Early Tertiary volcanic rocks in Well 163/6-1A, Rockall Trough

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Authors:Morton, A. C.; Dixon, J. E.; Fitton, J. G.; Macintyre, R. M.; Smythe, D. K.; Taylor, P. N.
Author Affiliations:Primary:
Br. Geol. Surv., United Kingdom
Other:
Inst. Oceanogr. Sci., United Kingdom
Univ. Edinburgh, United Kingdom
Scott. Univ. Res. and React. Cent., United Kingdom
Univ. Oxford, United Kingdom
Volume Title:Early Tertiary volcanism and the opening of the NE Atlantic
Volume Authors:Morton, A. C., editor; Parson, L. M.
Source:Geological Society Special Publications, Vol.39, p.293-308; Early Tertiary volcanism and the opening of the NE Atlantic, London, United Kingdom, Mar. 18-19, 1987, edited by A. C. Morton and L. M. Parson. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719. ISBN: 0-632-02171-3
Publication Date:1988
Note:In English. 33 refs.; illus. incl. 6 tables, geol. sketch map
Summary:Well 163/6-1A, located in the northern part of the Rockall Trough, proved the presence of a thick sequence of extrusive igneous rocks below Upper Palaeocene sediments. K/Ar dating suggests that the lavas were extruded at approx 55 m.y. The lava sequence comprises three distinct lithologies. The upper part of the pile consists of olivine tholeiites that show alkalic and picritic tendencies and have a distinct within-plate composition. These are underlain by another group of olivine tholeiites that are much closer in composition to normal MORB. The Sr and Pb isotopic compositions of the basalts suggest possible contamination by continental crustal material. The basalts are underlain by a sequence of cordierite- phyric dacites of remarkably homogeneous composition. Their highly aluminous nature, high Ni and Cr contents and their Sr and Pb isotopic compositions indicate that they are not differentiates of a basaltic parent magma, and are considered to have originated by melting of argillaceous and possibly, arenaceous rocks at depth. Organic-rich black shale lithologies may have been involved. [Authors' abstract] [J.M.H.]
Subjects:Absolute age; Age; Alkaline earth metals; Basaltic composition; Basalts; Cenozoic; Chemical composition; Chromium; Composition; Dacites; Dates; Extrusive rocks; Hydrocarbons; Igneous rocks; Isotopes; K/Ar; Lava; Lead; Lithostratigraphy; Lower Tertiary; Magmas; Major elements; Metals; Mid-ocean ridge basalts; Nickel; Olivine tholeiite; Organic compounds; Paleocene; Paleogene; Pb-206/Pb-204; Pb-207/Pb-204; Peraluminous composition; Petrography; Petrology; Pollution; Radioactive isotopes; Rare earths; Sr-87/Sr-86; Stable isotopes; Stratigraphy; Strontium; Tertiary; Trace elements; Volcanic rocks; Atlantic Ocean; North Atlantic; Rockall Trough; Evolution
Coordinates:N594839 N594839 W0085757 W0085757
Abstract Numbers:90M/0938
Record ID:1989014741
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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