Potential climatic transitions with profound impact on Europe     

Anders Levermann  Jonathan L. Bamber  Sybren Drijfhout  Andrey Ganopolski  Winfried Haeberli  Neil R. P. Harris  Matthias Huss  Kirstin Krüger  Timothy M. Lenton  Ronald W. Lindsay  Dirk Notz  Peter Wadhams  Susanne Weber 《Climatic change》2012,110(3-4):845-878

We discuss potential transitions of six climatic subsystems with large-scale impact on Europe, sometimes denoted as tipping elements. These are the ice sheets on Greenland and West Antarctica, the Atlantic thermohaline circulation, Arctic sea ice, Alpine glaciers and northern hemisphere stratospheric ozone. Each system is represented by co-authors actively publishing in the corresponding field. For each subsystem we summarize the mechanism of a potential transition in a warmer climate along with its impact on Europe and assess the likelihood for such a transition based on published scientific literature. As a summary, the ‘tipping’ potential for each system is provided as a function of global mean temperature increase which required some subjective interpretation of scientific facts by the authors and should be considered as a snapshot of our current understanding.  相似文献   

Post-collisional plutonism with adakite-like signatures: the Eocene Saraycık granodiorite (Eastern Pontides,Turkey)     

Gültekin?TopuzEmail author  Rainer?Altherr  Winfried?H.?Schwarz  Wolfgang?Siebel  Muharrem?Sat?r  Abdurrahman?Dokuz 《Contributions to Mineralogy and Petrology》2005,150(4):441-455

The post-collisional Saraycık granodiorite intruded into a late Paleocene to early Eocene nappe pile that formed during collision of the Pontides in the North and the Anatolide-Tauride platform in the South, leading to the formation of the İzmir-Ankara-Erzincan suture. A relatively shallow pluton intrusion depth (∼5 to 8 km) was estimated from Al-in-hornblende geobarometry and contact metamorphic assemblages. The emplacement age is tightly constrained to ∼52 Ma by two Ar–Ar plateau and total fusion ages on biotite. The main mass of the pluton consists of metaluminous to peraluminous biotite granodiorite and hornblende-biotite granodiorite. In addition, up to 10-m thick dacitic and <25-cm thick aplitic dikes occur. Granodiorites and dacites show many close compositional similarities to high-silica adakites from supra-subduction zone settings, but tend to be slightly more felsic and to have a higher aluminium saturation index. Chondrite-normalized (cn) rare earth element patterns are characterized by high ratios of (La/Yb)_cn, concave-upward shapes of the HREE and a lack of significant Eu anomalies. In conjunction with relatively high abundances of Ba and Sr as well as low abundances of Y, HREE and Sc, these patterns suggest a feldspar-poor, garnet ± amphibole-rich fractionating mineral assemblage (residue). All samples have very similar Nd–Sr isotopic characteristics, regardless of rock type. Initial ε_Nd values range from −0.3 to −1.2 and initial ⁸⁷Sr/⁸⁶Sr ratios from 0.70491 to 0.70529. It is suggested that the magmas formed by partial melting of mafic lower crust at elevated pressures (∼1 to 2 GPa).  相似文献   

Über Bau,Alter und Metamorphose des Altkristallins der Schobergruppe,Osttirol     

Georg Troll  Rainer Forst  Frank Söllner  Winfried Brack  Hermann Köhler  Dieter Müller-Sohnius 《International Journal of Earth Sciences》1976,65(1):483-511

Zusammenfassung Zwei Komplexe sind zu trennen, ein Liegendkomplex aus wechsellagernden Glimmerschiefern und Quarziten mit gegenseitigen Übergängen und ein Hangendkomplex, der durch Einschaltungen von Hornblendegneisen, (Eklogit-)Amphiboliten und spärlich Amphibol-Eklogiten gekennzeichnet ist. Gerade die Amphibol-Eklogite dokumentieren eine polyphase Metamorphosegeschichte. Beide Einheiten sind durch eine horizontale bis sehr flach einfallende tektonische Grenze (Schuppenzone) getrennt, an der als Leitgestein ein Mikroklin-Augengneis von wenigen Metern Mächtigkeit auftritt.Hangend- und Liegendkomplex weisen ein verwickeltes und zum Teil gleichartiges tektonisches Inventar auf. Der Komplex der Eklogitamphibolite ist als eigenständige tektonische Einheit zu betrachten. B₁ ca. senkrecht B₂ zeigt weiträumige Verbiegungen der Gesteine (geringe Amplituden, große Wellenlängen, NE- oder SW-Tauchen). Die stärkste Einengung verläuft NE-SW (isoklinales B₂ mit 10–25° SE-Tauchen). Auch in den Schiefer- und Gneisserien finden sich zwei Faltenachsenrichtungen (B₁=25–35°-Tauchen nach ENE; Anlage von Störungen in 0kl und ac). B₁ und B₁ sind ähnlich. B₃ kann alpidisch sein (Tauchen flach nach E), was aber noch abgesichert werden muß.Das Maximum der Metamorphose liegt bei den Amphibol-Eklogiten zwischen Glaukophanschiefer- und Amphibolitfazies (350–550° C; 4,5–8 kb). In einer weiteren Phase ist die nachträgliche Amphibolitisierung der Eklogite auf eine Temperaturerhöhung unter gleichzeitigem Druckabfall (Symplektitbildung) zurückzuführen. Der H₂O-Druck spielt selektiv eine hervorragende Rolle. Die achsenparallele Lineation der progressiv metamorphen Minerale ist als syntektonische Kristallisation mit der B₂-Faltenphase anzusehen.Von den Augen- und Flasergneisen sind Altersbestimmungen nach der Rb-Sr-Gesamtgesteinsmethode durchgeführt worden. Die gemessenen Proben (8 Proben aus dem Wangenitzseegebiet, dessen nächste Entfernung zum Tauernfenster 10 km beträgt) ergeben eine Isochrone mit einem Alter von 439±20 (2) Mill. Jahren ( _{Rb 87}=1.47 · 10^–11 · a^–1) und einem Sr⁸⁷/Sr⁸⁶-Anfangsverhältnis von 0.7107±0.0016 (2). Das kaledonische Gesamtgesteinsalter stimmt mit der bisher bekannten geodynamischen Geschichte des Gebietes überein.

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Two complexes can be distinguished, an upper and a lower complex. The latter is set up by alternating mica schists and quartzites. Both of these show continuous transitions to each other. The upper complex is characterized by intercalations of hornblende gneisses, (eclogite) amphibolites and rarely amphibole eclogites. Particularly the amphibole eclogites show a polyphase history of metamorphism. Both units are divided by a horizontal to very gently dipping tectonic boundary. A microcline augengneiss of a few metres in thickness occurs parallel to this boundary.The upper and lower complex show a similar but complicated tectonic pattern, the complex of the eclogite amphibolites can be considered as a separate tectonic unit. B₁ ca. perpendicular to B₂, appears in ample flexures and folds (slight amplitudes large wavelengths, plunging to NE or SW). The strongest compression is directed from NE to SW (isoclinal B₂ plunging 10–25° to SE). Also in the series of schists and gneisses two fold axes are found (B₁ plunging 25–35° to ENE; first formation of faults in Okl and ac directions). B₁ and B₁ are similar. B₃ may be of alpidic age (plunging gently to E), but that has yet to be verified.The maximum of metamorphism for the amphibole eclogites is between glaucophane schist facies and amphibolite facies (350–550° C; 4,5–8 kb). In a further phase the later amphibolitization of the eclogites has to be attributed to an elevation of temperature under synchronous decrease of the pressure (formation of symplektite). The H₂O pressure plays a selective but eminent role. The lineation of the progressively metamorphic minerals parallel to the fold axes, represents syntectonic crystallization at the time of the B₂ folding.Age determinations of the augengneisses and flasergneisses have been carried out by the Rb-Sr whole rock method. The measured samples (8 samples from the Wangenitz lake area, at a distance of 10 km south of the margin of the Tauern Window) give an isochron resulting an age of 439±20 (2) m. y. ( _{Rb 87}=1.47 · 10^–11 · a^–1) and an initial Sr⁸⁷/Rb⁸⁶ ratio of 0.7107±0.0016 (2). The caledonian whole rock age is consistent with the presently known regional geodynamic history.

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Résumé On peut distinguer deux complexes: un complexe inférieur composé d'alternances de micaschistes et de quartzites passant les uns aux autres, et un complexe supérieur caractérisé par des intercalations de gneiss à hornblende, d'amphibolites éclogitiques et plus rarement d'éclogites à amphiboles. C'est précisément ces éclogites à amphiboles qui montrent le déroulement métamorphique en plusieurs phases. Les deux unités sont séparées par une limite tectonique horizontale à faiblement inclinée («zone des écailles»). Un augengneiss à microcline d'une épaisseur de quelques mètres sert d'horizon — repère pour les séparer. Ces complexes inférieur et supérieur fournissent un inventaire tectonique compliqué et, en partie, analogue. Il faut considérer le complexe à amphibolites éclogitiques comme une unité tectonique autonome. B₁ à peu près perpendiculaire à B₂, montre des déformations sur de grandes étendues (amplitudes faibles grandes longeurs d'onde, plongements NE ou SW. Le resserrement le plus fort se fait suivant la direction NE-SW (B₂ isoclinal avec plongement SE de 10° à 25°). De même dans les séries des schistes et des gneiss, on trouve deux directions d'axes de plis (B₁ = inclinaison de 25° à 35° vers ENE prédisposition à failles dans Ohl et ac). B₁ et B₁ sont semblables. B₃ peut-être alpin (inclinaison faible vers l'E), ce qui cependant reste encore à démontrer.Le maximum du métamorphisme dans les éclogites à amphiboles se situe entre les faciès des schistes à glaucophane et des amphibolites (350° à 550° C; 4,5 à 8 kb). C'est à une autre phase qu'il faut attribuer l'amphibolisation ultérieure des éclogites, due à une élévation de température et à une diminution de pression simultanée (formation de symplectites). La pression de H₂O joue un rôle sélectif considérable. On doit considérer la linéation, parallèle aux axes de plis, des minéraux du métamorphisme progressif comme une cristallisation syntectonique de la phase des plis B₂.Les augengneiss et des flasergneiss ont fourni les déterminations d'âge d'après la méthode Rb-Sr appliquée aux roches totales. Les échantillons mesurés (8 provenant de la région du lac de Wangenitz, dont la distance la plus courte jusqu'à la fenêtre des Tauern est de 10 km) donnent une isochrone d'un âge estimé à 439±20 (2) millions d'années ( _{Rb 87}=1.47 · 10^–11 · a^–1) et un rapport initial Sr⁸⁷/Sr⁸⁶ de 0,7107±0,0016 (2). L'âge «calédonien» de l'ensemble concorde avec l'histoire géodynamique connue jusqu'à maintenant de ce domaine.

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: () , , ( -) -. - . (« »), . , , . - , . B_{1 2} : — , , - , - . - : ₂ 10–25° -. : B₁=25 35° ENE, Ok1 . b_{1 2} , — . . - (350–550° ; 4,5–8 ). , . . , ₂. Rb/Sr. — 8 , 10 , — 439±20 . (_Rb87=1.47·10^–11·^–1), Sr⁸⁷/Sr⁸⁶ 0,7107±0,0016. « » .

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Waste Heat Balance in Aquifers Calculated by a Computer Programme     

Wolfram Kley  Winfried Heekmann 《Ground water》1981,19(2):144-148

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Sind detritische Zirkone rötlicher Farbe auch in Mitteleuropa Indikatoren für präkamhrische Liefergebiete?     

Dr. Winfried Zimmerle 《International Journal of Earth Sciences》1972,61(1):116-139

Zusammenfassung Detritische Zirkone rötlicher Farbe wurden erstmals in Großbritannien vonMackie (1923) als sicherer Hinweis auf präkambrische Liefergebiete gewertet. Unter diesem Gesichtspunkt wurde nun auch in Mitteleuropa in Sandstein- und Konglomeratproben vom Kambrium bis zum Tertiär der Anteil an rötlichem Zirkon bestimmt. Untersucht wurden drei stratigraphische Richtprofile aus dem Hohen Venn, aus der Saar-NaheSenke sowie aus dem Harz und Harzvorland, ferner Proben aus dem Massiv von Rocroi, dem Massiv von Brabant und aus Nordspanien. Auch in den Sedimentgesteinen Mitteleuropas nimmt der Anteil an rötlichem Zirkon, statistisch gesehen, mit dem geologischen Alter zu.Zum Schluß der Arbeit wird hingewiesen auf die Bedeutung solch spezifischer Mineraluntersuchungen für eine verfeinerte Schwermineralanalyse und, darüber hinaus, für die Lösung einfacher stratigraphischer Probleme.

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Detrital zircons of pink color were considered byMackie (1923) to be a clue to Pre-Cambrian source rocks in Great Britain. Basing on this observation, the amount of detrital pink zircon was determined in sandstone and conglomerate samples of Cambrian to Tertiary age from Central Europe. Three stratigraphic standard profiles from the Hohes Venn, the Saar-Nahe trough as well as from the Harz and the Harzvorland have been studied. In addition, samples from the Rocroi massif, Brabant massif and northern Spain have been examined. Statistically, the sedimentary rocks of Central Europe show an increase in detrital pink zircon with growing geological age.In conclusion, the significance of such specific mineral studies to improve heavy mineral analysis and to solve simple stratigraphic problems is emphasized.

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Resumen Circón detrítico de color rojizo fué considerado porMackie (1923) de estar proveniente del Precámbrico en Gran Bretañia. Basándose en esta observación el porcentaje de circón rojizo detrítico fué determinado en muestras de areniscas y conglomerates de edad cambriana hasta tertiaria en Europa Central. Tres perfiles estratigráficas estandardizadas se han estudiado de la Hohes Venn, de la Saar-Nahe depresión y de la región de Harz. Además muestras fueron examinadas del macizo de Rocroi (Francia), del macizo de Brabante (Bélgica) y de España septentrional. Estadísticamente se nota un aumento de ciroón rojizo detrítico con la edad geológica progresiva.En conclusion, se alude le significación de tales estudios mineralógicos específicos para perfeccionar el analysis por minerales pesados y para solver problemas estratigráficos sencillos.

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(1923) , , , . . , , -, , , . . .

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A Reappraisal of the 40Ar/38Ar Dating Technique via Irradiation with γ-Rays     

Jens Hopp  Manfred Vogt  Winfried H. Schwarz  Mario Trieloff 《Geostandards and Geoanalytical Research》2023,47(3):579-594

In a reconnaissance study, we investigated the potential of γ-ray induced production of ³⁸Ar_K from ³⁹K for geochronological applications. For this purpose, various age monitors commonly in use for the established ⁴⁰Ar/³⁹Ar-method were co-irradiated for 60 h at 17.6 MeV maximum energy in the ELBE facility, Dresden-Rossendorf, Germany. Because the available energy was low, total production of ³⁸Ar_K was depressed, leading to low J₃₈-values of (2.1–4.1) × 10^-6 and hence resulted in only minor ³⁸Ar excess when compared with atmospheric ³⁸Ar_/³⁶Ar ratios. In spite of these restrictions, ages of younger monitors could be reproduced within error, whereas older age reference materials showed discrepancies due to the low production rate. We observed Ca-derived contributions on ³⁶Ar in analysed CaF₂ reference materials, and calculated a limit for Ca-interference on ³⁸Ar_Ca of (³⁸Ar/³⁶Ar)_Ca = 0.07 ± 0.03 (1s). In addition, we investigated a potential recoil redistribution of ³⁸Ar by stepwise heating experiments, but could not quantify this further because of concurring processes. More work at higher photon energies is necessary to resolve other open issues, in particular the potential of utilising ⁴⁰Ar/³⁷Ar ratios for age determination and the possibility of ⁴²Ar production from ⁴⁴Ca, which would allow correction for Ca-interference reactions on other Ar isotopes. This would be a pre-requisite for dating extra-terrestrial rocks.  相似文献   

Structural identification of the C₂₅ highly branched isoprenoid pentaene in the marine diatom Rhizosolenia setigera     

Jaap S. Sinninghe Damst  Stefan Schouten  W. Irene C. Rijpstra  Ellen C. Hopmans  Harry Peletier  Winfried W. C. Gieskes  Jan A. J. Geenevasen 《Organic Geochemistry》1999,30(12):918

2,6,10,14-tetramethyl-7-(3-methylpent-4-enyl)-pentadeca-2,5E,9E,13-tetraene I possessing a C₂₅ highly branched isoprenoid skeleton has been isolated from the marine diatom Rhizosolenia setigera and identified by ¹H and ¹³C NMR spectroscopy.  相似文献   

Cosmetic Isotope Analyses Applied to River Longitudinal Profile Evolution: Problems and Interpretations     

Michele A. Seidl  Robert C. Finkel  Marc W. Caffee  G. Bryant Hudson  William E. Dietrich 《地球表面变化过程与地形》1997,22(3):195-209

The use of cosmogenic isotopes to determine surface exposure ages has grown rapidly in recent years. The extent to which cosmogenic nuclides can distinguish between mechanistic hypotheses of landscape evolution is an important issue in geomorphology. We present a case study to determine whether surface exposure dating techniques can elucidate the role knickpoint propagation plays in longitudinal profile evolution. Cosmogenically produced ¹⁰Be, ²⁶Al, ³⁶Cl, ³He and ²¹Ne were measured in olivines collected from 5·2 Ma basalt flows on Kauai, Hawaii. Several obstacles had to be overcome prior to the measurement of In situ-produced radionuclides, including removal of meteoric ¹⁰Be from the olivine grains. Discrepancies between the radionuclide and noble gas data may suggest limits for exposure dating. Approximate surface exposure ages calculated from the nuclide concentrations indicate that large boulders may remain in the Hawaiian valley below the knickpoint for hundreds of thousands of years. The ages of samples collected above the knickpoint are consistent with estimates of erosion based on the preservation of palaeosurfaces. Although the exposure ages can neither confirm nor reject the nickpoint hypothesis, boulder ages downstream of the knickpoint are consistent with a wave of incision passing upvalley. The long residence time off the coarse material in the valley bottom further suggests that knickpoint propagation beneath a boulder pile is necessary for incision of the bedrock underlying the boulders to occur. © 1997 by John Wiley & Sons, Ltd.  相似文献   

U‐Pb dating of zircons from an impact melt of the Nördlinger Ries crater     

Winfried H. Schwarz  Michael Hanel  Mario Trieloff 《Meteoritics & planetary science》2020,55(2):312-325

In situ U‐Pb measurements on zircons of the Ries impact crater are presented for three samples from the quarry at Polsingen. The U‐Pb data of most zircons plot along a discordia line, leading to an upper intercept of Carboniferous age (331 ± 32 Ma [2σ]). Four zircons define a concordia age of 313.2 ± 4.4 Ma (2σ). This age most probably represents the age of a granite from the basement target rocks. From granular textured zircon grains (including baddeleyite and anatase/Fe‐rich phases, first identified in the Ries crater), most probably recrystallized after impact (13 analyses, 4 grains), a concordia age of 14.89 ± 0.34 Ma (2σ) and an error weighted mean ²⁰⁶Pb*/²³⁸U age of Ma 14.63 ± 0.43 (2σ) is derived. Including the youngest concordant ages of five porous textured zircon grains (24 spot analyses), a concordia age of 14.75 ± 0.22 Ma (2σ) and a mean ²⁰⁶Pb*/²³⁸U age of 14.71 ± 0.26 Ma (2σ) can be calculated. These results are consistent with previously published ⁴⁰Ar/³⁹Ar ages of impact glasses and feldspar. Our results demonstrate that even for relatively young impact craters, reliable U‐Pb ages can be obtained using in situ zircon dating by SIMS. Frequently the texture of impact shocked zircon grains is explained by decomposition at high temperatures and recrystallization to a granular texture. This is most probably the case for the observed granular zircon grains having baddeleyite/anatase/Fe‐rich phases. We also observe non‐baddeleyite/anatase/Fe‐rich phase bearing zircons. For these domains, reset to crater age is more frequently for high U,Th contents. We tentatively explain the higher susceptibility to impact resetting of high U,Th domains by enhanced Pb loss and mobilization due to higher diffusivity within former metamict domains that were impact metamorphosed more easily into porous as well as granular textures during decomposition and recrystallization, possibly supported by Pb loss during postimpact cooling and/or hydrothermal activity.  相似文献   

A Carnian 40Ar/39Ar age for the Paasselkä impact structure (SE Finland)—An update          下载免费PDF全文

Winfried H. Schwarz  Martin Schmieder  Elmar Buchner  Mario Trieloff  Jarmo Moilanen  Teemu Öhman 《Meteoritics & planetary science》2015,50(1):135-140

A recrystallized band of pale feldspathic impact melt in a gneissic impact breccia from the approximately 10 km Paasselkä impact structure in southeast Finland was dated via ⁴⁰Ar/³⁹Ar step‐heating. The newly obtained plateau age of 228.7 ± 1.8 (2.2) Ma (2σ) (MSWD = 0.32; p = 0.93) is equal to the previously published pseudoplateau age of 228.7 ± 3.0 (3.4) (2σ) for the impact event. According to the current international chronostratigraphic chart and using the most recent published suggestions for the K decay constants, a Carnian (Late Triassic) age for the Paasselkä impact structure of 231.0 ± 1.8 (2.2) Ma (2σ) is calculated and considered the most precise and accurate age for this impact structure. The new plateau age for Paasselkä confirms the previous dating result but is, based on its internal statistics, much more compelling.  相似文献