Evolution of the Grenada and Tobago basins and implications for arc migration     

Trevor Aitken  Paul Mann 《Marine and Petroleum Geology》2011,28(1):235-258

The tectonic mechanisms controlling how volcanic arcs migrate through space and geologic time within dynamic subduction environments is a fundamental tectonic process that remains poorly understood. This paper presents an integrated stratigraphic and tectonic evolution of Late Cretaceous to Recent volcanic arcs and associated basins in the southeastern Caribbean Sea using seismic reflection data, wide-angle seismic refraction data, well data, and onland geologic data. We propose a new tectonic model for the opening of the Grenada and Tobago basins and the 50-250-km eastward jump of arc volcanism from the Late Cretaceous Aves Ridge to the Miocene to Recent Lesser Antilles arc in the southeast Caribbean based on the mapping of three seismic megasequences. The striking similarity of the half-graben structure of the Grenada and Tobago basins that flank the Lesser Antilles arc, their similar smooth basement character, their similar deep-marine seismic facies, and their similar Paleogene sediment thickness mapped on a regional grid of seismic data suggest that the two basins formed as a single, saucer-shaped, oceanic crust Paleogene forearc basin adjacent to the now dormant Aves Ridge. This single forearc basin continued to extend and widen through flexural subsidence during the early to middle Eocene probably because of slow rollback of the subducting Atlantic oceanic slab. Rollback may have been accelerated by oblique collision of the southern Aves Ridge and southern Lesser Antilles arc with the South American continent. Uplift and growth of the southern Lesser Antilles arc divided the Grenada and Tobago basins by early to middle Miocene time. Inversion of normal faults and uplift effects along both edges of the Lesser Antilles arc are most pronounced in its southern zone of arc collision with the South American continent. The late Miocene to Recent depositional histories of the Grenada and Tobago basins are distinct because of isolation of the Grenada basin by growth and uplift of the Neogene Lesser Antilles volcanic ridge.  相似文献   

Genesis of marine terrace soils,Barbados, West Indies: Evidence from mineralogy and geochemistry     

Daniel R. Muhs  Russell C. Crittenden  John N. Rosholt  Charles A. Bush  Kathleen C. Stewart 《地球表面变化过程与地形》1987,12(6):605-618

Well-developed, clay-rich soils dominated by interstratified kaolinite-smectite are found on the uplifted coral reef terraces on the island of Barbados. The reef limestone is unlikely to have been the soil parent material however, because it is 98 per cent CaCO₃ and geomorphic evidence argues against the 20 m of reef solution required to produce the soils by this process. The mineralogy of the sand, silt, and clay fractions of the soils, and trace element geochemistry, suggest that aeolian materials carried on the trade winds from Africa, volcanic ash from the island of St. Vincent, and quartz from Tertiary bedrock on the island itself are the parent materials for the soils.  相似文献   

Barbados: maturation,source rock potential and burial history within a Cenozoic accretionary complex     

D.K. Larue  J. Schoonmaker  R. Torrini  J. Lucas-Clark  M. Clark  R. Schneider 《Marine and Petroleum Geology》1985,2(2):96-110

A number of diagenetic properties were studied in sedimentary rocks exposed along a 25 km across-strike transect on Barbados, the crest of the Barbados accretionary complex. The island of Barbados consists of three structural levels: a lower (mostly Eocene or undated) basal complex composed of quartzose turbidites, hemipelagites and melange; an intermediate level (Eocene to Miocene) of nappes composed mostly of calcareous pelagite; and a Pleistocene coral cap. Diagenetic studies concentrated on the basal complex although preliminary data from the nappes are also presented. The following subjects were studied: (1) clay mineralogy (% illite interlayers in mixed-layer clays); (2) vitrinite reflectance; (3) organic type and maturation, by Rock-Eval pyrolysis; (4) thermal alteration index of spores and pollen; (5) dry bulk density; (6) silica mineralogy. Taken together, the data can be interpreted to indicate maximum temperatures attained during diagenesis of less than 80°C. Based on a uniform palaeogeothermal gradient of 15°C km^?1, and a temperature at the sediment/water interface of 10°C, maximum burial depths of basement complex rocks were about 2–5 km. Minimum possible burial depths are < 1 km. No across-strike changes in maturation are observed indicating that these trench-associated rocks were uplifted uniformly. Mudstones are typically rich in total organic carbon (> 1 %), and are immature. Organic matter was derived mostly from terrigenous or oxidized sources (type III kerogens), although some marine planktonic sources are indicated locally (type II kerogens). Organic matter is therefore primarily gas-prone.  相似文献   

Producing/contesting whiteness: rebellion, anti-slavery and enslavement in Barbados, 1816     

David Lambert 《Geoforum》2005,36(1):29-43

The increasing attention paid by geographers to white identities represents a welcome corrective to research on race and ethnicity that focused on non-white subjectivities and promises to deconstruct the purportedly `normal' or `unremarkable' status often afforded to whiteness. Such work is a vital part of a critical geographical agenda. This paper seeks to contribute to such an agenda by responding to Bonnett [Area 29 (1997) 193, White Identities: Historical and International Perspectives, Prentice Hall, 2000] call for a historical geographical engagement with `white studies'. To do so, it begins by considering how such a critical geography might be spatially and theoretically framed. It then introduces a specific context for such an engagement--the revolt of 1816 by enslaved people of African origin in the British Caribbean colony of Barbados. Reading this not as a single event but as a locus of multiple and conflicting narrations, each linked to particular assertions and contestations of whiteness, the paper argues that geographies of white identities must emphasise struggles between `white' subjects, as well as the role of subaltern acts and representations in white racialisation. This is important if postcolonial, and therefore critical, geographies of white identities are to be produced.  相似文献   

Liquefied vs stratified sediment mobilization processes: Insight from the South of the Barbados accretionary prism   总被引：3，自引：1，他引：3  

Eric Deville  Sophie-Hlne Guerlais  Yannick Callec  Roger Griboulard  Pascale Huyghe  Siegfried Lallemant  Alain Mascle  Mark Noble  Julien Schmitz  the collaboration of the Caramba working group 《Tectonophysics》2006,428(1-4):33-47

This paper discusses the nature and origin of subsurface sediment mobilization processes in deep marine clay-rich environments. In the studied area of the southern Barbados accretionary prism, new geophysical acquisitions have emphasized the spectacular widespread development of mud volcanoes that are well-developed along ramp anticlines and along sigmoidal rises with trends that are oblique to the axes of the main folds of the accretionary wedge. On some active mud volcanoes, heat-flow measurements show high positive anomalies related to high fluxes of mud transfer. The mobilized solid fraction expelled by the mud volcanoes does not originate from a unique source bed but from various formations pierced by the mud conduits and is driven by the water phase. The area studied also exhibits trends of structures corresponding to sub-circular massive local uplifts of deformed but well-preserved stratified sediments (turbidites and hemipelagics). No piercing shale diapirs have been encountered in this area. Some of these local uplift structures are complicated by the development of collapses, calderas, and superimposed mud volcanoes. Mud volcanism corresponds fundamentally to fluid displacement (water and gas), whereas massive sedimentary uplift corresponds to large vertical displacements of stratified solid levels but for which the deep cause could be partly the intrusion of mud plugs. Both are dynamic phenomena controlled by the development of overpressure at depth, contributing to sedimentary mobilizations.  相似文献