Abstract
Rb/Sr and U/Pb data from this complex, a carbonatite associated with the Kapuskasing structural zone, indicate a mid-Proterozoic age. A 207Pb/206Pb age of 1872 + or - 13 m.y. is interpreted as the emplacement age of this body, grouping it with other approx 1900 m.y. complexes that are the oldest known carbonatites associated with the Kapuskasing structure. A 206Pb/238U age of 1894 + or - 29 m.y. agrees with the Pb/Pb age. A Rb/Sr whole-rock isochron date of 1807 + or - 13 m.y. probably indicates later resetting of the Rb/Sr system. The epsilonSr(T) and epsilonNd(T) values for Borden indicate derivation of the Sr and Nd from a source with a time-integrated depletion in LIL elements. These closely resemble the epsilon values for Sr and Nd from the Cargill and Spanish River complexes, two other 1900 m.y. old plutons. The estimated Pb/Pb ratios from Borden calcites plot well below growth curves for average continental crust, a pattern similar to those found in MORB and most ocean-island volcanic rocks, again suggesting a source depleted in LIL. The combined data strongly favour a mantle origin for the Borden complex, with little or no crustal contamination, and support the hypothesis that many carbonatites intruded into the Canadian Shield were derived from an ancient, LIL-depleted subcontinental upper mantle.-P.Br.
| Original language | English |
|---|---|
| Pages (from-to) | 24-30 |
| Number of pages | 7 |
| Journal | Canadian Journal of Earth Sciences |
| Volume | 24 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1987 Jan 1 |
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All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)
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Age and radiogenic isotopic systematics of the Borden carbonatite complex, Ontario, Canada. / Bell, K.; Blenkinsop, J.; Kwon, Sung Tack; Tilton, G. R.; Sage, R. P.
In: Canadian Journal of Earth Sciences, Vol. 24, No. 1, 01.01.1987, p. 24-30.Research output: Contribution to journal › Article
TY - JOUR
T1 - Age and radiogenic isotopic systematics of the Borden carbonatite complex, Ontario, Canada.
AU - Bell, K.
AU - Blenkinsop, J.
AU - Kwon, Sung Tack
AU - Tilton, G. R.
AU - Sage, R. P.
PY - 1987/1/1
Y1 - 1987/1/1
N2 - Rb/Sr and U/Pb data from this complex, a carbonatite associated with the Kapuskasing structural zone, indicate a mid-Proterozoic age. A 207Pb/206Pb age of 1872 + or - 13 m.y. is interpreted as the emplacement age of this body, grouping it with other approx 1900 m.y. complexes that are the oldest known carbonatites associated with the Kapuskasing structure. A 206Pb/238U age of 1894 + or - 29 m.y. agrees with the Pb/Pb age. A Rb/Sr whole-rock isochron date of 1807 + or - 13 m.y. probably indicates later resetting of the Rb/Sr system. The epsilonSr(T) and epsilonNd(T) values for Borden indicate derivation of the Sr and Nd from a source with a time-integrated depletion in LIL elements. These closely resemble the epsilon values for Sr and Nd from the Cargill and Spanish River complexes, two other 1900 m.y. old plutons. The estimated Pb/Pb ratios from Borden calcites plot well below growth curves for average continental crust, a pattern similar to those found in MORB and most ocean-island volcanic rocks, again suggesting a source depleted in LIL. The combined data strongly favour a mantle origin for the Borden complex, with little or no crustal contamination, and support the hypothesis that many carbonatites intruded into the Canadian Shield were derived from an ancient, LIL-depleted subcontinental upper mantle.-P.Br.
AB - Rb/Sr and U/Pb data from this complex, a carbonatite associated with the Kapuskasing structural zone, indicate a mid-Proterozoic age. A 207Pb/206Pb age of 1872 + or - 13 m.y. is interpreted as the emplacement age of this body, grouping it with other approx 1900 m.y. complexes that are the oldest known carbonatites associated with the Kapuskasing structure. A 206Pb/238U age of 1894 + or - 29 m.y. agrees with the Pb/Pb age. A Rb/Sr whole-rock isochron date of 1807 + or - 13 m.y. probably indicates later resetting of the Rb/Sr system. The epsilonSr(T) and epsilonNd(T) values for Borden indicate derivation of the Sr and Nd from a source with a time-integrated depletion in LIL elements. These closely resemble the epsilon values for Sr and Nd from the Cargill and Spanish River complexes, two other 1900 m.y. old plutons. The estimated Pb/Pb ratios from Borden calcites plot well below growth curves for average continental crust, a pattern similar to those found in MORB and most ocean-island volcanic rocks, again suggesting a source depleted in LIL. The combined data strongly favour a mantle origin for the Borden complex, with little or no crustal contamination, and support the hypothesis that many carbonatites intruded into the Canadian Shield were derived from an ancient, LIL-depleted subcontinental upper mantle.-P.Br.
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U2 - 10.1139/e87-003
DO - 10.1139/e87-003
M3 - Article
AN - SCOPUS:0023162978
VL - 24
SP - 24
EP - 30
JO - Canadian Journal of Earth Sciences
JF - Canadian Journal of Earth Sciences
SN - 0008-4077
IS - 1
ER -