Other
Scientific paper
Dec 1991
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1991gecoa..55.3809p&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 55, Issue 12, pp.3809-3830
Other
5
Scientific paper
A detailed stable isotope (S, O) and elemental (major, trace, S content) study of peraluminous S-type granites and granodiorites of the South Mountain Batholith and the Meguma Group metasediments into which the batholith was intruded has been conducted on a regional and local scale near Mt. Uniacke. Sulfur contents of the metasediments range from 5 to 2440 ppm, and 34 S ranges from -3.7 to +26.3%. Sulfur contents of the igneous rocks range from 6 to 570 ppm, with the granites ( 20 ppm) having lower sulfur contents than the granodiorites ( 300 ppm). Approximately 30 to 60% of the sulfur in the granodiorites is present as pyrrhotite (a late phase), with most of the remainder being present as sulfur substituted into biotite (an early phase). 18 OQ Quartz values of the Mt. Uniacke granodiorites are heavy ( a + 12.2%.) indicating formation of the magmas by partial melting of sedimentary rocks. Major element variations suggest that the granites are related to the granodiorites by fractional crystallization of plagioclase, quartz, and biotite. Comparison of the sulfur contents of the granodiorites with experimental determinations of sulfur solubility suggest that the distribution coefficient of sulfur ( D s ) between the cumulate and the magma during fractional crystallization 4. The regional granodiorites have a relatively restricted range of 34 S values (+5.4 to + 8.4%.), while the regional granites have a wide range of 34 S values ( + 1.6 to + 15.0%.). Granodiorites at Mt. Uniacke with normal magmatic values (+0.76 to +1.42%.) for 18 O (Quartz-Feldspar) have 34 S values between +6.6 and +12.3%., and show good negative correlations between 34 S and S, FeO, and MgO contents. Some granodiorites at Mt. Uniacke have anomalously low sulfur contents for their major element composition, and 18 O (Quartz-Feldspar) values (-0.45 to +0.67%. ) indicate that these samples have undergone hydrothermal alteration, and this alteration event is probably responsible for the low sulfur contents. A number of processes have been considered in order to understand the variations of 34 S. Partial melting of inhomogeneous source rocks may be responsible for some of the regional 34 S variations, but this implies that the granites are not genetically related to the granodiorites. Inhomogeneous source rocks are an unlikely explanation for the systematic variations of 34 S observed over only a few kilometres at Mt. Uniacke. Rayleigh fractionation accompanying the fractional crystallization of biotite [ 34 S(pyrrhotiteS -- silicate-S) +0.5 to +1.0%. ] can account for only a small component of the observed 34 S variations. The assimilation of isotopically variable sulfur derived from the Meguma Group metasediments during fractional crystallization (combined assimilation-fractional crystallization, or AFC) provides the best explanation for the 34 S variations. Transfer of sulfur from the country rock may have been possible by either bulk AFC (where all of the country rock material is incorporated into the magma) or by selective AFC (where sulfur and other volatile elements only are transferred from the country rock into the magma). Selective AFC could have been effected by a sloping mechanism of intrusion, followed by the heating of country rock xenoliths to the point where extensive desulfidation reactions took place, with sulfur being transferred from the country rock to the magma by a fluid phase.
Kubilius Walter P.
Ohmoto Hiroshi
Poulson Simon R.
No associations
LandOfFree
Geochemical behavior of sulfur in granitoids during intrusion of the South Mountain batholith, Nova Scotia, Canada 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 Geochemical behavior of sulfur in granitoids during intrusion of the South Mountain batholith, Nova Scotia, Canada, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Geochemical behavior of sulfur in granitoids during intrusion of the South Mountain batholith, Nova Scotia, Canada will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1538345