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Controls on sediment transport from rivers to trenches in passive and active continental margins

Science China Earth Sciences 2024年

作者： Letian ZENG Ce WANG david a.foster Ming SU Heqi CUI Junmin JIA School of Marine Sciences Sun Yat-sen University Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering Department of Geological Sciences University of Florida

Active and passive continental margins exhibit significant differences in sediment transport. However, opportunities to quantify these specific sedimentary processes remain limited. The northeastern South China Sea hosts both active and passive continental margins, offering a distinct opportunity to compare the relative contributions from a large passive continental margin with those from a smaller but more dynamic active margin. We present detrital zircon U-Pb ages from marine sediments in the northeastern South China Sea to decipher their provenance and reveal the control of transport processes in the margins. Our results show varied provenance of sediments from the shelf to the trench. In the continental shelf, sediments were primarily derived from the Jiulong and Gaoping rivers, controlled by the topography and ocean currents in the passive margin. In contrast,the sediments in the submarine canyons predominantly originated from the Gaoping and Zhuoshui rivers in western Taiwan Island. Quantitative results indicate that the Gaoping submarine canyon provided approximately 86.2% of sediments to the Manila Trench by directly linking to the Gaoping River in the active margin. Based on the provenance results, we propose a distinct sedimentary process in the active and passive margins. In passive margins, sediments from drainage systems enter the shelf and are transported by ocean currents, but topographic highs often block these sediments, preventing them from reaching the deep sea. In contrast, active margins feature narrow shelves, which facilitate direct connections between submarine canyons and river mouths, allowing gravity flows to carry sediments directly to the trenches. Our study provides an understanding of the sediments transported from rivers to trenches in the northeastern South China Sea and highlights the controls(ocean currents,dramatic topography, and gravity flows) during the sediment transport in the continental margins.

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从河流到海沟:主动和被动陆缘沉积搬运的主控因素

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中国科学:地球科学 2024年

作者：曾乐田王策 david a.foster 苏明崔贺旗贾俊民中山大学海洋科学学院南方海洋科学与工程广东省实验室(珠海) 广东省海洋资源与近岸工程重点实验室 Department of Geological Sciences University of Florida

主动和被动陆缘沉积物的输送存在显著差异,然而定量研究这些特定沉积过程的机会相对较少.南海东北部既包含主动陆缘,也包含准被动陆缘,为区分这两类陆缘沉积物物源和搬运过程提供了独特的研究区域.本研究通过分析表层沉积物中的碎屑锆石... 详细信息

主动和被动陆缘沉积物的输送存在显著差异,然而定量研究这些特定沉积过程的机会相对较少.南海东北部既包含主动陆缘,也包含准被动陆缘,为区分这两类陆缘沉积物物源和搬运过程提供了独特的研究区域.本研究通过分析表层沉积物中的碎屑锆石U-Pb年龄来示踪南海东北部不同区域沉积物的物源,揭示影响陆缘沉积物搬运的主要控制因素.研究结果显示,南海东北部从大陆架到马尼拉海沟的沉积物物源在空间上存在显著差异.陆架区沉积物主要来源于华南东部的九龙江和台湾岛西南部的高屏溪,沉积物搬运受被动陆缘地形和洋流的控制.相比之下,澎湖-高屏峡谷系统中的沉积物主要来自于台湾岛西部的高屏溪和浊水溪.定量分析结果表明,由于高屏峡谷与高屏溪直接相连,该峡谷为马尼拉海沟提供了～86.2%的陆源碎屑物质.基于物源分析结果,本研究提出了不同类型陆缘的沉积物搬运模式.在被动陆缘,入海水系带来的沉积物进入大陆架后受洋流的影响显著,而较高的地形会阻碍其搬运,导致沉积物难以进入海沟系统.相反,在主动陆缘,由于陆架较窄,海底峡谷可与河口直接相连,重力流能够将大量沉积物直接输送至海沟进行沉积.该研究有助于揭示南海东北部沉积物从河流到海沟的搬运过程,并探讨影响陆缘沉积物输送的主要控制因素.

关键词：沉积物搬运过程物源示踪碎屑锆石海底峡谷陆缘中国南海

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Deformation correlations,stress field switches and evolution of an orogenic intersection:The Pan-African Kaoko-Damara orogenic junction,Namibia

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Geoscience Frontiers 2017年第6期8卷 1187-1232页

作者： Ben Goscombe david a.foster david Gray Ben Wade Antonios Marsellos Jason Titus Integrated Terrane Analysis Research(ITAR) 18 Cambridge RdAldgate5154SAAustralia Department of Geological Sciences University of FloridaGainesvilleFL32611USA School of Earth Sciences University of TasmaniaHobartTASAustralia Adelaide Microscopy University of AdelaideAdelaide5005SAAustralia Hofstra University HempsteadNYUSA

Age calibrated deformation histories established by detailed mapping and dating of key magmatic time markers are correlated across all tectono-metamorphic provinces in the Damara Orogenic *** across structural belts result in an internally consistent deformation framework with evidence of stress field rotations with similar timing,and switches between different deformation *** principle compressive stress rotated clockwise ~180°in total during Kaoko Belt evolution,and^135° during Damara Belt *** most stages,stress field variation is progressive and can be attributed to events within the Damara Orogenic System,caused by changes in relative trajectories of the interacting Rio De La Plata,Congo,and Kalahari *** orogenesis occurred earliest and evolved from collision and obduction at ~590 Ma,involving E-W directed shortening,progressing through different transpressional states with ~45° rotation of the stress field to strike-slip shear under NW-SE shortening at ~550-530 *** orogenesis evolved from collision at ~555-550 Ma with NW-SE directed shortening in common with the Kaoko Belt,and subsequently evolved through ~90°rotation of the stress field to NE-SW shortening at ~512-508 *** Kaoko and Damara orogenic fronts were operating at the same time,with all three cratons being coaxially convergent during the 550-530 Ma period;Rio De La Plata directed SE against the Congo Craton margin,and both together over-riding the Kalahari Craton margin also towards the *** stress field rotation was punctuated by rapid and significant switches at ~530-525 Ma,~508 Ma and ~505 *** three events included:(1)Culmination of main phase orogenesis in the Damara Belt,coinciding with maximum burial and peak metamorphism at 530-525 *** occurred at the same time as termination of transpression and initiation of transtensional reactivation of shear zones in the Kaoko *** compressive stress switched from NW-

关键词： Damara Orogen Stress fields Orogeny Assembly of Gondwana Event geochronology Deformation correlations

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TGF-β信号缺陷是否是人类癌症中的致命弱点?

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癌症 2008年第8期27卷 882-884页

作者： david a.foster Noga Gadir Department of Biological Sciences Hunter College of the City University of New YorkNew YorkUSA Department of Biological Sciences Hunter College of the City University of New YorkNew YorkNew YorkUSA Department of Molecular GeneticsWeizmann Institute of ScienceRehovot 76100Israel

癌细胞中的存活信号可激活mTOR-哺乳动物雷帕霉素靶蛋白。mTOR可抑制TGF-β信号,后者可使细胞周期停滞于G1后期,因此,活化后的mTOR可防止细胞周期停滞于TGF-β介导的检验点。雷帕霉素可重新激活TGF-β信号,从而导致G1期细胞停滞。在人... 详细信息

癌细胞中的存活信号可激活mTOR-哺乳动物雷帕霉素靶蛋白。mTOR可抑制TGF-β信号,后者可使细胞周期停滞于G1后期,因此,活化后的mTOR可防止细胞周期停滞于TGF-β介导的检验点。雷帕霉素可重新激活TGF-β信号,从而导致G1期细胞停滞。在人类癌症中,TGF-β信号通常发生缺陷,相反,在雷帕霉素作用下,TGF-β信号缺陷的癌细胞不发生G1期停滞,而发生凋亡。因此,在基于雷帕霉素的抗癌治疗策略中,TGF-β信号缺陷可能是癌细胞的致命弱点。

关键词： TGF-β mTOR 雷帕霉素凋亡存活信号癌细胞

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The magnetosheath at high spectral resolution

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Earth and Planetary Physics 2024年第1期8卷 234-246页

作者： K.D.Küntz D.Koutroumpa W.R.Dunn a.foster F.S.Porter D.G.Sibeck B.Walsh The Henry A.Rowland Department of Physics and Astronomy Johns Hopkins University3701 San Martin DriveBaltimoreMD21218USA NASA Goddard Space Flight Center 8800 Greenbelt RoadGreenbeltMD 20771USA LATMOS-OVSQ CNRSUVSQ Paris-SaclaySorbonne Université11 Boulevard d’Alembert78280GuyancourtFrance Department of Physics and Astronomy University College LondonLondonUK The Centre for Planetary Science at UCL/Birkbeck Gower StreetLondon WC1E 6BTUK Center for Astrophysics Harvard University&Smithsonian Institution60 Garden StreetCambridgeMA 02138USA Center for Space Physics Boston University110 Cummington MallBostonMAUSA

While we eagerly anticipate SMILE’s(Solar wind Magnetosphere Ionosphere Link Explorer)unprecedented X-ray observations of the Earth’s magnetosheath and the initiation of a new era of magnetospheric research,it seems appropriate to look ahead to the abilities of the next generation of astrophysics *** these,the Line Emission Mapper(LEM),a large aperture micro-calorimeter based mission,is currently planned to be able to observe the magnetosheath at high spectral resolution(~2 eV).With a field of view of~30′,LEM will allow higher spatial resolution and higher cadence measurement of the motion of a very small portion of the magnetopause over relatively short periods of time(multiple hours),complementing SMILE’s global ***’s strength is its spectral *** will be able to measure the abundance of a broad range of elements and ionization states,many of which are inaccessible to current in situ instruments,and will be able to separate the emission from the magnetosheath from the emission from the cosmic X-ray background using the difference in their relative velocities.

关键词： magnetosheath charge exchange solar wind abundances

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Late Ordovician Mass Extinction: Earth, fire and ice

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National Science Review 2024年第1期11卷 51-65页

作者： david A.T.Harper Palaeoecosystems Group Department of Earth SciencesDurham University

The Late Ordovician Mass Extinction was the earliest of the ‘big’ five extinction events and the earliest to affect the trajectory of metazoan life. Two phases have been identified near the start of the Hirnantian period and in the middle. It was a massive taxonomic extinction, a weak phylogenetic extinction and a relatively benign ecological extinction. A rapid cooling, triggering a major ice age that reduced the temperature of surface waters, prompted a drop in sea level of some 100 m and introduced toxic bottom waters onto the shelves. These symptoms of more fundamental planetary processes have been associated with a range of factors with an underlying driver identified as volcanicity. Volcanic eruptions, and other products, may have extended back in time to at least the Sandbian and early Katian, suggesting the extinctions were more protracted and influential than hitherto documented.

关键词： Ordovician LOME paleoecology palaeobiogeography biotas

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One-dimensional monotone nonautonomous dynamical systems

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Science China Mathematics 2024年第2期67卷 281-314页

作者： david Cheban Faculty of Mathematics and Computer Science Laboratory of Fundamental and Applied MathematicsMoldova State UniversityChisinau 2009Moldova

This work is devoted to the study of the dynamics of one-dimensional monotone nonautonomous(cocycle) dynamical systems. A description of the structures of their invariant sets, omega limit sets,Bohr/Levitan almost periodic and almost automorphic motions, global attractors, and pinched and minimalsets is given. An application of our general results is given to scalar differential and difference equations.

关键词： one-dimensional dynamics pinched and minimal sets global attractors monotone nonautonomous cocycle almost periodic solutions scalar differential/difference equations

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Kerogen Kinetic Distributions and Simulations Provide Insights into Petroleum Transformation Fraction (TF) Profiles of Organic-Rich Shales

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Journal of Earth Science 2024年第3期35卷 747-757页

作者： david A.Wood DWA Energy Limited Lincoln LN59JPUnited Kingdom

Two hundred and fifty single first-order Arrhenius reactions are simulated to generate S2 pyrograms at three heating rates 25,15,and 5°C·*** activation energy(E)and pre-exponential factor(A)of the reactions simulated follow a long-established trend of those variable values displayed by shales and *** characteristics of the transformation fraction(TF)profiles(product generation window temperatures)of the simulated single reactions are compared to the TF profiles of recorded shale pyrograms generated by multiple reactions with different E-A values lying near the defined E-A *** similarities and differences are observed between the TF profile values of the two *** similarities support the spread of E-A values involved in shale pyrogram best *** differences are most likely explained by the complexity of the multiple kerogen first-order and second-order reactions contributing to the recorded shale pyrograms versus the simplicity and crispness of the single first-order reactions *** results also justify the validity of using the previously described“variable E-A pyrogram-fitting method”of multi-heating-rate shale pyrograms enabling optimizers to choose multiple reactions from an unlimited range of E-A *** contrast,further doubt is cast on the validity of the constant-A pyrogram-fitting method used by the Easy%Ro technique,in that a distribution of reactions with a single A value is unlikely to represent the complex variety of kerogen macerals observed in shale *** profiles generated by the variable E-A pyrogram-fitting method lie close to the established E-A trend and are likely to provide more realistic TF generation window temperatures than TF profiles generated by the constant-A pyrogram-fitting method.

关键词： transformation fraction profiles simulated S2 pyrograms multiple heating rates kerogen/shale kinetics S2 pyrogram fitting techniques kerogen petroleum research.

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Analysis of ancient mass extinction recoveries in marine environments: generating strategies for managing outcomes of the current mass extinction

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National Science Review 2024年第1期11卷 8-10页

作者： david J.Bottjer Department of Earth Sciences University of Southern California

The defining feature of a mass extinction and its associated recovery is the global amount of extinction that occurred[1]. However, there is finer-scale detail to the story, as seen in the ongoing modern mass extinction(the sixth mass extinction), which exhibits variable effects among marine ecosystems and environments, and hence geographic areas [1].

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Risk factors for hepatocellular carcinoma associated with hepatitis C genotype 3 infection:A systematic review

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World Journal of Gastrointestinal Oncology 2024年第4期16卷 1596-1612页

作者： Hamzah Z Farooq Michael James Jane Abbott Patrick Oyibo Pip Divall Naheed Choudhry Graham R foster Blizard Institute Queen Mary University of LondonLondon E12ATUnited Kingdom School of Health and Psychological Sciences University of LondonLondon EC1V 0HBUnited Kingdom University Hospitals of Leicester Library University Hospitals of Leicester NHS TrustLeicester LE39QPUnited Kingdom

BACKGROUND Hepatitis C virus(HCV)is a blood-borne virus which globally affects around 79 million people and is associated with high morbidity and *** infection leads to cirrhosis in a large proportion of patients and often causes hepatocellular carcinoma(HCC)in people with *** the 6 HCV genotypes(G1-G6),genotype-3 accounts for 17.9%of *** genotype-3 responds least well to directly-acting antivirals and patients with genotype-3 infection are at increased risk of HCC even if they do not have *** To systematically review and critically appraise all risk factors for HCC secondary to HCV-G3 in all ***,we studied possible risk factors for HCC due to HCV-G3 in the literature from 1946 to *** This systematic review aimed to synthesise existing and published studies of risk factors for HCC secondary to HCV genotype-3 and evaluate their strengths and *** searched Web of Science,Medline,EMBASE,and CENTRAL for publications reporting risk factors for HCC due to HCV genotype-3 in all settings,*** Four thousand one hundred and forty-four records were identified from the four databases with 260 records removed as *** thousand eight hundred and eighty-four records were screened with 3514 *** hundred and seventy-one full-texts were assessed for eligibility with seven studies included for *** the seven studies,three studies were retrospective case-control trials,two retrospective cohort studies,one a prospective cohort study and one a cross-sectional study *** were based in hospital settings with four in Pakistan,two in South Korea and one in the United *** total number of participants were 9621 of which 167 developed HCC(1.7%).All seven studies found cirrhosis to be a risk factor for HCC secondary to HCV genotype-3 followed by higher age(five-studies),with two studies each showing male sex,high alpha feto-protein,directly-acting antivirals trea

关键词： Hepatocellular carcinoma Hepatitis C Genotype 3 Systematic review Blood-borne viruses Liver cancer

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