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81.
Norbert R. Nowaczyk Martin Antonow Jochen Knies Robert F. Spielhagen 《Geophysical Journal International》2003,155(3):1065-1080
82.
1. Introduction
The main-hole of the Chinese Continental Scientific Drilling Project (CCSD) in Donghai of the Dabie-Sulu UHP metamorphic belt in East China has reached its final depth of 5118 m in March 2005. As shown in Fig. 相似文献
83.
正The papers in this issue stem from the 13th International Symposium on River Sedimentation held in September 2016 at the University of Stuttgart,Germany.The Symposiums on River Sedimentation aim to provide a platform for scientists and engineers for fruitful and in-depth knowledge exchange.The objectives are to develop sustainable revitalization and management strategies that address the ongoing negative effects of anthropogenic activities,whilst improving river systems toward a healthy ecological status.The fundamental research and understanding of interactive 相似文献
84.
Richard A. Battye Jochen Weller 《Monthly notices of the Royal Astronomical Society》2005,362(1):171-183
We consider the optimum depth of a cluster survey selected using the Sunyaev–Zel'dovich effect. By using simple models for the evolution of the cluster mass function and detailed modelling for a variety of observational techniques, we show that the optimum survey yield is achieved when the average size of the clusters selected is close to the size of the telescope beam. For a total power measurement, we compute the optimum noise threshold per beam as a function of the beam size and then discuss how our results can be used in more general situations. As a by-product we gain some insight into what is the most advantageous instrumental set-up. In the case of beam switching observations one is not severely limited if one manages to set the noise threshold close to the point which corresponds to the optimum yield. Considering a variety of alternative scenarios, we discuss how robust our conclusions are to modifications in the cluster model and cosmological parameters. The precise optimum is particularly sensitive to the amplitude of fluctuations and the profile of the gas in the cluster. 相似文献
85.
Compared with the oceanic crust, knowledge about the formation of the continental crust (CC) is relatively poor. Although melting of subducted slabs in the early history of the Earth has been considered as the major way that shaped the chemical characteristics of the CC by most geologists, as the CC shares many characteristics with modern adakites, some geologists argued that Archean TTG was formed in the same way as modern arcs rather than slab melting, whereas others proposed that melting at the bottom of the thickened oceanic crust was more important. Recently,the debate is mainly focused on the unique subchondritic Nb/Ta value of the CC, and particularly, how Nb and Ta fractionated from each other and consequently how, in detail, the CC was built. 相似文献
86.
1 Introduction
Recent improvements in the precision of Li and B isotope measurements have demonstrated the potential of these elements in tracing a wide range of geological processes. The Li and B isotope systematics of ultrahigh-pressure (UHP) metamorphic rocks provides a unique opportunity to investigate the behaviour of Li and B during fluid-rock interaction at high temperatures and very high pressures and to constrain the fluid budget and the recycling of subducted crustal materials into the mantle during UHP metamorphism. 相似文献
87.
J. Stephen Fries Rachel T. Noble Hans W. Paerl Gregory W. Characklis 《Estuaries and Coasts》2007,30(2):359-364
Monitoring of estuarine condition depends on water quality parameters that have significant and interpretable ecological effects
and can be assessed either in situ or via rapid laboratory techniques. Two commonly measured parameters are water column turbidity
(NTU) and total suspended solids (TSS). Under certain conditions, either of these measures could represent a proxy for runoff
and provide rapid, in situ measures to improve protection of the public by decreasing the time required to detect and monitor
associated effects (e.g., reduced water clarity and eutrophication). The Neuse River Estuary (NRE) has experienced a decline
in water quality due to anthropogenic inputs, including stormwater containing nutrient and particle loads. Water samples were
collected from the NRE during both dry weather and storm events over 16 mo across the entire estuarine gradient. Particle
size distributions, ratio of particulate organic carbon to nitrogen, chlorophylla (chla), TSS, and NTU were measured in each of these samples, with the data separated into regions based on salinity and depth of
sample collection. Particle analyses were directed at identifying suspensions dominated by phytoplankton, runoff particles,
or resuspended sediments. Particle size distributions for suspensions in Region I (all samples with salinity less than 2)
varied little during sampling, resulting in a robust NTU-TSS relationship. This relationship confirmed the usefulness of turbidity
as a measure of runoff and resuspension of recently deposited runoff in the upper NRE. Phytoplankton cells represented a majority
of the particles in Region II (surface samples with salinity greater than 2), based on the close relationship between chla and total particle volume in these samples. Suspensions of large, nearly uniform diameter particles, which are likely aggregates
and resuspended sediment, were observed in Region III (bottom samples with salinity greater than 2). Using these techniques
as part of routine monitoring, particle suspension measures in different hydrographic regions of an estuary provide evidence
useful for identifying the source and water quality consequences of particle suspensions (e.g., microbial contamination and
algal blooms). 相似文献
88.
John Wilson Stewart Fotheringham Gary Hunter Jochen Albrecht 《Transactions in GIS》2007,11(4):479-481
89.
McMahon K Bengtson Nash S Eaglesham G Müller JF Duke NC Winderlich S 《Marine pollution bulletin》2005,51(1-4):325-334
Low concentrations of herbicides (up to 70 ng l(-1)), chiefly diuron (up to 50 ng l(-1)) were detected in surface waters associated with inter-tidal seagrass meadows of Zostera muelleri in Hervey Bay, south-east Queensland, Australia. Diuron and atrazine (up to 1.1 ng g(-1) dry weight of sediment) were detected in the sediments of these seagrass meadows. Concentration of the herbicides diuron, simazine and atrazine increased in surface waters associated with seagrass meadows during moderate river flow events indicating herbicides were washed from the catchment to the marine environment. Maximum herbicide concentration (sum of eight herbicides) in the Mary River during a moderate river flow event was 4260 ng l(-1). No photosynthetic stress was detected in seagrass in this study during low river flow. However, with moderate river flow events, nearshore seagrasses are at risk of being exposed to concentrations of herbicides that are known to inhibit photosynthesis. 相似文献
90.
Jochen Kolb Sven Sindern Alexander F. M. Kisters F. Michael Meyer Stephan Hoernes Jens Schneider 《Mineralium Deposita》2005,40(5):473-491
Gold mineralization at Kochkar (Urals, Russia) is hosted mainly by quartz lodes, which developed at lithological contacts
between mafic dikes and granitoids of the Plast massif during late Carboniferous to early Permian, regional E–W compression
in the East Uralian Zone (EUZ). The alteration mineralogy in mafic dikes comprises biotite, actinolite, albite, K-feldspar,
quartz, epidote, tourmaline, sericite, pyrite, arsenopyrite, chalcopyrite, sphalerite, fahlores, galena, bismuthinite, and
gold, and in Plast granitoids quartz, sericite, calcite, epidote, and ore minerals. Geochemically, an enrichment of Si, K,
Rb, Ba, S, base metals, W, and Au can be observed. The ore fluid had δ18O values between 8.2‰ and 9.5‰ typical for metamorphic or deep magmatic fluids. The tectonometamorphic evolution of the EUZ
is marked by peak metamorphic conditions at 635±40°C and 5–6 kbar through 500±20°C during gold mineralization, and 300–350°C
and 2–3 kbar. The last event was dated on a late, barren quartz vein formed during greenschist facies metamorphism at 265±3 Ma
by the Rb–Sr method. Fluids related to this overprint had a δ18O value of 5.2‰ and an initial 87Sr/86Sr ratio of 0.70685 indicating that they are largely equilibrated with metamorphic lithologies of the EUZ. The Plast granitoids
and the adjacent Borisov granite, which was dated at 358±23 Ma (U–Pb zircon age), have an adakitic character. This, together
with the arc-signature of the mafic dikes, supports the setting of the EUZ within the Valerianovsky continental arc. Eastward
subduction of the Uralian Ocean below this arc began during the late Devonian to early Carboniferous. Between 320 and 265 Ma,
the oblique closure of the ocean resulted in doming of granitoid massifs in a sinistral transpressional regime, subsequent
retrograde gold mineralization during E–W compression and a later greenschist facies overprint. This long-lasting retrograde
evolution of the EUZ was caused by the lack of postcollisional collapse. Heat for a “deep-later" type of metamorphism and
triggering the auriferous fluid system was supplied by radiogenic heating of an overthickened crust. The greenschist facies
overprint at Kochkar and coeval crustal melting in the EUZ was additionally initiated by local external heating of the terrane.
This could have been caused by syn- to postcollisional slab rollback or delamination resulting in magmatic underplating of
the EUZ, which postdates orogenic gold mineralization at Kochkar. The tectonic interpretation of the EUZ indicates that gold
mineralization at Kochkar formed in a mid-crustal environment of a continental magmatic arc at the cessation of active subduction
predating post orogenic plutonism. 相似文献