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@article{1432498,
author = {Scribner, ED and Groat, LA and Cempírek, Jan},
article_location = {Praha},
article_number = {2},
doi = {http://dx.doi.org/10.3190/jgeosci.259},
keywords = {dravite; uvite; feruvite; fluor-uvite; lamprophyre dikes; O'Grady Batholith},
language = {eng},
issn = {1802-6222},
journal = {Journal of Geosciences},
title = {Mineralogy of Ti-bearing, Al-deficient tourmaline assemblages associated with lamprophyre dikes near the O'Grady Batholith, Northwest Territories, Canada},
url = {http://dx.doi.org/10.3190/jgeosci.259},
volume = {63},
year = {2018}
}
TY - JOUR
ID - 1432498
AU - Scribner, ED - Groat, LA - Cempírek, Jan
PY - 2018
TI - Mineralogy of Ti-bearing, Al-deficient tourmaline assemblages associated with lamprophyre dikes near the O'Grady Batholith, Northwest Territories, Canada
JF - Journal of Geosciences
VL - 63
IS - 2
SP - 123-135
EP - 123-135
PB - Česká geologická společnost
SN - 18026222
KW - dravite
KW - uvite
KW - feruvite
KW - fluor-uvite
KW - lamprophyre dikes
KW - O'Grady Batholith
UR - http://dx.doi.org/10.3190/jgeosci.259
N2 - Calc-alkaline lamprophyre dikes are hosted by tourmalinized metasedimentary rocks in the Northwest Territories, Canada. Some of these lamprophyre dikes are cross-cut by aplite and pegmatite dikes, as well as tourmaline-bearing quartz veins that were all derived from the nearby granitic O'Grady Batholith. The lamprophyre dikes are composed of actinolite to magnesio-hornblende, plagioclase, K-feldspar and quartz with minor phlogopite (up to 4.13 wt. % TiO2), titanite, apatite, pyrite, allanite-(Ce), and zircon. A zone near the margin of one of the dikes has been altered to tourmaline associated with actinolite to magnesio-hornblende, clinochlore, titanite and quartz, with minor clinopyroxene and apatite. Two generations of tourmaline are recognized: Tur I occurs in quartz at the margin of the dike and Tur II forms a massive aggregate with common inclusions of other minerals in an altered lamprophyre zone near the margin of the dike. The vast majority of the analyzed tourmaline is Al-deficient, with less than 6 apfu Al at the Z site (on average 5.691 apfu in Tur I and 5.601 apfu in Tur II). Tur I is mostly dravite with uvite, plus minor feruvite and fluor-uvite, while Tur II contains a greater proportion uvite, feruvite, and fluor-uvite. The most evolved tourmaline compositions observed are feruvite with up to 2.17 wt. % TiO2, and fluor-uvite with up to 0.84 wt. % F. The tourmaline composition reflects the unique geochemical environment in which it crystallized; from Tur I to Tur II, tourmaline becomes richer in Ca-, Fe-, and Ti, presumably due to the reaction of B-bearing fluids with the Al-poor, Ca-, Mg-Fe-, and Ti-bearing minerals in the lamprophyre dike. The high F contents of some tourmaline species suggest that it crystallized from fluids derived from the aplite and pegmatite dikes.
ER -
SCRIBNER, ED, LA GROAT and Jan CEMPÍREK. Mineralogy of Ti-bearing, Al-deficient tourmaline assemblages associated with lamprophyre dikes near the O'Grady Batholith, Northwest Territories, Canada. \textit{Journal of Geosciences}. Praha: Česká geologická společnost, 2018, vol.~63, No~2, p.~123-135. ISSN~1802-6222. Available from: https://dx.doi.org/10.3190/jgeosci.259.
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