The Chan Hol cave near Tulum (Quintana Roo,Mexico): evidence for long‐lasting human presence during the early to middle Holocene          下载免费PDF全文

Fabio Hering  Wolfgang Stinnesbeck  Jens Folmeister  Eberhard Frey  Sarah Stinnesbeck  Jerónimo Avilés  Eugenio Aceves Núñez  Arturo González  Alejandro Terrazas Mata  Martha Elena Benavente  Carmen Rojas  Adriana Velázquez Morlet  Norbert Frank  Patrick Zell  Julia Becker 《第四纪科学杂志》2018,33(4):444-454

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WSO-UV—ultraviolet mission for the next decade     

Boris Shustov  Mikhail Sachkov  Ana I. Gómez de Castro  Maohai Huang  Klaus Werner  Norbert Kappelmann  Isabella Pagano 《Astrophysics and Space Science》2009,320(1-3):187-190

The World Space Observatory UltraViolet (WSO–UV) is an international space mission devoted to UV spectroscopy and imaging. The observatory includes a 170 cm aperture telescope capable of high-resolution and long slit low-resolution spectroscopy, and deep UV and optical imaging. The observatory is designed for observations in the ultraviolet domain where most of astrophysical processes can be efficiently studied with unprecedented capability.  相似文献   

Fast numerical method for growth and retreat of subsurface ice on Mars     

Norbert Schorghofer 《Icarus》2010,208(2):598-607

Subsurface water ice on Mars evolves due to exchange of vapor with the atmosphere, in the form of loss of ice to the atmosphere or in the form of the growth of interstitial ice. Described here is an accelerated numerical method for the long-term evolution of subsurface ice. This accelerated method is five orders of magnitude faster than explicit vapor transport calculations, enabling fundamentally new types of climate models. Its speed matches that of purely thermal models. The speedup is achieved primarily by solving time-averaged equations for vapor transport and ice volume change. Processes incorporated are growth of interstitial pore ice, retreat of pore ice, retreat of an ice sheet, and retreat of pore ice due to geothermal heating from below. Two example applications illustrate this numerical method’s capabilities. Near the permafrost margin at 55° latitude, ice is periodically depleted and slowly recharged, leading to a pore ice layer estimated to be currently no more than a few meters thick. At the Phoenix Landing Site, it shows the formation of a three layered structure, whereby the layer of pore ice can be very thin.  相似文献   

Fractures,hydrothermal alterations and permeability in the Soultz Enhanced Geothermal System     

Béatrice Ledésert  Ronan Hebert  Albert Genter  Danièle Bartier  Norbert Clauer  Céline Grall 《Comptes Rendus Geoscience》2010,342(7-8):607-615

Borehole studies of the Soultz-sous-Forêts granite are dedicated to deep geothermics. The hydraulic properties of the reservoir are mainly controlled by the occurrence of some altered cataclastic shear zones showing a low natural permeability characterized by the occurrence of brines. Those zones show a fracture cluster organisation with sealed fractures of various types (post-filled joints, sheared fractures, veins). The main hydrothermal deposits observed within the permeable zones are geodic quartz, carbonates, illite and more locally sulphides. The fracture wall–rocks are intensely transformed: dissolution of igneous minerals, crystallization of new minerals, porosity and permeability increase. It is important to characterize the newly-formed minerals in order to choose the reagents used to improve the permeability of the exchanger by chemical stimulations. This article represents a synthesis of the studies completed by the authors between 1990 and 2008 on the fracture networks, hydrothermal alterations and mineral crystallizations they induced and data about the flow pathways in the exchanger.  相似文献   

Microborer ichnocoenoses in Quaternary corals from New Caledonia: reconstructions of paleo-water depths and reef growth strategies in relation to environmental changes     

Richet Rémy  Chazottes Véronique  Cabioch Guy  Frank Norbert  S. Burr George 《Quaternary Science Reviews》2011,30(19-20):2827-2838

Coral reef growth and development depend on several environmental factors, including tectonic and climatic parameters and local ecological drivers. Reef growth is especially sensitive to sea-level variations. Paleo-water depth reconstructions are essential tools used to determine reef growth patterns during different periods of reef growth. Assemblages of corals and/or coralline algae have been commonly used in such paleodepth reconstructions. This study shows that using microendolith ichnocoenoses can sometimes provide better accuracy than traditional coralgal analyses, particularly in the depth-range 0–10 m where coralgal assemblages usually show broad distribution ranges. Holocene and Pleistocene cores from two barrier reef sites on the west coast of Grande Terre in New Caledonia are examined here. Holocene reef development at these sites feature examples of microendolith ichnocoenoses that document rapid environmental changes and small sea-level variations of about 2–5 m in amplitude, and record these changes with more accuracy than coral and coralline algae assemblages which are highly dependant on the hydrodynamic energy of the setting. During the Pleistocene, which was less chronologically constrained, the microendolith ichnocoenoses also reflect paleo-water depths and reef-growth patterns at different periods of reef history.  相似文献   

Longitudinal velocities in a clay during plastic compression     

Norbert Morgenstern  Denzil Taylor-Smith 《Pure and Applied Geophysics》1964,58(1):123-128

Summary During uniaxial compression of clay cylinders it was observed that the longitudinal velocity decreased as each load increment was applied and then increased under constant stress. It is suggested that the load increment induces an increase in pore water pressure thereby reducing the effective stress. The velocity is dependent upon the effective stress and it decreases accordingly. The velocity then increases due to the dissipation of the pore pressure.  相似文献   

K-Ar dating of white micas from the Ventersdorp Contact Reef of the Witwatersrand Basin, South Africa: timing of post-depositional alteration     

B. Zhao  N. Clauer  L. J. Robb  H. Zwingmann  T. Toulkeridis  F. M. Meyer 《Mineralogy and Petrology》1999,66(1-3):149-170

Summary White micas from metamorphosed and hydrothermally-altered basaltic lavas, conglomerates, quartzites and shales in and around the Ventersdorp Contact Reef of the Witwatersrand Basin, South Africa, were dated by the K-Ar method to constrain post-depositional thermal and mineralization processes. The minerals were separated into various grain sizes between < 0.4 and 10m, and characterized in terms of composition, paragenetic sequence and texture, by XRD, SEM and TEM techniques. The K-Ar isochron of all white micas in the basaltic lavas suggests an age of 1994 ± 60 Ma, and that of the smaller mica particles (< 2m) in the quartzites defines a younger age of 1917 ± 66 Ma. This range is considered to reflect the timing of long-lived hydrothermal alteration in the Ventersdorp Contact Reef. The older age is slightly younger than the intrusion of the Bushveld Complex (2060–2054 Ma) and the Vredefort catastrophism (2020 Ma), which are well-documented events that were superimposed onto the Witwatersrand Basin. The younger age may be associated with the Eburnian orogenesis along the western edge of the Kaapvaal Craton resulting in continental-scale fluid migration and hydrothermal activity that extended throughout the Griqualand Basin and even into the Witwatersrand Basin. The K-Ar ages obtained here for the white mica fractions of the Ventersdorp Contact Reef in the Witwatersrand Basin confirm that the period between 2.0 and 1.9 Ga was significant, as far as alteration, and possibly also gold mobilization, was concerned.

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K-Ar Datierung von Hellglimmern aus dem hentersdorp Contact Reef des Witwatersrand Beckens, Südafrika: die zeitliche Eingrenzung der nach der Sedimentablagerung erfolgten Alteration

Zusammenfassung Hellglimmer von metamorph und hydrothermal überprägtem Basalt, Konglomerat, Quarzit und Pelit aus dem Ventersdorp Contact Reef im Witwatersrand Becken, Südafrika, wurden mittels der K-Ar Methode datiert, um das Alter der postsedimentären thermischen Überprägung einzugrenzen. Mineralkörner wurden in einzelne Fraktionen zwischen < 0.4 und 10m separiert und auf deren Zusammensetzung, Paragenese und Textur mittels Röntgendiffraktometrie und Elektronenmikroskopie untersucht. Das Isochronenalter für alle Hellglimmerproben aus dem Metabasalt liegt bei 1994 ± 60 Ma, jenes für die Glimmer mit einer Korngröße < 2m im Quarzit bei 1917 ± 66 Ma. Diese Altersspanne wird als Ausdruck einer lang anhaltenden hydrothermalen Veränderung des Ventersdorp Contact Reef interpretiert. Das ältere Alter ist etwas jünger als die Intrusion des Bushveld Komplex (2060–2054 Ma) und die Vredefort Katastrophe (2020 Ma) - zwei gut dokumentierte Ereignisse, die das Witwatersrand Becken erfaßten. Das jüngere Alter könnte mit der eburnischen Orogenese entlang des Westrandes des Kaapvaal Kratons in Zusammenhang stehen, während der es zu Fluid Migration und hydrothermaler Aktivität quer über den Kontinent vom Griqualand Becken bis in das Witwatersrand Becken kam. Die neuen K-Ar Alter bestätigen somit, daß die Zeitspanne von 2.0–1.9 Ga wesentlich für die Alteration und möglicherweise auch für die Mobilisierung von Gold im Witwatersrand Becken war.

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Métamorphisme hydrothermal en faciès salins et pénésalins sur l'exemple du complexe salifère de l'extrême Nord Tunisien     

Norbert Crampon 《Contributions to Mineralogy and Petrology》1973,39(2):117-140

Résumé Les roches sédimentaires des formations salifères de l'extrême Nord tunisien ont fréquemment subies une recristallisation ou une dolomitisation notable, à laquelle se superpose souvent un envahissement de minéraux automorphes, quartz et feldspaths principalement. L'étude des inclusions fluides de ces cristaux conduit à des conditions thermométriques de genèse qui dépassent le stade d'une simple diagenèse. Les transformations subies relèvent davantage d'un épimétamorphisme, en milieu aquifère hypersalin, lié à des anomalies thermiques vraisemblablement en rapport avec des manifestations volcaniques.

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Hydrothermal low grade metamorphism within saline and penesaline facies with reference to the saliferous complex in Northern Tunisia

The sedimentary rocks of saliferous formations in the tunisian far North have gone through frequent recrystallization or a notable dolomitization which an invading of idiomorph minerals mainly made up of quartz and feldspar crystals is frequently added to. Studies carried out on fluid inclusions from these crystals lead thermometric figures clearly exceeding the range of values met with in diagenesis. New paragenesis are best related to low grade metamorphism in aquiferous hypersalted medium bearing relation with thermal anomalies likely connected to volcanism.

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Pb and Sr isotopic systematics of some basalts and sulfides from the East Pacific Rise at 21°N (project RITA)     

Ph. Vidal  N. Clauer 《Earth and Planetary Science Letters》1981,55(2):237-246

Tholeiitic basalts and sulfide deposits from the “Cyana” and “Alvin” diving programs (RITA project) on the East Pacific Rise were analyzed for Pb and Sr isotopes. The basalt data plot within the field defined previously by other East Pacific Rise basalts (²⁰⁶Pb/²⁰⁴Pb: 18.35–18.58;²⁰⁷Pb/²⁰⁴Pb: 15.48–15.53;²⁰⁸Pb/²⁰⁴Pb: 37.8–38.1;⁸⁷Sr/⁸⁶Sr: 0.7022–0.7025). Pb, U and Sr contents (～0.5, ～0.05 and ～110 ppm, respectively) and μ values (～6) are typical of MORB, whereas Th/U ratios (～3.5) are significantly higher.The Pb isotopic ratios of the sulfide samples are very homogeneous (²⁰⁶Pb/²⁰⁴Pb～18.47²⁰⁷Pb/²⁰⁴Pb～15.49²⁰⁸Pb/²⁰⁴Pb～37.90), and plot in the middle of the basalt field. This indicates that (1) the sulfide Pb was derived from the basaltic crust without any significant contribution from either seawater or hemipelagic sediments, and (2) the solutions from which the sulfides were deposited had uniform Pb isotopic composition. The Pb contents of three sulfide samples is relatively high (170–1310 ppm).The Sr contents of five sulfide samples are widely scattered from 12 to 210 ppm, with⁸⁷Sr/⁸⁶Sr ratios intermediate between basaltic and seawater values (0.70554±0.00005 to0.70795±0.00011). Leaching experiments show that both basalt-derived Sr and seawater Sr were present in the solutions which deposited the sulfides. In some cases, Sr was also adsorbed from seawater onto the sulfides following their deposition. Basalt-derived Sr and seawater Sr are also present in associated non-sulfide phases.  相似文献   

Composition isotopique du strontium d'eaux interstitielles extraites de sédiments récents: un argument en faveur de l'homogénéisation isotopique des minéraux argileux     

Norbert Clauer  Michel Hoffert  Daniel Grimaud  Georges Millot 《Geochimica et cosmochimica acta》1975,39(11):1579-1582

The ${}^{87}\text{Sr}{}^{86}\text{Sr}$ ratio of interstitial waters squeezed from recent sediments of the Pacific Ocean increases from 0.70920 ± 0.00017 (2σ) to 0.70960 ± 0.0023 and 0.70984 ± 0.00040 at 1.50 and 1.60 m depth—reference value for sea water: 0.70910 ± 0.00035. This variation underlines the likely existence of exchanges between the clays and the interstitial environment. The isotopic homogenization of strontium between the clays and their environment, result of these changes, becomes thus a credible phenomenon. This is a new argument for the dating of clays by the $\text{Rb}\text{Sr}$ method.  相似文献