Multiple age components in individual molybdenite grains (2024)

Aleinikoff, J. N., Creaser, R. A., Lowers, H. A., Magee, C. W., & Grauch, R. I. (2012). Multiple age components in individual molybdenite grains. Chemical Geology, 300-301, 55-60. https://doi.org/10.1016/j.chemgeo.2012.01.011

Aleinikoff, John N. ; Creaser, Robert A. ; Lowers, Heather A. et al. / Multiple age components in individual molybdenite grains. In: Chemical Geology. 2012 ; Vol. 300-301. pp. 55-60.

@article{67bce9713bcf44b2b91c206687b207ca,

title = "Multiple age components in individual molybdenite grains",

abstract = "Re-Os geochronology of fractions composed of unsized, coarse, and fine molybdenite from a pod of unusual monazite-xenotime gneiss within a granulite facies paragneiss, Hudson Highlands, NY, yielded dates of 950.5 ± 2.5, 953.8 ± 2.6, and 941.2 ± 2.6. Ma, respectively. These dates are not recorded by co-existing zircon, monazite, or xenotime. SEM-BSE imagery of thin sections and separated grains reveals that most molybdenite grains are composed of core and rim plates that are approximately perpendicular. Rim material invaded cores, forming irregular contacts, probably reflecting dissolution/reprecipitation. EPMA and LA-ICP-MS analyses show that cores and rims have different trace element concentrations (for example, cores are relatively enriched in W). On the basis of inclusions of zircon with metamorphic overgrowths, we conclude that molybdenite cores and rims formed after high-grade regional metamorphism. The discovery of cores and rims in individual molybdenite grains is analogous to multi-component U-Pb geochronometers such as zircon, monazite, and titanite; thus, molybdenite should be carefully examined before dating to ensure that the requirement of age hom*ogeneity is fulfilled.",

keywords = "Geochemical analysis, Growth episodes, Molybdenite, Re-Os dating",

author = "Aleinikoff, {John N.} and Creaser, {Robert A.} and Lowers, {Heather A.} and Magee, {Charles W.} and Grauch, {Richard I.}",

year = "2012",

month = mar,

day = "18",

doi = "10.1016/j.chemgeo.2012.01.011",

language = "English",

volume = "300-301",

pages = "55--60",

journal = "Chemical Geology",

issn = "0009-2541",

publisher = "Elsevier B.V.",

}

Aleinikoff, JN, Creaser, RA, Lowers, HA, Magee, CW & Grauch, RI 2012, 'Multiple age components in individual molybdenite grains', Chemical Geology, vol. 300-301, pp. 55-60. https://doi.org/10.1016/j.chemgeo.2012.01.011

Multiple age components in individual molybdenite grains. / Aleinikoff, John N.; Creaser, Robert A.; Lowers, Heather A. et al.
In: Chemical Geology, Vol. 300-301, 18.03.2012, p. 55-60.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Multiple age components in individual molybdenite grains

AU - Aleinikoff, John N.

AU - Creaser, Robert A.

AU - Lowers, Heather A.

AU - Magee, Charles W.

AU - Grauch, Richard I.

PY - 2012/3/18

Y1 - 2012/3/18

N2 - Re-Os geochronology of fractions composed of unsized, coarse, and fine molybdenite from a pod of unusual monazite-xenotime gneiss within a granulite facies paragneiss, Hudson Highlands, NY, yielded dates of 950.5 ± 2.5, 953.8 ± 2.6, and 941.2 ± 2.6. Ma, respectively. These dates are not recorded by co-existing zircon, monazite, or xenotime. SEM-BSE imagery of thin sections and separated grains reveals that most molybdenite grains are composed of core and rim plates that are approximately perpendicular. Rim material invaded cores, forming irregular contacts, probably reflecting dissolution/reprecipitation. EPMA and LA-ICP-MS analyses show that cores and rims have different trace element concentrations (for example, cores are relatively enriched in W). On the basis of inclusions of zircon with metamorphic overgrowths, we conclude that molybdenite cores and rims formed after high-grade regional metamorphism. The discovery of cores and rims in individual molybdenite grains is analogous to multi-component U-Pb geochronometers such as zircon, monazite, and titanite; thus, molybdenite should be carefully examined before dating to ensure that the requirement of age hom*ogeneity is fulfilled.

AB - Re-Os geochronology of fractions composed of unsized, coarse, and fine molybdenite from a pod of unusual monazite-xenotime gneiss within a granulite facies paragneiss, Hudson Highlands, NY, yielded dates of 950.5 ± 2.5, 953.8 ± 2.6, and 941.2 ± 2.6. Ma, respectively. These dates are not recorded by co-existing zircon, monazite, or xenotime. SEM-BSE imagery of thin sections and separated grains reveals that most molybdenite grains are composed of core and rim plates that are approximately perpendicular. Rim material invaded cores, forming irregular contacts, probably reflecting dissolution/reprecipitation. EPMA and LA-ICP-MS analyses show that cores and rims have different trace element concentrations (for example, cores are relatively enriched in W). On the basis of inclusions of zircon with metamorphic overgrowths, we conclude that molybdenite cores and rims formed after high-grade regional metamorphism. The discovery of cores and rims in individual molybdenite grains is analogous to multi-component U-Pb geochronometers such as zircon, monazite, and titanite; thus, molybdenite should be carefully examined before dating to ensure that the requirement of age hom*ogeneity is fulfilled.

KW - Geochemical analysis

KW - Growth episodes

KW - Molybdenite

KW - Re-Os dating

UR - http://www.scopus.com/inward/record.url?scp=84856789980&partnerID=8YFLogxK

U2 - 10.1016/j.chemgeo.2012.01.011

DO - 10.1016/j.chemgeo.2012.01.011

M3 - Article

SN - 0009-2541

VL - 300-301

SP - 55

EP - 60

JO - Chemical Geology

JF - Chemical Geology

ER -

Aleinikoff JN, Creaser RA, Lowers HA, Magee CW, Grauch RI. Multiple age components in individual molybdenite grains. Chemical Geology. 2012 Mar 18;300-301:55-60. doi: 10.1016/j.chemgeo.2012.01.011