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| 1 | An examination by GC×GC-TOFMS of organic molecules present inhighly degraded oils emerging from Caribbean terrestrial seeps of Cretaceous age显示文摘For our ancestors, oil seeps were both a fascination and a resource but as the planet's reserves of high quality low density oil becomes increasingly depleted, so there is now a renewed interest in heavier,biodegraded oils such as those encountered in terrestrial seeps. One such seep is Pitch Lake in the Caribbean island of Trinidad, which is the largest natural deposit of asphalt in the world. At the northern end of the Caribbean, oil emerges along a tectonic contact on the island on Cuba. The sources of the oils from these seeps are relatively recent and both are subject to intense weathering due to the tropical conditions. When analysed by gas chromatography(GC) both oils appear as unresolved complex mixtures(UCM) and show a very high degree of biodegradation thus presenting an analytical challenge. In this case study, these two Caribbean seep oils were analysed by comprehensive two dimensional GC with time of flight mass spectrometry(GC×GC-TOFMS) to expose many thousands of the individual compounds that comprise the UCM. The high chromatographic resolution of the GC×GC-TOFMS produced good quality mass spectra allowing many compounds including molecular fossil ‘biomarkers' to be identified. Compound classes included diamondoid hydrocarbons, demethylated hopanes and secohopanes, mono-and tri-aromatic steroids. D-ring aromatised structures of the 8,14-seco-hopanes,including demethylated forms were present in both oils but further demethylation, probably at position C-25 during biodegradation, was only observed in the Pitch Lake oil. Many polycyclic aromatic hydrocarbons(PAHs) were absent although the fungal-derived pentacyclic PAH perylene was present in both oils. The presence of the angiosperm biomarker lupane in the Pitch Lake oil constrained the age to the Late Cretaceous. The higher degree of biodegradation observed in the Cuban oil was likely due to relatively slow anaerobic processes whereas oil within Pitch Lake was probably subject to additional more rapid aerobic metabolism within the lake. | Alan G.Scarlett Ana Ibis Despaigne-Diaz Simon A.Wilde Kliti Grice | 2019 | Geoscience Frontiers2019，10，1： | 5 |
| 2 | How Central Asian Orogeny Evolves:New Insights from End-Permian to Middle Triassic Magmatic Record along the Solonker Suture Zone显示文摘Objective The modern Earth is characterized by two types of orogens:collisional orogen and accretionary orogen.It is widely accepted that the Central Asian Orogenic Belt(CAOB)is made up of widespread multiple ancient archipelagos.It has been recognized as a non-collisional orogen,contrasting with the archetypical AlpineHimalayan-type collisional orogens.Although the CAOB | LI Shan CHUNG Sunlin Simon A.WILDE WANG Tao XIAO Wenjiao GUO Qianqian | 2016 | Acta Geologica Sinica(English Edition)2016，90，5： | 2 |
| 3 | Decoupling between Oxygen and Radiogenic Isotopes: Evidence for Generation of Juvenile Continental Crust by Partial Melting of Subducted Oceanic Crust显示文摘There is increasing evidence indicating that melts derived from subducted oceanic crust and sediments may have played a key role in building continental crust. This mechanism predicts that juvenile arc crust should have oxygen isotope characteristics ranging from mantle-like to supracrustal, but consistent mantle-like radiogenic(Nd-Hf) isotopic signatures. Here we present in-situ zircon U-Pb dating, Hf-O isotope analyses, and whole rock major-trace element and Nd isotope analyses of a granitoid from NW India. In-situ secondary ion mass spectrometry(SIMS) zircon U-Pb dating yields a weighted mean ^(207)Pb/^(206)Pb age of 873±6 Ma for the granitoid. It displays mantle-like zircon εHf(εHf(873 Ma)= +9.3 to +10.9) and whole-rock Nd(εNd(873 Ma)= +3.5) values but supracrustal δ^(18)O values, the latter mostly varying between 9‰ and 10‰. The calculated whole-rock δ^(18)O value of 11.3‰±0.6‰ matches well with those of hydrothermally-altered pillow lavas and sheeted dykes from ophiolites. The major and trace element composition of the granitoid is similar to petrological experimental melts derived from a mixture of MORB+sediments. Thus, the granitoid most likely represents the product of partial melting of the uppermost oceanic crust(MORB+sediments). We propose that the decoupling between Hf-Nd and O isotopes as observed in this granitoid can be used as a powerful tool for the identification of slab melting contributing to juvenile continental crustal growth. Such isotopic decoupling can also account for high δ^(18)O values observed in ancient juvenile continental crust, such as Archean tonalitetrondhjemite-granodiorite suites. | Xuan-Ce Wang Qiuli Li Simon A.Wilde Zheng-Xiang Li Chaofeng Li Kai Lei Shao-Jie Li Linlin Li Manoj K.Pandit | 2021 | Journal of Earth Science2021，32，5： | 1 |
| 4 | Revisiting Rhenium-Osmium Isotopic Investigations of Petroleum Systems: From Geochemical Behaviours to Geological Interpretations显示文摘Recent decades have witnessed an increasing number of studies investigating petroleum systems with the application of rhenium-osmium(Re-Os) isotopic geochemistry. Here, we review the use of the 187 Re-187 Os geochronometer with respect to the geochemical behaviour of rhenium and osmium in hydrocarbon-related geological processes. The Re-Os budget in hydrocarbon source rock predominantly originates from natural water columns during its deposition. Open seawater tends to have a homogeneous Os isotopic composition because its residence time in seawater is longer than the time taken for ocean mixing. On the contrary, restricted water bodies(e.g., lakes) may have heterogeneous Os isotopic compositions due to the greater amount of terrigenous input. Hydrogenous Re and Os atoms are sequestered from the water body into sedimentary organic matter and transferred into crude oil through thermal maturation of organic matter. Thermal maturation likely does not significantly alter the Re-Os isotopic systematics of the source rock as a Re-Os isochron age of 442±21 Ma(2σ) is yielded in this study for over matured source rocks within the Silurian Longmaxi Formation from the Sichuan Basin. Re-Os atoms are mainly hosted by the highly polar/aggregating/aromatic asphaltenes in hydrocarbons, possibly chelating with organic complexes or occurring as metalloporphyrins. Resin and aromatic hydrocarbons also contribute to the Re-Os budget, but are 2 to 3 orders of magnitude lower than that of asphaltenes, whereas saturates do not contain appreciable Re-Os contents. The distribution of Re-Os atoms in hydrocarbons is heterogeneous because the duplicate analysis of pure single bitumen samples yields similar ^(187)Os/^(188)Os ratios whereas variable ^(187)Re/^(188)Os ratios. The Re-Os system in crude oils can be reset during transport away from the source rocks, with Os-rich organic fractions more readily expelled than Re-rich fractions. Contact with metal-rich fluids(e.g., hydrothermal fluid) or compositional changes related to asphaltene contents(e.g., deasphalting, biodegradation, thermal cracking and thermochemical sulphate reduction) are also likely to alter the Re-Os systematics in hydrocarbons. These geochemical features enable the ^(187)Re-^(187)Os isotopic system to have robust applicability for petroleum system investigations, which may use the Re-Os radiometric tool for:(1) stratigraphic correlation of source rocks,(2) dating geological events altering the asphaltene content in hydrocarbon such as hydrocarbon generation, thermochemical sulphate reduction, etc., and,(3) fingerprinting hydrocarbons. Regardless of the robustness of the ^(187)Re-^(187)Os geochronometer for petroleum system investigations, there are several pending questions such as partitioning between solid organic species or between organic matter and sulphide, chelating sites in hydrocarbons and Os isotopic equilibration between hydrocarbon subfractions. To improve the understanding of the Re-Os behaviour in petroleum systems, we underscore multi-proxies-based geochemistry(e.g., inorganic-organic geochemistry) and experimental studies(e.g., hydrous pyrolysis). | Shao-Jie Li Xuan-Ce Wang Simon A.Wilde Zhuyin Chu Chaofeng Li Sheng He Keyu Liu Xingzhi Ma Yuxiang Zhang | 2021 | Journal of Earth Science2021，32，5： | 1 |
| 5 | 解密超大陆-超地幔柱旋回在大陆地壳生长演化中的角色显示文摘理解壳-幔相互作用是揭示地球动力学系统工作机理的关键.我们认为控制地球动力学系统的主要因素是超大陆-超地幔柱旋回,它控制了板块运动和大陆地壳的形成和演化.深部地幔过程极有可能通过控制了物质交换和热源,进而影响年轻大陆地壳的形成及其后续演化.然而,岩石组合和大陆地壳的化学组分是非常不均一的,因此一个关键问题在于如何定义和识别年轻大陆地壳的特征. | 王选策 Simon A.Wilde 李正祥 李劭杰 李琳琳 | 2020 | 地球科学2020，45，10： | 0 |
| 6 | Do Supercontinent-Superplume Cycles Control the Growth and Evolution of Continental Crust?显示文摘The evolution of continental crust can be directly linked to the first-order supercontinent-superplume cycles.We demonstrate that:(1)a mantle-like oxygen isotopic signature is not a diagnostic feature for distinguishing crustal addition from the reworking of pre-existing continental crust;(2)juvenile continental crust shows a wide range of whole-rock Hf isotopic compositions throughout Earth's history;and(3)detrital zircon Hf model ages cannot reliably determine the growth of continental crust.Thus,the wide use of zircon Hf model ages,based on zircon grains with mantle-like oxygen isotopes,is inappropriate for estimating the timing of continental crustal generation.Based on an analysis of global Hf and O isotope and zircon age databases,we argue that the actual U-Pb crystallization ages of juvenile zircon grains provide the best opportunity to unravel crustal growth through time and to test its relationship with supercontinent-superplume cycles.Furthermore,when the Hf isotopes of these juvenile grains plot within the field of juvenile continental crust,they correlate well with times of global mantle depletion as recorded by Os and He isotopes,plume activity as recorded by LIP events,and periods of crustal growth and the breakup of supercontinents.In contrast,zircon grains crystallized from magmas that were produced by partial melting of pre-existing continental crust show U-Pb age peaks that correspond mainly to times of supercontinent assembly and crustal reworking.Detailed analysis shows the key role played by recycling of mafic crustal components in the generation of juvenile continental crust. | Xuan-Ce Wang Simon A.Wilde Zheng-Xiang Li Shaojie Li Linlin Li | 2020 | Journal of Earth Science2020，31，6： | 0 |
| 7 | 华北中部造山带在2560~1850Ma期间发生了什么地质事件?显示文摘 | 赵国春 刘树文 孙敏 李三忠 Simon A.WILDE 夏小平 张健 何艳红 | 2006 | 地质学报2006，80，12： | 0 |
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