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The Mysterious Mid-Carnian “Wet Intermezzo” Global Event

Journal of Earth Science 2015年第2期26卷 181-191页

作者： James G.Ogg department of Earth Atmospheric and Planetary Sciences Purdue University Key Laboratory of Biogeology and environmental geology of Ministry of Education China University of Geosciences

Approximately 230 million years ago in the middle of the Carnian stage of the Upper Triassic, the sedimentary records in different regional basins display dramatic changes. Tropical carbonate platforms abruptly ended, and engorged river systems left widespread sand-rich layers across inland basins and coastal regions. This pulse lasted less than a million years in some basins, but constituted a permanent shift in others. Following this event, the Late Carnian has the earliest record of significant dinosaurs on land and the emergence of the calcareous nannoplankton in the oceans that now govern Earth＇s carbon cycle. This ＂most distinctive climate change within the Tri- assic＂ has been interpreted by some geoscientists as a global disruption of the Earth＇s land-ocean-biological system. The eruption of the Wrangellia large igneous province may have been the trigger for a sudden carbon-dioxide-induced warming and associated increased rainfall in some of these regions. Indeed, some workers have proposed that this ＂wet intermezzo＂ warming event is a useful analog to aid in predicting the effects of our future greenhouse on land ecosystems and ocean chemistry. However, the understanding of the onset, duration, global impacts and relatively rapid termination of this postulated warming pulse has been hindered by lack of a global dataset with inter-calibrated terrestrial and marine biostratigraphy, precise radio-isotopic ages, stable isotope records of temperature and the carbon system, and cycle-calibrated rates of regional and global change.

关键词： Triassic Carnian climate pluvial Wrangellia carbon isotope excursion dolomite China LIP Yangtze Platform Wet Intermezzo large igneous province.

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Palynomorph assemblage biozonation of Paleogene strata in Bende–Umuahia Area,Niger Delta Basin, southeastern Nigeria

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Journal of Palaeogeography 2020年第2期9卷 168-180页

作者： Okechukwu Nicodemus Ikegwuonu Obianuju Patricia Umeji Osita Igwebuike Chiaghanam Kingsley KNwozor Otobong Sunday Ndukwe Kingsley Chukwuebuka Chiadikobi department of geology Chukwuemeka Odumegwu Ojukwu UniversityUliNigeria department of geology University of NigeriaEnuguNigeria department of geology Federal UniversityOye-EkitiNigeria.

Cenozoic sediments form extensive outcrops in the Niger Delta Basin. Detailed palynostratigraphic study was undertaken across Paleogene sequences exposed in Bende–Umuahia Area in up-dip sectors of the Niger Delta Basin, southeastern Nigeria, to establish different palynomorphs assemblage zones, with their corresponding *** analysis was carried out on 27 selected outcrop samples, using the conventional maceration technique for recovering acid-insoluble organic-walled microfossils from sediments. Three Cenozoic lithostratigraphic units, including Imo Formation, Ameki Formation, and Ogwashi Formation, are exposed in the study area. Lithologies are sandstone, carbonaceous shale, mudstone, limestone, and the lignite. A total of 65 species of sporomorphs and 51 dinoflagellate cysts were identified. The recovered spores and pollen grains were used to establish six informal palynomorph assemblage zones, labeled as zone A – zone F, based on the first and the last occurrences of two or more species. These palynomorph assemblage zones include:(1) zone A — middle Paleocene Scabratriporites simpliformis–Bombacidites annae zone;(2) zone B — late Paleocene Foveotricolporites crassiexinus–Mauritidiites crassiexinus zone;(3) zone C — early Eocene Striatopollis catatumbus–Momipites africanus zone;(4) zone D — middle Eocene Margocolporites umuahiaensis–Gemmastephanocolporites brevicolpites zone;(5)zone E — late Eocene Cicatricosisporites dorogensis–Perfotricolpites nigerianus zone;and,(6) zone F — Oligocene–early Miocene Verrucatosporites usmensis–Magnastriatites howardii zone. The erected palynozones were correlated and compared with existing biozones in subsurface, down-dip sectors of the Niger Delta Basin, with pantropical palynological zones in tropical areas of Africa, and with palynofloral provinces of northern South America. A comparison of palynozones studied in southeastern Nigeria with other international palynozones, in this study, will assist in establishing

关键词： Palynology Stratigraphy Biozonation Spores and pollen grains Dinoflagellate cysts Cenozoic Niger Delta Basin

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Rare Earth Elements Geochemistry of Sheikh-Marut Laterite Deposit,NW Mahabad,West-Azarbaidjan Province,Iran

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Acta Geologica Sinica(English Edition) 2013年第1期87卷 176-185页

作者： Ali ABEDINI Ali Asghar CALAGARI geology department Faculty of SciencesUrmia University geology department Faculty of Natural SciencesUniversity of Tabriz

Laterite deposit at Sheikh-Marut （NW occurred within middle-upper Permian carbonate Mahabad, West-Azarbaidjan province, Iran） rocks. It consists of seven stratiform and/or discontinuous lenticular layers extending over 4.2 km in length and having thicknesses ranging from 3 to 14 m. Mineralogical data show that the ores contain kaolinite and hematite as major and boehmite, diaspore, halloysite, amesite, anatase, and muscovite-illite as minor mineral phases. The computed Ce anomaly values in the ores range from 0.05 to 20.84. Conservative index （e.g., Eu/Eu＊） suggests that this deposit is a product of alteration and weathering of basaltic rocks. Rhythmic increment of EREE values of the ores with approaching to the carbonate bedrocks shows an in-situ occurrence of lateritization processes. Mass change calculations of elements indicate that two competing processes namely leaching and fixation were the major regulating factors in concentration variation of REEs （La-Lu） in this deposit. The obtained results show that pH increase of weathering solutions by carbonate bedrocks, existence of organic matters, and the degree of comlexation with organic ligands played remarkable role in distribution of REEs during lateritization. Further geochemical considerations revealed that secondary phosphates, Mn-oxides and -hydroxides, diaspore, and anatase were the potential hosts for REEs in this deposit.

关键词： laterite geochemistry REEs Sheikh-Marut deposit Mahabad Iran

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Electromicrobiology and biotechnological applications of the exoelectrogens Geobacter and Shewanella spp.

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Science China(Technological Sciences) 2019年第10期62卷 1670-1678页

作者： SHI MeiMei JIANG YongGuang SHI Liang department of Biological Sciences and Technology School of Environmental StudiesChina University of GeosciencesWuhan430074China State Key Laboratory of Biogeology and environmental geology China University of GeosciencesWuhan430074China

Electromicrobiology is a sub-discipline of microbiology that investigates electrical interplay between microorganisms and redox active materials, such as electrodes and solid-phase minerals, and the mechanisms underlying microbial ability to exchange electrons with the redox active materials that are external to the microbial cells. The microorganisms with extracellular electron transfer capability are often referred to as exoelectrogens. Although exoelectrogens were documented in early 1900’s, discovery of the dissimilatory metal-reducing microorganisms Geobacter and Shewanella spp. in late 1980’s marked the beginning of modern electromicrobiology. Since then, thorough and rigorous studies have made Geobacter and Shewanella spp. the two best characterized groups of exoelectrogens. These include identification and characterization of the molecular mechanisms for exchanging electrons with electrodes by Geobacter sulfurreducens and Shewanella oneidensis. In addition, a variety of applications of Geobacter and Shewanella spp. in microbial fuel cells and electrobiosynthesis, such as maintenance of redox balance during fermentations and bioremediations, have also been developed. This review briefly discusses the molecular mechanisms by which G. sulfurreducens and S. oneidensis exchange electrons with electrodes and then focuses on biotechnological applications of Geobacter and Shewanella spp. in microbial fuel cells and electrobiosynthesis as well as the future directions of this research area.

关键词： electromicrobiology exoelectrogen Geobacter Shewanella microbial fuel cells electrobiosynthesis

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Transferring Google Earth observations to GIS-software: example from gully erosion study

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International Journal of Digital Earth 2013年第2期6卷 196-201页

作者： Amaury Frankl Ann Zwertvaegher Jean Poesen Jan Nyssen department of Geography Ghent UniversityGhentBelgium department of geology and Soil Science Ghent UniversityGhentBelgium department of Earth and environmental Sciences KU LeuvenHeverleeBelgium

High-resolution images availableonGoogle Earth are increasingly beingconsulted in geographic ***,most studies limit themselves to visualizations or on-screen *** Earth allows users to create points,lines,and polygons on-screen,which can be saved as Keyhole Markup Language(KML)***,the use of R statistics freeware is proposed to easilyconvertthese files to the shapefile format[or‘.shp file format’],which can be loaded into Geographic Information System(GIS)software(ESRI ArcGIS 9 in our example).The geospatial data integration in GIS strongly increases the analysis possibilities.

关键词： geographic study geospatial data integration Google Earth

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Petrology,geochemistry,and zircon U-Pb geochronology of the Zambezi Belt in Zimbabwe:Implications for terrane assembly in southern Africa

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Geoscience Frontiers 2019年第6期10卷 2021-2044页

作者： Yusuke Kuribara Toshiaki Tsunogae Yusuke Takamura Yukiyasu Tsutsumi Graduate School of Life and environmental Sciences University of TsukubaIbaraki 305-8572Japan department of geology University of JohannesburgAuckland Park 2006South Africa department of geology and Paleontology National Museum of Nature and ScienceIbaraki 305-0005Japan

The Zambezi Belt in southern Africa has been regarded as a part of the 570-530 Ma Kuunga Orogen formed by a series of collision of Archean cratons and Proterozoic orogenic ***,we report new petrological,geochemical,and zircon U-Pb geochronological data of various metamorphic rocks(felsic to mafic orthogneiss,pelitic schist,and felsic paragneiss)from the Zambezi Belt in northeastern Zimbabwe,and evaluate the timing and P-T conditions of the collisional event as well as protolith *** data of felsic orthogneiss indicate within-plate granite signature,whereas those of mafic orthogneiss suggest MORB,ocean-island,or within-plate *** P-Testimates for orthogneisses indicate significant P-T variation within the study area(700-780 C/6.7-7.2 kbar to 800-875 C/10-11 kbar)suggesting that the Zambezi Belt might correspond to a suture zone with several discrete crustal *** cores from felsic orthogneisses yielded two magmatic ages:2655±21 Ma and 813士5 Ma,which suggests Neoarchean and Early Neoproterozoic crustal growth related to within-plate *** zircons from metasediments display various ages from Neoarchean to Neoproterozoic(ca.2700-750 Ma).The Neoarchean(ca.2700-2630 Ma)and Paleoproterozoic(ca.2200-1700 Ma)zircons could have been derived from the adjacent Kalahari Craton and the Magondi Belt in Zimbabwe,*** Choma-Kalomo Block and the Lufilian Belt in Zambia might be proximal sources of the Meso-to Neoproterozoic(ca.1500-950 Ma)and early Neoproterozoic(ca.900-750 Ma)detrital zircons,*** detrital zircons from adjacent terranes possibly deposited during late Neoproterozoic(744-670 Ma),and subsequently underwent highgrade metamorphism at 557-555 Ma possibly related to the collision of the Congo and Kalahari Cratons during the latest Neoproterozoic to *** contrast,670-627 Ma metamorphic ages obtained from metasediments are slightly older than previous reports,but consistent with^68

关键词： Geothermobarometry Detrital zircon Neoproterozoic Congo Craton Kalahari Craton Gondwana

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Sedimentary facies analysis of a high-frequency,small-scale,peritidal carbonate sequence in the Lower Jurassic of the Tripolis carbonate unit (central western Crete,Greece):Long-lasting emergence and fossil laminar dolocretes horizons

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Journal of Palaeogeography 2016年第3期5卷 241-257页

作者： Fotini A.Pomoni Vassilis Karakitsios Section of Historical geology and Paleontology Department of Geology and GeoenvironmentNational and Kapodistrian University of Athens

Abstract The study examines a Lower Jurassic （late Liassic） cyclic lagoonal-peritidal stratigraphic unit outcropping in central western Crete （Tripolis unit）, which corresponds to the eastern （internal） part of the mainland Gavrovo-Tripotis platform, the most significant external platform of the Hetlenides. The studied Tripolis carbonate sequence consists of meter-scale, shallowing-upward successions of restricted inner- carbonate platform facies, including cyclically repeated subtidal, intertidal and supratidal facies, that are separated by erosion surfaces （elementary cycles）. Each cycle starts with relatively open-marine facies, which are overlain by shallower, more restricted facies （tidal fiat progradation）. The lithofacies association includes dotomitic intraclastic-peloidal-bioclastic wackestones-packstones/floatstones and grainstones/rudstones dominated by a restricted shallow-marine fauna （bivalves, gastropods, ostracods and seldom benthic fora- minifers）, representing a shaUow subtidal to intertidal, moderately high-energy environment within an inner- platform setting （peritidal environment to restricted lagoon）. This lithofacies association has been intermit- tently subaeriaUy exposed and has undergone diagenetic processes in an inter- or supratidal environment, exhibiting features of vadose diagenesis and pedogenesis due to long-lasting exposure along certain horizons. The peritidat facies are capped by dolocretes controlled by root-activities （laminar dolocretes, petoi- dat-pisoid dolocretes and massive dotocretes）, marking the end of each depositional cycle, and, thus, dis- tinguishing the successive episodes of a prolonged subaerial exposure period and birth of pateosol horizons. Dotocretes consist a diagenetic facies, characterized by several vadose and pedogenic fabrics, including fenestral cavities with geopetal structures, ＂flower spar＂ to blocky sparry cement in primary pores, micritic coatings, crudely pelleted watts, atveotar-septat texture, in

关键词： External Heltenides Lower Jurassic Tripotis carbonate unit Peritidat environment Cyclo-thems Penesaline dolomites Dotocrete horizons "flower spar" dolomite cement

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geology and Mineral Chemistry of Gold Mineralization in Mirge-Naqshineh Occurrence(Saqez,NW Iran):Implications for Transportation and Precipitation of Gold

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Acta Geologica Sinica(English Edition) 2018年第1期92卷 210-224页

作者： Golale ASGHARI Samad ALIPOUR Hossein AZIZI Hassan MIRNEJAD department of geology Urmia University Mining department Faculty of Engineering University of Kurdistan department of geology Faculty of Science University of Tehran

The Mirge-Naqshineh gold district is situated at northwest of Iran with a NW-trending brittle- ductile shear zone. It is hosted by Precambrian meta-sedimentary and meta-volcanic units traversed by mineralized quartz veins. In terms of cross-cutting relationships and sulfide content three types of quartz veins are identified in the region. Among those, parallel to bedding quartz vein （type I） is the main host for gold mineralization. Gold is found in three different forms： 1） submicrometer-size inclusions of gold in arsenian pyrite, 2） as electrum and 3） in the crystal lattice of sulfides （pyrite, galena and chalcopyrite）. Six types of pyrite （Pyl-Py6） were identified in this ore reserve. Py3 coexists with arsenopyrite and contains the greatest As-Au concentrations. There is a negative correlation between the As and S contents in Py2 and Py3, implying the substitution of sulfur by arsenic. Pyrites and mineralized quartz veins were formed via metamorphic-hydrothermal fluid and reflect the gold-transportation as Au（HS）2 under reducing and acidic conditions. The gold precipitation mainly controlled by crystallization of arsenian pyrite during fluid/rock interactions and variation offO2. The volcanic host rock has played an important role in gold concentration, as Py3 in this rock contains inclusion of gold particles, but gold is within the lattice of pyrite in phyllite or other units.

关键词： gold quartz veins mineral chemistry EPMA Mirge-Naqshineh Iran

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environmental Isotopic Characterization of Groundwater and Surface Water in Northeast Missan Province,South Iraq

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Acta Geologica Sinica(English Edition) 2014年第4期88卷 1227-1238页

作者： Hussein Badr GHALIB Ali Riza SGüT Selcuk University college of EngineeringGeology DepartmentSelcukTurkey Basrah University Geology DepartmentBasrahIraq

The present work studies the environmental isotopes assess groundwater characteristics of the different parts of the main aquifer in the northeast Missan Province in south of Iraq. Water samples of groundwater and surface water were collected for two dry and wet seasons during the water year of 2011-2012. The study shows that most of the groundwater in the aquifer falls above the global meteoric water line, and all the samples fall below the Mediterranean meteoric water line, indicating that these samples are a mixture of two water types. The tritium content of these samples supports this conclusion. The overall conclusion of this study indicates that there are two sources of groundwater recharge in the studied area： the ephemeral streams （Teeb and Dewerge） and major precipitation sources. According to the tritium levels at or below one tritium unit （TU） obtained from the water, supply wells are highly confined or ＂not vulnerable＂. Overall, the 3^H results imply that recent recharge has taken place during the last four to five decades. In the recharge area, the high tritium content in the southern part of the Teeb area suggests that the recharge originates from rapid infiltration of surface runoff. Therefore, the groundwater resources in the study area should be protected from contamination, because it will influence the aquifer in a relatively short period of time if any contamination enters the recharge areas of the aquifer.

关键词： Groundwater recharge Tritium environmental isotope meteoric water line Iraq

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Precise dating of abrupt shifts in the Asian Monsoon during the last deglaciation based on stalagmite data from Yamen Cave, Guizhou Province, China

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Science China Earth Sciences 2010年第5期53卷 633-641页

作者： EDWARDS R. Lawrence department of geology and Geophysics University of Minnesota

Based on 33 U/Th dates and 1020 oxygen isotopic data from stalagmite Y1 from Yamen Cave, Guizhou Province, China, a record of the Asian Summer Monsoon (ASM) was established. The record covers the last deglaciation and the early Holocene (from 16.2 to 7.3 ka BP) with an average oxygen isotope resolution of 9 years. The main millennial-scale deglacial events first identified in Greenland (Greenland Interstadial Events: GIS 1e through GIS 1a) and later in China are clearly present in the Y1 record. By analogy to earlier work, we refer to these as Chinese Interstadials (CIS): CIS A.1e to CIS A.1a. The onset of these events in Y1 δ18O records are nominally dated at: 14750±50, 14100±60, 13870±80, 13370±80, and 12990±80 a BP. The end of CIS A.1a or the beginning of the Younger Dryas (YD) event is nominally at 12850±50 a BP and the end of the YD dates to 11500±40 a BP. The δ18O values shift by close to 3‰ during the transition into the Bφlling-Allerφd (BA, the onset of CIS A.1e) and at the end of the YD. Comparisons of Y1 to previously published early Holocene records show no significant phase differences. Thus, the East Asia Monsoon and the Indian Monsoon do not appear to have been out of phase during this interval. The Y1 record confirms earlier work that suggested that solar insolation and North Atlantic climate both affect the Asian Monsoon.

关键词： stalagmite Asian Monsoon the last deglaciation Holocene U-series dating Yamen Cave

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