An 'Ionospheric Weather' Index     

T. M. Georges 《Geophysical Journal International》1971,26(1-4):243-245

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The giant clam Tridacna maxima communities of three French Polynesia islands: comparison of their population sizes and structures at early stages of their exploitation     

Gilbert  Antoine; Andrefouet  Serge; Yan  Laurent; Remoissenet  Georges 《ICES Journal of Marine Science》2006,63(9):1573-1589

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Accretion and tectono-sedimentary progradation: The Taranto Gulf (Southern Italy)     

Georges Mascle  Jean Mascle 《Geo-Marine Letters》1983,3(1):9-12

The geological structures of the eastern Calabrian Apenninic front within the Gulf of Taranto, southern Italy, are compared to those of a convergent margin, using simple criteria such as the origin and volume of the sediment supply, and the relative ratio between sediments carried by the sinking plate and those directly supplied by the overriding margin. Based on this criteria we distinguish four main types of sedimentary accretion occurring at convergent continental margins: (a) Pacific type, (b) Indonesian type, (c) Caribbean type, and (d) Apenninic type.  相似文献   

Active oceanic spreading in the northern North Fiji Basin: Results of the NOFI cruise of R/V L'Atalante (newstarmer project)   总被引：1，自引：0，他引：1  

Yves Lagabrielle  Etienne Ruellan  Manabu Tanahashi  Jacques Bourgois  Georges Buffet  Giovanni de Alteriis  Jérôme Dyment  Jean Goslin  Eulàlia Gràcia-Mont  Yo Iwabushi  Philip Jarvis  Masato Joshima  Anne-Marie Karpoff  Takeshi Matsumoto  Hélène Ondréas  Bernard Pelletier  Olivier Sardou 《Marine Geophysical Researches》1996,18(2-4):225-247

The South Pandora and the Tripartite Ridges are active spreading centers located in the northern part of the North Fiji Basin. These spreading centers were surveyed over a distance of 750 km during the NOFI cruise of R/V L'Atalante (August–September 1994) which was conducted in the frame of the french-japanese Newstarmer cooperation project. SIMRAD EM12-dual full coverage swath bathymetric and imagery data as well as airgun 6-channel seismic, magnetics and gravity profiles were recorded along and offaxis from 170°40 E to 178° E. Dredging and piston coring were also performed along and off-axis. The axial domain of the South Pandora Ridge is divided into 5 first-order segments characterized by contrasted morphologies. The average width of the active domain is 20 km and corresponds either to bathymetric highs or to deep elongated grabens. The bathymetric highs are volcanic constructions, locally faulted and rifted, which can obstruct totally the axial valley. The grabens show the typical morphology of slow spreading axes, with two steep walls flanking a deep axial valley. Elongated lateral ridges may be present on both sides of the grabens. Numerous volcanoes, up to several kilometers in diameter, occur on both flanks of the South Pandora Ridge. The Tripartite Ridge consists of three main segments showing a sigmoid shape. Major changes in the direction of the active zones are observed at the segment discontinuities. These discontinuities show various geometrical patterns which suggest complex transform relay zones. Preliminary analysis of seismic reflection profiles suggest that the Tripartite Ridge is a very young feature which propagates into an older oceanic domain characterized by a significant sedimentary cover. By contrast, a very thin to absent sedimentary cover is observed about 100 km on both flanks of the South Pandora Ridge active axis. The magnetic anomaly profiles give evidence of long and continuous lineations, parallel to the South Pandora Ridge spreading axis. According to our preliminary interpretation, the spreading rate would have been very low (8 km/m.y. half rate) during the last 7 Ma. The South Pandora and Tripartite Ridges exhibit characteristics typical of active oceanic ridges: (1) a segmented pattern, with segments ranging from 80 to 100 km in length; (2) an axial tectonic and volcanic zone, 10 to 20 km wide; (3) well-organized magnetic lineations, parallel to the active axis; (4) clear signature on the free-air gravity anomaly map. However, no typical transform fault is observed; instead, complex relay zones are separating first-order segments.  相似文献   

The remarkable population size of the endangered clam Tridacna maxima assessed in Fangatau Atoll (Eastern Tuamotu, French Polynesia) using in situ and remote sensing data     

Andrefouet  Serge; Gilbert  Antoine; Yan  Laurent; Remoissenet  Georges; Payri  Claude; Chancerelle  Yannick 《ICES Journal of Marine Science》2005,62(6):1037-1048

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Contrasting sedimentary processes along a convergent margin: the Lesser Antilles arc system     

Michel Picard  Jean-Luc Schneider  Georges Boudon 《Geo-Marine Letters》2006,26(6):397-410

Sedimentation processes occurring in an active convergent setting are well illustrated in the Lesser Antilles island arc. The margin is related to westward subduction of the North and/or the South America plates beneath the Caribbean plate. From east to west, the arc can be subdivided into several tectono-sedimentary depositional domains: the accretionary prism, the fore-arc basin, the arc platform and inter-arc basin, and the Grenada back-arc basin. The Grenada back-arc basin, the fore-arc basin (Tobago Trough) and the accretionary prism on the east side of the volcanic arc constitute traps for particles derived from the arc platform and the South American continent. The arc is volcanically active, and provides large volumes of volcaniclastic sediments which accumulate mainly in the Grenada basin by volcaniclastic gravity flows (volcanic debris avalanches, debris flows, turbiditic flows) and minor amounts by fallout. By contrast, the eastern side of the margin is fed by ash fallout and minor volcaniclastic turbidites. In this area, the dominant component of the sediments is pelagic in origin, or derived from South America (siliciclastic turbidites). Insular shelves are the locations of carbonate sedimentation, such as large platforms which develop in the Limestone Caribbees in the northern part of the margin. Reworking of carbonate material by turbidity currents also delivers lesser amounts to eastern basins of the margin. This contrasting sedimentation on both sides of the arc platform along the margin is controlled by several interacting factors including basin morphology, volcanic productivity, wind and deep-sea current patterns, and sea-level changes. Basin morphology appears to be the most dominant factor. The western slopes of the arc platform are steeper than the eastern ones, thus favouring gravity flow processes.  相似文献   

    

Georges Perrier 《Journal of Geodesy》1946,20(1):22-32

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Würmian deglaciation of western Lake Geneva (Switzerland) based on seismic stratigraphy     

Julien Fiore  Stéphanie Girardclos  André Pugin  Georges Gorin  Walter Wildi 《Quaternary Science Reviews》2011,30(3-4):377-393

Western Lake Geneva (le Petit-Lac) was filled during the Quaternary over a major erosion surface truncating the cemented, folded and thrusted Tertiary sediments of the foreland Alpine basin. The carving of the lake occurred during Quaternary glaciations with ice originating from the Rhone valley catchment basin flowing in two branches oriented SW and NE over the Swiss Plateau. Lake Geneva is situated on the South-Western branch of this paleo ice-cap.For the first time, a dense grid of high-resolution seismic profiles (airgun 5-inch³, airgun 1-inch³ and echosounder) has imaged the whole Quaternary sequence, providing a paleoenvironmental interpretation and a detailed reconstruction of the Rhone glacier retreat stages during glacial events that led to the formation of western Lake Geneva.The Quaternary sequence filling up the bedrock valley is exceptionally thick with up to 220 m of deposits and consists of glacial, glacio-lacustrine and lacustrine sediments. Fourteen seismic units have been defined (units U1–U14). Unit U1 represents the remnants of glacial deposits older than the last glacial cycle, preserved in the deepest part of the lake and in secondary bedrock valleys. Unit U2 represents gravel and sands deposited by meltwater circulation at the bottom of the glacial valley. Unit U3 is a thick, stratified unit marking the beginning of the deglaciation, when the Rhone glacier became thinner and buoyant and allowed the formation of a subglacial lake. Younger glacial units (units U4, U5, U7, U9, U11) are acoustically chaotic sediments deposited subglacially under the water table (undermelt tills), while the glacier was thinning. These glacial units are bounded by synform erosion surfaces corresponding to readvances of the glacier.The transition from a glacial to a glacio-lacustrine environment started with the appearance of a marginal esker-fan system (unit U6). Esker formation was followed by a small advance–retreat cycle leading to the deposition of unit U7. Then, the ice front receded and stratified sediments were deposited in a glacio-lacustrine environment (units U8, U10 and U12). This retreat was punctuated by two readvances – Coppet (unit U9) and Nyon (unit U11) – producing large push moraines and proglacial debris flows. Finally, a lacustrine environment with a characteristic lake current pattern and mass movement deposits took place (units U13 and U14).Except for unit U1, the sedimentary sequence records the Würmian deglaciation in a fjord-like environment occupied by a tidewater glacier with a steep, calving ice front. The presence of an esker-fan system reveals the importance of subglacial meltwater flow in continental deglaciation. Push-moraines and erosion surfaces below the glacier indicate at least 5 readvances during the deglaciation thus revealing that oscillations of ice front are the key process in deglaciation of perialpine fjord-lakes. The dating of these continental glacier fluctuations would allow correlation with oceanic and ice records and help to understand the climatic mechanisms between oceans and continents.  相似文献   

Cretaceous black shale: a window into microbial life adaptation     

Georges Gorin  Marc Massault  Johannes Stadler 《地学学报》2011,23(6):362-368

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An Early Cretaceous flora from Cusano Mutri, Benevento, southern Italy     

Antonello Bartiromo  Georges BaraleMaria Rosaria Barone Lumaga  Sergio BraviFilippo Barattolo 《Cretaceous Research》2012,33(1):116-134

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