cr,V/(Ni+V) and Th/U as well as Ce and Eu anomalies indicate that the sedimentary environment of the Kaili Formation at the Jianshan section was oxidizing,that benthic redox conditions were less oxic,and may have been influenced by freshwater as compared to the Balang area.Moreover,the Eu anomalies observed in the Kaili Formation are similar to the negative Eu anomalies observed in post-Archean sedimentary rocks,and reveal fluctuations in oxygen content from the bottom to the top of the Kaili Formation.     

Uppermost Permian Radiolarian Biostratigraphy of Southern Guizhou,Southwest China

With abundant deep-water upper Permian sediments,Guizhou is an ideal place for the re-search of radiolarian biostratigraphy of Upper Permian.The sections of Sidazhai and Lekang in southern Guizhou Province are studied.Lithology and biostratigraphy of the siliceous rock sequence of uppermost Permian in the two sections are introduced.Radiolarian assemblage zones,Neoalbaillella optima assem-blage zone and Klaengspongus spinosus assemblage zone in ascending order are established for the top-most Permian of southern Guizhou.The Klaengspongus spinosus zone has been the topmost radiolarian assemblage zone of Permian,which is also correlated with former ones in a considerable depth.     

Progress, Problems and Prospects on the Stratigraphy and Correlation of the Kungurian Stage, Early Permian (Cisuralian) Series

The Kungurian Stage is one of the three remaining stages of the Permian that is not yet defined at the base by a Global Stratotype Section and Point (GSSP). The candidate section at the Yuryuzan’River in the Urals yields few conodonts, and contains non-marine sediments near the boundary. The search for a suitable, continuous marine succession is a principal task for the Subcommission on Permian Stratigraphy. The Leonardian, with its type area in the southwest United States, and in objective stratigraphic succession directly beneath the basal Guadalupian Roadian Stage, has priority to serve as a subseries of the Lower Permian. However, distinct provincialism limits the correlation of Leonardian fossil zones with the fusuline-based Tethyan timescale. Conodonts can be correlated in many important regions on opposite sides of Pangea, yet contradictions arise when relating conodont zones with fusuline and ammonoid zones. The different taxonomic philosophies are highly suspected for the cause of the conflicts, but also there are different conodonts from the type Roadian in West Texas. Given that the Pamir and Darvaz in central Asia are difficult to access, further investigations should focus on South China, where abundant fusulines and ammonoids facilitate correlation throughout the Tethyan region, and where conodonts permit correlation with North America.