1995
DOI: 10.1130/spe296-p123
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Porosity, permeability, and basalt metamorphism

Abstract: The effects of primary porosity on fluid flow during contact metamorphism were studied in basalts from central East Greenland. The gabbroic Skaergaard magma intruded interbedded massive and aa basalts with mean macroscopic primary porosities of 4% and 11%, respectively. Heat transport from the cooling gabbros led to three metamorphic mineral zones within 1 km of the contact: the actinolite + chlorite zone beyond 250 m, where the mineral assemblage records peak temperatures (7) of <550 °C; the pyroxene zone (T … Show more

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Cited by 20 publications
(18 citation statements)
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“…The variability of temperatures derived from twopyroxene thermometry suggests that chemical equilibrium was attained only within 100 m of the contact during the metamorphic peak. The sharply defined transition between the pyroxene and actinolite þ chlorite zones (with no intervening hornblende zone) represents a significant apparent step-wise temperature change and is consistent with non-progressive metamorphism (Manning et al, 1993;Manning & Bird, 1995). Taylor & Forester (1979) present a detailed oxygen and hydrogen isotope study of the hydrothermal system associated with the Skaergaard intrusion.…”
Section: G E O L O G I C a L S E T T I N Gmentioning
confidence: 99%
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“…The variability of temperatures derived from twopyroxene thermometry suggests that chemical equilibrium was attained only within 100 m of the contact during the metamorphic peak. The sharply defined transition between the pyroxene and actinolite þ chlorite zones (with no intervening hornblende zone) represents a significant apparent step-wise temperature change and is consistent with non-progressive metamorphism (Manning et al, 1993;Manning & Bird, 1995). Taylor & Forester (1979) present a detailed oxygen and hydrogen isotope study of the hydrothermal system associated with the Skaergaard intrusion.…”
Section: G E O L O G I C a L S E T T I N Gmentioning
confidence: 99%
“…Contact metamorphism of the basaltic rocks that form the upper walls and roof of the magma chamber resulted in the development of three zones, defined by the presence of actinolite þ chlorite (4250 m from the contact), clinopyroxene þ orthopyroxene (10^250 m from the contact), and olivine (5 10 m from the contact) (Manning & Bird, 1991, 1995Manning et al, 1993). Rocks in the pyroxene and olivine zones have granoblastic polygonal microstructures whereas basalts from the actinolite þ chlorite zone retain relict igneous microstructures (Manning & Bird, 1991).…”
Section: G E O L O G I C a L S E T T I N Gmentioning
confidence: 99%
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“…Typical basalts from the Scoresby Sund region that have undergone zeolite facies metamorphism contain 1-2 wt % H 2 O . In the Miki Fjord region, where actinolite + chlorite, prehnite + epidote and prehnite + calcite mineral assemblages fill primary pore spaces in the basalts (Bird et al 1985;Manning & Bird, 1995), and where extreme Ca metasomatism of dolerite dykes produces lithologies with modes of prehnite of 40-100 % (Rose & Bird, 1994), the bulk water content of the metabasalts is likely to be double that in the Scoresby Sund region. Assuming that all H 2 O is lost from the metabasaltic xenoliths to the enclosing magma during dehydration suggests that metasomatic wehrlites and metabasaltic xenoliths should be present in volume ratios between 1:1 and 2:1.…”
Section: A Evolution Of the Noe-nygaard Intrusionmentioning
confidence: 96%
“…Manning and Bird, 1995;Magganas and Koutsovitis, 2015 and references therein). During the exhumation stage circulating subduction related fluids and/or oceanic thermal waters may alter the ophiolitic rocks.…”
Section: Metamorphic and Metasomatic Processesmentioning
confidence: 99%