Based on the quantitative analyses of abundance of planktonic foraminifera, benthic foraminifera, calcareous nannofossils, the ratios of calcareous to siliceous microfossils,and the determination of carbonate contents...Based on the quantitative analyses of abundance of planktonic foraminifera, benthic foraminifera, calcareous nannofossils, the ratios of calcareous to siliceous microfossils,and the determination of carbonate contents in the surface sediments of the northeastern South China Sea, it has been found that the carbonate contents, the abundance of planktonic foraminifera and calcareous nannoplankton, and the ratio of calcareous microfossils decrease rapidly while the ratio of the benthic foraminifera to the total foraminiferal fauna, specific value of siliceous microfossils, and the percentage of the agglutinated tests in the benthic foraminiferal fauna increase with the water depth. The results indicate that the microfossils abundance and ratio, and the carbonate content are closely related to the carbonate lysocline and carbonate compensation depth (CCD) in the study area. In addition, the carbonate lysocline and the CCD are different between the southern and northern parts of the South China Sea. Both the lysocline and the CCD are deeper in the south with 2?600 and 3?600 m than in the north with 2?200 and 3?400 m, respectively.展开更多
This paper reports for the first time on the microfossils discovered in the black cherts of the basal part of the Lower Cambrian Shuijingtuo Formation at Miaohe village, Zigui County, Hubei Province, all of which were...This paper reports for the first time on the microfossils discovered in the black cherts of the basal part of the Lower Cambrian Shuijingtuo Formation at Miaohe village, Zigui County, Hubei Province, all of which were observed in thin sections. Nine genera, 9 species and 3 indeterminate species (including a new species) are described. According to these microfossils, the conclusion is made that the microfossil zone may be equivalent to the small shelly fossil assemblage zones 2—3 of the Meishucun stage. They have provided another important line of evidence for the correlation of the Sinian-Cambrian boundary strata with those of the adjacent areas.展开更多
Quantitative analyses of microfossils and stable isotopic analysis were carried out for Core SCS-12 in the southwestern slope of the South China Sea (SCS). A high-resolution paleoceanographic record for the last 13 ka...Quantitative analyses of microfossils and stable isotopic analysis were carried out for Core SCS-12 in the southwestern slope of the South China Sea (SCS). A high-resolution paleoceanographic record for the last 13 ka was revealed with the AMS 14 C dates. The southern SCS has experienced stepwise paleoceanographic changes since the last deglaciation. The oxygen isotopic stage 1/2 boundary around 12.05 ka B.P. and the end of the last deglaciation around 7.70 ka B.P. are two rapid change periods (corresponding to the termination I\-A and termination I\-B, respectively), in between is a slow change period. The authors infer that the sea level stood at -110 m before the termination I\-A, roughly the same as today after the termination I\-B, and about -50 m in between. Subsequently, the average winter sea surface temperature and salinity obviously increased while paleo-productivity decreased since 12.05 ka B.P. The early Holocene CaCO\-3 preservation spike, coupled with a high abundance of pteropoda and CaCO\-3 content, occurred around 7.70 ka B.P.展开更多
Microfossils from the Malan Loess profiles, Miaodao Islands, have been quantitatively studied. The microfauna is composed mainly of benthic foraminifers together with a few planktonic foraminifers, ostracods, gastropo...Microfossils from the Malan Loess profiles, Miaodao Islands, have been quantitatively studied. The microfauna is composed mainly of benthic foraminifers together with a few planktonic foraminifers, ostracods, gastropods, bivalves and echinoid spines. With the exception of indigenous gastropods, benthic foraminifers, ostracods, bivalves and echinoid spines were transported from the north or northwest of the Bohai Sea in the glacial period by the prevailing winter monsoon, while planktonic foraminifers were probably driven from the Yellow Sea or even the northern East China Sea by southerly winds. The upward decrease of marine microfossil abundance and diversity in the Malan Loess profiles shows that the microfossil transportation occurred mainly at the beginning of the regression.展开更多
The age of the Taowan Group is still a hot topic in the Northern Qinling Orogenic Belt, because of limited fossil evidence from these strata and different ideals on the Cambrian fossils of the conglomerate beds and li...The age of the Taowan Group is still a hot topic in the Northern Qinling Orogenic Belt, because of limited fossil evidence from these strata and different ideals on the Cambrian fossils of the conglomerate beds and limestone blocks. Early Ordovician acritarchs, chitinozoa and scolecodonts occur in the siltstone and muddy slate beds of the Guoling, Sanchakou, Fengmaimiao and Goushenmiao Formations of the Taowan Group, indicating the age of the Taowan Group should be the Ordovician. These fossil assemblages consist of 7 genera and 13 species of acritarchs, 7 genera and 9 species of chitinozoa, and 2 genera and 2 species of scolecodonts.展开更多
Based on numerous microfossils in Mesozoic of North Carnarvon Basin in Australia,the Mesozoic paleoclimate and paleoenvironment were analyzed,the paleogeographic background and development model of Mesozoic high-quali...Based on numerous microfossils in Mesozoic of North Carnarvon Basin in Australia,the Mesozoic paleoclimate and paleoenvironment were analyzed,the paleogeographic background and development model of Mesozoic high-quality source rocks were investigated and discussed.Variation of microfossil species and their relative contents in Mesozoic different intervals indicates changes of paleoclimate and paleoenvironment.The paleoclimate shows a cycle variation of aridehumidearidehumid,the regression occurred in the Early TriassiceLate Triassic and the transgression occurred in the Late TriassiceLate Cretaceous.Four sedimentary facieses including delta facies,littoral facies,restricted sea facies and open sea facies were developed in the Mesozoic.The open sea was mainly developed in the Early Triassic,the delta was distributed in the MiddleeLate Triassic,the restricted sea was especially well developed in the Jurassic,and the restricted sea and open sea were mainly distributed in the Cretaceous.Characteristics of microfossil assemblage in these four sedimentary facies are dramatically different.From the delta facies,littoral facies,restricted sea facies to open sea facies,content of pollen gradually decreases,but content of the dinoflagellate+acritarch gradually increases.The delta facies and littoral facies are dominated by the pollen.In the restricted sea facies,content of the pollen is equivalent to that of the dinoflagellate+acritarch.The open sea facies is dominated by the dinoflagellate and acritarch.Supply of sediment and formation of organic matter are influenced by the paleoclimate and paleoenvironment,and type of organic matter is controlled by the microfossil assemblage.Based on the palaeogeographic background,paleoclimatic condition and microfossil assemblage,two developmental models of the Mesozoic source rocks such as the development model of terrestrial organic matter under the background of large delta and the development model of mixed organic matter under the background of the restricted sea,were proposed.展开更多
THE microfossils were obtained by using 5%—7% HF acid from Qingbaikouian Dazhuang Formation in Luonan County, Shaanxi Province, with an age of 800—1000 Ma. The fossils may be one type of the oldest skeletal mierofos...THE microfossils were obtained by using 5%—7% HF acid from Qingbaikouian Dazhuang Formation in Luonan County, Shaanxi Province, with an age of 800—1000 Ma. The fossils may be one type of the oldest skeletal mierofossils.展开更多
Demonstrating the biogenicity of presumptive microfossils in the geological record often requires supporting chemical signatures, including isotopic signatures. Understanding the mechanisms that promote the preservati...Demonstrating the biogenicity of presumptive microfossils in the geological record often requires supporting chemical signatures, including isotopic signatures. Understanding the mechanisms that promote the preservation of microbial biosignatures associated with microfossils is fundamental to unravelling the palaeomicrobiological history of the material. Organomineralization of microorganisms is likely to represent the first stages of microbial fossilisation and has been hypothesised to prevent the autolytic degradation of microbial cell envelope structures. In the present study, two distinct fossilisation textures(permineralised microfossils and iron oxide encrusted cell envelopes)identified throughout iron-rich rock samples were analysed using nanoscale secondary ion mass spectrometry(NanoSIMS). In this system, aluminium is enriched around the permineralised microfossils, while iron is enriched within the intracellularly, within distinct cell envelopes. Remarkably,while cell wall structures are indicated, carbon and nitrogen biosignatures are not preserved with permineralised microfossils. Therefore, the enrichment of aluminium, delineating these microfossils appears to have been critical to their structural preservation in this iron-rich environment. In contrast,NanoSIMS analysis of mineral encrusted cell envelopes reveals that preserved carbon and nitrogen biosignatures are associated with the cell envelope structures of these microfossils. Interestingly, iron is depleted in regions where carbon and nitrogen are preserved. In contrast aluminium appears to be slightly enriched in regions associated with remnant cell envelope structures. The correlation of aluminium with carbon and nitrogen biosignatures suggests the complexation of aluminium with preserved cell envelope structures before or immediately after cell death may have inactivated autolytic activity preventing the rapid breakdown of these organic, macromolecular structures.Combined, these results highlight that aluminium may play an important role in the preservation of microorganisms within the rock record.展开更多
Carbonate rocks contain prolific hydrocarbon reserves all over the world,particularly in the Middle East.For exploration and production strategies,it is essential to understand carbonate reservoirs in terms of their i...Carbonate rocks contain prolific hydrocarbon reserves all over the world,particularly in the Middle East.For exploration and production strategies,it is essential to understand carbonate reservoirs in terms of their internal characteristics,depositional environment,relative age,diagenetic processes and impact on petrophysical properties.This study has been performed on exposed Cretaceous,Paleocene and Miocene marine carbonate sedimentary sequences in two localities(Maghdoucheh and Qennarit)near the city of Sidon(Southern Lebanon).It represents the first comprehensive study that takes into consideration the carbonate reservoir facies,diagenetic history and reservoir quality in the area.Rocks at Maghdoucheh are mainly dominated by limestone beds showing sedimentary structures and erosive bases alternating with microfossil-rich silty marls,related to a shallowing upward sequence in a restricted marine platform environment.Shells of benthic foraminifera and mollusks dominate the fossil assemblage extracted from the studied rocks.The microfossil and nannofossil assemblage detected in the Maghdoucheh sections indicates a middle Miocene age.Rocks at Qennarit are composed of mudstone/wackestone limestone beds rich in planktonic foraminifera and nannofossils related to open marine conditions.Based on the nannofossil content,rocks from Qennarit 1 and 2 are Paleocene and Cretaceous in age,respectively.Four main types of microfacies have been identified,i.e.(1)microbioclastic peloidal calcisiltite,(2)pelagic lime mudstone and wackestone with planktonic microfossils,(3)grainstone/packstone with abundant foraminifera and(4)fenestral bindstones,mudstones and packstones with porostromate microstructures.The porosity-permeability(poro-perm)analysis of representative samples reveals moderate to good porosity but very low permeability.This is mainly due to the presence of large moldic pores that are isolated in nature.The diagenetic features are dominated by micritization and dissolution(both fabric selective and non-fabric selective).Among all diagenetic features,dissolution in both localities contributes to porosity enhancement,while micritization,cementation,compaction and the filled fractures have negative impacts on permeability;hence the overall reservoir quality.展开更多
An archaeometric analysis of the James Ossuary inscription “James Son of Joseph Brother of Jesus” strengthens the contention that the ossuary and its engravings are authentic. The beige patina can be observed on the...An archaeometric analysis of the James Ossuary inscription “James Son of Joseph Brother of Jesus” strengthens the contention that the ossuary and its engravings are authentic. The beige patina can be observed on the surface of the ossuary, continuing gradationally into the engraved inscription. Fine long striations made by the friction of falling roof rocks continuously crosscut the letters. Many dissolution pits are superimposed on several of the letters of the inscription. In addition to calcite and quartz, the patina contains the following minerals: apatite, whewellite and weddelite (calcium oxalate). These minerals result from the biogenic activity of microorganisms that require a long period of time to form a bio-patina. Moreover, the heterogeneous existence of wind-blown microfossils (nannofossils and foraminifers) and quartz within the patina of the ossuary, including the lettering zone, reinforces the authenticity of the inscription.展开更多
The Volgian-Valanginian succession of shallow-water deposits from the Olenek section(Anabar-Lena region,Arctic Siberia)has been studied by sedimentological and palaeontological methods.High-resolution biostratigraphy ...The Volgian-Valanginian succession of shallow-water deposits from the Olenek section(Anabar-Lena region,Arctic Siberia)has been studied by sedimentological and palaeontological methods.High-resolution biostratigraphy of studied interval is based on the ammonites,foraminifers,marine and terrestrial palynomorphs.Foraminiferal and palynological zones have important regional implications providing well-constrained biostratigraphy of the Anabar-Lena region.Sedimentological studies together with ecological analysis of the associations of microbenthos,microphytoplankton and terrestrial palynomorphs allow the palaeoenvironmental reconstructions for the marginal area of the Anabar-Lena palaeosea and coastal land areas.展开更多
New anatomical features revealed in some Early Cambrian calcareous microfossils suggest comparison with Rhodophyta (red algae), which makes it possible to define their taxonomic position. A taxonomically rich Early Ca...New anatomical features revealed in some Early Cambrian calcareous microfossils suggest comparison with Rhodophyta (red algae), which makes it possible to define their taxonomic position. A taxonomically rich Early Cambrian paleobiocoenosis has been discovered in northern Tien Shan, which exemplifies the existence on earth at 535-513 Ma (million years) of morphologically complex fungiform microorganisms and red algae in a shallow-water biotope where environmental conditions favorable for life were created as a result of submarine volcanic eruptions.展开更多
The Jiachala Formatiom is a new lithostratigraphic unit set up in this paper. This is the first report on the Paleogene marine sequences and microfaunas in Gyangze to the southern side of the Yarlung-Zangbo suture zon...The Jiachala Formatiom is a new lithostratigraphic unit set up in this paper. This is the first report on the Paleogene marine sequences and microfaunas in Gyangze to the southern side of the Yarlung-Zangbo suture zone. On the basis of fossil abundance, species diversity, dominant species and first and last occurrences of key species, three dinoflagellate assemblages and three polynological assemblages were recognized in the Jiachala Formatiom. They are in ascending order as follows: Apectodinium quinquelatum-Apectodinium hyperacanthum, Cannin- gia chinensis-Palaeoperidinium pyrophorum and Cymatiosphaera reticulosa-Samlandia chla- mydophora dinoflagellate assemblages, and Arliaceoipollenites baculatus-Anacolosidites sub- trudens, Aglaoreidia cyclops-Pinuspollenites microinsigis, and Elaeangnacites asper-Ilexpol- lenites iliacus polynological Assemblages. According to the assemblages, the age of the Jiachala Formation is referred to Paleocene-early Eocene. The preliminary study on the Jiachala Forma- tion shows that this group of Paleogene deposits accumulated in an underfilled peripheral fore- land basin which was in response to the load of the crust thickening resulted from the Asia-India collision. The stratigraphic evidences provided by the evolution of foreland basin indicate that the India-Asia initional collision should occure near the Cretaceous/Paleogene boundary. The de- velopment and evolution of the southern Tibet foreland basin was under the control of the stress field from the subduct-collision between India and Asia and the structure pattern of the basement. The withering of Tethys Sea might occur after early Eocene in the Gyangze basin and should be after Priabonian of late Eocene in southern Tibet.展开更多
China is one of the main global centers of origin of agriculture. Foxtail millet(Setaria italica), common millet(Panicum miliaceum), and rice(Oryza sativa) were the first crops to be domesticated in China. There remai...China is one of the main global centers of origin of agriculture. Foxtail millet(Setaria italica), common millet(Panicum miliaceum), and rice(Oryza sativa) were the first crops to be domesticated in China. There remain many uncertainties and controversies in our current understanding of the chronology, locations, and plant types at the origins and the process of evolution of prehistoric millet and rice farming, and their relationships with climate change and human adaptation. This review summarizes the research progress made by Chinese scientists over the last decade on the origins and evolution of prehistoric agriculture. It highlights novel techniques and methods for identifying early crop remains, including plant macrofossils(carbonized seeds, spikelets), microfossils(phytoliths, calciphytoliths, starch, pollen), and biomarkers; new evidence on the origins, development, and spread of early agriculture; and research related to climate and environmental changes. Further, we pinpoint and discuss existing challenges and potential opportunities for further in-depth investigation of the origins and evolution of agriculture and the adaption of human activities to climate change.展开更多
The Liangzhu Culture(5300–4300 cal.a BP)has been regarded as the culmination of the Neolithic Age in the Yangtze Delta and as an archaic state.However,the reason behind the collapse of the Liangzhu Culture remains co...The Liangzhu Culture(5300–4300 cal.a BP)has been regarded as the culmination of the Neolithic Age in the Yangtze Delta and as an archaic state.However,the reason behind the collapse of the Liangzhu Culture remains controversial.Some scholars attributed it to social conflicts or foreign invasions,while others suggested that environmental deterioration,such as cold episodes,inundation and palaeo-typhoon events,disrupted the civilization.Notably,the yellowish silty sediments widely overlying the Liangzhu group sites have been presumed to be one of the vital clues to resolving these issues.The process and cause of their formation are key to understanding the decline in the Liangzhu Culture.In this study,two typical profiles composed of the Liangzhu cultural layer and yellowish silty sediments were collected in Liangzhu Ancient City.Multiple proxies,including pollen,phytoliths and diatoms,along with radiocarbon and optically stimulated luminescence dating and synthesized geochemical evidence from different sediments,were applied to reconstruct ecological and hydrological changes and discuss their linkage to cultural collapse.The regional ecology was typical freshwater wetlands during 4800–4400 cal.a BP,which facilitated rice farming and large-scale architectural engineering in Liangzhu Ancient City.Evidence from microfossils and dating of the yellowish silty sediments indicated that Liangzhu Ancient City was significantly affected by seawater after abandonment during 4300–3400 cal.a BP.Furthermore,geochemical evidence,including trace element and Sr-Nd isotopic compositions,suggested that the primary provenance of the yellowish silt was a mixture of sediments from the Qiantang River,East China Sea,Yangtze River and Yellow River,which had been transported to Liangzhu Ancient City by the Yellow Sea Coastal Current and a marine transgression.Therefore,based on evidence from archaeological sites and numerical simulation in the Yangtze Delta,it was supposed that the short-term accelerated relative sea-level rise at approximately 4400 cal.a BP caused a marine transgression around Taihu Lake,formed a large range of yellowish silty sediments,destroyed rice farming production,and ultimately led to the collapse of the Liangzhu Culture.展开更多
Various microbial fabrics characterize late Moscovian mounds in Houchang Town,southern Guizhou,South China.The dominant components of the mounds are microbial boundstones with stromatolitic structures,irregular oncoid...Various microbial fabrics characterize late Moscovian mounds in Houchang Town,southern Guizhou,South China.The dominant components of the mounds are microbial boundstones with stromatolitic structures,irregular oncoid-like forms,and wrinkle structures.Calcimicrobes recognized in the mounds include Girvanella,Ortonella,Wetheredella-like,Palaeomicrocodium-like,and some problematic calcimicrobes occurring in deposits between microbial boundstones,in thrombolitic textures,and in some intraclasts.Microbial carbonates are common in the substrate and interior of the mounds,including thrombolitic textures,microstromatolites,microbial ooids,oncoids,irregular encrusted layers,microbial mat debris,and microbial micrite.Calcimicrobes and microbial carbonates played an important role in the construction of the mounds:Girvanella might have contributed as a source of lime mud that formed the mound and stabilized the coral frame;thrombolitic mats could trap and fix sediments and bioclasts,contributing to the stabilization of substrate and mound limestones;and,microbial boundstone,clotted micrite and micritized bioclast could provide a hard substrate for encrusting metazoans(e.g.,bryozoans,Ivanovia).The abundant microbial fabrics in the mounds indicate that microbial activity was widespread in Moscovian reef mounds in southern Guizhou,and this suggests that microbial organisms were the primary mound builders in the study area.展开更多
Vase-shaped microfossils(VSMs) described herein mainly occur as isolated individuals in thin bedded siltstone and silty carbonate of the Gaojiashan Member of the upper Ediacaran Dengying Formation(ca.551-541 Ma).Altho...Vase-shaped microfossils(VSMs) described herein mainly occur as isolated individuals in thin bedded siltstone and silty carbonate of the Gaojiashan Member of the upper Ediacaran Dengying Formation(ca.551-541 Ma).Although these fossils are abundant,chained tests or other types of colonial aggregates have not been observed.Specimens in the siltstones can easily be isolated from the host rocks by ultrasonic vibrators.Compared with the co-occurring fossils Gaojiashania and Conotubus,VSMs are rarely pyritized,yet they are always three-dimensionally persevered with little deformation,suggesting that their tests were sturdy and possibly mineralized.Petrological observation and elemental mapping reveal two types of tests that are respectively calcareous and siliceous in composition.Calcareous tests typically consist of two to three crypto-crystal laminae,somewhat resembling bilamellar walls of foraminifers.Siliceous tests consist of fine-grained particles agglutinated with siliceous cement,similar to agglutinated walls of foraminifers.The Gaojiashan VSMs are broadly similar,at least in gross morphology,to the testate amoebae-like VSMs,but their relative large sizes(600-2400 μm) and possibly mineralized(rather than organic) tests argue against this comparison.They also show some similarities to other protozoans,especially tintinnids.However,tintinnids have robust pesudochitinous loricae consisting of both secreted and agglutinated materials.Moreover,tintinnid loricae differ in shape from the Gaojiashan VSM tests in having a constricted aboral end(sometimes with a caudal appendix) and a flaring oral opening.If the Gaojiashan VSMs are indeed related to foraminifers,they indicate that foraminifers were important players in late Ediacaran communities.展开更多
Deformation in the Zagros suture zone is a result of the oblique collision of the AfroArabian continent with the Central Iranian microcontinents.Various types of folding and faulting are characteristic features of the...Deformation in the Zagros suture zone is a result of the oblique collision of the AfroArabian continent with the Central Iranian microcontinents.Various types of folding and faulting are characteristic features of the study area and indicate the performance of a high strain tectonic regime in this region.To distinguish deformation geometry during the collisional events,strain measurements have been carried out,using the R_(f)/φ method on deformed radiolarian microfossils,in the Zagros suture zone.Based on the results,the strain ellipsoid shape is in the range of general flattening to plane strain(K=0.16 – 1.12).Measured mean kinematic vorticity number(W_(m)) in the deformed radiolarian rocks ranges between 0.50 and 0.87,which implies that exhumation of the Abade-Tashk area was facilitated by a general shear flow(35%<simple shear<65% and 45%<pure shear<65%).Kinematic vorticity numbers,the amounts of Octahedral shear strain,the ellipsoid eccentricity,and strain ratios systematically increasing towards the thrust fault.The study of deformation in the study area shows that the Zagros suture zone can be considered as a transpressional zone.展开更多
The middle Miocene Badenian evaporite basin of the Carpathian Foredeep Basin was a saline lake, separated by a barrier from the sea and supplied with seawater seeping through the barrier or overflowing it occasionally...The middle Miocene Badenian evaporite basin of the Carpathian Foredeep Basin was a saline lake, separated by a barrier from the sea and supplied with seawater seeping through the barrier or overflowing it occasionally in the form of short-lived marine transgressions. Such transgressions could leave behind marine microfossils in marly clay intercalations. One of them(2.3 m thick) occurs in the uppermost part of the sulphate sequence, in the unit ‘o’, in the Babczyn 2 borehole section. It contains marine palynomorphs(dinoflagellate cysts) and foraminiferal assemblages indicating a marine environment. The low-diversity benthic foraminiferal assemblages are dominated by opportunistic, shallow infaunally living species, preferring muddy or clayey substrate for thriving, brackish to normal marine salinity, and inner shelf environment. Dinoflagellate cyst assemblages, although taxonomically impoverished, consist of marine species;euryhaline forms that tolerate increased salinity are missing. Relatively common microfossils found in clay intercalations within gypsum have important palaeogeographical implications:they strongly suggest that there existed an additional inflow channel supplying the Polish Carpathian Basin from the south during the evaporite deposition and afterwards.展开更多
To determine the characteristics and potential indicators of modern typhoon deposition in a sandy lagoon off the coast of Guangdong Province(southern China),we analysed the ^(210)Pb,sedimentology,and microfossils of s...To determine the characteristics and potential indicators of modern typhoon deposition in a sandy lagoon off the coast of Guangdong Province(southern China),we analysed the ^(210)Pb,sedimentology,and microfossils of samples from ten cores obtained before and after the passage of Typhoon Rammasun in 2014.Typhoon deposition showed a thinning trend from internal areas of the lagoon to its mouth,with the maximum thickness inside the lagoon of~35 cm.These typhoon deposits are dominated by overwash and differ from sediments deposited under normal weather conditions.Under normal weather conditions,lagoon sediment has a210 Pb curve that follows a model of exponential decay,has a unimodal granularity frequency curve,and lacks organic matter and microfossils(diatoms and foraminifera).However,210 Pb is low in the typhoon deposits,the grain size is coarse,and the granularity frequency curve is obviously bimodal.There are also abundant foraminifera in the typhoon deposits.We found a clear double-layered structure in the typhoon deposits,which was caused by strong hydrodynamic disturbance that mixed sediments originally from the offshore area with those of the lagoon.The lower layer has coarse-grained particles with medium sorting,low organic matter content,and low diatom content.The upper layer has fine-grained particles with poor sorting,high organic matter content,and abundant diatoms.The rate of fragmentation of diatoms in the upper layer was very high(40%-60%).The diatom assemblage contained offshore and freshwater species carried by storm runoff.Therefore,we believe that the sediments of this typical sand bar-lagoon environment retain evidence of typhoon events along the southern China coast that is displayed in the marked sedimentological and microfossil characteristics.展开更多
文摘Based on the quantitative analyses of abundance of planktonic foraminifera, benthic foraminifera, calcareous nannofossils, the ratios of calcareous to siliceous microfossils,and the determination of carbonate contents in the surface sediments of the northeastern South China Sea, it has been found that the carbonate contents, the abundance of planktonic foraminifera and calcareous nannoplankton, and the ratio of calcareous microfossils decrease rapidly while the ratio of the benthic foraminifera to the total foraminiferal fauna, specific value of siliceous microfossils, and the percentage of the agglutinated tests in the benthic foraminiferal fauna increase with the water depth. The results indicate that the microfossils abundance and ratio, and the carbonate content are closely related to the carbonate lysocline and carbonate compensation depth (CCD) in the study area. In addition, the carbonate lysocline and the CCD are different between the southern and northern parts of the South China Sea. Both the lysocline and the CCD are deeper in the south with 2?600 and 3?600 m than in the north with 2?200 and 3?400 m, respectively.
基金This paper is a part of the results of project "Stratotype Section of the Sinian System in China" funded by the China National Foundation of Natural Science. Prof. Xing Yusheng, the leader of the project, also took part in the field work.
文摘This paper reports for the first time on the microfossils discovered in the black cherts of the basal part of the Lower Cambrian Shuijingtuo Formation at Miaohe village, Zigui County, Hubei Province, all of which were observed in thin sections. Nine genera, 9 species and 3 indeterminate species (including a new species) are described. According to these microfossils, the conclusion is made that the microfossil zone may be equivalent to the small shelly fossil assemblage zones 2—3 of the Meishucun stage. They have provided another important line of evidence for the correlation of the Sinian-Cambrian boundary strata with those of the adjacent areas.
文摘Quantitative analyses of microfossils and stable isotopic analysis were carried out for Core SCS-12 in the southwestern slope of the South China Sea (SCS). A high-resolution paleoceanographic record for the last 13 ka was revealed with the AMS 14 C dates. The southern SCS has experienced stepwise paleoceanographic changes since the last deglaciation. The oxygen isotopic stage 1/2 boundary around 12.05 ka B.P. and the end of the last deglaciation around 7.70 ka B.P. are two rapid change periods (corresponding to the termination I\-A and termination I\-B, respectively), in between is a slow change period. The authors infer that the sea level stood at -110 m before the termination I\-A, roughly the same as today after the termination I\-B, and about -50 m in between. Subsequently, the average winter sea surface temperature and salinity obviously increased while paleo-productivity decreased since 12.05 ka B.P. The early Holocene CaCO\-3 preservation spike, coupled with a high abundance of pteropoda and CaCO\-3 content, occurred around 7.70 ka B.P.
基金Project supported by the National Natural Science Foundation of China.
文摘Microfossils from the Malan Loess profiles, Miaodao Islands, have been quantitatively studied. The microfauna is composed mainly of benthic foraminifers together with a few planktonic foraminifers, ostracods, gastropods, bivalves and echinoid spines. With the exception of indigenous gastropods, benthic foraminifers, ostracods, bivalves and echinoid spines were transported from the north or northwest of the Bohai Sea in the glacial period by the prevailing winter monsoon, while planktonic foraminifers were probably driven from the Yellow Sea or even the northern East China Sea by southerly winds. The upward decrease of marine microfossil abundance and diversity in the Malan Loess profiles shows that the microfossil transportation occurred mainly at the beginning of the regression.
基金the Geological Surveying Project of China (Grant No. 1212010611807)the Natural the Major Project of Science and Technologic Support and the National Major Project of Developing Basic Research (Grant No. 2002CB412608)
文摘The age of the Taowan Group is still a hot topic in the Northern Qinling Orogenic Belt, because of limited fossil evidence from these strata and different ideals on the Cambrian fossils of the conglomerate beds and limestone blocks. Early Ordovician acritarchs, chitinozoa and scolecodonts occur in the siltstone and muddy slate beds of the Guoling, Sanchakou, Fengmaimiao and Goushenmiao Formations of the Taowan Group, indicating the age of the Taowan Group should be the Ordovician. These fossil assemblages consist of 7 genera and 13 species of acritarchs, 7 genera and 9 species of chitinozoa, and 2 genera and 2 species of scolecodonts.
基金The work was supported by the National Science and Technology Major Project of China(No.2011ZX05030).
文摘Based on numerous microfossils in Mesozoic of North Carnarvon Basin in Australia,the Mesozoic paleoclimate and paleoenvironment were analyzed,the paleogeographic background and development model of Mesozoic high-quality source rocks were investigated and discussed.Variation of microfossil species and their relative contents in Mesozoic different intervals indicates changes of paleoclimate and paleoenvironment.The paleoclimate shows a cycle variation of aridehumidearidehumid,the regression occurred in the Early TriassiceLate Triassic and the transgression occurred in the Late TriassiceLate Cretaceous.Four sedimentary facieses including delta facies,littoral facies,restricted sea facies and open sea facies were developed in the Mesozoic.The open sea was mainly developed in the Early Triassic,the delta was distributed in the MiddleeLate Triassic,the restricted sea was especially well developed in the Jurassic,and the restricted sea and open sea were mainly distributed in the Cretaceous.Characteristics of microfossil assemblage in these four sedimentary facies are dramatically different.From the delta facies,littoral facies,restricted sea facies to open sea facies,content of pollen gradually decreases,but content of the dinoflagellate+acritarch gradually increases.The delta facies and littoral facies are dominated by the pollen.In the restricted sea facies,content of the pollen is equivalent to that of the dinoflagellate+acritarch.The open sea facies is dominated by the dinoflagellate and acritarch.Supply of sediment and formation of organic matter are influenced by the paleoclimate and paleoenvironment,and type of organic matter is controlled by the microfossil assemblage.Based on the palaeogeographic background,paleoclimatic condition and microfossil assemblage,two developmental models of the Mesozoic source rocks such as the development model of terrestrial organic matter under the background of large delta and the development model of mixed organic matter under the background of the restricted sea,were proposed.
文摘THE microfossils were obtained by using 5%—7% HF acid from Qingbaikouian Dazhuang Formation in Luonan County, Shaanxi Province, with an age of 800—1000 Ma. The fossils may be one type of the oldest skeletal mierofossils.
基金support from the Vale S.A.-UQ Geomicrobiology initiative and the Australian Research Council Linkage Program(LP140100805) to G. Southam and P. Vasconcelos
文摘Demonstrating the biogenicity of presumptive microfossils in the geological record often requires supporting chemical signatures, including isotopic signatures. Understanding the mechanisms that promote the preservation of microbial biosignatures associated with microfossils is fundamental to unravelling the palaeomicrobiological history of the material. Organomineralization of microorganisms is likely to represent the first stages of microbial fossilisation and has been hypothesised to prevent the autolytic degradation of microbial cell envelope structures. In the present study, two distinct fossilisation textures(permineralised microfossils and iron oxide encrusted cell envelopes)identified throughout iron-rich rock samples were analysed using nanoscale secondary ion mass spectrometry(NanoSIMS). In this system, aluminium is enriched around the permineralised microfossils, while iron is enriched within the intracellularly, within distinct cell envelopes. Remarkably,while cell wall structures are indicated, carbon and nitrogen biosignatures are not preserved with permineralised microfossils. Therefore, the enrichment of aluminium, delineating these microfossils appears to have been critical to their structural preservation in this iron-rich environment. In contrast,NanoSIMS analysis of mineral encrusted cell envelopes reveals that preserved carbon and nitrogen biosignatures are associated with the cell envelope structures of these microfossils. Interestingly, iron is depleted in regions where carbon and nitrogen are preserved. In contrast aluminium appears to be slightly enriched in regions associated with remnant cell envelope structures. The correlation of aluminium with carbon and nitrogen biosignatures suggests the complexation of aluminium with preserved cell envelope structures before or immediately after cell death may have inactivated autolytic activity preventing the rapid breakdown of these organic, macromolecular structures.Combined, these results highlight that aluminium may play an important role in the preservation of microorganisms within the rock record.
基金funded by the URB of the American University of Beirut(Award#103603,Project#24687)。
文摘Carbonate rocks contain prolific hydrocarbon reserves all over the world,particularly in the Middle East.For exploration and production strategies,it is essential to understand carbonate reservoirs in terms of their internal characteristics,depositional environment,relative age,diagenetic processes and impact on petrophysical properties.This study has been performed on exposed Cretaceous,Paleocene and Miocene marine carbonate sedimentary sequences in two localities(Maghdoucheh and Qennarit)near the city of Sidon(Southern Lebanon).It represents the first comprehensive study that takes into consideration the carbonate reservoir facies,diagenetic history and reservoir quality in the area.Rocks at Maghdoucheh are mainly dominated by limestone beds showing sedimentary structures and erosive bases alternating with microfossil-rich silty marls,related to a shallowing upward sequence in a restricted marine platform environment.Shells of benthic foraminifera and mollusks dominate the fossil assemblage extracted from the studied rocks.The microfossil and nannofossil assemblage detected in the Maghdoucheh sections indicates a middle Miocene age.Rocks at Qennarit are composed of mudstone/wackestone limestone beds rich in planktonic foraminifera and nannofossils related to open marine conditions.Based on the nannofossil content,rocks from Qennarit 1 and 2 are Paleocene and Cretaceous in age,respectively.Four main types of microfacies have been identified,i.e.(1)microbioclastic peloidal calcisiltite,(2)pelagic lime mudstone and wackestone with planktonic microfossils,(3)grainstone/packstone with abundant foraminifera and(4)fenestral bindstones,mudstones and packstones with porostromate microstructures.The porosity-permeability(poro-perm)analysis of representative samples reveals moderate to good porosity but very low permeability.This is mainly due to the presence of large moldic pores that are isolated in nature.The diagenetic features are dominated by micritization and dissolution(both fabric selective and non-fabric selective).Among all diagenetic features,dissolution in both localities contributes to porosity enhancement,while micritization,cementation,compaction and the filled fractures have negative impacts on permeability;hence the overall reservoir quality.
文摘An archaeometric analysis of the James Ossuary inscription “James Son of Joseph Brother of Jesus” strengthens the contention that the ossuary and its engravings are authentic. The beige patina can be observed on the surface of the ossuary, continuing gradationally into the engraved inscription. Fine long striations made by the friction of falling roof rocks continuously crosscut the letters. Many dissolution pits are superimposed on several of the letters of the inscription. In addition to calcite and quartz, the patina contains the following minerals: apatite, whewellite and weddelite (calcium oxalate). These minerals result from the biogenic activity of microorganisms that require a long period of time to form a bio-patina. Moreover, the heterogeneous existence of wind-blown microfossils (nannofossils and foraminifers) and quartz within the patina of the ossuary, including the lettering zone, reinforces the authenticity of the inscription.
基金Financial support:Russian Science Foundation 18-17-00038Scientific support:Russian FSI 0331-2019-0004IGCP 679,632
文摘The Volgian-Valanginian succession of shallow-water deposits from the Olenek section(Anabar-Lena region,Arctic Siberia)has been studied by sedimentological and palaeontological methods.High-resolution biostratigraphy of studied interval is based on the ammonites,foraminifers,marine and terrestrial palynomorphs.Foraminiferal and palynological zones have important regional implications providing well-constrained biostratigraphy of the Anabar-Lena region.Sedimentological studies together with ecological analysis of the associations of microbenthos,microphytoplankton and terrestrial palynomorphs allow the palaeoenvironmental reconstructions for the marginal area of the Anabar-Lena palaeosea and coastal land areas.
文摘New anatomical features revealed in some Early Cambrian calcareous microfossils suggest comparison with Rhodophyta (red algae), which makes it possible to define their taxonomic position. A taxonomically rich Early Cambrian paleobiocoenosis has been discovered in northern Tien Shan, which exemplifies the existence on earth at 535-513 Ma (million years) of morphologically complex fungiform microorganisms and red algae in a shallow-water biotope where environmental conditions favorable for life were created as a result of submarine volcanic eruptions.
文摘The Jiachala Formatiom is a new lithostratigraphic unit set up in this paper. This is the first report on the Paleogene marine sequences and microfaunas in Gyangze to the southern side of the Yarlung-Zangbo suture zone. On the basis of fossil abundance, species diversity, dominant species and first and last occurrences of key species, three dinoflagellate assemblages and three polynological assemblages were recognized in the Jiachala Formatiom. They are in ascending order as follows: Apectodinium quinquelatum-Apectodinium hyperacanthum, Cannin- gia chinensis-Palaeoperidinium pyrophorum and Cymatiosphaera reticulosa-Samlandia chla- mydophora dinoflagellate assemblages, and Arliaceoipollenites baculatus-Anacolosidites sub- trudens, Aglaoreidia cyclops-Pinuspollenites microinsigis, and Elaeangnacites asper-Ilexpol- lenites iliacus polynological Assemblages. According to the assemblages, the age of the Jiachala Formation is referred to Paleocene-early Eocene. The preliminary study on the Jiachala Forma- tion shows that this group of Paleogene deposits accumulated in an underfilled peripheral fore- land basin which was in response to the load of the crust thickening resulted from the Asia-India collision. The stratigraphic evidences provided by the evolution of foreland basin indicate that the India-Asia initional collision should occure near the Cretaceous/Paleogene boundary. The de- velopment and evolution of the southern Tibet foreland basin was under the control of the stress field from the subduct-collision between India and Asia and the structure pattern of the basement. The withering of Tethys Sea might occur after early Eocene in the Gyangze basin and should be after Priabonian of late Eocene in southern Tibet.
基金supported by the National Natural Science Foundation of China(Grant No.41230104)the National Basic Research Program of China(Grant No.2015CB953801)+1 种基金the“Strategic Priority Research Program:Climate Change,Carbon Budget and Relevant Issues”of the Chinese Academy of Sciences(Grant No.XDA05130602)the“Macroevolutionary Processes and Paleoenvironments of Major Historical Biota”of the Chinese Academy of Sciences(Grant No.XDPB0503)
文摘China is one of the main global centers of origin of agriculture. Foxtail millet(Setaria italica), common millet(Panicum miliaceum), and rice(Oryza sativa) were the first crops to be domesticated in China. There remain many uncertainties and controversies in our current understanding of the chronology, locations, and plant types at the origins and the process of evolution of prehistoric millet and rice farming, and their relationships with climate change and human adaptation. This review summarizes the research progress made by Chinese scientists over the last decade on the origins and evolution of prehistoric agriculture. It highlights novel techniques and methods for identifying early crop remains, including plant macrofossils(carbonized seeds, spikelets), microfossils(phytoliths, calciphytoliths, starch, pollen), and biomarkers; new evidence on the origins, development, and spread of early agriculture; and research related to climate and environmental changes. Further, we pinpoint and discuss existing challenges and potential opportunities for further in-depth investigation of the origins and evolution of agriculture and the adaption of human activities to climate change.
基金supported by the National Natural Science Foundation of China(Grant Nos.41830322,41902187)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB26000000)the China Postdoctoral Science Foundation(Grant No.2020M670444)。
文摘The Liangzhu Culture(5300–4300 cal.a BP)has been regarded as the culmination of the Neolithic Age in the Yangtze Delta and as an archaic state.However,the reason behind the collapse of the Liangzhu Culture remains controversial.Some scholars attributed it to social conflicts or foreign invasions,while others suggested that environmental deterioration,such as cold episodes,inundation and palaeo-typhoon events,disrupted the civilization.Notably,the yellowish silty sediments widely overlying the Liangzhu group sites have been presumed to be one of the vital clues to resolving these issues.The process and cause of their formation are key to understanding the decline in the Liangzhu Culture.In this study,two typical profiles composed of the Liangzhu cultural layer and yellowish silty sediments were collected in Liangzhu Ancient City.Multiple proxies,including pollen,phytoliths and diatoms,along with radiocarbon and optically stimulated luminescence dating and synthesized geochemical evidence from different sediments,were applied to reconstruct ecological and hydrological changes and discuss their linkage to cultural collapse.The regional ecology was typical freshwater wetlands during 4800–4400 cal.a BP,which facilitated rice farming and large-scale architectural engineering in Liangzhu Ancient City.Evidence from microfossils and dating of the yellowish silty sediments indicated that Liangzhu Ancient City was significantly affected by seawater after abandonment during 4300–3400 cal.a BP.Furthermore,geochemical evidence,including trace element and Sr-Nd isotopic compositions,suggested that the primary provenance of the yellowish silt was a mixture of sediments from the Qiantang River,East China Sea,Yangtze River and Yellow River,which had been transported to Liangzhu Ancient City by the Yellow Sea Coastal Current and a marine transgression.Therefore,based on evidence from archaeological sites and numerical simulation in the Yangtze Delta,it was supposed that the short-term accelerated relative sea-level rise at approximately 4400 cal.a BP caused a marine transgression around Taihu Lake,formed a large range of yellowish silty sediments,destroyed rice farming production,and ultimately led to the collapse of the Liangzhu Culture.
基金supported by the National Natural Science Foundation of China(Grant No.41572004)
文摘Various microbial fabrics characterize late Moscovian mounds in Houchang Town,southern Guizhou,South China.The dominant components of the mounds are microbial boundstones with stromatolitic structures,irregular oncoid-like forms,and wrinkle structures.Calcimicrobes recognized in the mounds include Girvanella,Ortonella,Wetheredella-like,Palaeomicrocodium-like,and some problematic calcimicrobes occurring in deposits between microbial boundstones,in thrombolitic textures,and in some intraclasts.Microbial carbonates are common in the substrate and interior of the mounds,including thrombolitic textures,microstromatolites,microbial ooids,oncoids,irregular encrusted layers,microbial mat debris,and microbial micrite.Calcimicrobes and microbial carbonates played an important role in the construction of the mounds:Girvanella might have contributed as a source of lime mud that formed the mound and stabilized the coral frame;thrombolitic mats could trap and fix sediments and bioclasts,contributing to the stabilization of substrate and mound limestones;and,microbial boundstone,clotted micrite and micritized bioclast could provide a hard substrate for encrusting metazoans(e.g.,bryozoans,Ivanovia).The abundant microbial fabrics in the mounds indicate that microbial activity was widespread in Moscovian reef mounds in southern Guizhou,and this suggests that microbial organisms were the primary mound builders in the study area.
基金supported by National Basic Research Program of China (Grant No. 2006CB806400)National Natural Science Foundation of China (Grant No. 40872021)Program for New Century Excellent Talents in University, State Key Laboratory of Continental Dynamics and Northwest University Doctoral Dissertation Funds (Grant No. 09YYB01)
文摘Vase-shaped microfossils(VSMs) described herein mainly occur as isolated individuals in thin bedded siltstone and silty carbonate of the Gaojiashan Member of the upper Ediacaran Dengying Formation(ca.551-541 Ma).Although these fossils are abundant,chained tests or other types of colonial aggregates have not been observed.Specimens in the siltstones can easily be isolated from the host rocks by ultrasonic vibrators.Compared with the co-occurring fossils Gaojiashania and Conotubus,VSMs are rarely pyritized,yet they are always three-dimensionally persevered with little deformation,suggesting that their tests were sturdy and possibly mineralized.Petrological observation and elemental mapping reveal two types of tests that are respectively calcareous and siliceous in composition.Calcareous tests typically consist of two to three crypto-crystal laminae,somewhat resembling bilamellar walls of foraminifers.Siliceous tests consist of fine-grained particles agglutinated with siliceous cement,similar to agglutinated walls of foraminifers.The Gaojiashan VSMs are broadly similar,at least in gross morphology,to the testate amoebae-like VSMs,but their relative large sizes(600-2400 μm) and possibly mineralized(rather than organic) tests argue against this comparison.They also show some similarities to other protozoans,especially tintinnids.However,tintinnids have robust pesudochitinous loricae consisting of both secreted and agglutinated materials.Moreover,tintinnid loricae differ in shape from the Gaojiashan VSM tests in having a constricted aboral end(sometimes with a caudal appendix) and a flaring oral opening.If the Gaojiashan VSMs are indeed related to foraminifers,they indicate that foraminifers were important players in late Ediacaran communities.
文摘Deformation in the Zagros suture zone is a result of the oblique collision of the AfroArabian continent with the Central Iranian microcontinents.Various types of folding and faulting are characteristic features of the study area and indicate the performance of a high strain tectonic regime in this region.To distinguish deformation geometry during the collisional events,strain measurements have been carried out,using the R_(f)/φ method on deformed radiolarian microfossils,in the Zagros suture zone.Based on the results,the strain ellipsoid shape is in the range of general flattening to plane strain(K=0.16 – 1.12).Measured mean kinematic vorticity number(W_(m)) in the deformed radiolarian rocks ranges between 0.50 and 0.87,which implies that exhumation of the Abade-Tashk area was facilitated by a general shear flow(35%<simple shear<65% and 45%<pure shear<65%).Kinematic vorticity numbers,the amounts of Octahedral shear strain,the ellipsoid eccentricity,and strain ratios systematically increasing towards the thrust fault.The study of deformation in the study area shows that the Zagros suture zone can be considered as a transpressional zone.
基金jointly supported by the National Science Centre, Poland,grant No. UMO-2017/27/B/ST10/01129 to the first authorthe statutory funds of the PGI-NRI (project 62.9012.1948.00.0 to the third author)。
文摘The middle Miocene Badenian evaporite basin of the Carpathian Foredeep Basin was a saline lake, separated by a barrier from the sea and supplied with seawater seeping through the barrier or overflowing it occasionally in the form of short-lived marine transgressions. Such transgressions could leave behind marine microfossils in marly clay intercalations. One of them(2.3 m thick) occurs in the uppermost part of the sulphate sequence, in the unit ‘o’, in the Babczyn 2 borehole section. It contains marine palynomorphs(dinoflagellate cysts) and foraminiferal assemblages indicating a marine environment. The low-diversity benthic foraminiferal assemblages are dominated by opportunistic, shallow infaunally living species, preferring muddy or clayey substrate for thriving, brackish to normal marine salinity, and inner shelf environment. Dinoflagellate cyst assemblages, although taxonomically impoverished, consist of marine species;euryhaline forms that tolerate increased salinity are missing. Relatively common microfossils found in clay intercalations within gypsum have important palaeogeographical implications:they strongly suggest that there existed an additional inflow channel supplying the Polish Carpathian Basin from the south during the evaporite deposition and afterwards.
基金the Key Program of National Natural Science Foundation of China(Grant No.41930538)the National Science Foundation of China(Grant No.41306083)+1 种基金the National Key Research and Development Program of China(Grant No.2019YFE0124700)the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources of China(Grant Nos.2019018,2019026,and 2020017)。
文摘To determine the characteristics and potential indicators of modern typhoon deposition in a sandy lagoon off the coast of Guangdong Province(southern China),we analysed the ^(210)Pb,sedimentology,and microfossils of samples from ten cores obtained before and after the passage of Typhoon Rammasun in 2014.Typhoon deposition showed a thinning trend from internal areas of the lagoon to its mouth,with the maximum thickness inside the lagoon of~35 cm.These typhoon deposits are dominated by overwash and differ from sediments deposited under normal weather conditions.Under normal weather conditions,lagoon sediment has a210 Pb curve that follows a model of exponential decay,has a unimodal granularity frequency curve,and lacks organic matter and microfossils(diatoms and foraminifera).However,210 Pb is low in the typhoon deposits,the grain size is coarse,and the granularity frequency curve is obviously bimodal.There are also abundant foraminifera in the typhoon deposits.We found a clear double-layered structure in the typhoon deposits,which was caused by strong hydrodynamic disturbance that mixed sediments originally from the offshore area with those of the lagoon.The lower layer has coarse-grained particles with medium sorting,low organic matter content,and low diatom content.The upper layer has fine-grained particles with poor sorting,high organic matter content,and abundant diatoms.The rate of fragmentation of diatoms in the upper layer was very high(40%-60%).The diatom assemblage contained offshore and freshwater species carried by storm runoff.Therefore,we believe that the sediments of this typical sand bar-lagoon environment retain evidence of typhoon events along the southern China coast that is displayed in the marked sedimentological and microfossil characteristics.
