نتایج جستجو برای: andesitic lavas
تعداد نتایج: 1569 فیلتر نتایج به سال:
The 1783–1784 AD fissure eruption of Laki (Iceland) produced 15 km of homogeneous basaltic lavas and tephra that are characterized by extreme (3‰) O-depletion relative to normal mantle. Basaltic tephra erupted over the last 8 centuries and as late as in November 2004 from the Grímsvötn central volcano, which together with Laki are a part of a single volcanic system, is indistinguishable in δO f...
[1] Although most Central American magmas have a typical arc geochemical signature, magmas in southern Central America (central Costa Rica and Panama) have isotopic and trace element compositions with an ocean island basalt (OIB) affinity, similar to the Galapagos-OIB lavas (e.g., Ba/La < 40, La/Yb > 10, Pb/Pb > 18.8). Our new data for Costa Rica suggest that this signature, unusual for a conve...
The 2021 Tajogaite eruption of Cumbre Vieja (La Palma, Spain) was typified by the emission low viscosity lavas that flowed at high velocities and inundated a large area. We experimentally investigated rheological evolution melt feeding through concentric cylinder viscometry to understand exceptional flowing ability these constrain its emplacement dynamics. conducted set cooling deformation expe...
The early Jurassic volcanism of Central Patagonia covers an extensive area 50,000 km2 where the volcanic deposits occur as isolated systems. records form elongated belt in which composition, depositional and genetic features, show several differences along with its distribution. Cañadón Chileno Complex (CCHC), located Río Negro province, provides opportunity to evaluate improve knowledge about ...
Measurements of chlorine concentrations in matrix glasses from 18 primitive (s 6 wt% MgO) and eight evolved lavas from active spreading centers in the Lau Basin back-arc system provide insight into the processes which control chlorine concentrations in subduction-related magmas, and can be used to investigate chlorine enrichment related to fluids derived from the underlying subducted slab. Chlo...
The Dom João de Castro seamount in the Hirondelle Basin (Azores) is a central volcano on ultraslow diverging Terceira Rift axis. combination of structural and geochemical data provides insights into evolution volcanoes oceanic rift systems above Azores melting anomaly. orientation fault scarps volcanic structures at D. adjacent fissure zone indicate that regional SW-NE extending stress field do...
The chemical and isotopic compositions of volcanic arc lavas often show evidence for involvement a sedimentary component during magma genesis. Determining where this is added to magmas vital importance constraining the extent which sediments volatiles are recycled at subduction zones. Lavas from Martinique in Lesser Antilles have wide ranging extending highly radiogenic values (e.g. 87 /Sr/ 86 ...
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