scholarly journals The spatial association of accessory minerals with biotite in granitic rocks from the South Mountain Batholith, Nova Scotia, Canada

Geosphere ◽  
2021 ◽  
Author(s):  
D. Barrie Clarke ◽  
Axel D. Renno ◽  
David C. Hamilton ◽  
Sabine Gilbricht ◽  
Kai Bachmann
Keyword(s):  
Nova Scotia ◽  
Boundary Layers ◽  
Random Distribution ◽  
Spatial Association ◽  
Granitic Rocks ◽  
Granitic Magma ◽  
Accessory Mineral ◽  
The South ◽  
Accessory Minerals ◽  
South Mountain Batholith

We use mineral liberation analysis (MLA) to quantify the spatial association of 15,118 grains of accessory apatite, monazite, xenotime, and zircon with essential biotite, and clustered with themselves, in a peraluminous biotite granodiorite from the South Mountain Batholith in Nova Scotia (Canada). A random distribution of accessory minerals demands that the proportion of accessory minerals in contact with biotite is identical to the proportion of biotite in the rock, and the binary touching factor (percentage of accessory mineral touching biotite divided by modal proportion of biotite) would be ~1.00. Instead, the mean binary touching factors for the four accessory minerals in relation to biotite are: apatite (5.06 for 11,168 grains), monazite (4.68 for 857 grains), xenotime (4.36 for 217 grains), and zircon (5.05 for 2876 grains). Shared perimeter factors give similar values. Accessory mineral grains that straddle biotite grain boundaries are larger than completely locked, or completely liberated, accessory grains. Only apatite-monazite clusters are significantly more abundant than expected for random distribution. The high, and statistically significant, binary touching factors and shared perimeter factors suggest a strong physical or chemical control on their spatial association. We evaluate random collisions in magma (synneusis), heterogeneous nucleation processes, induced nucleation in passively enriched boundary layers, and induced nucleation in actively enriched boundary layers to explain the significant touching factors. All processes operate during the crystallization history of the magma, but induced nucleation in passively and actively enriched boundary layers are most likely to explain the strong spatial association of phosphate accessories and zircon with biotite. In addition, at least some of the apatite and zircon may also enter the granitic magma as inclusions in grains of Ostwald-ripened xenocrystic biotite.

Petrology of the South Mountain Batholith, Nova Scotia

1975 ◽  
Vol 12 (7) ◽  
pp. 1209-1218 ◽  
Author(s):  
C. B. McKenzie ◽  
D. B. Clarke
Keyword(s):  
Nova Scotia ◽  
Fractional Crystallization ◽  
Lower Crust ◽  
Granitic Rocks ◽  
The South ◽  
South Mountain Batholith ◽  
Partial Fusion ◽  
Acadian Orogeny

Approximately one-third of western Nova Scotia is underlain by granitic rocks of the South Mountain batholith. The pi u ton is an epizonal complex of granodiorite, adamellite and alaskite which was emplaced after the folding and metamorphic events of the Acadian orogeny. Chemical and petrographic data suggest that the rocks comprise a single comagmatic suite related by the fractional crystallization of biotite and plagioclase. The magma for the batholith may have been produced by partial fusion of the lower crust, or through a hybridization of mantle and crustal melts.

Syn-Acadian emplacement model for the South Mountain batholith, Meguma Terrane, Nova Scotia: Magnetic fabric and structural analyses

1997 ◽  
Vol 109 (10) ◽  
pp. 1279-1293 ◽  
Author(s):  
Keith Benn ◽  
Richard J. Horne ◽  
Daniel J. Kontak ◽  
Geoffrey S. Pignotta ◽  
Neil G. Evans
Keyword(s):  
Nova Scotia ◽  
Magnetic Fabric ◽  
The South ◽  
South Mountain Batholith ◽  
Meguma Terrane

Oxygen isotope evidence for the genesis of Upper Paleozoic granitoids from southwestern Nova Scotia

1980 ◽  
Vol 17 (1) ◽  
pp. 132-141 ◽  
Author(s):  
F. J. Longstaffe ◽  
T. E. Smith ◽  
K. Muehlenbachs
Keyword(s):  
Nova Scotia ◽  
Oxygen Isotope ◽  
Large Scale ◽  
The South ◽  
Metasedimentary Rocks ◽  
South Mountain Batholith ◽  
Oxygen Isotope Ratios ◽  
Upper Paleozoic ◽  
Isotope Evidence ◽  
Alteration Processes

The oxygen isotope ratios for 127 rocks and coexisting minerals from Paleozoic granitoids and clastic metasedimentary rocks of southwestern Nova Scotia have been measured. The whole-rock δ18O values for samples of the South Mountain batholith range from 10.1–12.0‰.But discrete granitoid plutons, located to the south of the South Mountain batholith, have lower δ18O values (7.8–10.4‰). Coexisting minerals from the Nova Scotia granitoids are near isotopic equilibrium, indicating that the whole-rock δ18O values primarily reflect the δ18O of the magma, rather than secondary alteration processes. The Meguma Group clastic metasedimentary rocks that host the Nova Scotia granitoids range in δ18O from 10.1–12.9‰. These clastic metasedimentary rocks show no systematic geographic variation in δ18O. The greenschist facies Meguma Group rocks that host the South Mountain batholith have similar δ18O values to the amphibolite facies equivalents located about the southern discrete plutons. Large scale isotopic exchange between the Meguma Group and the South Mountain batholith, or the southern plutons, is not evident.The relatively high δ18O values of the peraluminous South Mountain batholith (10.1–12.0‰) indicate that it formed by anatexis of 18O-rich clastic metasedimentary rocks. The southern plutons were also derived by partial melting of clastic metasedimentary rocks, but their lower δ18O values reflect exchange of the source material with a low 18O reservoir (mafic magmas?) prior to, or during anatexis.The sheared Brenton pluton is much lower in δ18O (5.0‰) than any of the other rocks, probably because of exchange with low 18O fluids during shearing.

Magmatic andalusite from the South Mountain batholith, Nova Scotia

1976 ◽  
Vol 56 (3) ◽  
pp. 279-287 ◽  
Author(s):  
D. B. Clarke ◽  
C. B. McKenzie ◽  
G. K. Muecke ◽  
S. W. Richardson
Keyword(s):  
Nova Scotia ◽  
The South ◽  
South Mountain Batholith

IMPLICATIONS OF ZIRCON PETROCHRONOLOGY OF THE SOUTH MOUNTAIN BATHOLITH (NOVA SCOTIA) FOR SN-W METALLOGENY

2020 ◽  
Author(s):  
Luke Bickerton ◽  
◽  
Daniel J. Kontak ◽  
Iain M. Samson ◽  
J. Brendan Murphy ◽  
...  
Keyword(s):  
Nova Scotia ◽  
The South ◽  
South Mountain Batholith

The distribution of the rare earth elements within the Carnmenellis pluton, Cornwall

1985 ◽  
Vol 49 (353) ◽  
pp. 495-504 ◽  
Author(s):  
N. L. Jefferies
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Electron Microprobe ◽  
Granitic Rocks ◽  
Accessory Mineral ◽  
Accessory Minerals ◽  
Essential Minerals ◽  
The Rare Earth

AbstractThe Carnmenellis pluton is a post-orogenic granite of Hercynian age, comprised largely of porphyritic biotite granites which possess LREE enriched patterns with slight negative Eu anomalies. Electron microprobe and ICP spectrometry data are presented for monazite, which occurs as an accessory mineral in all granite types, and it is demonstrated that this mineral is the principal host for LREE in the biotite granites. HREE are strongly partitioned into the accessory minerals xenotime, apatite, and zircon; only Eu substitutes significantly into the essential minerals. The behaviour of the REE during granite differentiation is controlled by the behaviour of the radioactive accessory minerals, which limits the usefulness of these elements in the petrogenetic modelling of granitic rocks.

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