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71.
Thermal and cold water chemistry from the southern flank of Mount Taftan was investigated in order to discriminate among hydrochemical facies, isotopic characteristics, geothermal reservoir and identify the major geochemical processes that affect water composition. 相似文献
72.
Kevin T. Pickering Hugo Pouderoux Lisa C. McNeill Jan Backman Farid Chemale Steffen Kutterolf Kitty L. Milliken Hideki Mukoyoshi Timothy J. Henstock Duncan E. Stevens Charlie Parnell Brandon Dugan 《Sedimentology》2020,67(5):2248-2281
Drill sites in the southern Bay of Bengal at 3°N 91°E (International Ocean Discovery Program Expedition 362) have sampled for the first time a complete section of the Nicobar Fan and below to the oceanic crust. This generally overlooked part of the Bengal–Nicobar Fan System may provide new insights into uplift and denudation rates of the Himalayas and Tibetan Plateau. The Nicobar Fan comprises sediment gravity-flow deposits, mostly turbidites, that alternate with hemipelagite drapes and pelagite intervals of varying thicknesses. The decimetre-thick to metre-thick oldest pre-fan sediments (limestones/chalks) dated at 69 Ma are overlain by volcanic material and slowly accumulated pelagites (0.5 g cm−2 kyr−1). At Expedition 362 Site U1480, terrigenous input began in the early Miocene at ca 22.5 Ma as muds, overlain by very thin-bedded and thin-bedded muddy turbidites at ca 19.5 Ma. From 9.5 Ma, sand content and sediment supply sharply increase (from 1–5 to 10–50 g cm−2 kyr−1). Despite the abundant normal faulting in the Nicobar Fan compared with the Bengal Fan, it offers a better-preserved and more homogeneous sedimentary record with fewer unconformities. The persistent connection between the two fans ceased at 0.28 Ma when the Nicobar Fan became inactive. The Nicobar Fan is a major sink for Himalaya-derived material. This study presents integrated results of International Ocean Discovery Program Expedition 362 with older Deep Sea Drilling Project/Ocean Drilling Program/International Ocean Discovery Program sites that show that the Bengal–Nicobar Fan System experienced successive large-scale avulsion processes that switched sediment supply between the Bengal Fan (middle Miocene and late Pleistocene) and the Nicobar Fan (late Miocene to early Pleistocene). A quantitative analysis of the submarine channels of the Nicobar Fan is also presented, including their stratigraphic frequency, showing that channel size/area and abundance peaked at ca 2 to 3 Ma, but with a distinct low at 3 to 7 Ma: the intervening stratigraphic [sub]unit was a time of reduced sediment accumulation rates. 相似文献
73.
Process refinements improve a hydrological model concept applied to the Niger River basin 总被引:1,自引:0,他引:1 下载免费PDF全文
Jafet C.M. Andersson Berit Arheimer Farid Traoré David Gustafsson Abdou Ali 《水文研究》2017,31(25):4540-4554
74.
Provenance record of late Maastrichtian–late Palaeocene Andean Mountain building in the Amazonian retroarc foreland basin (Madre de Dios basin,Peru) 下载免费PDF全文
Mélanie Louterbach Martin Roddaz Pierre‐Olivier Antoine Laurent Marivaux Sylvain Adnet Julien Bailleul Elton Dantas Roberto Ventura Santos Farid Chemale Jr Patrice Baby Caroline Sanchez Ysabel Calderon 《地学学报》2018,30(1):17-23
Biostratigraphic, sedimentological and provenance analyses suggest that a proto‐Andean Cordillera already existed in southern Peru by late Maastrichtian–late Palaeocene times. A 270‐m‐thick stratigraphic section shows changes in depositional environments from shallow marine (early Maastrichtian) to non‐marine (late Maastrichtian) then back to estuarine (late Palaeocene) conditions. An erosional surface separates lower Maastrichtian from upper Maastrichtian deposits. Above this surface, the late Maastrichtian unit exhibits moderately developed palaeosols and syn‐sedimentary normal faults. The sedimentary evolution is accompanied by a decrease in sedimentation rate and by changes in provenance. Shallow marine lower Maastrichtian deposits have a cratonic provenance as shown by their low εNd(0) values (?15 to ?16) and the presence of Precambrian inherited zircon grains. The upper Maastrichtian deposits have a mixed Andean and cratonic origin with εNd(0) values of ~12.6 and yield the first Cretaceous and Permo‐Triassic zircon grains. Estuarine to shallow marine upper Palaeocene deposits have an Andean dominant source as attested by higher εNd(0) values (?6 to ?10) and by the presence of Palaeozoic and Late Cretaceous zircon grains. The changes in depositional environments and sedimentation rates, as well as the shift in detrital provenance, are consistent with a late Maastrichtian–late Palaeocene period of Andean mountain building. In agreement with recently published studies, our data suggest that an Andean retroarc foreland basin was active by late Maastrichtian–late Palaeocene times. 相似文献
75.
Acta Geotechnica - During the tunnel boring machine-based tunnelling, the grout loss caused by the grout penetration and filtration in sandy soils is a complicated multiphysics process. In this... 相似文献
76.
Mohamed BADAWI Mahmoud ABDELATIF Ali SHEBL Farid MAKROUM Ahmed SHALABY Norbert NEMETH 《《地质学报》英文版》2023,97(2):662-680
The Eastern Desert of Egypt suffered a protracted period of deformation triggered by cratonization of the new juvenile crust known as the Arabian Nubian Shield (ANS), which has been proposed for potential gold discoveries associated with the corresponding tectonic event. The Fatira area, on the border of Egypt''s Northern and Central Eastern Deserts, is covered with metavolcanic rocks twisted by a dextral relocation of the Fatira Shear Zone (FSZ) relative to the Barud magmatic body. The recent study evaluated many deformed post-orogenic granitic intrusions and felsite dikes associated with promising mineralization localities, notably orogenic gold deposits. The combination of various field observations and remote sensing data, followed by the analysis of aeromagnetic enhanced maps, allowed the differentiation of distinct lithologies, structural features, and hydrothermal alterations in the study area. Additionally, the integrated results obtained from the different interpretation techniques are utilized to identify and confirm the previously supposed mineralized localities in the Fatira and Abu Zawal areas and predict other matched localities. The final ASTER, Sentinel 2 hydrothermal alteration, and orientation entropy heat maps demonstrate the association between these mineralized regions and major structures related to the FSZ late stage of deformation rather than other structures studied throughout the area of interest. 相似文献
77.
Shojaeddin Niroomand Richard J. Goldfarb Farid Moore Mohammad Mohajjel Erin E. Marsh 《Mineralium Deposita》2011,46(4):409-428
The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj–Sirjan Zone (SSZ) in the West Azerbaijan
province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian
plate during the Cretaceous–Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well
as altered andesite and dacite dikes. Structural analysis indicates that the rocks underwent tight to isoclinal recumbent
folding and were subsequently co-axially refolded to upright open folds during a second deformation. Late- to post-tectonic
Cenozoic granites and granodiorites occur northeast of the deposit area. Mineralization mainly is recognized within NW-trending
extensional structures as veins and breccia zones. Normal faults, intermediate dikes, and quartz veins, oriented subparallel
to the axial surface of the Kharapeh antiform, indicate synchronous extension perpendicular to the fold axis during the second
folding event. The gold-bearing quartz veins are >1 km in length and average about 6 m in width; breccia zones are 10–50 m
in length and ≤1 m in width. Hydrothermal alteration mainly consists of silicification, sulfidation, chloritization, sericitization,
and carbonatization. Paragenetic relationships indicate three distinct stages—replacement and silicification, brecciation
and fracture filling, and cataclastic brecciation—with the latter two being gold-rich. Fluid inclusion data suggest mineral
deposition at temperatures of at least 220–255°C and depths of at least 1.4–1.8 km, from a H2O–CO2±CH4 fluid of relatively high salinity (12–14 wt.% NaCl equiv.), which may reflect metamorphism of passive margin carbonate sequences.
Ore fluid δ18O values between about 7‰ and 9‰ suggest no significant meteoric water input, despite gold deposition in a relatively shallow
epizonal environment. Similarities to other deposits in the SSZ suggest that the deposit formed as part of a diachronous gold
event during the middle to late Tertiary throughout the SSZ and during the final stages of the Zagros orogeny. The proximity
of Kharapeh to the main tectonic suture of the orogen, well-developed regional fold systems with superimposed complex fracture
geometries, and recognition of nearby volcanogenic massive sulfide systems that suggest a region characterized by sulfur-
and metal-rich crustal rocks, collectively indicate an area of the SSZ with high favorability for undiscovered gold resources. 相似文献
78.
Jo?o Luiz Luft Jr Farid Chemale Jr Richard Armstrong 《International Journal of Earth Sciences》2011,100(2-3):305-321
Detailed structural and isotopic analyses in the Hoanib and Ugab River Valleys indicate the existence of an exotic 1.7- to 1.8-Ga terrane in the Pan-African Kaoko Belt. This crustal block, called as Mudorib Complex, is imbricated between autochthonous and para-autochthonous rocks of Congo Craton, Kaoko Basin, and Western Kaoko Batholith units during the main tectono-thermal phase of Kaoko Belt collision around 580?Ma, involving the Rio de La Plata, Congo and Kahalari paleoplates. This terrain is positioned between the 1.9-Ga Pruwes Complex units of SW edge of the Congo Craton and the 0.58- to 0.55-Ga Amspoort Suite granitoids of the Western Kaoko Batholith. It is coincident with a regional positive aeromagnetic anomaly trending from NNW in the Ugab region to the Namibia-Angola border. Internally, Mudorib Complex consists in 1.73- to 1.81-Ga tonalitic?Ctrondhjemitic?Cdioritic?Cgranodioritic sequence of gneisses associated with cogenetic gabbroic and anothositic-gneisses in the core zone of this Pan-African structure. Field relationship and U?CPb zircon and Sm?CNd whole-rock isotope data combined with geochemical information suggest the existence of two rock associations in the Mudorib Complex, namely late Paleoproterozoic tonalitic?Ctrondhjemitic?Cdioritic-gneisses with island-arc affinity and tholeiitic metabasites of juvenile origin, showing Nd model age of 1.73?C2.17?Ga and ??Nd(t) of ?2.05?C+4.3. This 1.8- to 1.7-Ga complex is also intruded by granitic dykes formed at 1.49?C1.50?Ga with Nd model age of 1.75?C2.34?Ga during stable tectonic conditions. In addition to widespread Pan-African tectono-metamorphic events, a secondary metamorphic event of ~1.3?Ga is also recognized in the Mudorib rocks, which may be associated with accretion process of the complex to the Paleoproterozoic to Archean nucleus of the Kaoko Belt in the Hoanib River Valley. 相似文献
79.
Cyprinid fish have pharyngeal teeth that mash ingested food. Here we show that roach (Rutilus rutilus L.), a common cyprinid in Swedish boreal lakes, often break the mandibles of ingested Chaoborus larvae into smaller fragments. The presence/absence of roach in historic fish communities could therefore possibly be determined
from the proportion of fragmented Chaoborus mandibles in lake sediments, which we assessed using the following three approaches. (1) Roach that were fed Chaoborus larvae in laboratory aquaria evacuated a significantly higher fraction of fragmented prey mandibles than perch (Perca fluviatilis L.). (2) Surface sediments from lakes in an acidified region in southwestern Sweden showed significantly higher proportions
of fragmented mandibles for lakes containing roach compared to lakes devoid of cyprinid fish. (3) A paleo-study in Lake Lysevatten,
into which roach were introduced in the 1880s and were extirpated in the 1960s, showed significantly higher proportions of
fragmented mandibles in sediment layers from the roach period. We conclude that mandible fragmentation was related to roach
presence, and propose that the proportion of fragmented Chaoborus mandibles in lake sediments may provide important information when historical cyprinid alterations are of interest, as in
paleo-studies on acidification, eutrophication, or fish introductions. 相似文献
80.
Nathan E. Bramall Richard Quinn Andrew Mattioda Kathryn Bryson Julie D. Chittenden Amanda Cook Cindy Taylor Giovanni Minelli Pascale Ehrenfreund Antonio J. Ricco David Squires Orlando Santos Charles Friedericks David Landis Nykola C. Jones Farid Salama Louis J. Allamandola Søren V. Hoffmann 《Planetary and Space Science》2012,60(1):121-130
The Space Environment Viability of Organics (SEVO) experiment is one of two scientific payloads aboard the triple-cube satellite Organism/ORganic Exposure to Orbital Stresses (O/OREOS). O/OREOS is the first technology demonstration mission of the NASA Astrobiology Small Payloads Program. The 1-kg, 1000-cm3 SEVO cube is investigating the chemical evolution of organic materials in interstellar space and planetary environments by exposing organic molecules under controlled conditions directly to the low-Earth orbit (LEO) particle and electromagnetic radiation environment. O/OREOS was launched on November 19, 2010 into a 650-km, 72°-inclination orbit and has a nominal operational lifetime of six months. Four classes of organic compounds, namely an amino acid, a quinone, a polycyclic aromatic hydrocarbon (PAH), and a metallo-porphyrin are being studied. Initial reaction conditions were established by hermetically sealing the thin-film organic samples in self-contained micro-environments. Chemical changes in the samples caused by direct exposure to LEO radiation and by interactions with the irradiated microenvironments are monitored in situ by ultraviolet/visible/near-infrared (UV/VIS/NIR) absorption spectroscopy using a novel compact fixed-grating CCD spectrometer with the Sun as its light source. The goals of the O/OREOS mission include: (1) demonstrating key small satellite technologies that can enable future low-cost astrobiology experiments, (2) deploying a miniature UV/VIS/NIR spectrometer suitable for in-situ astrobiology and other scientific investigations, (3) testing the capability to establish a variety of experimental reaction conditions to enable the study of astrobiological processes on small satellites, and (4) measuring the chemical evolution of organic molecules in LEO under conditions that can be extrapolated to interstellar and planetary environments. In this paper, the science and technology development of the SEVO instrument payload and its measurements are described. 相似文献