Statistical Analysis On Biostratigraphy Division And Paleoecology Of Permian Radiolarians

Radiolarian is an important group of micropaleontology in the ocean which widely distributes from the equator to the poles in a variety of seas,while the vertical distribution of radiolarian is from the ocean-surface layer down to depths of thousands-meters deep.Radiolarian fossils are widely found in the sediments of the ancient oceans and can be used for global stratigraphic correlations.They are particularly important to divide the strata in the orogenic belts and those deep-water environments where other fossils are missing.Radiolarian in sediments provides abundant information of paleoenvironment.Its taxonomy composition and diversity contribute to the establishment of sea level variation and reconstruction of the paleoenvironment.This paper tentatively uses statistical paleoecology and paleobiostratigraphy methods to focus on the Permian radiolarian biostratigraphy and the relationship between radiolarians and paleowater depth.The content of this paper is mainly divided into three parts:(1)systematic study in the Changhsingian radiolarians from South China;(2)water depths of the latest Permian(Changhsingian)radiolarians estimated from correspondence analysis;(3)low-latitudinal standard Permian radiolarian biostratigraphy for multiple purposes with statistical methods.The progress achieved includes:(1)Systematic study in the Changhsingian radiolarians from South ChinaDue to the formation of Pangaea,the global mass regression occurred between the Paleozoic and Mesozoic,leading to the Permian-Triassic sedimentary missing.However,South China basin located in the Paleo-Tethys,so the Permian-Triassic sequence is commonly continuous.Herein three sections(Rencunping section from Sangzhi,Hunan Province;Kejiao section from Huishui,Guizhou Province and Xiaojiaba section from Guangyuan,Sichuan Province)from Yangtze interplatform basin are chosen for systematic study.After radiolarian fossils examined,there are 69 species belonging to 27 genera,including one new genus,four new species and two new subspecies.Micro-XCT method is then used to examine the internal structures of a spherical to elliptical polycystine with two bi-polar main spines,Dalongicaepa bipolaris Xiao and Suzuki gen.et sp.nov.,from the Dalong Formation(Changhsingian)of South China.The new genus is characterized by four to seven densely concentric shells with a large spherical hollow in the center and two cylindrical spines at both poles of the cortical shell,and belongs to the family Spongotortilispinidae.Spherical to elliptical polycystines with bi-polar main spines are similar in external appearance,and their phylogenetic relationships are only determinable by examination of the internal structures.We therefore analyzed all Permian and Mesozoic spherical to elliptical polycystines with bi-polar main spines showing internal structures,using cluster analysis to measure similarity.The results show distinctive differences in internal structures and suggest that family level relationships should be revised in the future.(2)Water depths of the latest Permian(Changhsingian)radiolarians estimated from correspondence analysisThis paper briefly summarizes current knowledge on water-depth indicators in Permian radiolarians,and compares this knowledge with observational evidence for water-depth indicators in living radiolarians.Studies on modern radiolarians demonstrate the feasibility of estimating floating depths at the species level,but not at higher taxonomic levels.This apparently contradicts the common assumption that the Subfamily Copicyntrinae indicates shallow water,and the Order Albaillellaria deep water in the Permian.We approach this contradiction in water-depth distributions by using a statistically driven correspondence analysis(CA),which so far has never been used for Permian radiolarian studies.CA was applied to multivariate meta-datasets of the Changhsingian Dalong Formation of South China and of pelagic deep cherts from Japan because the depositional water depths from these successions have been well studied and the evidence is reliable.These two regions belonged to the same low-latitude region in the Lopingian(Late Permian)based on fusulinids and tectonic reconstructions.The CA results indicate that the output Dimension 1 largely represents depositional water depths,from very shallow(positive value)to deep(negative value),and Dimension 2 seems to be closely related with siliciclastic input.Following the scores along Dimension 1,the nine examined sections were categorized into five water-depth zones: ‘very shallow'(Xinmin and Shangsi),‘shallow'(Pingdingshan and Hushan),‘upper intermediate'(Rencunping),‘middle intermediate'(Dongpan),and ‘lower intermediate–pelagic deep'(Gujo-hachiman,Itsukaichi and Shikoku).This order roughly agrees with empirical water-depths based on palaeontological and geological evidence.Based on this water-depth order,species were categorized into five water-depth zones(14 very shallow-water species,18 shallow-water species,14 upper intermediate-water species,39 middle intermediate-water species,and seven lower intermediate-to deep-water species).For the first time,our data also statistically prove that Entactinaria and Spumellaria did not live in very deep water and that most Latentifistularia and Albaillellaria species are upper intermediate-to deep-water species.This result partly supports the utility of water-depth indicators at the taxonomic order level in the Late Permian.(3)Low-latitudinal standard Permian radiolarian biostratigraphy for multiple purposes with Unitary Association,Graphic Correlation,and Bayesian inference methodsThe ideal goal of biostratigraphic studies is to make stratigraphic ranges of all species clear and to fix globally synchronous biohorizons as age controls.However,it is difficult to achieve this goal in simple,traditional ways,and so a new solution is proposed for Permian radiolarian biostratigraphy.To achieve this goal(including to establish a globally applicable biostratigraphy,to estimate the numerical age of biohorizons,and to determine stratigraphic ranges at species level),all 400 known Permian radiolarian species,approximately 70 stratigraphic sections,and 1560 samples from 350 previously published papers about the low-latitude Tethys and Panthalassa oceans were analyzed.Issues of Permian studies are summarized and a solution is proposed from the Cenozoic point of view.Considering traditional methods,as well as successful methods in Cenozoic radiolarian studies,here we implement newly proposed methods that have never been used for Permian radiolarian studies: Unitary Association Method(UAM),“Minimum Disordered Biohorizon Algorithm”(MDBA),Graphic Correlation(GC),and ‘Reiteration Estimation Rounds'(RER).Of these,our proposed RER is a new method to predict the probability of the estimated age for a sample by Bayesian inference and joint probability(both statistical methods).As these four methods are applicable to any biostratigraphic study,the principals and practical applications of these methods are carefully explained so non-specialists can understand the logical procedure.As a result,15 Unitary Association Zones(UAZs)are established for the entire Permian biostratigraphic scheme by UAM,the numerical ages of 42 first occurrences(FOs)are estimated from non-parametric data from the middle Guadalupian(middle Permian)to the uppermost Lopingian(uppermost Permian)by MDBA and GC,and the statistical likelihood UAZ ranges of 165 species in the entire Permian were obtained using the RER procedure.A usability test of our UAZs shows that 97.96% of the 933 tested samples from previously published papers are well correlated and without contradiction.Within the statistical error of Cenozoic synchronous biohorizons at 1.4 Myr,23 of 42 FOs are potentially regarded as synchronous events.As the statistical likelihoods of UAZ ranges are estimated by Bayesian inference,these ranges can be updated by anyone.In addition,the statistical likelihood UAZ ranges obtained was used to date the UAZ of tectonic slices of the Shitishuiku section in Bancheng,Guangxi.This section has many faults and folds developed in the fractured strata,thus is a complex sequence of siliceous strata formed in different ages.Through the deduction of the UAZ to which tectonic slice belongs,the age was confirmed,and the usability of UAZ and its probability of statistical likelihood ranges was confirmed.The above results showed the significance on Permian radiolarian taxonomy,reconstruction of paleo-water depth and high-resolution deep-sedimentary stratigraphic division and correlation that based on the ecological evolution rules of modern marine organisms,using micro-XCT and other new techniques and a variety of statistical methods.It indicates that the new method and statistical analysis have obvious practical value and application prospects in the micro-fossils of the older strata.Permian is a transitional period from the Carboniferous Ice Age to the Triassic Greenhouse.It records multiple environmental changes and biological events.Thus it is an important geological historical reference for the evolution of modern climate and biological environment.The application of more and updated technical methods and statistics methods in the study of Permian paleontological fossils,especially microscopic marine organisms such as radiolarians,may be the necessary research approach and development tendency to predict biological and marine changes in modern greenhouse climates and establish objective historical comparisons.