scholarly journals Quantifying the Seawater Sulfate Concentration in the Cambrian Ocean

2021 ◽  
Vol 9 ◽  
Author(s):  
Guangyou Zhu ◽  
Tingting Li ◽  
Tianzheng Huang ◽  
Kun Zhao ◽  
Wenbo Tang ◽  
...  
Keyword(s):  
Sulfur Isotopes ◽  
Sulfide Oxidation ◽  
Cambrian Explosion ◽  
Geochemical Data ◽  
Sulfate Concentration ◽  
Tarim Block ◽  
Seawater Sulfate ◽  
Pyrite Content ◽  
Sulfur Isotope Data ◽  
Sweet Spots

Although the earliest animals might have evolved in certain “sweet spots” in the last 10 million years of Ediacaran (550–541 Ma), the Cambrian explosion requires sufficiently high levels of oxygen (O2) in the atmosphere and diverse habitable niches in the substantively oxygenated seafloor. However, previous studies indicate that the marine redox landscape was temporally oscillatory and spatially heterogeneous, suggesting the decoupling of atmospheric oxygenation and oceanic oxidation. The seawater sulfate concentration is controlled by both the atmospheric O2 level and the marine redox condition, with sulfide oxidation in continents as the major source, and sulfate reduction and pyrite burial as the major sink of seawater sulfate. It is thus important to quantify the sulfate concentration on the eve of the Cambrian explosion. In this study, we measured the pyrite contents and pyrite sulfur isotopes of black shale samples from the Yurtus Formation (Cambrian Series 2) in the Tarim Block, northwestern China. A numerical model is developed to calculate the seawater sulfate concentration using the pyrite content and pyrite sulfur isotope data. We first calibrate some key parameters based on observations from modern marine sediments. Then, the Monte Carlo simulation is applied to reduce the uncertainty raised by loosely confined parameters. Based on the geochemical data from both Tarim and Yangtze blocks, the modeling results indicate the seawater sulfate concentration of 8.9–14 mM, suggesting the seawater sulfate concentration was already 30–50% of the present level (28 mM). High seawater sulfate concentration might be attributed to the enhanced terrestrial sulfate input and widespread ocean oxygenation on the eve of the Cambrian explosion.

Basal Cambrian microfossils from the Yangtze Gorges area (South China) and the Aksu area (Tarim block, northwestern China)

2009 ◽  
Vol 83 (1) ◽  
pp. 30-44 ◽  
Author(s):  
Lin Dong ◽  
Shuhai Xiao ◽  
Bing Shen ◽  
Chuanming Zhou ◽  
Guoxiang Li ◽  
...  
Keyword(s):  
Geographic Distribution ◽  
South China ◽  
Northwestern China ◽  
Cambrian Explosion ◽  
Filamentous Cyanobacteria ◽  
Primary Producers ◽  
Tarim Block ◽  
Eukaryotic Phytoplankton ◽  
History Of ◽  
Wide Geographic Distribution

The basal Cambrian marks the beginning of an important chapter in the history of life. However, most paleontological work on the basal Cambrian has been focused on skeletal animal fossils, and our knowledge about the primary producers—cyanobacteria and eukaryotic phytoplankton (e.g., acritarchs)—is limited. In this research, we have investigated basal Cambrian acritarchs, coccoidal microfossils, and cyanobacteria preserved in phosphorites and cherts of the Yanjiahe Formation in the Yangtze Gorges area (South China) and the Yurtus Formation in the Aksu area (Tarim Block, northwestern China). Our study confirms the occurrence in these two formations of small acanthomorphic acritarchs characteristic of the basal CambrianAsteridium–Comasphaeridium–Heliosphaeridium(ACH) assemblage. These acritarchs include abundantHeliosphaeridium ampliatimi(Wang, 1985) Yao et al., 2005, commonYurtusia uniformisn. gen. and n. sp., and rareComasphaeridium annulare(Wang, 1985) Yao et al., 2005. In addition, these basal Cambrian successions also contain the clustered coccoidal microfossilArchaeophycus yunnanensis(SonginLuo et al., 1982) n. comb., several filamentous cyanobacteria [Cyanonema majusn. sp.,Oscillatoriopsis longaTimofeev and Hermann, 1979, andSiphonophycus robustum(Schopf, 1968) Knoll et al., 1991], and the tabulate tubular microfossilMegathrix longusL. Yin, 1987a, n. emend. Some of these taxa (e.g.,H. ampliatum, C. annulare, andM. longus) have a wide geographic distribution but occur exclusively in basal Cambrian successions, supporting their biostratigraphic importance. Comparison between the stratigraphic occurrences of microfossils reported here and skeletal animal fossils published by others suggests that animals and phytoplankton radiated in tandem during the Cambrian explosion.

scholarly journals Sulfur isotope analysis for representative regional background atmospheric aerosols collected at Mt. Lulin, Taiwan

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chuan-Hsiung Chung ◽  
Chen-Feng You ◽  
Shih-Chieh Hsu ◽  
Mao-Chang Liang
Keyword(s):  
Atmospheric Aerosols ◽  
Sulfur Isotopes ◽  
Isotope Analysis ◽  
Background Level ◽  
P Value ◽  
Sulfate Concentration ◽  
Fossil Fuel Burning ◽  
Regional Background ◽  
Report Analysis ◽  
Regional Background Level

AbstractAir pollution resulted from fossil fuel burning has been an environmental issue in developing countries in Asia. Sulfur-bearing compounds, in particular, are species that are regulated and monitored routinely. To assess how the species affect at local and global scales, regional background level has to be defined. Here, we report analysis of sulfur isotopes in atmospheric sulfate, the oxidation end product of sulfur species, in particulate phase collected at the Lulin observatory located at 2862 m above mean sea level in 2010. The averaged sulfate concentration for 44 selected samples is 2.7 ± 2.3 (1-σ standard deviation) μg m−3, and the averaged δ34S is 2.2 ± 1.6‰, with respect to the international standard Vienna Canyon Diablo Troilite. Regardless of the origins of air masses, no noticeable difference between the low-altitude Pacific and high-altitude free troposphere sulfate aerosols is observed. Also, no identifiable seasonal cycle in seen. Correlation analysis with respect to coal burning tracers such as lead and oil industry tracers such as vanadium shows sulfate concentration is in better correlation with vanadium (R2 = 0.86, p-value < 0.001) than with lead (R2 = 0.45, p-value < 0.001) but no statistically significant correlation is found in δ34S with any of physical quantities measured. We suggest the sulfate collected at Lulin can best represent the regional background level in the Western Pacific, a quantity that is needed in order to quantitatively assess the budget of sulfur in local to country scales.

scholarly journals Vosnesensky Cu-porphyry deposit (Southern Urals): formation conditions, trace elements, sulfur isotopes and fluid sources

Georesursy ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 48-54
Author(s):  
Sergey E. Znamensky ◽  
Natalya N. Ankusheva ◽  
Dmitry A. Artemiev
Keyword(s):  
Fluid Inclusions ◽  
Sulfur Isotopes ◽  
Southern Urals ◽  
Optical Microscope ◽  
Geochemical Data ◽  
Mass Spectrometers ◽  
Porphyry Deposit ◽  
Ree Distribution ◽  
Geochemical Markers ◽  
Host Rocks

The paper shows new fluid inclusion and isotopic-geochemical data for minerals from sulphide-carbonate-quartz veins of Vosnesensky Cu-porphyry deposit. Fluid inclusions were analyzed by means Linkam TMS-600 cryostage equipped with Olympus BX 51 optical microscope; trace element amounts were performed used Agilent 7700x and ELAN 9000 mass-spectrometers; sulphur isotopic composition was analyzed on DeltaPLUS Advantagе mass-spectrometer. We determined that fluid inclusions in quartz were homogenized between 215 and 315 ºС, and in latest calcite, they are 230–280 ºС. Fluids are К-Na water chloride with salinity of 3–12 wt % NaCl-eq. Quartz contain high amounts of Al (184–5180 ppm), K (20.1–1040 ppm), Na (30.2–1570 ppm) and Ti (38.4–193 ppm). The REE distribution spectra of pyrite are characterized by light lanthanides accumulation (LaN/YbN = 3.6–6.44), and negative of Ce anomalies (0.7–0.92) and Eu (0.78–0.99). The Y/ Ho ratio in pyrite varies from 27.6 up to 36.8. The δ34S values in pyrite were –1.01…0.8 ‰, in chalcopyrite – 0.9 ‰. The data testify the Cu-porphyry mineralization of Vosnesensky deposit was formed due to magmatic acid high-aluminous К-Na chloride fluid enriched with light REE in mesothermal environment. We identified the geochemical markers of interaction between fluid and host rocks.

scholarly journals A National Geoscience Data Platform and its Application in Paleobiodiversity Studies: Experiences from Estonia

2019 ◽  
Vol 3 ◽  
Author(s):  
Olle Hints ◽  
Mare Isakar ◽  
Ursula Toom
Keyword(s):  
User Interfaces ◽  
Data Model ◽  
Management Tool ◽  
Cambrian Explosion ◽  
Geochemical Data ◽  
Baltic Region ◽  
Geological Time ◽  
Deep Time ◽  
Data Platform ◽  
The Baltic

Studying deep time biodiversity and environments is largely based on collections of fossils and sedimentary rocks, and the information acquired thereof. The sedimentary bedrocks of Estonia and neighbouring areas constitute a well-preserved archive of Earth history from the late Precambrian to the Devonian period. This interval of geological time hosts several key events in the diversification of life, notably the Cambrian explosion, the Great Ordovician Biodiversification Event and the Hirnantian mass extinction. Documenting and understanding these events has benefited from the geological and paleontological collections from the Baltic region, a large part of which are deposited in Estonia. Since 2004 Estonia has had a 'national geological collection' that virtually joins the archives of three major collection-holding institutions: Tallinn University of Technology, University of Tartu and the Estonian Museum of Natural History (Hints et al. 2008). A key to the functioning of this national consortium is the common database system 'SARV', which started as a simple collection management tool, but has grown into a geoscience data platform linking various types of geoscientific information and supporting also the needs of researchers. Technically the system is based on a relational data model and central database server, a REST API and a number of web-based user interfaces from data management tools to public portals and more specialized applications. Individual components of the system are now built on open source software including MySQL, Apache Solr, Django REST framework, and Angular and Vue JavaScript frameworks. The data model and all recently developed software are available in a Github repository (https://github.com/geocollections). Data on individual fossil specimens, digital images, localities, regional stratigraphic units, rock samples, datasets, published references, field notebooks etc. are publicly accessible in the Estonian geoscience collections portal (https://geocollections.info). A separate gateway provides access to the information on fossil taxa and their distribution in the Baltic region (https://fossiilid.info). Another example of using the same underlying data platform specifically for paleobiodiversity research is the Baltic chitinozoan database CHITDB (http://chitinozoa.net; Hints et al. 2018). Chitinozoans are an enigmatic group of Paleozoic microfossils, very useful in biostratigraphy. Some of the largest collections of these fossils worldwide derive from the Baltica paleocontinent and are deposited in Estonia. The chitinozoan portal was developed for managing and publishing the occurrence-level data on chitinozoans, and for quantitatively analysing their diversification history and biotic crises through the Ordovician and Silurian periods. The main benefit of using such an integrated data system is that a user may easily turn back to individual samples and specimen images (for instance, to verify identifications), and combine the paleontological data with information about past environments and climate that might derive from publications, first-hand geochemical data or even from descriptions in field notebooks. Global tools, such as the Paleobiology database, cannot provide such functionality for the time being. The next steps in enhancing the national geoscience data platform in Estonia are related to the development of new data collection and publication modules, building a complete digital library of geoscience publications related to Estonia and widening the user base of the system. Participation in the national research infrastructure roadmap project NATARC as well as the Pan-European DiSSCo will support achieving this and safeguarding the sustainability of geoscience data and corresponding e-services in Estonia.

Geology and geochemistry of the Dengjiashan Zn–Pb SEDEX deposit, Qinling Belt, China

2007 ◽  
Vol 44 (4) ◽  
pp. 479-492 ◽  
Author(s):  
Guoliang Ma ◽  
Georges Beaudoin ◽  
Shaojun Zhong ◽  
Ying Li ◽  
Zhangren Zeng
Keyword(s):  
Sulfate Reduction ◽  
Sulfur Isotopes ◽  
Tectonic Setting ◽  
Massive Sulfide ◽  
Western Qinling ◽  
Crustal Rocks ◽  
Open Platform ◽  
Basement Rocks ◽  
Seawater Sulfate ◽  
Extensional Tectonic

Dengjiashan, with 25 Mt at 4.77% Zn, 1.27% Pb, and 14 g/t Ag, is one of the largest SEDEX (sedimentary-exhalative) Zn–Pb sulfide deposits in the western Qinling orogenic belt, China. The ore is hosted in chert stratigraphically conformable with underlying bioclastic micrite and overlying phyllite of an intensely folded and faulted Middle Devonian sedimentary sequence. The fact that the major orebodies are located between platformal limestone and overlying phyllite indicates that mineralization took place when the Dengjiashan sedimentary sub-basin subsided from an open platform to a shallow-marine basin within an extensional tectonic setting. The deposit comprises 16 sulfide orebodies, of which the #1 and #9 orebodies are the two largest and account for 95% of ore reserves. The massive sulfide lenses are mainly composed of sphalerite, pyrite, and galena, with minor chalcopyrite, tetrahedrite, cinnabar, pyrargyrite, freibergite, boulangerite, polybasite, and trace amounts of owyheeite and native gold. The gangue is dominated by quartz, calcite, barite, and ankerite, with minor amounts of sericite, chlorite, celsian, cymrite, and albite. The rare-earth element patterns of sulfide beds and host chert suggest that the mineralizing fluids were dominated by oxidized seawater that leached Eu from feldspar in basement rocks. Strontium isotopes also suggest that the hydrothermal fluids were composed of Devonian seawater that leached radiogenic Sr along the flow path. Lead isotope ratios form an array between the upper crust and orogene curves in the 207Pb/204Pb–206Pb/204Pb diagram, indicating that lead was leached from crustal rocks below the deposits. Sulfur isotopes indicate that bacterial sulfate reduction (BSR) sulfide formed in a sub-basin restricted to sulfate where it mixed with heavy hydrothermal sulfur from thermochemical sulfate reduction (TSR) of Devonian seawater sulfate.

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