Integrated radiolarian and conodont biostratigraphy of the Middle Permian Gufeng Formation (South China)

Radiolarians are usually abundant in chert sequences and they have thus been widely used for the biostratigraphy of deep-water sediments. However, there are many difficulties in the correlation of radiolarian biostratigraphic schemes with the standard conodont zones. In this study, 21 radiolarian species were extracted from the Gufeng Formation that crops out in the Luojiaba (LJB) section (western Hubei, China), together with 5 co-occurring conodont species. In this way, it is the first time that the Pseudoalbaillella globosa, Follicucullus monacanthus and F. scholasticus radiolarian zones can be directly correlated with the Jinogondolella nankingensis gracilis, J. aserrata and J. postserrata conodont zones. Accordingly, the 3 radiolarians zones are now firmly correlated with the Roadian to middle Capitanian interval (Middle Permian).     

The interplay between event and background sedimentation and the origin of fossil‐rich carbonate concretions: a case study in Permian rocks of the Paraná Basin,Brazil

The Permian Serra Alta Formation was generated under transgressive conditions within a large, calm epeiric sea. A monotonous succession of ‘barren’, massive mudstones deposited under oxygen‐deficient conditions (mainly below storm wave base) is the main lithofacies of this unit. Fossils are generally rare and diluted in the matrix, but certain intervals contain shell‐rich concentrations with well‐preserved, closed articulated bivalves, mixed with shells and comminuted debris with variable quality of preservation, all encased in carbonate concretions. Two main scenarios may account for the origin of these bivalve‐rich concretions (i.e. unique events in sea‐water chemistry or unique burial‐starvation couplets). Sedimentological and taphonomic information indicates that the final deposition of the original shell‐rich mudstone intervals was probably tied to episodic influx of fine‐grained sediments in distal settings. Moderate bioturbation is also recorded suggesting low rates of sedimentation prior to early diagenesis. Hence, the fossil concentrations in concretions were formed due to the interplay of event and background sedimentation. These are internally simple concentrations with complex depositional histories. The concretion‐bearing beds are not randomly distributed in the Serra Alta Formation. Rather, they are found in the sparsely fossiliferous offshore deposits of the basal to intermediate portions of the unit. Thus, the concretionary mudstone beds and associated deposits are preserved in particular intervals and can be tracked for kilometres. This indicates that the conditions essential for concretion development existed only at particular stratigraphical intervals. Finally, our study strongly corroborates the idea that concretions are critical sources of sedimentological, taphonomic and stratigraphical information.     

Discovery of Anticostia uniformis from the Xiazhen Formation at Zhuzhai,South China and its stratigraphic implication

The Xiazhen Formation is an Upper Ordovician lithostratigraphic unit in the Jiangshan-Changshan-Yushan (JCY) area, which contains series of Late Ordovician reef successions. The reef successions of the Xiazhen Formation at Zhuzhai are critical for evaluation of the Late Ordovician marine diversity and palaeoecology. However, their age has long been uncertain and generally is regarded as of upper Katian, based on the occurrences of shelly fossils and correlation with the stratigraphic equivalent Changwu Formation. The newly discovered graptolite species Anticostia uniformis, in the Xiazhen Formation, together with the combined evidence of brachiopods and sedimentology, indicates an age range for the graptolite locality from the Dicellograptus complanatus Biozone to the Diceratograptus mirus Subzone of late Katian, but the graptolites do not rule out the possibility that it is Hirnantian.     

Middle Permian smaller foraminifers from the Maokou Formation at the Tieqiao section,Guangxi, South China

This paper documents smaller foraminifers from the Maokou Formation (Guadalupian) at the Tieqiao section in Laibin area, South China. The assemblage of smaller foraminifers reported herein consists of 69 species of 42 genera. Although the Maokou Formation of this section was deposited in a relatively deep-water environment, smaller foraminifers are diverse and abundant, especially in debris flow deposits and thin turbidite beds. This fauna bears most similarity with coeval foraminiferal assemblages from the other Palaeotethyan regions. There is a sharp decrease in the diversity and abundance of smaller foraminifers at the lithological boundary between the Maokou and Heshan formations. An overwhelming majority of genera of smaller foraminifers that occur in the Maokou Formation at this section can be found in the Lopingian strata of South China. The study of smaller foraminiferal fauna of the Guadalupian at the Tieqiao section indicates a much less pronounced effect of the pre-Lopingian crisis on smaller foraminifers.     

华南亚热带山地土壤有机质更新特征及其影响因子

选择鼎湖山自然保护区及中国科学院华南植物研究所小良生态站6个土壤剖面,根据土壤有机质碳稳定同位素特征、^14C放射性水平、有机质含量、粒度特征,研究土壤有机质更新特征及其制约因素。结果表明,土壤有机质分解呈明显阶段性：有机质快速分解发生在0－100a之内,自地表向下,有机质含量急剧降低,因碳同位素分馏效应,有机质δ^13C值迅速增加;至170／240a,有机质δ^13C值达最大;自170／240－800／1400a,有机质分解速度变慢,有机质含量缓慢降低,因高δ^13C值组分分解,δ^13C值逐渐减小;约在1500a之后,有机质含量变化甚微,δ^13C值趋于稳定。对比研究表明,粘粒对有机质赋存状态及其更新有直接影响,粒度是制约土壤有机质动态的重要因子;地表植被类型及其发育特征直接影响土壤有机质更新,在植被类型相似情况下,植被覆盖史对土壤剖面有机质动态有明显影响。     

Lopingian (Late Permian) brachiopods around the Wuchiapingian-Changhsingian boundary at the Meishan Sections C and D, Changxing, South China

The strata below the defined Wuchiapingian-Changhsingian boundary GSSP are mostly covered and obscured by faulting at the Meishan Section D. Therefore, it is very difficult to collect fossils there. After an intensive excavation at Meishan Section C, a diverse fauna based on high-resolution biostratigraphy comprising brachiopods, ammonoids, conodonts, fusulinids and small foraminifers were found. Among these fossils, brachiopods are the most dominant. Eleven species of 10 genera based on more than 1300 specimens are identified. This brachiopod fauna is of late Wuchiapingian-Changhsingian of Lopingian (Late Permian) in age as well constrained by the associated ammonoid Pseudogastrioceras sp., Jinjiangoceras and Konglingites sp., the fusulinid Palaeofusulina and the conodont lineage from C. longicuspidata to C. wangi. In terms of the changes of brachiopod fauna composition around Wuchiapingian-Changhsingian boundary, it clearly indicates a continuous transgression from the upper part of the Lungtan Formation to the lower part of the Changhsing Formation. A new species, Neochonetes (Huangichonetes) meishanensis, is described and some other species are discussed based on the new collection from Meishan Sections C and D.     

Dickinsonia from the Ediacaran Dengying Formation in the Yangtze Gorges area,South China

Dickinsonia is an iconic fossil of the Ediacara biota (~575–539 Ma). It was previously known from siliciclastic successions of the White Sea assemblage in Australia, Baltica, and possibly India. Here we describe Dickinsonia sp. from the terminal Ediacaran Shibantan Member limestone (ca. 551–543 Ma) of the Dengying Formation in the Yangtze Gorges area of South China. The stratigraphic distribution of Ediacara-type fossils in the Shibantan Member indicates that this biota uniquely preserves both the White Sea and Nama assemblages in stratigraphic succession. The new data presented here suggests that Dickinsonia had wider paleogeographic and paleoenvironmental distributions, implying its strong dispersal capability and environmental tolerance.     

New insights into the base of the Emsian (Lower Devonian) in South China

Traditionally, the lower boundary of the Emsian (Lower Devonian) has been defined as the base of the dehiscens Zone marked by the first entry of the conodont Polygnathus dehiscens. However, following taxonomic revision of P. dehiscens, the current practice is to use the first appearance of P. kitabicus to define the base of the Emsian. As a result, specimens previously identified as P. dehiscens from South China need to be thoroughly reviewed. Careful examination of the oral and aboral features of the platform reveal that most specimens previously described as P. dehiscens from nine sections in Guangxi and Yunnan actually refer to P. excavatus excavatus or P. excavatus ssp. 114. In the South China Block, widespread and massive deposition of Devonian carbonates began during the time of the excavatus Zone, whereas the kitabicus Zone is probably located in the underlying strata, which mainly comprise marine siliciclastic rocks. Thus, the precise level of the lower boundary of the Emsian in South China is still unknown.     

Biotic structure and morphology of patch reefs from South China (Ningqiang Formation, Telychian, Llandovery, Silurian)

Summary Ningqiang Formation (late Telychian, Llandovery, Silurian), characterized by nearly 3000 m of shales in tercalated with carbonates, is situated between Ningqiang (S. Shaanxi Province) to Guangyuan (N. Sichuan Province) adjacent to the northwest margin of the Yangtze Platform. The high diversity “Xiushan Fauna”, and abundant reef development, illustrate a relatively warm and persistent shallo marine environment in these early Silurian sediments. The sequence shows reef radiation after recovery from the end Ordovician mass extinction envents. Multiple horizons of reef-building occurred within a relatively short geological interval and resulted in more than 30patch reefs up to 200 m in diameter and 1–50 m vertically, composed of abundant fossils. Reef biota include frame-building corals, stromatoporoids, bryozoans, and microbialites, and reef-associated oranisms such as crinoids, brachiopods, trilobites, gastropods, nautiloids and ostracods. Three reefrelated biotic associations are recognised: a) reefs dominated by framework with crinoids and microbia; b) reefs dominated by only crinoids and microbia; and c) crinoiddomainated facies. Seven representative reef examples illustrate different morphologies and growth styles. A high terrigenous debris input and shallow epicontinental ramp, which lacked obvious topographic variation, were major controls which resulted in rather simple reefs; sedimentation was apparently the main constraint on lateral and vertical extension of reefs, and prevented large-scale reef complexes developing.     

Isotope variability of particulate organic matter at the PN section in the East China Sea

The source of particulate organic matter at the PN section in the East China Sea has been evaluated using stable carbon and nitrogen isotopes. The results showed that the ¹³C and ¹⁵N compositions varied from –19 to –31 and 0.7–9.5 respectively, and the isotope compositions were statistically distinct, enabling, by use of a simple components mixing equations, assessment of the ability of each tracer to estimate the terrestrial, Kuroshio Water, marine and remineralized sources' contributions. The dominance of terrestrial inputs of the Changjiang could be observed 250 km far from the river mouth in the East China Sea. In the shelf water column, the remineralization of biogenic organic matter becomes an important source except for the terrigenous and marine sources. The estimation of sources recorded by ¹³C data was partly confirmed by equivalent ¹⁵N and C/N compositions that reflected greater control by organic matter diagenesis and biological processing. However, the lighter contribution of ¹³C data of the Kuroshio samples also indicates the alteration of the isotope values by microbial or other processes. The net export flux of POC in the PN section is estimated to be 4.1 kmol C/s and the annual export is 129 Gmol C/yr, which is account for 20% of the East China Sea.     

广东湛江鲤鱼墩遗址人骨的C、N稳定同位素分析:华南新石器时代先民生活方式初探

相对于长江流域和黄河流域而言,华南地区先民生活方式的了解一直较为缺乏。广东湛江鲤鱼墩遗址人骨的C和N稳定同位素分析,显示此遗址的先民主要以海生类资源为食,陆生资源(包括可能的块茎类原始农业和动物)只占次要地位。通过与约同时代黄河流域、长江流域先民的稳定同位素数据比较,可以看出,早在6000年前,我国先民的生活方式就已出现3大类型。     

The Origin and Age of Biogeochemical Trends in Deep Fracture Water of the Witwatersrand Basin,South Africa

Water residing within crustal fractures encountered during mining at depths greater than 500 meters in the Witwatersrand basin of South Africa represents a mixture of paleo-meteoric water and 2.0–2.3 Ga hydrothermal fluid. The hydrothermal fluid is highly saline, contains abiogenic CH ₄ and hydrocarbon, occasionally N ₂ , originally formed at ～ 250–300°C and during cooling isotopically exchanged O and H with minerals and accrued H ₂ , ⁴ He and other radiogenic gases. The paleo-meteoric water ranges in age from ～ 10 Ka to > 1.5 Ma, is of low salinity, falls along the global meteoric water line (GMWL) and is CO ₂ and atmospheric noble gas-rich. The hydrothermal fluid, which should be completely sterile, has probably been mixing with paleo-meteoric water for at least the past ～100 Myr, a process which inoculates previously sterile environments at depths > 2.0 to 2.5 km. Free energy flux calculations suggest that sulfate reduction is the dominant electron acceptor microbial process for the high salinity fracture water and that it is 10 ⁷ times that normally required for cell maintenance in lab cultures. Flux calculations also indicate that the potential bioavailable chemical energy increases with salinity, but because the fluence of bioavailable C, N and P also increase with salinity, the environment remains energy-limited. The ⁴ He concentrations and theoretical calculations indicate that the H ₂ that is sustaining the subsurface microbial communities (e.g. H ₂ -utilizing SRB and methanogens) is produced by water radiolysis at a rate of ～1 nM yr ^?1 . Microbial CH ₄ mixes with abiogenic CH ₄ to produce the observed isotopic signatures and indicates that the rate of methanogenesis diminishes with depth from ～ 100 at < 1 kmbls, to < 0.01 nM yr ^?1 at > 3 kmbls. Microbial Fe(III) reduction is limited due to the elevated pH. The δ¹³C of dissolved inorganic carbon is consistent with heterotrophy rather than autotrophy dominating the deeper, more saline environments. One potential source of the organic carbon may be microfilms present on the mineral surfaces.     

Spatial and temporal distribution of carbon isotopes in soil organic matter at the Dinghushan Biosphere Reserve, South China

The spatial and temporal distribution of carbon isotopes (¹³C, ¹⁴C) in soil organic matter (SOM) were studied based on SOM content, SOM ¹⁴C and SOM ¹³C of thinly layered soil samples for six soil profiles with different elevations at the Dinghushan Biosphere Reserve (DHSBR), South China. The results indicate that variations of SOM ¹³C with depth of the soil profiles at different elevations are controlled by soil development, and correlate well with SOM composition in terms of SOM compartments with different turnover rates, and SOM turnover processes at the DHSBR. The effect of carbon isotope fractionation was obvious during transformation of organic matter (OM) from plant debris to SOM in topsoil and SOM turnover processes after the topsoil was buried, which resulted in great increments of OM ¹³C, respectively. Increments of SOM ¹³C of topsoil from ¹³C of plant debris were controlled by SOM turnover rates. Both topsoil SOM ¹³C and plant debris ¹³C increase with elevation, indicating regular changes in vegetation species and composition with elevation, which is consistent with the vertical distribution of vegetation at the DHSBR. The six soil profiles at different elevations had similar characteristics in variations of SOM ¹³C with depth, alterations of SOM contents with depth and that SOM ¹⁴C apparent ages increasing with depth, respectively. These are presumably attributed to the regular distribution of different SOM compartments with depth because of their regular turnover during soil development. Depth with the maximal SOM ¹³C value is different in mechanism and magnitude with penetrating depth of ¹⁴C produced by nuclear explosion into atmosphere from 1952 to 1962, and both indicate controls of topography and vegetation on the distribution of SOM carbon isotopes with depth. Elevation exerts indirect controls on the spatial and temporal distribution of SOM carbon isotopes of the studied mountainous soil profiles at the DHSBR. This study shows that mountainous soil profiles at different elevations and with distinctive aboveground vegetation are presumably ideal sites for studies on soil carbon dynamics in different climatic-vegetation zones.     

黑翅鸢在华南的分布

自1997年1月至2000年3月,在自海南经雷州半岛向东直达汕头地区的沿海区域内8次近距离在红树林和田野见到黑翅鸢,总数达20只之多,证实了海南省和广东南部沿海地区为黑翅鸢在华南的分布区。     

A late Devonian (Frasnian) coral-bafflestone reef at Houshan in Guilin, South China

Summary Givetian to early Carboniferous sediments of South China are characterized by carbonates. Middle and Late Devonian strata are best developed in the Guilin area. Reefs and organic shoals are recorded by various lithofacies types indicating the existence of an extended carbonate platform and a change of the composition of reef communities in time. Starting in the late Devonian, stromatoporoids and corals were replaced by algae that subsequently played an important role together with stromatoporoids, receptaculitids and fasciculate rugose corals in reef communities. In Houshan, 5 km west of Guilin, a coral-bafflestone reef occurs in the Frasnian strata, situated near an offshore algal-stromatoporoid reef. The coral reef was formed in a back-reef area adjacent to the inner platform margin. The coral-bafflestone reef is unique among the late Devonian reefs of South China with regard to the biotic composition. The reef is composed of fasciculate colonies ofSmithiphyllum guilinense n. sp. embedded within in packstones and wackestones. The height of colonies reaches 1 m. The community is low-diverse. The species ofSmithiphyllum occurring in the Frasnian reef complexes of Guilin exhibit a distinct facies control:Smithiphyllum guilinense occurs in or near to margin facies and formed bafflestone, constituting a coral reef whereasSmithiphyllum occidentale Sorauf, 1972 andSmithiphyllum sp.—characterized by small colonies with thin corallites—are restricted to the back-reef and marginal slope facies. The bush-like coral colonies baffled sediments. Algae and stromatoporoids (mainlyStachyodes) are other reef biota. Reef-dwelling organisms are dominated by brachiopods. The reefs are composed from base to top of five lithofacies types: 1) cryptalgal micrite, 2) peloidal packstone, 3) stromatactis limestone, 4) coral-bafflestone, and 5) pseudopeloidal packstone. The reef complex can be subdivided into back-reef subfacies, reef flat and marginal subfacies, and marginal fore-slope subfacies. The Houshan coral-bafflestone reef is not a barrier reef but a coral patch reef located near the inner margin of a carbonate platform.     

Sphenophyllum Brongniart (Sphenopsida) from the Upper Devonian of South China

Sphenophyllum Brongniart constitutes a common and important element in the Carboniferous and Permian floras around the world, but its records in the Devonian Period are limited and remain to be investigated with respect to their morphology, anatomy, and distribution. Diversity of Sphenophyllum during Late Devonian in South China was significant with the presence of the well-known species including S. lungtanense Gothan and Sze, S. pseudotenerrimum Sze, and S. changxingense Huang et al. In this article, we describe a new species of the genus, S. fanwanense n. sp., from the Fanwan section of Changxing County, Zhejiang Province, characterized by having at least two orders of axes, with six spoon-shaped leaves attached at the node. A comprehensive review of previous records of Sphenophyllum from the Upper Devonian of South China shows that at least four species (S. fanwanense, S. lungtanense, S. pseudotenerrimum and S. changxingense), each with distinct leaf morphology, occur in South China in the Late Devonian, mostly from the Wutong Formation (Famennian). Given the lack of concrete evidence for anisophylly or heterophylly among the Devonian Sphenophyllum species (and more broadly, the Devonian sphenopsids), we suggest that the development of these features later in the Carboniferous and Permian periods was likely related to an increase in complexity of forest communities through time.     

南海北部夏季基础生物生产力分布特征及影响因素

2008年夏季对南海北部不同海区的基础生物生产力(初级生产力及细菌生产力)进行了调查。结果表明,表层初级生产力(C)和真光层水柱初级生产力平均值(C)分别为(0.83±1.15)mg·m-·3h-1和(225.39±136.64)mg·m-·2d-1;表层细菌生产力(C)和真光层水柱细菌生产力平均值(C)分别为(0.14±0.19)mg·m-·3h-1和(128.14±74.86)mg·m-·2d-1。基础生产力的平面分布整体呈由近岸向深海降低的趋势,同时在西沙群岛邻近水域存在一个基础生物生产力的高值区。与环境因子的相关分析表明,温度、营养盐不是影响南海细菌生产力的主要因素,细菌生产力与浮游植物生物量及初级生产过程密切相关IBP:IPP比平均值为(67.55±37.13)%。与细菌生产力的分布规律不同,IBP:IPP比值在深海海域明显高于近岸水域,在吕宋海峡附近水域发现了IBP:IPP100%的高比值区,说明异养细菌在南海寡营养海域碳循环体系中的重要生态作用。     

A new oryctocephalid trilobite from the Balang Formation (Cambrian Stage 4) of northwestern Hunan,South China,with remarks on the classification of oryctocephalids

A new trilobite, Longaspis paiwuensis n. gen. n. sp., from the Balang Formation (Cambrian Stage 4) in northwestern Hunan, South China, is described. This rare trilobite adds to an expanding taxonomic list of organisms recognized from the Balang Lagerstätte, a deposit of exceptional preservation from the Cambrian. Longaspis paiwuensis is an unusually large-sized, micropygous oryctocephalid trilobite that has proparian facial sutures, pit-like lateral glabellar furrows, up to 17 thoracic segments, and a distinct medial notch in the pygidium; it lacks marginal spines.The classification of the family Oryctocephalidae is reviewed. Three subfamilies are recognized, and Longaspis n. gen. is assigned to the subfamily Oryctocarinae.     

First palynological data from the Jurassic South Xiangshan Formation (Nanjing area,China)

The outcrops of the Xiangshan Group have been studied since the beginning of the twentieth century, yielding a rich macroflora (the Xiangshan Flora), mainly from the lower part of the Xiangshan Group (South Xiangshan Formation). Nevertheless, no palynological data have been published so far from the South Xiangshan Formation. The present study provides the first palynostratigraphic data of the South Xiangshan Formation. More than 50 fossil taxa from 30 fossil genera have been identified, allowing for a more accurate dating. The most characteristic taxa are Polycingulatisporites triangularis, Quadraeculina anellaeformis, Manumia delcourtii, Ischyosporites variegatus, Callialasporites turbatus, C. trilobatus, C. minus, and Sestrosporites pseudoalveolatus, suggesting a late Toarcian-late Aalenian age for the South Xiangshan Formation. These results are consistent with previous studies suggesting a middle-late Early Jurassic age for this formation; consequently, the most probable age for the South Xiangshan Formation is late Toarcian (late Early Jurassic).     

Lower Abundance of Ammonia-Oxidizing Archaea Than Ammonia-Oxidizing Bacteria Detected in the Subsurface Sediments of the Northern South China Sea

Diversity and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in samples of the northern South China Sea subsurface sediment were assessed by analyzing the amoA gene sequences retrieved from the samples. The microbial diversity was assessed using rarefaction and phylogenetic analyses. The deep-sea subsurface sediments harbored diverse and distinct AOA and AOB communities, but the abundance of AOA was lower than that of AOB, consistent with many other studies about bacteria and archaea in subsurface sediments. Diversity of AOA shown in the OTUs and Shannon index was correlated with the concentration of nitrite in the Pearson analysis, but no obvious relationships between the diversity or abundance of AOB and the physicochemical parameters could be identified in the present study, indicating the concentration of ammonium may not be an important factor to determine the diversity and abundance of ammonia-oxidizing prokaryotes in the subsurface sediments. Additionally, Nitrosomonas-like AOB was found to be dominant in subsurface sediments of the northern South China Sea showing a different adaption strategy comparing with some Nitrosospira-like AOB lineages. Concentration of nitrite was correlated with diversity of AOA, but no correlations between diversity and abundance of AOB and the physicochemical parameters were established in the study. Supplementary materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the free supplemental files.