Late Quaternary relative sea-level changes and the role of glaciation upon continental shelves     

H.-P. Plag  W.E.N. Austin  D.F. Belknap  R.J.N. Devoy  J. England  H. Josenhans  J.D. Peacock  K.S. Petersen  K. Rokoengen  J.D. Scourse  D.E. Smith  R.T.R. Wingfield 《地学学报》1996,8(3):213-222

Sea levels of the past 20 kyr are largely determined by the response of the Earth to the last ice age. Consequently, sea-level indicators are an important source of information about the interaction between cryosphere and hydrosphere and the solid Earth. Based on the material presented at a recent European Science Foundation conference, the present paper pin-points some of the topics currently under discussion with respect to sea-level evidence found on continental shelves. These topics include possible effects of erosion and changes in palaeotidal ranges on indicators of former relative sea levels as well as the problems involved in the determination of palaeo-water depth in addition to former sea levels. More evidence is being gathered for substantial small-scale patterns in the sea-level changes at or nearby to the former ice margins. These patterns are not reproduced by the available geophysical models, which reconcile on first-order level only the large-scale pattern.  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   

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   

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   

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   

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   

南极菲尔德斯半岛地区土壤中主要元素的迁移与富集   总被引：1，自引：0，他引：1       下载免费PDF全文

陈杰  龚子同 《极地研究》2000,12(2):81-96

对 Si、Al、Fe、Ca、Mg、Mn、K、Na和 P等元素在南极菲尔德斯半岛地区三个代表性土壤剖面 (不饱和寒冻雏形土、纤维质寒冻有机土和鸟成土 )中的迁移与富集规律进行了研究 ,结果表明 ,本区土壤中物质移动和元素迁移现象明显 ;几种主要元素在不同类型土壤以及同一土壤不同层次中的移动行为有显著差异 ,土壤自由水状况和地表生物活动在元素迁移与富集过程中发挥重要作用。另外 ,在土壤发育和土壤粘粒形成过程中 ,不同元素在不同土壤颗粒之间的再分配现象存在较大差异。  相似文献   

Accumulation Rate Measurements at Taylor Dome, East Antarctica: Techniques and Strategies for Mass Balance Measurements in Polar Environments     

David L. Morse  Edwin D. Waddington  Hans-Peter Marshall  Tomas A. Neumann  Eric J. Steig  Jack E. Dibb  Dale P. Winebrenner  & Robert J. Arthern 《Geografiska Annaler: Series A, Physical Geography》1999,81(4):683-694

Accumulation rate measurements on the East Antarctic plateau are challenging due to both spatial and temporal variability. Annual stratigraphy is often not reliably or consistently preserved in the firn, and so accumulation cannot be determined from snow pit stratigraphy. We present a suite of accumulation rate measurements collected over several seasons at Taylor Dome, East Antarctica. We compare net accumulation results from direct burial rate measurements and β -activity firn cores along a 35 km traverse. The two methods are consistent and show that the net accumulation varies from greater than 10 cm a⁻¹ to about 1 cm a⁻¹ (ice equivalent) southwest to northeast across the dome. We map the depth of shallow radar layering to interpolate and extrapolate these point-location measurements and show that considerable variations occur over kilometer scales resulting from subtle surface topography. We also present accumulation rates estimated from concentration of the cosmogenic isotope ¹⁰Be and from activity profiles of ²¹⁰Pb. Finally, satellite passive microwave data are used to estimate spatially averaged accumulation rates on the regional to continental scale to provide a context for these local observations. We show that robust mass balance measurements in this environment must rely on spatial and/or temporal averaging.  相似文献   

Fluid-mediated modification of garnet interiors under ultrahigh-pressure conditions     

Alexei L. Perchuk  Michael Burchard  Walter V. Maresch  Hans-Peter Schertl 《地学学报》2005,17(6):545-553

We report the results of a novel experimental study on eclogitic garnets with abundant inclusions of clinozoisite, quartz and rutile subjected to temperatures (T) of 800–1100 °C and a pressure (P) of 4 GPa, representative of ultrahigh-pressure (UHP) metamorphic terranes such as the Kokchetav massif, Saxonian Erzgebirge, etc. The experiments reveal extremely rapid recrystallization and partial melting of garnet interiors controlled by fluids liberated from the breakdown of the hydrous mineral inclusions. The traditional assumption that inclusions of minerals and primary fluid inclusions should be representative of the peak or even earlier metamorphic history cannot be strictly applied in this case. We argue that inclusions in UHP garnets may mirror P–T conditions postdating growth of the host crystal or even P–T conditions never actually experienced by the rock itself. The above modification of garnet interiors produces a typical patchy microstructure that occurs in natural eclogitic garnet from the diamond-bearing UHP Kokchetav massif.  相似文献