Palaeomagnetism of the teschenitic rocks (Lower Cretaceous) in the Outer Western Carpathians of Poland: constraints for tectonic rotations in the Silesian unit     

J. Grabowski  L. Krzemi&#;ski  P. Nescieruk  E. Starnawska 《Geophysical Journal International》2006,166(3):1077-1094

Results of palaeomagnetic investigations of the Lower Cretaceous teschenitic rocks in the Silesian unit of the Outer Western Carpathians in Poland bring evidence for pre-folding magnetization of these rocks. The mixed-polarity component reveals inclinations, between 56° and 69°, which might be either of Cretaceous or Tertiary age. Apparently positive results of fold and contact tests in some localities and presence of pyrhotite in the contact aureole suggest that magnetization is primary, although a Neogene or earlier remagnetization cannot be totally excluded since inclination-only test between localities gives 'syn-folding' results. Higher palaeoinclinations (66°–69°) correlate with a younger variety of teschenitic rocks dated for 122–120 Ma, while lower inclinations (56°–60°) with an older variety (138–133 Ma). This would support relatively high palaeolatitudes for the southern margin of the Eurasian plate in the late part of the Early Cretaceous and relatively quick northward drift of the plate in this epoch, together with the Silesian basin at its southern margin. Declinations are similar to the Cretaceous–Tertiary palaeodeclinations of stable Europe in the eastern part of the studied area but rotated ca. 14°–70° counter-clockwise in the western part. This indicates, together with older results from Czech and Slovakian sectors of the Silesian unit, a change in the rotation pattern from counter-clockwise to clockwise at the meridian of 19°E. The rotations took place before the final collision of the Outer Carpathians nappe stack with the European foreland.  相似文献   

Redistribution of recent collision push and ridge push in Central Europe: insights from FEM modelling   总被引：2，自引：0，他引：2  

M. Jarosi&#;ski  F. Beekman  G. Bada  S. Cloetingh 《Geophysical Journal International》2006,167(2):860-880

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Drainage spacing regularity on a fault-block: A case study from the eastern Ruahine Range     

Heather Purdie  Martin Brook 《New Zealand geographer》2006,62(2):97-104

Abstract:  Recent research has indicated river basin outlets draining linear sections of large, uplifting mountain belts often show a regularity of spacing, transverse to the main structural trend. A morphometric analysis of part of the Ruahine Range, on the North Island was undertaken to test whether drainage regularity may exist in smaller, younger mountain ranges. The ratio, R , of the half-width of the mountain belt, W , and the outlet spacing, S , was used to characterize drainage networks on the eastern side of the range. The spacing ratio for the range of 1.31 is lower than R results from studies of larger mountain belts ( R  = 1.91–2.23). We suggest the cause of this lower ratio is related to eastward migration of the Ruahine drainage divide.  相似文献   

Seismotectonics of the Cyprian Arc   总被引：1，自引：0，他引：1  

Shimon Wdowinski  Zvi Ben-Avraham  Ronald Arvidsson  Goran Ekström 《Geophysical Journal International》2006,164(1):176-181

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The Dahuiyeh (Zarand) earthquake of 2005 February 22 in central Iran: reactivation of an intramountain reverse fault   总被引：3，自引：0，他引：3  

M. Talebian  J. Biggs  M. Bolourchi  A. Copley  A. Ghassemi  M. Ghorashi  J. Hollingsworth  J. Jackson  E. Nissen  B. Oveisi  B. Parsons  K. Priestley  A. Saiidi 《Geophysical Journal International》2006,164(1):137-148

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New data on Upper Kimmeridgian-Tithonian biostratigraphy and ammonites of the eastern Crimea     

V. V. Arkad’ev  M. A. Rogov 《Stratigraphy and Geological Correlation》2006,14(2):185-199

Based on ammonites, Upper Kimmeridgian sediments are first established in the Crimean Mountains. The Kimmeridgian-Tithonian boundary recognizable in a continuous section is placed inside the Dvuyakomaya Formation of uniform largely clayey sediments. Assemblages of Kimmeridgian ammonites Lingulaticeras cf. procurvum (Ziegler), Pseudowaagenia gemmellariana Oloriz, Euvirgalithacoceras cf. tantalus (Herbich), Subplanites sp.) and Tithonian forms (?Lingulaticeras efimovi (Rogov), Phylloceras consaguineum Gemmellaro, Oloriziceras cf. schneidi Tavera, and Paraulacosphinctes cf. transitorius (Oppel) are described. A new biostratigraphic scheme proposed for the upper Tithonian-Berriasian of the Crimean Mountains includes the following new biostratigraphic units: the Euvirgalithacoceras cf. tantalus Beds of the upper Kimmeridgian, ?Lingulaticeras efimovi Beds of the lower Tithonian, and Oloriziceras cf. schneidi and Paraulacosphinctes cf. transitorius beds of the upper Tithonian. The middle Tithonian is proposed to consist of the fallauxi and semiforme (presumably) zones. The ammonities found determine the early Kimmeridgian-Berriasian age of the Dvuyakornaya Formation that is most likely in tectonic contact with the underlying Khutoran Formation.  相似文献   

Review of the neotectonics of the Eastern Turkish–Armenian Plateau by geomorphic analysis of digital elevation model imagery     

Damien Dhont  Jean Chorowicz 《International Journal of Earth Sciences》2006,95(1):34-49

Digital elevation model (DEM) images provide synoptic views of the Earth’s surface allowing the analysis of landforms of still active tectonic and volcanic structures at regional scale. A DEM at 250 m pixel size constitutes regional scale data particularly efficient to investigate the late Miocene–Quaternary deformation of the Eastern Turkish–Armenian Plateau in the Arabian–Eurasian area of convergence. Geomorphic analysis of the DEM image associated with review of fault-plane solutions of earthquakes show that faults are mostly strike-slip with small vertical component. Here we show that the orientations of the tectonic and volcanic structures fit with a tectonic regime characterized by N–S shortening and E–W lengthening, consistent with westward escape of Anatolia perpendicular to the direction of the Arabia–Eurasia shortening. The uniform uplift of the plateau, the predominance of strike-slip faulting, the lack of major thrusts and the occurrence of normal faults do not support a model of going-on crustal thickening due to intracontinental convergence. On the contrary, our observations can be better interpreted in terms of lithospheric thinning and mantle upwelling related to gravity escape of Anatolia.  相似文献   

3D Modeling and Kinematics of the External Zone of the French Western Alps (Belledonne and Grand Chatelard Massifs, Maurienne Valley, Savoie)     

Didier Marquer  Philippe Calcagno  Jean-Claude Barfety  Thierry Baudin 《Eclogae Geologicae Helvetiae》2006,99(2):211-222

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Faulted backfold versus reactivated backthrust: the role of inherited structures during late extension in the frontal Piémont nappes east of Pelvoux (Western Alps)     

Pierre Tricart  Christian Sue 《International Journal of Earth Sciences》2006,95(5):827-840

In the central part of the internal Western Alps, widespread multidirectional normal faulting resulted in an orogen-scale radial extension during the Neogene. We revisit the frontal Piémont units, between Doire and Ubaye, where contrasting lithologies allow analysing the interference with the N–S trending Oligocene compressive structures. A major extensional structure is the orogen-perpendicular Chenaillet graben, whose development was guided by an E–W trending transfer fault zone between the Chaberton backfold to the north and the Rochebrune backthrust to the south. The Chaberton hinge zone was passively crosscut by planar normal faults, resulting in a E–W trending step-type structure. Within the Rochebrune nappe, E–W trending listric normal faults bound tilted blocks that slipped northward along the basal backthrust surface reactivated as an extensional detachment. Gravity-driven gliding is suggested by the general northward tilting of the structure in relation with the collapse of the Chenaillet graben. The stress tensors computed from brittle deformation analysis confirm the predominance of orogen-parallel extension in the entire frontal Piémont zone. This can be compared with the nearby Briançonnnais nappe stack where the extensional reactivation of thrust surfaces locally resulted in prominent orogen-perpendicular extension. Such a contrasting situation illustrates how the main direction of the late-Alpine extension may be regionally governed by the nature and orientation of the pre-existing structures inherited from the main collision stage.  相似文献   

Ca-rich Garnet-Clinopyroxene Rocks at Hujialin in the Su-Lu Terrane (Eastern China): Deeply Subducted Arc Cumulates?   总被引：3，自引：0，他引：3  

YANG  JIAN-JUN 《Journal of Petrology》2006,47(5):965-990

Layers of Ca-rich garnet–clinopyroxene rocks enclosedin a serpentinite body at Hujialin, in the Su–Lu terraneof eastern China, preserve igneous textures, relict spinel ingarnet, and exsolution lamellae of Ca-rich garnet, ilmenite/magnetite,Fe-rich spinel, and also amphibole in clinopyroxene. In termsof their major and trace element compositions, the studied samplesform a trend from arc cumulates towards Fe–Ti gabbros.Reconstructed augite compositions plot on the trend for clinopyroxenein arc cumulates. These data suggest that the rocks crystallizedfrom mantle-derived magmas differentiated to various extentsbeneath an arc. The Ca-rich garnet + diopside assemblage isinferred to have formed by compressing Ca-rich augite, whereasthe relatively Mg-rich cores of garnet porphyroblasts may haveformed at the expense of spinel. The protolith cumulates weresubducted from near the crust–mantle boundary (c. 1 GPa)deep into the upper mantle (4·8 ± 0·6 GPaand 750 ± 50°C). Negatively sloped P–T pathsfor the garnet–clinopyroxene rocks and the corollary ofcorner flow induced subduction of mantle wedge peridotite arenot supported by the available data. Cooling with, or without,decompression of the cumulates after the igneous stage probablyoccurred prior to deep subduction. KEY WORDS: arc cumulates; Ca-rich garnet; garnet–clinopyroxene rocks; Su–Lu terrane; UHP metamorphism  相似文献