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Anatomy of a eustatic event during the Turonian (Late Cretaceous) hot greenhouse climate

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Science China Earth Sciences 2017年第1期60卷 20-29页

作者： Bilal U. HAQ Brian T. HUBER Department of Paleobiology MRC-121Smithsonian InstitutionWashington D C 20013USA Sorbonne ISTEP Pierre&Marie Curie UniversityParis 75005France

Sequence stratigraphic studies consider relative change in sea level(as regulated by eustasy,local tectonics and sediment supply)as the main builder of the stratigraphic *** has generally been considered as a consequence of the growth and decay of continental ice sheets that would explain large,rapid changes in sea level,even during periods of relative global climatic ***,such a mechanism has become increasingly difficult to envision during times of extreme global warmth such as the Turonian,when the equator-to-pole temperature gradient was very low and the presence of polar ice seems *** paper investigates the timing and extent of sea level falls during the late Cenomanian through Turonian,especially the largest of those events,sequence boundary KTu4,which occurred during the middle to late Turonian peak of the Cretaceous hot greenhouse *** conclude that the amplitude of the widespread third-order sea level fall in the middle Turonian that is centered at^91.8 Ma varies at different locations depending on the influence of dynamic topography on local tectonics and regional climatic *** volume variations seem unlikely as a mechanism for controlling sea level at this ***,this causal factor cannot be ruled out completely since Antarctic highlands(if they existed in the Late Cretaceous)could sequester enough water as ice to cause eustatic *** ascertain this requires detailed tomographic imaging of Antarctica,followed by geodynamic modeling,to determine whether high plateaus could have existed to accumulate ephemeral ice *** mechanisms for sea level change,such as transference between ground water(a small amplitude shorter time scale effect)and the ocean and entrainment and release of water from the mantle to the oceanic reservoir(a potentially large amplitude and longer time scale process),are intriguing and need to be explored further to prove their efficacy at third-order time scales.

关键词： Eustatic event Turonian Hot greenhouse climate

Provenance of Late Mesozoic Strata and Tectonic Implications for the Southwestern Ordos Basin,North China:Evidence from Detrital Zircon U-Pb Geochronology and Hf Isotopes

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Journal of Earth Science 2022年第2期33卷 373-394页

作者： Zuoqiang Li Fengjie Li Zheng'an Chen Xuelian Lai Xiaokang Ma State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Chengdu University of TechnologyChengdu 610059China Institute of Sedimentary Geology Chengdu University of TechnologyChengdu 610059China 207 Geological Brigade of Sichuan Bureau of Exploration&Development of Geology&Mineral Resources Leshan 614000China

In order to determine the provenance and variation characteristics of sandstone-type uranium deposits located in the southwest Ordos Basin,U-Pb geochronology and Hf isotope analyses were conducted on detrital zircons from the Late Mesozoic strata of the SD01 well in the Zhenyuan *** detrital zircon U-Pb ages of four samples exhibited four main peaks at 250–330,420–500,1720–2000,and 2340–2580 Ma,with a small number of zircons dated at 770–1100 *** detrital zircon age spectrum and further restriction provided by the in-situ Hf isotopic data suggest that the provenance of each stratum was mainly derived from the crystalline basement rock series(Khondalites,intermediate-acidic intrusive rocks,and metamorphic rocks)of the Alxa Block to the northwest and the Yinshan Block to the north,with minor amounts of Caledonian magmatic rocks and Jingning Period rocks from the western part of the northern Qilian orogenic belt to the west and the northern Qinling orogenic belt to the *** provenance of the sandbody has not changed significantly and is of the Middle Jurassic–Early *** clear variations in the zircon ages of the samples from the Zhiluo and Anding formations were likely influenced by climate change during the Middle–Late *** Triassic zircon age(<250 Ma)first appeared in Early Cretaceous strata,suggesting that tectonic activity was relatively strong in the northern Qinling orogenic belt during the Late Jurassic and produced extensive outcrops of Indo-Chinese granite,which were a source of basin sediments.

关键词： Southwestern Ordos Basin provenance analysis Late Mesozoic detrital zircon U-Pb geochronology Hf isotopes geochemistry

Stable isotope paleohydrology and chemostratigraphy of the Albian Wayan Formation from the wedge-top depozone,North American Western Interior Basin

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Science China Earth Sciences 2017年第1期60卷 44-57页

作者： Jeffrey B.ROSS Greg A.LUDVIGSON Andreas MOLLER Luis A.GONZALEZ J.D.WALKER Department of Geology University of Kansas Kansas Geological Survey University of Kansas

Understanding of the role of atmospheric moisture and heat transport in the climate system of the Cretaceous greenhouse world represents a major challenge in Earth system science. Stable isotopic paleohydrologic data from mid-Cretaceous paleosols in North America, from paleoequatorial to paleoArctic latitudes, have been used to constrain the oxygen isotope mass balance of the Albian hydrologic cycle. Over the range from 40°-50°N paleolatitude, sideritic paleosols predominate, indicating paleoenvironments with positive precipitation-evaporation （P-E） balances. Local exceptions occur on leeward side of the Sevier Orogen, where calcic paleosols in the wedge-top depozone record paleoenvironments with negative P-E balances in the orographic rain shadow. Stratigraphic sections in the Wayan Formation of Idaho （WF） were sampled from the wedge-top depozone. The units consist of stacked m-scale mudstone paleosols separated by m-scale sandstone-siltstone beds. Sections were sampled for organic carbon isotope profiles, and B-horizons from 6 well-developed paleosols were sampled for detrital zircons to determine maximum depositional ages. The first of these from the WF has produced a U-Pb concordia age of 101.0±1.1 Ma. This same WF section has produced a stratigraphic trend of upwardly decreasing δ18C values ranging from -24‰ upwards to -27‰ VPDB, suggesting correlation to the late Albian C15 C-isotope segment. Pedogenic carbonates from the WF principally consist of micritic calcite, with carbon-oxygen isotope values that array along meteoric calcite lines （MCLs） with δ18O values that range from -9.47‰ up to -8.39‰ VPDB. At approximately 42°N paleolatitude, these MCL values produce calculated paleoprecipitation values of-8.12‰ to -7.04‰ VSMOW, a range that is consistent with the estimates produced from other proxies at the same paleolatitudes across North America. These results indicate that despite the orographic rain shadow effect, the processes of meridional atmospheric moist

关键词： Cretaceous Paleoclimate Wayan Formation Pedogenic carbonates Geochronology

Characterization of the negative carbon isotope shift in segment C2,its global implications as a harbinger of OAEla

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Science China Earth Sciences 2017年第1期60卷 30-43页

作者： Jander SOCORRO Florentin J-M. R. MAURRASSE Yosmel SANCHEZ-HERNANDEZ Department Earth and Environment Florida International University 11200 SW 8 Street Miami FL 33199 USA

Lower Cretaceous C-isotope records show intermittent negative/positive spikes, and consistent patterns of coevalchemostratigraphic curves thus document shifts that signal simultaneous responses of temporal changes in the global carbon reservoir. The standard pattern registered by the δ13Corg and δ13Ccarb in Lower Aptian sediments includes distinct isotope segments C1 to C8 （Menegatti et al., 1998）. In the E1 Pui section, Organy Basin, Spain, C-isotope segment C2 is the longest interval preceding segments C3-C6 associated with oceanic anoxic event la （OAE la）, and reveals a distinct negative shift of-1.8‰ to -2.23‰ defining the C-isotope pattern within that interval. Total inorganic carbon （TIC）, total organic carbon （TOC）, δ13Corg, microfacies, n-alkanes show no difference before, during, or after the negative inflection. The biomarkers indicate that organic matter （OM） mainly originates from algal/microbial sources because short-chain length homologues （〈 nCtg） dominate, nC2o through nC25 indicate some contribution from aquatic vegetation, but little from higher plants （〉nC20, as also suggested by the terrestrial/aquatic ratio ofn-alkanes or （TAR） = [（nf27＋nf29＋nC31）/（nC15＋nCt7＋rlCt9）] （averages 0.085）. We suggest that conjoint pulses of contemporaneous LIPs （Ontong Java） and massive explosive volcanism in northeast Asia, the Songliao Basin （SB-V）, best conform to plausible causes of the negative intra-C2 carbon isotopic excursion （CIE） at that time. Because of its apparent common occurrence the intra-C2 inflection could be a useful marker harbinger to the more pronounced CIE C3, the hallmark of OAE 1 a.

关键词： Oceanic Anoxic Event la (OAEla) Aptian Organy Basin Chemostratigraphy Pyrenees

On the Karst Ecosystem

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Acta Geologica Sinica(English Edition) 2001年第3期75卷 336-338页

作者： Yuan Daoxian Karst Dynamics Laboratory Ministry of Land and Resources Guilin 541004GuangxiChina

In this paper the author gives a definition of the karst ecosystem and discusses the characteristics of the karst environment and karst ecosystem and the relationship between life and the karst environment. Finally he... 详细信息

关键词： karst ecosystem carbonate rock karst environment

Detrital zircon U-Pb ages of Late Cenozoic sediments from the Yangtze delta:Implication for the evolution of the Yangtze River

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Chinese Science Bulletin 2010年第15期55卷 1520-1528页

作者： JIA JunTao ZHENG HongBo HUANG XiangTong WU FuYuan YANG ShouYe State Key Laboratory of Marine Geology Tongji University Shanghai 200092 China School of Earth Science and Engineering Nanjing University Nanjing 210093 China State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Detrital zircon grains of Late Cenozoic sediments dated back to ca.3.6 Ma from core DY03 in the Yangtze delta were dated by LA-ICP-MS,in order to investigate the sedimentary provenance and to find some clue for the evolution of the Yangtze *** of the detrital zircon U-Pb ages are distributed at 100 300 Ma,350 550 Ma,600 1000 Ma,1400 2000 Ma and 2200 2800 Ma,which correspond well with the main tectonic and magmatic events in the Yangtze *** detrital zircon age patterns show distinct difference between the 3 samples below 189.8 m and other 6 above 189.8 m.43% 55% zircons in the 3 samples below 189.8 m fall within Cretaceous,while ages from 150 to 2800 Ma are distributed with no obvious peaks,which indicate the sedimentary provenance may be limited to the lower Yangtze *** 6 samples above 189.8 m show similar age patterns,and the ages are relatively evenly distributed,indicating the sedimentary provenance broadened *** 6 samples deposited later than ca.3.2 Ma show age information from the upper Yangtze drainage (including the Emeishan large igneous province),indicating that the Three Gorges may have already been cut through by then.

关键词：长江三角洲活动年龄碎屑锆石晚新生代沉积物演化 Pb 峨眉山大火成岩省

Characteristics of Pegmatite-Related Fluids and Significance to Ore-Forming Processes in the Zhaxikang Pb-Zn-Sb Polymetallic Deposit,Tibet,China

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Acta Geologica Sinica(English Edition) 2015年第3期89卷 811-821页

作者： XIE Yuling WANG Bogong LI Yingxu LI Guangming DONG Suiliang GUO Xiang WANG Lei School of Civil and Environmental Engineering University of Science and Technology Beijing Key Laboratory of High-Efficient Mining and Safety of Metal Mines Ministry of Education Chengdu Institute of Geology and Mineral Resources

The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic *** to the porphyry deposits in the Gangdese belt,much less researches have addressed these deposits,and the genesis of the Zhaxikang deposit is still *** on field investigation,petrographic,microthermometric,Laser Raman Microprobe（LRM） and SEM/EDS analyses of fluid,melt-fluid,melt and solid inclusions in quartz and beryl from pegmatite,this paper documents the characteristics and the evolution of primary magmatic fluid which was genetically related to greisenization,pegmatitization,and silification in the *** results show that the primary magmatic fluids were derived from unmixing between melt and fluid and underwent a phase separation process soon after the *** primary magmatic fluids are of low salinity,high temperature,and can be approximated by the H_2O-NaCl-CO_2 *** presence of Mn-Fe carbonate in melt-fluid inclusions and a Zn-bearing mineral（gahnite） trapped in beryl and in inclusions from pegmatite indicates high Mn,Fe,and Zn concentrations in the parent magma and magmatic fluids,and implies a genetic link between pegmatite and Pb-Zn-Sb *** B and F concentrations in the parent magma largely lower the solidus of the magma and lead to late fluid exsolution,thus the primary magmatic fluids related to pegmatite have much lower temperature than those in most porphyry *** of the primary magmatic fluids leads to high-salinity and high-temperature fluids which have high capacity to transport Pb,Zn and *** decrease in temperature and mixing with fluids from other sources may have caused the precipitation of Pb-Zn-Sn（Au） minerals in the distal fault systems surrounding the causative intrusion.

关键词： Zhaxikang Pb-Zn-Sb deposit South Tibte Sb-Au metallogenic belt fluid inclusion,pegmatite ore-forming process

Zooming in REE and Other Trace Elements on Conodonts:Does Taxonomy Guide Diagenesis?

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Journal of Earth Science 2021年第3期32卷 501-511页

作者： Luca Medici Martina Savioli Annalisa Ferretti Daniele Malferrari National Research Council of Italy Institute of Methodologies for Environmental AnalysisC.da S.Loja-Zona Industriale85050 Tito ScaloPotenzaItaly Department of Chemical and Geological Sciences University of Modena and Reggio EmiliaVia Campi 10341125 ModenaItaly

Conodont elements are calcium phosphate(apatite structure)mineralized remains of the cephalic feeding apparatus of an extinct marine *** to the high affinity of apatite for rare earth elements(REE)and other high field strength elements(HFSE),conodont elements were frequently assumed to be a reliable archive of sea-water composition and changes that had occurred during ***,the crystallinity index of bioapatite,i.e.,the rate of crystallinity of biologically mediated apatite,should be generally linearly dependent on diagenetic alteration as the greater(and longer)the pressure and temperature to which a crystal is exposed,the greater the resulting *** this study,we detected the uptake of HFSE in conodont elements recovered from a single stratigraphic horizon in the Upper Ordovician of Normandy(France).Assuming therefore that all the specimens have undergone an identical diagenetic history,we have assessed whether conodont taxonomy(and morphology)impacts HFSE uptake and crystallinity *** found that all conodont elements are characterized by a clear diagenetic signature,with minor but significant differences among *** distinctions are evidenced also by the crystallinity index values which show positive correlations with some elements and,accordingly,with diagenesis;however,correlations with the crystallinity index strongly depend on the method adopted for its calculation.

关键词： bioapatite crystallinity index HFSE laser ablation mass spectrometry microdiffraction Normandy Ordovician

Sandbox Experi mental Study on the Influence of Rock Strength and Gravity on Formation of Thrusts

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Journal of China University of Geosciences 2006年第1期17卷 43-48页

作者：魏春光周建勋何雨丹 School of Earth Sciences and Resources China University of Geosciences Beijing100083 China Key Laboratory for Hydrocarbon Accumulation China University of Petroleum Beijing102249 China International Exploration Company of SINOPEC Beijing100083 China

A sandbox experiment model was designed to simulate how differences in rock strength and gravity between two blocks can influence the formation characteristics of thrusts. In the experiment the compression was from one direction with basement shortening and the initial surfaces of the model were oblique. The results show that if the initial surface was horizontal or the slope angle was smaller than 7°, the compression induced two groups of thrusts with opposite dip orientations. If the slope angle of the initial surface was greater than 7°, the compression induced only one group of thrusts with a dip orientation contrary to the original compression direction. This result is similar to the actual section of a collision zone between two continental blocks. By applying stress analysis, rock strength is shown to be an important factor in deformation. As other boundary conditions are changeless, it is the change of gravitational potential energy that leads to different deformation styles.

关键词： sandbox experiment strength surface slope thrusts energy gravity