Progressive changes in magma transport at the active Serreta Ridge, Azores

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http://hdl.handle.net/10138/311681

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Romer , R H W , Beier , C , Haase , K M , Klügel , A & Hamelin , C 2019 , ' Progressive changes in magma transport at the active Serreta Ridge, Azores ' , Geochemistry, geophysics, geosystems G³. , vol. 20 , pp. 5394-5414 . https://doi.org/10.1029/2019GC008562

Title: Progressive changes in magma transport at the active Serreta Ridge, Azores
Author: Romer, R.H.W.; Beier, C.; Haase, K.M.; Klügel, A.; Hamelin, C.
Contributor: University of Helsinki, Department of Geosciences and Geography
Date: 2019-11-28
Number of pages: 21
Belongs to series: Geochemistry, geophysics, geosystems G³.
ISSN: 1525-2027
URI: http://hdl.handle.net/10138/311681
Abstract: Volcanism in the Eastern Azores Plateau occurs at large central volcanoes and along subaerial and submarine fissure zones, resulting from a mantle melting anomaly combined with transtensional stresses. Volcanic structures are aligned WNW-ESE and NW-SE, reflecting two tectonic stress fields that control the direction of lateral melt transport. Terceira Island is influenced by both stress fields, dividing the island into an eastern and western part. Several submarine volcanic ridges with variable orientations are located west of Santa Barbara, the youngest central volcano on Terceira. Major, trace element and Sr-Nd-Pb-Hf isotope compositions from submarine lavas and glasses, in part associated with the 1998-2001 Serreta Ridge eruption, vary between different lava suites, suggesting a formation from different mantle sources. Submarine lavas are more primitive than those from Santa Barbara volcano, indicating that they are not laterally connected with the shallow magma reservoir located in 2- to 5-km depth beneath the central volcano. Mineral thermobarometric data suggest that the older Serreta magmas were laterally transported at depths >5 km from Santa Barbara predominantly in WNW direction. We propose that lithospheric extension controls magma transport from the central volcano to Serreta Ridge. The youngest Serreta lavas differ from Santa Barbara and other submarine ridges in having less radiogenic Pb and higher Hf isotope ratios representing a new magma pulse ascending from the mantle. We conclude that lateral magma transport and the morphology of volcanic ridges are controlled by tectonic stresses in the lithosphere, whereas vertical melt transport is initiated by processes in the mantle.
Subject: 1171 Geosciences
ocean island
magmatic
tectonic
evolution
melt transport
Azores
TERCEIRA ISLAND AZORES
K-AR AGES
ISOTOPE EVIDENCE
JORGE ISLAND
MANTLE HETEROGENEITY
VOLCANIC ISLANDS
SAO-MIGUEL
PLATE BOUNDARY
RIFT ZONES
MID-ATLANTIC RIDGE
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