Polyphase structural evolution of the southwestern Argentine Precordillera     

W. von Gosen 《Journal of South American Earth Sciences》1995,8(3-4)

The western and southwestern parts of the Argentine Precordillera display complex geometries which are not consistent with those of a typical high-level fold-and-thrust belt. They are the result of a polyphase structural evolution which spans the Early Paleozoic to Late Tertiary period. After an Early Paleozoic folding and shearing event under a greenschist facies metamorphism, uplift, erosion, and deposition of Late Carboniferous to Early Permian clastics were accompanied by extensional faulting. This was followed by a Permian folding and faulting event which led to a partial inversion of the Late Carboniferous-Early Permian graben fill. Permian to Triassic crustal extension was combined with block faulting and the deposition of a thick volcanic sequence. The subsequent Late Tertiary crustal shortening partly reactivated older fault lines. Excluding folds, a few thrusts, and reverse faults, the crustal shortening within the older blocks was accommodated by a dominant sinistral strike-slip faulting under a W-E compressive regime. Above a major décollement, the entire sequence of faulted and folded blocks was carried from west to east towards its present position. The regional situation indicates that this southern part of the orogen was transferred further to the east with respect to the central thin-skinned parts. The movements are interpreted to be related to an important thrust fault which obliquely cuts through the fold-and-thrust belt.  相似文献   

Late Proterozoic Patsy Springs Canyon,Adelaide Geosyncline: submarine or subaerial origin?     

C. C. von der  BORCH  A. E. GRADY  K. H. EICKHOFF  P. DIBONA  N. CHRISTIEBLICK 《Sedimentology》1989,36(5):777-792

A significant aspect of Late Proterozoic sedimentation in the Adelaide Geosyncline, South Australia, is the presence of kilometre-deep erosional incisions which have been termed canyons. These structures were formerly described to be of submarine origin, cut and filled in an inferred basin-slope setting by subaqueous processes. Subsequent detailed research, particularly on a specific incision known as Patsy Springs Canyon, indicates that sedimentary structures within some of the canyon-filling sediments are indicative of deposition above fair weather wave base. In addition, an unusual carbonate unit, which is observed to veneer upper portions of canyon shoulders and to contribute to carbonate breccias interbedded with canyon-fill, has a stable isotope signature which may imply a non-marine origin. The presence of the carbonate veneer, where it is in situ, suggests that at least upper portions of the canyons could have been emergent during the canyon-filling phase. Considering these observations, and combining them with regional stratigraphical relationships, an alternative model for canyon genesis is proposed involving subaerial erosion and subsequent filling by coastal onlap. Such a model requires base-level changes of the order of 1 km, in order to account for observed canyon cutting and filling. Vertical movements associated with halokinesis, or thermally-induced uplift of the order of 1 km, could have resulted in the observed erosional events. Alternatively, a Messinian-style evaporitic lowering of base-level is currently receiving serious attention. With present knowledge this mechanism most satisfactorily explains all observations.  相似文献   

Triassic to Cenozoic evolution of the NW Australian continental margin and the birth of the Indian Ocean (preliminary results of ODP Legs 122 and 123)     

Dr. Ulrich von Rad  Dr. Jürgen Thurow  Bilal U. Haq  Felix Gradstein  John Ludden  the ODP Leg / shipboard scientific parties 《International Journal of Earth Sciences》1989,78(3):1189-1210

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Human impact on the forests of Bermuda: the decline of endemic cedar and palmetto since 1609, recorded in the Holocene pollen record of Devonshire Marsh     

Bruce F. Rueger  Theodore N. von Wallmenich 《Journal of Paleolimnology》1996,16(1):59-66

The wreck of the Sea Venture on Bermuda reefs in 1609 initiated continuous habitation by humans on these islands. Colonization brought significant changes to the native and endemic flora of Bermuda. Original floral diversity was low, due to the effects of isolation and lack of previous anthropogenic influences. Two dominant endemic components of the flora, Bermuda cedar (Juniperus bermudiana) and Bermuda palmetto (Sabal bermudana), were extensively utilized by the colonists. Cedar was used for housing, furniture, shipbuilding and export, while the palmetto was used for roof thatch, basketry, food and drink. Exploitation of these species occurred to such extent that the General Laws of Bermuda included resolutions protecting them as early as 1622. Later, in the period between 1946 and 1951, two accidentally introduced scale insects eliminated 95% of the existing cedar population.While the flora and geography of upland habitats on Bermuda have been drastically modified by humans, the peat marsh basins have remained relatively unaffected. From the peats of one of these, Devonshire Marsh, a 9-m core was extracted for pollen analysis and to evaluate the potential for further study. The pollen record below 1.6 m indicated very little change in the native and endemic flora of Bermuda, but above that depth statistically significant changes in the relative abundances of pollen of Bermuda cedar and Bermuda palmetto are noted. Relative abundances of both species decreases significantly above this depth. This decrease is interpreted to represent the arrival of colonists and their impact on the cedar and palmetto populations. A second decrease in relative abundance of Bermuda cedar is recorded above 0.7 m. This reflects the scale infestation and decimation of the remaining cedar population. Coincident with decreases in cedar and palmetto are increases in relative abundance of Poaceae and Asteraceae, indicative of cleared land and the spread of weedy taxa. A radiocarbon date of 520±70 yr BP at a depth of 1.7 m and major changes in relative abundance of palynomorphs in proximity to the marsh surface allows their interpretation as a record of human impact on the endemic flora of Bermuda.This is the 19th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.  相似文献   

A systematic analysis of natural magnetic mineral assemblages based on modelling hysteresis loops with coercivity-related hyperbolic basis functions     

Tilo von  Dobeneck 《Geophysical Journal International》1996,124(3):675-694

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IV. Bücher- und Zeitschriftenschau     

Rheinboldt  W. Salomons  Wcks  H. G. Strinmann jun.  S. von Bubnoff  Otto Wilckens 《International Journal of Earth Sciences》1926,17(5):377-382

Ohne Zusammenfassung  相似文献   

Der Bau des Französischen Zentralplateaus     

von Gaertner  Hans Rudolf 《International Journal of Earth Sciences》1937,28(1-2):48-68

Ohne Zusammenfassung  相似文献   

Versuch einer Skizze der paläogeographischen Beziehungen Südamerikas     

Friedrich von Huene 《International Journal of Earth Sciences》1929,20(2):81-96

Zusammenfassung In der im vorhergehenden auseinandergesetzten Weise glaubt Verf. die Hypothese eines bis Südamerika von Osten her reichenden Gondwanalandes durch eine annehmbarere ersetzt zu haben. Die hier aufgestellte Annahme einer Verbindung Südamerikas mit SO-Asien durch die australische Region erklärt nicht nur die auffallenden Verhältnisse der Landfaunen, sondern ist auch durch eine große Menge von geologischen Ereignissen und Zuständen gestützt, die nicht Hypothesen, sondern Tatsachen sind. Am Schluß des Paläozoikums ist der hier nicht genauer aufgeführte Parallelismus der geologischen Geschehnisse in Südafrika und in Südamerika ein auffallender, er reicht auch noch ins Mesozoikum hinein. Faunistische Beziehungen sind durch die Mesosaurier unleugbar gegeben, aber im Mesozoikum fehlen sie schon fast ganz. Im Laufe des Mesozoikums tritt ein ebenso starker Parallelismus des geologischen Geschehens zwischen Australasien und Südamerika ein. Aber die Erforschung der Lebewelt sowohl Südamerikas in vergangener Zeit als auch Australasiens besonders muß noch große Fortschritte machen, bis ein volles Bild dieser Vorgänge vor uns liegt; bis jetzt besteht es fast nur aus einer Reihe von Lücken. Diese Zeilen wollen neue Arbeit wecken, die Kenntnis zu erhöhen.  相似文献   

Tektonische Beziehungen der Münchberger Gneismasse zum Erzgebirge und nördlichen Böhmerwald     

W. von Seidlitz 《International Journal of Earth Sciences》1922,12(6-8):270-292

Ohne Zusammenfassung  相似文献   

Protest gegen die Arbeitsweise des Herrn Dr. F. F. Hahn-Stuttgart im alpinen Gebiet     

H. Arlt  K. Boden  E. Dacqué  H. Krauss  K. Leuchs  K. Chr von Loesoh 《International Journal of Earth Sciences》1914,5(4):319-320

Ohne ZusammenfassungÜber den sachlichen Inhalt derHahnschn Arbeiten wollen die Unterzeichneten hiermit kein Urteil gefällt haben.  相似文献