Experimental Study of Sand Bed Configurations in Front of a Vertical Wall Under Wave Action     

JAN Chyan-Deng 《中国海洋工程》1998,(4)

—When a 2-D progressive wave train normally or obliquely approaches a vertical wall and thenis normally or obliquely reflected from it,the combination of the approaching and reflected waves may re-sult in a standing wave or a short-crested wave in front of the wall.This paper presents the experimentalobservations of sand bed configurations under the action of these water waves in front of the wall.The ge-ometry of sand ripples under these water waves in front of the vertical wall is presented as a function offlow parameters,such as the water particle semi-excursion and the mobility number.  相似文献   

Carl C:zon Caldenius - geologist, geotechnician, predecessor of IGCP     

JAN LUNDQVIST 《Boreas: An International Journal of Quaternary Research》1991,20(2):183-189

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Palaeomagnetic records from two varved clay sequences in the Middle Swedish ice marginal zone     

PER SANDGREN  SVANTE BJÖRCK  LARS BRUNNBERG  JAN KRISTIANSSON 《Boreas: An International Journal of Quaternary Research》1988,17(2):215-227

Two varved clay sequences, at Rystad and Tottnäs, situated in the Middle Swedish ice marginal zone were analysed palaeomagnetically. Two parallel profiles were sampled and analysed at each site. The varved clay at Rystad was dated by floating varve chronology. The varves at Tottnäs can be linked to Swedish time scale, expressed in calendar years B.P. Due to the distance between the sites they cannot be correlated by means of varve diagrams. Palaemagnetic methods were used as an alternative. Based an AF demanetization of pilot samples, the palaeomanetic to be too low, in the order of15, compared to the site latitude. At Tottnäs the inclination records are very close to the expected inclination with respect to the site latitude. Because of a systematic inclination error in the Rystad profiles the correlation was based on the declination records. Statistical comparisons of these records between the two sites indicate that the sediment successions are partly synchronous. It is concluded that the deglaciation at Tottnäs started c. 130 years earlier than at Rystad. This mean that the Swedish ice marginal zone east of Rystad will have a more northeasterly extension than previously thought.  相似文献   

Modelling dry deposition of SO₂     

JAN WILLEM ERISMAN  DENNIS BALDOCCHI 《Tellus. Series B, Chemical and physical meteorology》1994,46(3):159-171

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The Late Weichselian glacial maximum in western Svalbard     

JAN MANGERUD  MAGNE BOLSTAD  ANNE ELGERSMA  DAG HELLIKSEN  JON Y. LANDVIK  ANNE KATRINE LYCKE  IDA LØNNE  OTTO SALVIGSEN  TOM SANDAHL  HANS PETTER SEJRUP 《Polar research》1987,5(3):275-278

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Modelling land atmosphere exchange of gaseous oxides of nitrogen in Europe     

JAN DUYZER  DAVID FOWLER 《Tellus. Series B, Chemical and physical meteorology》1994,46(5):353-372

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Potassic Magmatism in Western Sichuan and Yunnan Provinces, SE Tibet, China: Petrological and Geochemical Constraints on Petrogenesis   总被引：31，自引：1，他引：30  

GUO  ZHENGFU; HERTOGEN  JAN; LIU  JIAQI; PASTEELS  PAUL; BOVEN  ARIEL; PUNZALAN  LEA; HE  HUAIYU; LUO  XIANGJUN; ZHANG  WENHUA 《Journal of Petrology》2005,46(1):33-78

Potassic volcanism in the western Sichuan and Yunnan Provinces,SE Tibet, forms part of an extensive magmatic province in theeastern Indo-Asian collision zone during the Paleogene (40–24Ma). The dominant rock types are phlogopite-, clinopyroxene-and olivine-phyric calc-alkaline (shoshonitic) lamprophyres.They are relatively depleted in Na₂O, Fe₂O₃, and Al₂O₃ comparedwith the late Permian–early Triassic Emeishan continentalflood basalts in the western part of the Yangtze craton, andhave very high and variable abundances of incompatible traceelements. Primitive mantle-normalized incompatible element patternshave marked negative Nb, Ta and Ti anomalies similar to thoseof K-rich subduction-related magmas, although the geodynamicsetting is clearly post-collisional. Spatially, some incompatibletrace element abundances, together with inferred depths of meltsegregation based on the Mg-15 normalized compositions of thesamples, display progressive zonation trends from SW to NE withincreasing distance from the western boundary of the Yangtzecraton. Systematic variations in major and trace element abundancesand Sr–Nd–Pb isotope compositions appear to havepetrogenetic significance. The systematic increases in incompatibletrace element abundances from the western margin to the interiorof the Yangtze craton can be explained by progressively decreasingextents of partial melting, whereas steady changes in some incompatibletrace element ratios can be attributed to changes in the amountof subduction-derived fluid added to the lithospheric mantleof the Yangtze craton. The mantle source region of the lamprophyresis considered to be a relatively refractory phlogopite-bearingspinel peridotite, heterogeneously enriched by fluids derivedfrom earlier phases of late Proterozoic and Palaeozoic subductionbeneath the western part of the Yangtze craton. Calculationsbased on a non-modal batch melting model show that the degreeof partial melting ranges from 0·6% to 15% and the proportionof subduction-derived fluid added from0·1% to 0·7%(higher-Ba fluid) or from 5% to 25% (lower-Ba fluid) from theinterior to the western margin of the Yangtze craton. Some pre-existinglithospheric faults might have been reactivated in the areaneighbouring the Ailao Shan–Red River (ASRR) strike-slipbelt, accompanying collision-induced extrusion of the Indo-Chinablock and left-lateral strike-slip along the ASRR shear zone.This, in turn, could have triggered decompression melting ofthe previously enriched mantle lithosphere, resulting in calc-alkalinelamprophyric magmatism in the western part of the Yangtze craton. KEY WORDS: Tibet; potassic magmatism; lithospheric mantle; metasomatism  相似文献   

Velocity and Structural Modeling of Mesozoic Chiltan Limestone and Goru Formation for Hydrocarbon Evaluation in the Bitrisim Area, Lower Indus Basin, Pakistan     

Sarfraz KHAN  Zahid LATIF  Muhammad HANIF  Irfan U. JAN  Shahid IQBAL 《《地质学报》英文版》2016,90(1):258-275

The present study focuses on building a workflow for structural interpretation and velocity modeling and implementing to Jurassic-Cretaceous succession (Chiltan Limestone and Massive sand of the Lower Goru Formation). 2D-Migrated seismic sections of the area are used as data set and in order to confirm the presence of hydrocarbons in the study area, P and S-wave seismic velocities are estimated from single-component seismic data. Some specific issues in the use of seismic data for modeling and hydrocarbon evaluation need to deal with including distinguishing the reservoir and cap rocks, and the effects of faults, folds and presence of hydrocarbons on these rocks. This study has carried out the structural interpretation and modeling of the seismic data for the identification of traps. The results demonstrate existence of appropriate structural traps in the form of horst and grabens in the area. 2D and 3D velocity modeling of the horizons indicates the presence of high velocity zones in the eastern half of the study while relatively low velocity zones are encountered in the western half of the area. Two wells were drilled in the study area (i.e. Fateh-01 and Ichhri-01) and both are dry. Immature hydrocarbons migration is considered as a failure reason for Fateh-01 and Ichhri-01 well.  相似文献   

Deep‐seated relict permafrost in northeastern Poland     

JAN SZEWCZYK  JERZY NAWROCKI 《Boreas: An International Journal of Quaternary Research》2011,40(3):385-388

Szewczyk, J. & Nawrocki, J. 2011: Deep‐seated relict permafrost in northeastern Poland. Boreas, Vol. 40, pp. 385–388. 10.1111/j.1502‐3885.2011.00218.x. ISSN 0300‐9483. A research borehole drilled in northeastern Poland revealed a permafrost layer at least 93 m thick within the Cretaceous sedimentary succession below a depth of 357 m. Its entire thickness has not been determined, owing to the borehole depth limit (450 m). The relict of permafrost, unexpected in this part of Europe, is in the ice–water transition phase at a temperature close to 0 °C. We estimate that the permafrost has been preserved in an area of several square kilometres located above the central part of the Suwa?ki anorthosite intrusion, which is covered by ～800 m of sedimentary rocks. We show that the remnants of the Last Glaciation, which ended at c. 13.4 ka BP, can, even at present, affect the thermal regime of the outer zone of the Earth's crust. These findings are of significant importance for the reconstruction of past climate conditions.  相似文献   

A multi‐dating approach applied to proglacial sediments attributed to the Most Extensive Glaciation of the Swiss Alps     

ANDREAS DEHNERT  FRANK PREUSSER  JAN D. KRAMERS  NAKI AKÇAR  PETER W. KUBIK  REGINA REBER  CHRISTIAN SCHLÜCHTER 《Boreas: An International Journal of Quaternary Research》2010,39(3):620-632

Dehnert, A., Preusser, F., Kramers, J. D., Akçar, N., Kubik, P. W., Reber, R. & Schlüchter, C. 2010: A multi‐dating approach applied to proglacial sediments attributed to the Most Extensive Glaciation of the Swiss Alps. Boreas, Vol. 39, pp. 620–632. 10.1111/j.1502‐3885.2010.00146.x. ISSN 0300‐9483. The number and the timing of Quaternary glaciations of the Alps are poorly constrained and, in particular, the age of the Most Extensive Glaciation (MEG) in Switzerland remains controversial. This ice advance has previously been tentatively correlated with the Riss Glaciation of the classical alpine stratigraphy and with Marine Isotope Stage (MIS) 6 (186–127 ka). An alternative interpretation, based on pollen analysis and stratigraphic correlations, places the MEG further back in the Quaternary, with an age equivalent to MIS 12 (474–427 ka), or even older. To re‐evaluate this issue in the Swiss glaciation history, a multi‐dating approach was applied to proglacial deltaic ‘Höhenschotter’ deposits in locations outside the ice extent of the Last Glacial Maximum. Results of U/Th and luminescence dating suggest a correlation of the investigated deposits with MIS 6 and hence with the Riss Glaciation. Cosmogenic burial dating suffered from large measurement uncertainties and unusually high ²⁶Al/¹⁰Be ratios and did not provide robust age estimates.  相似文献