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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Petrochemistry of Dinantian volcanism in northern Britain

Smedley, Pauline Lesley January 1986 (has links)
No description available.
62

Genesis and evolution of calc-alkaline magmas at Soufriere volcano, St Vincent, Lesser Antilles arc

Heath, Emily January 1997 (has links)
Soufriere of St. Vincent is the most active subaerial volcano in the Lesser Antilles arc, and is composed of basalts and basaltic andesites. Eruptive style has tended to alternate between predominantly effusive and explosive, although magma compositions show no systematic variations with time. New Ar-Ar and 14C dates help to constrain the geological evolution of the (- 0.6 Ma) volcano. Parental, possibly primary, magmas at Soufriere had MgO contents exceeding 12 wt.% (mg# 75) and were probably nepheline-normative. They may be representative of the parental magmas of the calc-alkaline suites of the Lesser Antilles arc. The source mantle probably resembled that of N-MORB, prior to metasomatic enrichment by hydrous slab-derived fluids, containing contributions from subducted sediments and oceanic crust. Parental magmas last equilibrated with the mantle at - 17 kbar pressure, with temperatures greater than 1130·C and f02 exceeding FMQ +1. Near-primary basaltic lavas were only erupted during the earliest (Pre-Somma) phase of volcanism. Basaltic andesites (and occasional andesites) were produced by fractionation of 01 + spinel + cpx + plag ± opx over a range of crustal pressures (5-10kbar), at temperatures mainly in the range 1000 - 1l00·C. The total amount of crystallization was some 76 wt. %, and amphibole was apparently not a fractionating phase. There is conflicting evidence as to the pre-eruptive water contents of Soufriere magmas; phenocryst compositions suggest H20 > 3 wt. %, whereas various projections into phase diagrams are more consistent with relatively anhydrous magmas. Magma mixing did not apparently play a significant role in the evolution of most Soufriere magmas, and fractional crystallization was not accompanied by crustal assimilation, judging from trace element and Sr-Nd isotope systematics. New U-Th mineral isochrons suggest that magmas resided for tens of thousands of years within the crust, which requires rather stable thermodynamic conditions in the magma chamber(s) beneath Soufriere.
63

Studies of volcanism on Santorini, Greece and Mount St. Helens U.S.A

Mellors, Robin Anthony January 1988 (has links)
No description available.
64

Early Tertiary tectonics and igneous activity adjacent to the N.W. European continental margin

Hall, Benjamin Dunstan January 1995 (has links)
No description available.
65

Explosive volcanism on Santorini, Greece

Druitt, T. H. January 1983 (has links)
No description available.
66

Geological and radiochemical studies of young volcanoes : Santorini, Greece and Ol Doinyo Lengai, Tanzania

Pyle, David Mark January 1990 (has links)
No description available.
67

Melting and melt extraction : the physics of flow in deformable porous media

Spiegelman, Marc Willard January 1989 (has links)
No description available.
68

Subsidence and volcanism in western Tethys

Wooler, Dan Anthony January 1993 (has links)
No description available.
69

Seismic anisotropy of the upper oceanic crust

Uniyal, Parashu Ram January 1989 (has links)
No description available.
70

Studies of continental margins

Fowler, S. R. January 1986 (has links)
No description available.

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