ISSN:
1432-0819
Keywords:
Bárdarbunga
;
Grímsvötn
;
Gjálp
;
Magma migration
;
Lateral intrusion
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
87 Sr/86Sr (0.70322) and δ 18O ( ∼2.9‰), whereas significantly lower and higher values, respectively, are found in samples from the Bárdarbunga volcanic system (0.70307 and 3.8‰). These results strongly indicate that the Gjálp magma originated from the Grímsvötn magma system. The 1996 magma is of an intermediate composition, representing a basaltic icelandite formed by 50% fractional crystallization of a tholeiite magma similar in composition to that expelled by the 1998 Grímsvötn eruption. The differentiation that produced the Gjálp magma may have taken place in a subsidiary magma chamber that last erupted in 1938 and would be located directly beneath the 1996 eruption site. This chamber was ruptured when a tectonic fracture propagated southward from Bárdarbunga central volcano, as indicated by the seismicity that preceded the eruption. Our geochemical results are therefore not in agreement with lateral magma migration feeding the 1996 Gjálp eruption. Moreover, the results clearly demonstrate that isotope ratios are excellent tracers for deciphering pathways of magma migration and permit a clear delineation of the volcanic systems beneath Vatnajökull ice sheet.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00008912
Permalink