The geochemical characteristics and conditions of petrogenesis of the volcanic rocks of the northern lesser antilles — A review

Rea, W. J.; Baker, P. E.

doi:10.1007/bf02598036

Cited by 18 publications

(5 citation statements)

References 16 publications

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“…For example, in the northern and central islands (Saba to St. Lucia) <10% of the erupted volcanic rocks are basaltic. Where basaltic rocks are present, they generally occur as small-volume centres adjacent to much larger andesitic volcanoes (Westercamp and Mervoyer, 1976;Rea and Baker, 1980;Macdonald et al 2000). This is exemplified on Montserrat (Fig.…”

Section: Geological Backgroundmentioning

confidence: 99%

Origin of Basalts by Hybridization in Andesite-dominated Arcs

Cassidy

Edmonds

Watt

et al. 2015

Journal of Petrology

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Mafic magmas are common in subduction zone settings, yet their high density restricts their ascent to the surface. Once stalled in the crust, these magmas may differentiate, assimilate crust and other melts and mushes to produce hybridised intermediate magmas. The Soufriere Hills Volcano on Montserrat is a 'type locality' for these hybridisation processes and yet, just 3 km south of the crater, voluminous basalts have erupted from the South Soufriere Hills volcano within the same time period as the Soufriere Hills Volcano was erupting hybrid andesites (131 -128 ka). Basaltic South Soufriere Hills magmas have 48 -53 wt% SiO2 and 4 -6 wt% MgO. They were hot (970 -1160 °C), volatile-rich (melt inclusions contain up to 6.2 wt% H2O) and were stored at 8 -13 km prior to eruption (based on olivine and pyroxene-hosted melt inclusion volatile geochemistry). Melt inclusions do not preserve basaltic liquids: they are andesitic to rhyolitic in composition, related to one another by a line of descent controlled by simple closed-system fractionation. Whole rock compositions, however, are best described by a hybridisation model involving "back"-mixing of andesitic to rhyolitic melts with mafic crystal phases such as magnetite, olivine, orthopyroxene and clinopyroxene. Phenocryst zoning illustrates repeated mixing events between evolved melts and mafic phenocrysts, which, when coupled with the heterogeneity of crystal compositions, strongly suggests that although the bulk composition is basalt (containing Fo80 olivine), they were assembled from disparate ingredients, likely derived from mafic crystal mushes and more evolved melt lenses of variable composition. The mixing events occur days to weeks prior to eruption. We propose that the South Soufriere Hills basaltic magmas, with their higher bulk density over andesites from neighbouring volcanoes, ultimately may have been eruptible owing to both the transtensional tectonics imposed by offshore grabens (related to the oblique subduction of the Lesser Antilles) and to surface unloading caused by large scale edifice collapse. Our observations support the idea that compositional changes in arcs might reflect not only changes in source compositions, but also effects caused by patterns in crustal strain and tectonics.

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Section: Geological Backgroundmentioning

confidence: 99%

Origin of Basalts by Hybridization in Andesite-dominated Arcs

Cassidy

Edmonds

Watt

et al. 2015

Journal of Petrology

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“…Three groups of islands can be distinguished petrologically. The northern group (Saba to Montserrat) is dominated by andesite, with minor dacite and rare rhyolite; small volumes of basalt (≤5 km 3 ) occur locally as blocks in pyroclastic deposits (Rea & Baker, ). The central group includes the largest islands (Guadeloupe, Dominica, Martinique, St Lucia) and is also characterized by predominant andesite, with some basalt, dacite and rare rhyolite.…”

Section: Barbados Island and Adjacent Sediment Sourcesmentioning

confidence: 99%

Multicyclic sediment transfer along and across convergent plate boundaries (Barbados, Lesser Antilles)

et al. 2015

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The main source of siliciclastic sediment in the Barbados accretionary prism is off‐scraped quartzose to feldspatho‐litho‐quartzose metasedimentaclastic turbidites, ultimately supplied from South America chiefly via the Orinoco fluvio‐deltaic system. Modern sand on Barbados island is either quartzose with depleted heavy‐mineral suites recycled from Cenozoic turbidites and including epidote, zircon, tourmaline, andalusite, garnet, staurolite and chloritoid, or calcareous and derived from Pleistocene coral reefs. The ubiquitous occurrence of clinopyroxene and hypersthene, associated with green‐brown kaersutitic hornblende in the north or olivine in the south, points to reworking of ash‐fall tephra erupted from andesitic (St Lucia) and basaltic (St Vincent) volcanic centres in the Lesser Antilles arc. Modern sediments on Barbados island and those shed by larger accretionary prisms such as the Indo‐Burman Ranges and Andaman‐Nicobar Ridge define the distinctive mineralogical signature of Subduction Complex Provenance, which is invariably composite. Detritus recycled from accreted turbidites and oceanic mudrocks is mixed in various proportions with detritus from the adjacent volcanic arc or carbonate reefs widely developed at tropical latitudes. Ophiolitic detritus, locally prominent on the Andaman Islands, is absent on Barbados, where the prism formed above a westward subduction zone with a shallow décollement plane. The four‐dimensional complexities inherent with multicyclic sediment dispersal along and across convergent plate boundaries require quantitative provenance analysis as a basic tool in paleogeographic reconstructions. Such analysis provides the link between faraway factories of detritus and depositional sinks, as well as clues on subduction geometry and the nature of associated growing orogenic belts, and even information on climate, atmospheric circulation and weathering intensity in source regions.

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“…These islands are predominantly volcanic in nature, in which igneous rock types fall within the calc-alkaline group. The major occurring rock variety is porphyritic andesite, in addition to minor amounts of basalts, basaltic andesite, dacite, and rhyolite (Rea & Baker 1980;Smith et al 1980). Based on differences in the occurrences of the latter rock types, three groups of islands can be distinguished.…”

Section: Geology and Occurrence Of Rock Materialsmentioning

confidence: 99%

“…Misery and South Soufriere eruption centres. The third group includes Basse Terre, Dominica, and Martinique, which possess higher proportions of more acidic rock types, such as rhyolites and dacites (Rea & Baker 1980).…”

Section: Geology and Occurrence Of Rock Materialsmentioning

confidence: 99%

Stone Artefact Production and Exchange among the Lesser Antilles

Knippenberg¹

2007

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The geochemical characteristics and conditions of petrogenesis of the volcanic rocks of the northern lesser antilles — A review

Cited by 18 publications

References 16 publications

Origin of Basalts by Hybridization in Andesite-dominated Arcs

Origin of Basalts by Hybridization in Andesite-dominated Arcs

Multicyclic sediment transfer along and across convergent plate boundaries (Barbados, Lesser Antilles)

Stone Artefact Production and Exchange among the Lesser Antilles

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