Computer Science
Scientific paper
Jan 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995gecoa..59..295i&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 59, Issue 2, pp.295-312
Computer Science
9
Scientific paper
Saline fluid inclusions (FI) trapped at close to the temperature of final solidification of a granitic melt occur in rocks from Bingham, Utah, Ascension Island, mid-Atlantic Ocean, and St. Austell, Cornwall. Slightly lower temperature FI occur at Butte, Montana. Argon, Kr, and Xe were extracted from FI by laser microprobe decrepitation of minute portions of the samples after neutron irradiation (along with synthetic FI of known composition), and measured in a low blank, high sensitivity, pulse-counting mass spectrometer. Results enable measurement of Cl, K, Br, and I simultaneously with 36 r, 40 Ar, 84 Kr, and 129 Xe, in ~10 -7 cc of fluid, the contents of a single spherical inclusion ~57 m in diameter. Average K/Cl in Bingham and St. Austell FI are ~0.25 and ~0.15, respectively, broadly consistent with the composition of fluids equilibrated with rocks at temperatures close to the eutectic in the granite system (400-600°C and 0.5 - 2 Kb). Within-sample variations in K/Cl are significant and may be a result of exsolution of fluids from magmas over a range of temperatures and/or pressures. Halogen ratios are confined to a narrow range, with I/Cl and Br/Cl in Bingham, Ascension, and some Butte FI ~ 1 - 8 × 10 -5 and 1 - 3 × 10 -3 , respectively, probably evidence of a common source of salinity, presumably part of the Earth's mantle. A component of salinity derived from continental crust may be indicated by higher I/Cl and lower Br/Cl in St. Austell Fl. Radiogenic 40 Ar produced in situ from K in FI after trapping is usually insignificant. 40 Ar e is defined as 40 Ar in excess of the amounts attributable to atmospheric gases and that produced by decay of K in FI. Variations in 40 Ar e /Cl in Bingham, Ascension, and St. Austell FI are greater than can be explained by just different Cl concentrations in FI, (typically between ~5 × 10 -7 and 8 × 10 -6 ), probably because Ar and Cl have been fractionated within these systems by outgassing of a magma in the interval between exsolution of different FI generations. Concentrations of Ar and 84 Kr in most Bingham, Ascension, and St. Austell FI are ~2 orders of magnitude greater than in most lavas and granites, with 84 Kr/ 36 Ar ranging between ~0.015 and ~0.08, grossly consistent with the composition of fluids exsolved from magmas. Several distinct fluid types are present at Butte: (1) rare "magmatic" FI having halogen and noble gas abundances similar to Bingham and Ascension and (2) abundant FI having 36 Ar and 84 Kr concentrations similar to air-saturated fresh waters, with slightly lower Br/Cl than FI at Bingham and Ascension (~5-10 × 10 -4 ) and relatively high 40 Ar e /Cl (~1 × 10 -5 and 2.8 × 10 -5 ). Mixing prior to trapping between fluid derived from magmas and meteoric water that acquired 40 Ar e plus some halogens by interaction with country rocks is the most likely origin of most Butte FI.
Irwin Jonathan
Roedder Edwin
No associations
LandOfFree
Diverse origins of fluid in magmatic inclusions at Bingham (Utah, USA), Butte (Montana, USA), St. Austell (Cornwall, UK), and Ascension Island (mid-Atlantic, UK), indicated by laser microprobe analysis of Cl, K, Br, I, Ba + Te, U, Ar, Kr, and Xe does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Diverse origins of fluid in magmatic inclusions at Bingham (Utah, USA), Butte (Montana, USA), St. Austell (Cornwall, UK), and Ascension Island (mid-Atlantic, UK), indicated by laser microprobe analysis of Cl, K, Br, I, Ba + Te, U, Ar, Kr, and Xe, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Diverse origins of fluid in magmatic inclusions at Bingham (Utah, USA), Butte (Montana, USA), St. Austell (Cornwall, UK), and Ascension Island (mid-Atlantic, UK), indicated by laser microprobe analysis of Cl, K, Br, I, Ba + Te, U, Ar, Kr, and Xe will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1820953