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Ordovician Granitoids and Silurian Mafic dikes in the Western Kunlun Orogen, Northwest China:Implications for Evolution of the Proto-Tethys

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Acta Geologica Sinica(English Edition) 2019年第1期93卷 30-49页

作者： ZHANG Qichao WU Zhenhan LI Shan LI Kan LIU Zhiwei ZHOU Qing Chinese Academy of Geological Sciences Key Laboratory of Deep-Earth Dynamics Ministry of Natural Resources Institute of Geology Chinese Academy of Geological Sciences Xi'an Institute of Geology and Mineral Resources Chinese Geological Survey Chengdu Institute of Geology and Mineral Resources Chinese Geological Survey

The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and Lu-Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons(466–455 Ma) and their Silurian mafic dikes(～436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high-K calcalkaline characteristics, with(^(87)Sr/^(86)Sr)_i value of 0.7129–0.7224, ε_(Nd)(t) values of -9.3 to -7.0 and zircon ε_(Hf)(t) values of -17.3 to -0.2, indicating that they were formed by partial melting of ancient lower-crust(metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto-Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial ^(87)Sr/^(86)Sr ratios of 0.7101–0.7152 and ε_(Nd)(t) values of -3.8 to -3.4 and zircon ε_(Hf)(t) values of -8.8 to -4.9, indicating that they were derived from enriched mantle in response to post-collisional slab break-off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto-Tethys.

关键词： High-K calc-alkaline granitoids mafic dikes Western Kunlun Orogen Proto-Tethys

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Geodynamics of dikes in North of Saveh

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Open Journal of Ecology 2015年第9期5卷 452-459页

作者： Mohammad-Hasan Bazoobandi Mohammad-Ali Arian Mohammad-Hashem Emami Gholam-Reza Tajbakhsh Abdollah Yazdi Department of Geology Faculty of Science North Tehran Branch Islamic Azad University Tehran Iran Department of Geology Faculty of Science Islamshahr Branch Islamic Azad University Tehran Iran Department of Geology Faculty of Science Yazd University Yazd Iran Department of Geology Faculty of Science Kahnooj Branch Islamic Azad University Kerman Iran

dikes can be divided into sheeted, feeder, cone and swarm types based on the origin and the formation. A group of dikes that are formed in dense in a relatively broad zone influenced by a particular tectonic regime are referred to as swarm dikes. Swarm dikes have numerous applications such as locating mantle plume centers, determining areas of longstanding tensions and detection of deformation networks. The purpose of this article is classified swarm dikes of “North of Saveh” based on previous studies. In one study, swarm dikes are classified based on their initial geometry into five types of I, II, III, IV and V. According to this classification, our study has been shown that the dikes in north of Saveh are of type IV. In another study, the swarm dikes are classified into three types: parallel, large radial and small radial. According to the classification, our study has been shown that the dikes of North Saveh are parallel that have arisen by tensions caused by the collision of the Arabian plate and the Central Iran plate. In addition to original tensions in the region, local faults have been effective on the arrangement and the establishment of dikes.

关键词： Swarm dikes Locating Mantle Plume dikes in North of Saveh dikes Classification

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Use of incipient motion data for backward erosion piping models

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International Journal of Sediment Research 2019年第5期34卷 401-408页

作者： Vera M.van Beek Bryant A.Robbins Gijs J.C.M.Hoffmans Adam Bezuijen Leo C.van Rijn Deltares U.S.Army Engineer Research and Development Center Ghent University Leovanrijn-Sediment-Consultancy

Backward erosion piping involves the gradual removal of granular material under the action of water flow from the foundation of a dam or levee, whereby shallow pipes are formed that grow in the direction opposite to the flow. This pipe-forming process can ultimately lead to failure of a water-retaining structure and is considered one of the most important failure mechanisms for dikes and levees in the Netherlands and the United States. Modeling of this mechanism requires the assessment of hydraulic conditions in the pipe, which are controlled by the particle equilibrium at the pipe wall. Since the pipe’s dimensions are controlled by the inflow to the pipe from the porous medium, the flow through the pipe is thought to be laminar for fine-to medium-grained sands. The literature provides data for incipient motion in laminar flow, which is reviewed here and complemented with data from backward erosion experiments. The experiments illustrate the applicability of the laminar incipient motion data to determine the erosion pipe dimensions and corresponding pipe hydraulics for fine-to medium-grained sands, for the purpose of backward erosion piping modeling.

关键词： Internal erosion Backward erosion piping Cylindrical test Incipient motion dikes Levees

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FISH ASSEMBLAGE RESPONSES TO DIFFERENT SECONDARY CHANNEL DESIGNS IN THE LOWER MISSISSIPPI RIVER,U.S.A.:A TEMPLATE FOR RIVER RESTORATION

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水生生物学报 2018年第6期42卷 1089-1106页

作者： KAISER Joseph E. SMITH Shannon C.F. SCHRAMM Jr.,HAROLD L. EGGLETON Michael A. Department of Aquaculture and Fisheries University of Arkansas at Pine Bluff1200 N.UniversityMail Slot 4912Pine BluffArkansas 71601U.S.A U.S.Geological Survey Mississippi Cooperative Fish and Wildlife Research UnitMississippi State University

The lower Mississippi River(LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to "notch" wing-dike structures that close secondary(side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer(rkm) 628(Louisiana-Mississippi, U.S.A.) upstream to rkm 1504(Missouri-Kentucky, U.S.A.). Four secondary channels were termed "permanent"(i.e.,with notched dikes) while three secondary channels were termed "temporary"(i.e., without notched dikes).Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad(Dorosoma cepedianum), threadfin shad(D. petenense), and white bass(Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish(Ictalurus furcatus), flathead catfish(Pylodictis olivaris), and freshwater drum(Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent seconda

关键词： Mississippi River Secondary channels dikes Fish assemblages River restoration River rehabilitation

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