LIPs and implications for the structure and evolution of continental crust     

Richard E. Ernst  Qin Wang 《《地质学报》英文版》2018,92(Z1):124-126

  相似文献   

Impacts of land use and land cover changes on hydrological processes and sediment yield determined using the SWAT model   总被引：1，自引：0，他引：1  

Edivaldo Afonso de Oliveira Serrao  Madson Tavares Silva  Thomas Rocha Ferreira  Lorena Conceiçao Paiva de Ataide  Cleber Assis dos Santos  Aline Maria Meiguins de Lima  Vicente de Paulo Rodrigues da Silva  Francisco de Assis Salviano de Sousa  Denis Jose Cardoso Gomes 《国际泥沙研究》2022,37(1):54-69

Land use and land cover (LULC) changes strongly affect local hydrology and sediment yields.The current study focused on a basin in the Brazilian Amazon and had the following three objectives:(1) to perform an effective diagnosis of flow and sediment yield,(2) to evaluate the impacts of LULC changes over the last 40 years on the hydro-sedimentological variables,and (3) to investigate the impacts of the possible trends or breaking points in the flow,surface runoff,and sediment yield series.The Soi...  相似文献   

Structural and tectonothermal evolution of the ultrahigh-temperature Bakhuis Granulite Belt,Guiana Shield,Surinam:Palaeoproterozoic to recent     

Frank F.Beunk  Emond W.F.de Roever  Keewook Yi  Fraukje M.Brouwer 《地学前缘(英文版)》2021,12(2):677-692

We constrain the multistage tectonic evolution of the Palaeoproterozoic UHT metamorphic(P=0.9–1.0 GPa,T>1000℃,t=2088–2031 Ma)Bakhuis Granulite Belt(BGB)in Surinam on the Guiana Shield,using large-to small-scale structures,Al-in-hornblende thermobarometry and published fluid inclusion and zircon geochronological data.The BGB forms a narrow,NE–SW striking belt between two formerly connected,~E–W oriented granite-greenstone belts,formed between converging Amazonian and West African continental masses prior to collision and Transamazonian orogeny.Inherited detrital zircon in BGB metasediments conforms agewise to Birimian zircon of West Africa and suggests derivation from the subsequently subducted African passive margin.Ultrahigh-temperature metamorphism may have followed slab break-off and asthenospheric heat advection.Peak metamorphic structures result from layer-parallel shearing and folding,reflecting initial transtensional exhumation of the subducted African margin after slab break-off.A second HT event involves intrusion,at ca.0.49 GPa,of charnockites and metagabbros at 1993–1984 Ma and a layered anorthosite at 1980 Ma,after the BGB had already cooled to<400℃.The event is related to northward subduction under the greenstone belts,along a new active margin to their south.A pronounced syntaxial bend in the new margin points northward towards the BGB and is likely the result of indentation by an anticlinorial flexural bulge of the subducting plate.Tearing of the subducting oceanic plate along this bulge explains why the charnockites are restricted to the BGB.The BGB subsequently experienced doming under an extensional detachment exposed in its southwestern border zone.Exhumation was focused in the BGB as a result of the flexural bulge in the subducting plate and localised heating of the overriding plate by charnockite magmatism.The present,straight NE–SW long-side boundaries of the BGB are superimposed mylonite zones,overprinted by pseudotachylites,previously dated at ca.1200 Ma and 950 Ma,respectively.The 1200 Ma mylonites reflect transpressional popping-up of the BGB,caused by EW-directed intraplate principal compressive stresses from Grenvillian collision preserved under the eastern Andes.Further exhumation of the BGB involved the 950 Ma pseudotachylite decorated faulting,and Phanerozoic faulting along reactivated Meso-and Neoproterozoic lineaments.  相似文献   

Mineralogical and Fluid Characteristics of the Fluorite-rich Monakoff and E1 Cu-Au Deposits, Cloncurry Region, Queensland, Australia: Implications for Regional F-Ba-rich IOCG Mineralization     

David A. HOLWELL  Megan R. WILLIAMS  Richard M. LILLY  Iain MCDONALD 《《地质学报》英文版》2014,88(Z2):350-351

Please?refer?to?the?attachment(s)?for?more?details.  相似文献   

Small-Scale Mineralogical Heterogeneity from Variations in Phase Assemblages in the Transition Zone and D Layer Predicted by Convection Modelling     

Arie P van den Berg  David A Yuen  Michael H G Jacobs  Maarten V de Hoop 《中国地质大学学报(英文版)》2011,(2)

Small-scale heterogeneity in the deep mantle is concentrated in the upper-mantle transi-tion zone(TZ),in the depth range 410-660 km and also at the bottom 250 km D region.This encour-ages a more detailed investigation of the potential for seismic reflectivity imaging by modelling hetero-geneous structures in mantle convection models including phase transitions of the TZ and D regions.We applied finite elements with variable spacing near the boundary layers in 2-D cylindrical geometry that allow for sufficie...  相似文献   

成功实施污水收集系统全面修复项目     

Richard  Dressel  William  Landin  Christopher  Michalos  王田青译  朱文鉴校 《岩土钻凿工程》2011,(2):117-121

本文介绍了科罗拉多市政公司对地下污水管网系统进行检测评估情况,包括干线、人井、沉淀池等,全面介绍了管网的材质情况、评估进度和费用等。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987111000405   总被引：1，自引：0，他引：1  

Jean de la Paix Mupenzi  Lanhai Li  Jiwen Ge  Achal Varenyam  Gabriel Habiyaremye  Nzayisenga Theoneste  Kamanzi Emmanuel 《地学前缘(英文版)》2011,2(4):599-607

This study has focused on the processes of soil degradation and chemical element concentration in tea-growing regions of Rwanda, Africa. Soil degradation accelerated by erosion is caused not only by topography but also by human activities. This soil degradation involves both the physical loss and reduction in the amount of topsoil associated with nutrient decline. Soil samples were collected from eleven tropical zones in Rwanda and from variable depth within each collecting site. Of these, Samples from three locations in each zone were analyzed in the laboratory, with the result that the pH of all soil samples is shown to be less than 5 (pH < 5) with a general average of 4.4. The elements such as iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn) are present in high concentration levels. In contrast calcium (Ca) and sodium (Na) are present at low-level concentrations and carbon (C) was found in minimal concentrations. In addition, elements derived from fertilizers, such as nitrogen (N), phosphorous (P), and potassium (K) which is also from minerals such as feldspar, are also present in low-level concentrations. The results indicate that the soil in certain Rwandan tea plantations is acidic and that this level of pH may help explain, in addition to natural factors, the deficiency of some elements such as Ca, Mg, P and N. The use of chemical fertilizers, land use system and the location of fields relative to household plots are also considered to help explain why tea plantation soils are typically degraded.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114001601   总被引：3，自引：2，他引：1  

Tim E.Johnson  Chris Clark  Richard J.M.Taylor  M.Santosh  Alan S.Collins 《地学前缘(英文版)》2015,6(3):373-387

Data from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure-temperature-time[P-T-t) evolution of the Nagercoil Block at the southernmost tip of peninsular India.An inferred peak metamorphic assemblage of garnet,K-feldspar.sillimanite,plagioclase,magnetite,ilmenite,spinel and melt is consistent with peak metamorphic pressures of 6-8 kbar and temperatures in excess of 900℃.Subsequent growth of cordierite and biotite record high-temperature retrograde decompression to around 5 kbar and 800 C.SHRIMP U-Pb dating of magmatic zircon cores suggests that the sedimentary protoliths were in part derived from felsic igneous rocks with Palaeoproterozoic crystallisation ages.New growth of metamorphic zircon on the rims of detrital grains constrains the onset of melt crystallisation,and the minimum age of the metamorphic peak,to around560 Ma.The data suggest two stages of monazite growth.The first generation of REE-enriched monazite grew during partial melting along the prograde path at around 570 Ma via the incongruent breakdown of apatite.Relatively REE-depleted rims,which have a pronounced negative europium anomaly,grew during melt crystallisation along the retrograde path at around 535 Ma.Our data show the rocks remained at suprasolidus temperatures for at least 35 million years and probably much longer,supporting a long-lived high-grade metamorphic history.The metamorphic conditions,timing and duration of the implied clockwise P-T-t path are similar to that previously established for other regions in peninsular India during the Ediacaran to Cambrian assembly of that part of the Gondwanan supercontinent.  相似文献   

A Century of Spinosaurs - A Review and Revision of the Spinosauridae with Comments on Their Ecology     

David William Elliott HONE  Thomas Richard HOLTZ 《《地质学报》英文版》2017,91(3):1120-1132

The spinosaurids represent an enigmatic and highly unusual form of large tetanuran theropods that were first identified in 1915. A recent flurry of discoveries and taxonomic revisions of this important and interesting clade has added greatly to our knowledge. Spinosaur body fossils are however generally rare and most species are known from only limited skeletal remains. Their unusual anatomical adaptations to the skull, limbs and axial column all differ from other large theropods and point to an unusual ecological niche and a lifestyle intimately linked to water.  相似文献   

Prevalence of Bacillus sp. among the biofilm forming community on Ti surface in marine environment     

PRIYA Chokkalingam  ARAVIND Ganessin  THILAGARAJ Wilson Richard 《海洋学报(英文版)》2017,36(6):89-94

Prevalence of bacterial species involved in biomineralization of manganese on titanium (Ti) surfaces in marine environment was revealed in this research work. This study involves one year sea water exposure of Ti and their periodical biofilm characterization was carried out to quantify the manganese oxidizing bacterial (MOB) presence in the biofilm formed on titanium surfaces. The total viable count study of Ti coupons exposed to sea water for one year resulted in 60% of the MOB in overall biofilm population. The biochemical characterization of MOB isolates were performed for the genus level identification of the seven bacterial isolates. Further, the seven strains were subjected to 16S rRNA gene sequencing. Evolutionary analysis was performed using MEGA 7 to obtain closely related strains within the groups. The manganese oxidizing ability of the bacterial isolates were determined with Leucoberbelin Blue Assay (LBB) and Atomic Absorption Spectroscopy studies (AAS). The results show that among the isolated marine MOB species, Bacillus sp. and Leptothrix sp. have the maximum Mn oxidizing property. The microtitre plate assay was performed to determine the biofilm forming ability of the isolated marine MOB species. All the results have confirmed the prevalence of Bacillus sp. among the biofilm colonizers on Ti surfaces when exposed in sea water.  相似文献