Jade in the Serpentinite Mélanges of the Rio San Juan Complex from the Dominican Republic     

SCHERTL Hans-Peter  MARESCH Walter V.  HERTWIG Andreas 《《地质学报》英文版》2015,89(Z2):79-80

<正>New occurrences of jadeitite,jadeite quartzites,and jadeite-lawsonitequartzites have recently been discovered in the Rio San Juan Complex(RSJC)of the northern Dominican Republic.These rocks are found in serpentinite mélanges associated with a former intra-oceanic  相似文献   

Noble gas composition,cosmic-ray exposure age, 39Ar-40Ar,and I-Xe analyses of ungrouped achondrite NWA 7325     

Jens Hopp  Natalie Schröter  Olga Pravdivtseva  Hans-Peter Meyer  Mario Trieloff  Ulrich Ott 《Meteoritics & planetary science》2018,53(6):1150-1163

Northwest Africa (NWA) 7325 is an anomalous achondrite that experienced episodes of large-degree melt extraction and interaction with melt under reducing conditions. Its composition led to speculations about a Mercurian origin and provoked a series of studies of this meteorite. We present the noble gas composition, and results of ⁴⁰Ar/³⁹Ar and ¹²⁹I-¹²⁹Xe studies of whole rock splits of NWA 7325. The light noble gases are dominated by cosmogenic isotopes. ²¹Ne and ³⁸Ar cosmic-ray exposure ages are 25.6 and 18.9 Ma, respectively, when calculated with a nominal whole rock composition. This ³⁸Ar age is in reasonable agreement with a cosmic-ray exposure age of 17.5 Ma derived in our ⁴⁰Ar/³⁹Ar dating study. Due to the low K-content of 19 ± 1 ppm and high Ca-content of approximately 12.40 ± 0.15 wt%, no reliable ⁴⁰Ar/³⁹Ar age could be determined. The integrated age strongly depends on the choice of an initial ⁴⁰Ar/³⁶Ar ratio. An air-like component is dominant in lower temperature extractions and assuming air ⁴⁰Ar/³⁶Ar for the trapped component results in a calculated integrated age of 3200 ± 260 (1σ) Ma. This may represent the upper age limit for a major reheating event affecting the K-Ar system. Results of ¹²⁹I-¹²⁹Xe dating give no useful chronological information, i.e., no isochron is observed. Considering the highest ¹²⁹Xe*/¹²⁸Xe_I ratio as equivalent to a lower age limit, we calculate an I-Xe age of about 4536 Ma. In addition, elevated ¹²⁹Xe/¹³²Xe ratios of up to 1.65 ± 0.18 in higher temperature extractions indicate an early formation of NWA 7325, with subsequent disturbance of the I-Xe system.  相似文献   

Sample return of interstellar matter (SARIM)     

Ralf Srama  Thomas Stephan  Eberhard Grün  Norbert Pailer  Anton Kearsley  Amara Graps  Rene Laufer  Pascale Ehrenfreund  Nicolas Altobelli  Kathrin Altwegg  Siegfried Auer  Jack Baggaley  Mark J. Burchell  James Carpenter  Luigi Colangeli  Francesca Esposito  Simon F. Green  Hartmut Henkel  Mihaly Horanyi  Annette Jäckel  Sascha Kempf  Neil McBride  Georg Moragas-Klostermeyer  Harald Krüger  Pasquale Palumbo  Andre Srowig  Mario Trieloff  Peter Tsou  Zoltan Sternovsky  Oliver Zeile  Hans-Peter Röser 《Experimental Astronomy》2009,23(1):303-328

The scientific community has expressed strong interest to re-fly Stardust-like missions with improved instrumentation. We propose a new mission concept, SARIM, that collects interstellar and interplanetary dust particles and returns them to Earth. SARIM is optimised for the collection and discrimination of interstellar dust grains. Improved active dust collectors on-board allow us to perform in-situ determination of individual dust impacts and their impact location. This will provide important constraints for subsequent laboratory analysis. The SARIM spacecraft will be placed at the L2 libration point of the Sun–Earth system, outside the Earth’s debris belts and inside the solar-wind charging environment. SARIM is three-axes stabilised and collects interstellar grains between July and October when the relative encounter speeds with interstellar dust grains are lowest (4 to 20 km/s). During a 3-year dust collection period several hundred interstellar and several thousand interplanetary grains will be collected by a total sensitive area of 1 m². At the end of the collection phase seven collector modules are stored and sealed in a MIRKA-type sample return capsule. SARIM will return the capsule containing the stardust to Earth to allow for an extraction and investigation of interstellar samples by latest laboratory technologies.  相似文献   

Spatio-temporal microseismicity clustering in the Cretan region     

Dirk Becker  Thomas Meier  Martina Rische  Marco Bohnhoff  Hans-Peter Harjes 《Tectonophysics》2006,423(1-4):3

Spatio-temporal clustering of microseismicity in the central forearc of the Hellenic Subduction Zone in the area of Crete is investigated. Data for this study were gathered by temporary short period networks which were installed on the islands of Crete and Gavdos between 1996 and 2004. The similarity of waveforms is quantified systematically to identify clusters of microseismicity. Waveform similarities are calculated using an adaptive time window containing both the P- and S-wave onsets. The cluster detection is performed by applying a single linkage approach. Clusters are found in the interplate seismicity as well as in the intraplate seismicity of the continental crust in the region of the transtensional Ptolemy structure. The majority of the clusters are off the southern coast of Crete, in a region of elevated intraplate microseismic activity within the Aegean plate. Clusters in the Gavdos region are located at depths compatible with the plate interface while cluster activity in the region of the Ptolemy trench is distributed along a nearly vertical structure throughout the crust extending down to the plate interface. Most clusters show swarm-like behaviour with seismic activity confined to only a few hours or days, without a dominant earthquake and with a power law distribution of the interevent times.For the largest cluster, precise relocations of the events using travel time differences of P- and S-waves derived from waveform cross correlations reveal migration of the hypocenters. This cluster is located in the region of the Ptolemy trench and migration occurs along the strike of the trench at  500 m/day.Relocated hypocenters as well as subtle differences in the waveforms suggest an offset between the hypocenters and thus the activation of distinct patches on the rupture surface. The observed microseismicity patterns may be related to fluids being transported along the plate interface and escaping towards the surface in zones of crustal weakness (Ptolemy structure), triggering swarm-like cluster activity along its way.  相似文献   

TOPO-EUROPE: The geoscience of coupled deep Earth-surface processes   总被引：2，自引：0，他引：2  

S.A.P.L. Cloetingh  P.A. Ziegler  P.J.F. Bogaard  P.A.M. Andriessen  I.M. Artemieva  G. Bada  R.T. van Balen  F. Beekman  Z. Ben-Avraham  J.-P. Brun  H.P. Bunge  E.B. Burov  R. Carbonell  C. Facenna  A. Friedrich  J. Gallart  A.G. Green  O. Heidbach  A.G. Jones  L. Matenco  J. Mosar  O. Oncken  C. Pascal  G. Peters  S. Sliaupa  A. Soesoo  W. Spakman  R.A. Stephenson  H. Thybo  T. Torsvik  G. de Vicente  F. Wenzel  M.J.R. Wortel  TOPO-EUROPE Working Group 《Global and Planetary Change》2007,58(1-4):1

TOPO-EUROPE addresses the 4-D topographic evolution of the orogens and intra-plate regions of Europe through a multidisciplinary approach linking geology, geophysics, geodesy and geotechnology. TOPO-EUROPE integrates monitoring, imaging, reconstruction and modelling of the interplay between processes controlling continental topography and related natural hazards. Until now, research on neotectonics and related topography development of orogens and intra-plate regions has received little attention. TOPO-EUROPE initiates a number of novel studies on the quantification of rates of vertical motions, related tectonically controlled river evolution and land subsidence in carefully selected natural laboratories in Europe. From orogen through platform to continental margin, these natural laboratories include the Alps/Carpathians–Pannonian Basin System, the West and Central European Platform, the Apennines–Aegean–Anatolian region, the Iberian Peninsula, the Scandinavian Continental Margin, the East-European Platform, and the Caucasus–Levant area. TOPO-EUROPE integrates European research facilities and know-how essential to advance the understanding of the role of topography in Environmental Earth System Dynamics. The principal objective of the network is twofold. Namely, to integrate national research programs into a common European network and, furthermore, to integrate activities among TOPO-EUROPE institutes and participants. Key objectives are to provide an interdisciplinary forum to share knowledge and information in the field of the neotectonic and topographic evolution of Europe, to promote and encourage multidisciplinary research on a truly European scale, to increase mobility of scientists and to train young scientists. This paper provides an overview of the state-of-the-art of continental topography research, and of the challenges to TOPO-EUROPE researchers in the targeted natural laboratories.  相似文献   

Diamonds and the Kokchetav Massif     

Schertl Hans-Peter 《《地质学报》英文版》2015,89(Z2):81-83

<正>A geodynamical revolution in modern geosciences was initiated by Chopin(1984)and Smith(1984),who discovered metamorphic coesite in rocks of the Dora Maira Massif,Italy and the Western gneiss region,Norway,respectively.The term"UHP metamorphism"was born and such rocks which initially have been considered as products of an exotic process on a local scale,  相似文献   

Optical microscope-cathodoluminescence (OM–CL) imaging as a powerful tool to reveal internal textures of minerals     

Jens Götze  Hans-Peter Schertl  Rolf D. Neuser  Ulf Kempe  John M. Hanchar 《Mineralogy and Petrology》2013,107(3):373-392

Optical microscope-cathodoluminescence (OM-CL) microscopy is a modern luminescence technique with widespread applications in geosciences. Many rock-forming and accessory minerals show specific CL properties that can be successfully used in geoscience and materials science research. One of the most spectacular applications is the visualization of growth textures, alteration, and other internal textures in minerals that are not discernible with other analytical techniques. These results provide information about the real structure of minerals and materials and can be used for the reconstruction of geological processes of mineral formation and subsequent alteration. The information obtained from CL imaging in combination with spectral measurements of the CL emission allows for a more thorough understanding of structural states of solids and/or trace-element incorporation. Additional information can be obtained when luminescence studies are combined with other analytical techniques with high sensitivity and high spatial resolution.  相似文献   

Post-glacial rebound and present-day three-dimensional deformations     

Hans-Peter Plag  Bjrn Engen  Thomas A. Clark  John J. Degnan  Bernd Richter 《Journal of Geodynamics》1998,25(3-4)

The WEGENER^† activities related to the study of post-glacial rebound are presented together with a review of the present state-of-the-art in this study field. Post-glacial rebound research is an unique tool for studying the viscoelastic behaviour of the Earth's mantle on time scales of thousands of years. The viscosity structure of the Earth's mantle determined from an inversion of observations of glacially induced deformations is a basic requirement for modelling long-term phenomena such as the convection in the Earth's mantle, and for better understanding unsolved questions such as the nature of the mantle discontinuities or the vertical scale of convection.First, an introduction to the scientific background is given, and the three principal ingredients for post-glacial rebound studies, namely the ice model, the Earth model, and the observations are briefly considered. For the ice model, the uncertainties due to a trade-off between ice model and Earth rheology are outlined. The different approaches used to model the Earth and its deformations in post-glacial rebound studies are discussed emphasising the preliminary nature of the derived rheologies and depth dependencies. The observations, in particular the relative sea-level changes and three-dimensional surface deformations, are described with special emphasis on observational gaps. Based on the discussion of the ingredients, an outline of the future developments in post-glacial rebound research is attempted with particular emphasis on the Earth model and the theory of deformations.For several decades extreme efforts have been made to precisely monitor the land uplift in Scandinavia. However, for the height component the existing data still are associated with large uncertainties while reliable data on the horizontal component are practically nil. The ongoing long-term (longer than ten years) spacegeodetic measurements are likely to provide the three-dimensional deformations with the spatial resolution and accuracy required in order to substantially contribute to post-glacial rebound studies. Thus, present-day three-dimensional deformations of the Earth's surface beneath and around the former ice sheets as a constraint for the mantle rheology and viscosity structure will increasingly become important as they become known from space-geodetic measurements with high spatial resolution and an accuracy approaching the mm/a-level.  相似文献   

Petrogenesis of early cretaceous andesite dykes in the Sulu orogenic belt,eastern China     

Wang  Songjie  Li  Xuping  Schertl  Hans-Peter  Feng  Qingda 《Mineralogy and Petrology》2019,113(1):77-97

Mineralogy and Petrology - This study presents data of in-situ mineral major and trace element chemistry, whole-rock major and trace element and Sr–Nd isotope geochemistry, as well as zircon...  相似文献   

Experimental constraints on the genesis of Jadeite quartzite from Shuanghe, Dabie Mountain ultra-high pressure metamorphic terrane     

ZHANG YanFei  WU Yao  WANG Chao  JIN ZhenMin  Hans-Peter SCHERTL 《中国科学:地球科学(英文版)》2014,57(1):104-116

Jadeite quartzite,essentially a two-phase rock made up of jadeite and quartz,is one of the most important UHP lithologies occurring in the Dabie Mountain ultrahigh pressure metamorphic belt and forms layers in biotite-plagioclase gneiss.High pressurehigh temperature studies on natural albite from the country rock gneiss were undertaken to reveal the—in parts—complex mineralogical changes that occur in the jadeite quartzite during prograde metamorphism.Experiments were conducted at 800–1200°C,in the pressure range of 2.0–3.5 GPa.One of the most intriguing results shows that the low pressure boundary of the jadeite+coesite stability field is located between about 3.2 GPa at 1000°C and 3.4 GPa at 1200°C,thus about(0.2–0.3)±0.1GPa higher than the quartz-coesite transition curve,given the uncertainty in the present study.Minor amounts of sodium and aluminum entering the structure of quartz and the intimate intergrowth texture of the run products may contribute to the observed pressure shift.Combined petrological and mineralogical studies on the run products and the natural rocks yield the following prograde reaction sequence to have occurred:The protolith of the jadeite-quartzite from Dabie Mountain is an albitized siltstone/greywacke characterized by an albite+quartz assemblage.During prograde metamorphism albite breaks down to form jadeite+quartz and thus at this stage two types of quartz can be distinguished whereas type-I-quartz already existed in the protolith,type-II-quartz represents a newly formed reaction product of albite.During further P-T-increase the pure type-I-quartz was transformed to coesite,whereas type-II-quartz(together with jadeite)was still present as a stable phase because of its impurities of Na and Al.At a later stage during further subduction,type-II-quartz also decomposes to form coesite.These studies represent an important puzzlement for a better understanding of the evolution of jadeite-quartzite from the Dabie Mountain during continental crust subduction and thus contribute to a more complete knowledge of the formation of the Dabie Mountain UHP orogenic belt in general.  相似文献