Isotopic and geochemical evidence for a heterogeneous mantle plume origin of the Virunga volcanics, Western rift, East African Rift system

Chakrabarti, Ramananda; Basu, Asish R.; Santo, Alba Patrizia; Tedesco, Dario; Vaselli, Orlando

doi:10.1016/j.chemgeo.2008.11.010

Cited by 129 publications

(109 citation statements)

References 69 publications

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“…Previous studies found that dissolved Ba in natural waters is largely determined by the geological composition of the streambed and weathering processes [47]. For instance, Ba is often rich in the geographic areas characterized by volcanic terrains, specifically alkaline-rich volcanic products or detrital (sedimentary) volcanic by-products (e.g., black shales) [55,56]. The levels of Ba concentration found in this study may indicate the role of geological origin of Ba.…”

Section: Spatial Variationmentioning

confidence: 53%

Spatiotemporal Distributions of Sr and Ba along an Estuarine River with a Large Salinity Gradient to the Gulf of Mexico

2016

Water

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Strontium and barium to calcium ratios are often used as proxies for tracking animal movement across salinity gradients. Many estuarine rivers face saltwater intrusion due to sea level rise, potentially causing changes in mobility and distribution of these metals upstream. From May 2013 to August 2015, monthly water samples were collected and in-situ measurements were performed at six sites along an estuary strongly affected by saltwater intrusion, the Calcasieu River, with salinity ranging from 0.02 to 29.50 Parts Per Thousand (ppt). Results showed that the total Sr concentration and the Sr/Ca ratio both increased significantly with increasing salinity. The average Sr concentration at the site closest to the Gulf of Mexico (Site 6) was 46.21 µmol/L, about 130 times higher than that of the site furthest upstream (Site 1, 0.35). The average Sr/Ca ratio at Site 6 (8.41 mmol/mol) was about three times the average Sr/Ca ratio at Site 1 (2.89). However, the spatial variation in total Ba concentration was marginal, varying from 0.36 to 0.47 µmol/L. The average Ba/Ca ratio at Site 1 (4.82 mmol/mol) was about 54 times the ratio at Site 6 (0.09), showing a negative relation between the Ba/Ca ratio and salinity. All elemental concentrations and ratios had considerable seasonal variations, with significant differences among sampling months for the Sr and Ba concentrations and the Ba/Ca ratio (p < 0.01). The results suggest that for low-gradient estuarine rivers such as the Calcasieu River, water chemistry upstream would experience substantial Sr and Ca enrichment, potentially affecting aquatic environments and biological communities.

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Section: Spatial Variationmentioning

confidence: 53%

Spatiotemporal Distributions of Sr and Ba along an Estuarine River with a Large Salinity Gradient to the Gulf of Mexico

2016

Water

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“…The shallow reservoir occurs at 1000 to 4000 m [Demant et al, 1994;Louaradi et al, 1993;Platz et al, 2004], while the deeper one is estimated to be at a depth of 10 to 14 km below the surface, as deduced from petrographic analysis [Demant et al, 1994;Platz et al, 2004], short-lived isotopes in lavas from the 2002 eruption [Chakrabarti et al, 2009], and seismic studies [Shuler and Ekström, 2009].…”

Section: 1002/2013jb010895mentioning

confidence: 99%

Dynamics of the Mount Nyiragongo lava lake

et al. 2014

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The permanent and presently rising lava lake at Mount Nyiragongo constitutes a major potential geological hazard to the inhabitants of the Virunga volcanic region in the Democratic Republic of Congo (DRC) and Rwanda. Based on two field campaigns in June 2010 and 2011, we estimate the lava lake level from the southeastern crater rim (~400 m diameter) and lava lake area (~46,550 m 2 ), which constrains, respectively, the lava lake volume (~9 × 10 6 m 3 ) and volume flow rate needed to keep the magma in a molten state (0.6 to 3.5 m 3 s À1

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“…Mantle plume melts directly interact with the depleted lithosphere causing partial melting at different depths. All these mechanisms are responsible for the development of different magma types such as; OIB, NMORB, EMORB and sometimes alkaline magma in different tectonic settings [13][14][15][16][17][18][19]. The northern and northeastern parts of Iraq are considered parts of the Zagros Orogenic Belt, which extends from southeast Turkey through northeast Iraq and northwest Iran to northern Oman.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry and geodynamics of the Mawat mafic complex in the Zagros Suture zone, northeast Iraq

Azizi¹,

Hadi

Asahara

et al. 2013

Open Geosciences

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Abstract:The Iraqi Zagros Orogenic Belt includes two separate ophiolite belts, which extend along a northwest-southeast trend near the Iranian border. The outer belt shows ophiolite sequences and originated in the oceanic ridge or supra-subduction zone. The inner belt includes the Mawat complex, which is parallel to the outer belt and is separated by the Biston Avoraman block. The Mawat complex with zoning structures includes sedimentary rocks with mafic interbedded lava and tuff, and thick mafic and ultramafic rocks. This complex does not show a typical ophiolite sequences such as those in Penjween and Bulfat. The Mawat complex shows evidence of dynamic deformation during the Late Cretaceous. Geochemical data suggest that basic rocks have high MgO and are significantly depleted in LREE relative to HREE. In addition they show positive ε N values (+5 to+8) and low 87Sr/86Sr ratios. The occurrence of some OIB type rocks, high Mg basaltic rocks and some intermediate compositions between these two indicate the evolution of the Mawat complex from primary and depleted source mantle. The absence of a typical ophiolite sequence and the presence of good compatibility of the source magma with magma extracted from the mantle plume suggests that a mantle plume from the D layer is more consistent as the source of this complex than the oceanic ridge or supra-subduction zone settings. Based on our proposed model the Mawat basin represents an extensional basin formed during the Late Paleozoic to younger along the Arabian passive margin oriented parallel to the Neo-Tethys oceanic ridge or spreading center. The Mawat extensional basin formed without creation of new oceanic basement. During the extension, huge volumes of mafic lava were intruded into this basin. This basin was squeezed between the Arabian Plate and Biston Avoraman block during the Late Cretaceous.

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Isotopic and geochemical evidence for a heterogeneous mantle plume origin of the Virunga volcanics, Western rift, East African Rift system

Cited by 129 publications

References 69 publications

Spatiotemporal Distributions of Sr and Ba along an Estuarine River with a Large Salinity Gradient to the Gulf of Mexico

Spatiotemporal Distributions of Sr and Ba along an Estuarine River with a Large Salinity Gradient to the Gulf of Mexico

Dynamics of the Mount Nyiragongo lava lake

Geochemistry and geodynamics of the Mawat mafic complex in the Zagros Suture zone, northeast Iraq

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