Compilation of Sm-Nd isotope analyses of igneous suites, western Churchill Province

Over 50 new Nd isotope analyses are presented for high-grade orthogneisses from Algonquin Park and surrounding region to map major Grenvillian thrust boundaries. Nd model ages display a consistent geographical pattern that allows detailed mapping of the boundary between the Algonquin and Muskoka domains, here interpreted as the local trajectory of the Ottawan-age Allochthon Boundary Thrust (ABT). The ABT is underlain by a domain with Paleoproterozoic Nd model ages, interpreted as a tectonic duplex entrained onto the base of the main allochthon. The boundaries determined using Nd isotope mapping are consistent with field mapping and with remotely sensed aeromagnetic and digital elevation data. The precise location of the ABT can be observed in a road-cut on Highway 60, on the north shore of Lake of Two Rivers in the centre of Algonquin Park.

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An application of Nd isotope mapping in structural geology: delineating an allochthonous Grenvillian terrane at North Bay, Ontario

Geological Magazine ◽

10.1017/s0016756803008070 ◽

2003 ◽

Vol 140 (5) ◽

pp. 539-548 ◽

Cited By ~ 15

Author(s):

A. P. DICKIN ◽

R. H. MCNUTT

Keyword(s):

Structural Geology ◽

Amphibolite Facies ◽

High Grade ◽

Grenville Province ◽

Nd Isotope ◽

Bay Area ◽

The North ◽

Depleted Mantle ◽

Different Types ◽

Isotope Analyses

Fifty new Nd isotope analyses are presented from the North Bay area of the Grenville Province in Ontario. These data are used to map the extent of an allochthonous Grenvillian terrane which is an outlier of the Allochthonous Polycyclic Belt of the Grenville Province. Amphibolite facies orthogneisses from the allochthonous terrane have depleted mantle Nd model ages (TDM) below 1.8 Ga, whereas the gneisses of the structurally underlying parautochthon almost invariably have model ages above 1.8 Ga. The distribution of model ages is consistent with the distribution of distinct types of metabasic rock, used by other researchers as the criterion for recognizing rocks of the allochthonous and parautochthonous belts of the Grenville Province. The agreement between these different types of evidence demonstrates that Nd isotope mapping is a reliable and powerful tool for mapping terrane boundaries in high-grade metamorphic belts.

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Fractionation and mixing in a thermal ionization mass spectrometer source: Implications and limitations for high-precision Nd isotope analyses

International Journal of Mass Spectrometry ◽

10.1016/j.ijms.2009.04.004 ◽

2009 ◽

Vol 285 (1-2) ◽

pp. 49-57 ◽

Cited By ~ 37

Author(s):

Rasmus Andreasen ◽

Mukul Sharma

Keyword(s):

High Precision ◽

Mass Spectrometer ◽

Thermal Ionization ◽

Ionization Mass ◽

Nd Isotope ◽

Thermal Ionization Mass Spectrometer ◽

Thermal Ionization Mass ◽

Isotope Analyses

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In situ Nd isotope analyses in geological materials with signal enhancement and non-linear mass dependent fractionation reduction using laser ablation MC-ICP-MS

Journal of Analytical Atomic Spectrometry ◽

10.1039/c4ja00243a ◽

2015 ◽

Vol 30 (1) ◽

pp. 232-244 ◽

Cited By ~ 29

Author(s):

Lei Xu ◽

Zhaochu Hu ◽

Wen Zhang ◽

Lu Yang ◽

Yongsheng Liu ◽

...

Keyword(s):

Laser Ablation ◽

High Efficiency ◽

Linear Mass ◽

Nd Isotope ◽

Bias Stability ◽

Icp Ms ◽

Non Linear ◽

Mass Dependent ◽

Mass Dependent Fractionation ◽

Isotope Analyses

Combining high-efficiency cones with the addition of nitrogen in laser ablation MC-ICP-MS not only enhances the sensitivity and mass bias stability, but also suppresses the non-linear mass fractionation for Nd isotope analyses.

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Use of 1012 ohm current amplifiers in Sr and Nd isotope analyses by TIMS for application to sub-nanogram samples

Journal of Analytical Atomic Spectrometry ◽

10.1039/c3ja30326h ◽

2013 ◽

Vol 28 (5) ◽

pp. 749 ◽

Cited By ~ 47

Author(s):

J. M. Koornneef ◽

C. Bouman ◽

J. B. Schwieters ◽

G. R. Davies

Keyword(s):

Nd Isotope ◽

Isotope Analyses

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Crustal formation in the Grenville Province: Nd-isotope evidence

Canadian Journal of Earth Sciences ◽

10.1139/e99-039 ◽

2000 ◽

Vol 37 (2-3) ◽

pp. 165-181 ◽

Cited By ~ 82

Author(s):

A P Dickin

Keyword(s):

North America ◽

Grenville Province ◽

Nd Isotope ◽

Precambrian Shield ◽

First Order ◽

Isotope Evidence ◽

Isotope Analyses

Ninety-eight new Nd-isotope analyses are presented for gneissic rocks from the Grenville Province. When combined with over 250 published Nd analyses and some unpublished analyses, these data can be used to establish a first-order crustal formation age map for most of the Grenville parautochthon and allochthonous polycyclic belt. In particular, the geographic extents of a juvenile Labradorian arc (Labradoria) and a juvenile 1.5 Ga arc (Quebecia) are defined, each with an area probably in excess of 100 000 km2. In addition, pre-1.75 Ga arcs are identified in Ontario (Barilia) and Labrador (Makkovikia). This work largely fills the last major gap in the continent-wide crustal formation age map of the Precambrian Shield of North America.

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Routine high-precision Nd isotope analyses: an optimized chromatographic purification scheme

Journal of Analytical Atomic Spectrometry ◽

10.1039/d1ja00169h ◽

2021 ◽

Author(s):

Eugenia Hyung ◽

François L. H. Tissot

Keyword(s):

High Precision ◽

Column Chromatography ◽

Chromatographic Purification ◽

Good Separation ◽

Chromatography Method ◽

Nd Isotope ◽

Purification Scheme ◽

High Yields ◽

Isotope Analyses

We present an optimized α-HIBA column chromatography method for Nd for high-precision isotope analyses (±2–5 ppm). It produces consistently high yields (>95%) and extremely good separation of Ce, Pr and Sm from Nd.

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Evidence of crustal contamination of mafic rocks associated with rapakivi rocks: an example from the Nordingrå complex, Central Sweden

Geological Magazine ◽

10.1017/s0016756801005672 ◽

2001 ◽

Vol 138 (4) ◽

pp. 371-386 ◽

Cited By ~ 10

Author(s):

ANDERS LINDH ◽

ULF BERTIL ANDERSSON ◽

THOMAS LUNDQVIST ◽

STEFAN CLAESSON

Keyword(s):

Trace Element ◽

Crustal Contamination ◽

Incompatible Trace Element ◽

Primitive Mantle ◽

Nd Isotope ◽

East Central ◽

Enriched Mantle ◽

Depleted Mantle ◽

Two Parameters ◽

Isotope Analyses

Gabbro and leucogabbro are volumetrically important rocks in the Nordingrå rapakivi complex, East Central Sweden. Plagioclase, ortho- and clinopyroxenes, and olivine dominate the gabbro. Perthitic orthoclase and quartz are interstitial in relation to the major minerals. The present work is based on 232 major-element and a large number of trace element analyses together with 15 whole rock Sm–Nd isotope analyses of the Nordingrå gabbroic rocks. εNd(T) values are negative, −1.1 to −3.2; the most negative values come from the gabbro. Most rocks are enriched in iron, some extremely enriched; none represent primitive mantle melts. The range of Mg-numbers is the same in the gabbro and the leucogabbro. Plots of the Ni-content vs. the Mg-number are scattered, but there is a positive correlation between these two parameters. The primary mantle-normalized ratios between similar trace elements are normally strongly different from one. Values larger as well as smaller than one are found for the same ratio in different rocks. The rare earth elements are only weakly fractionated with small Eu anomalies, negative for the gabbros and positive for the leucogabbros. The primary magma of the Nordingrå gabbro-anorthosite is thought to have been derived from a mildly depleted mantle source. Variations in the degree of partial melting of a reasonably homogeneous enriched mantle do not explain the observed chemical evolution. Crystal differentiation can account for some geochemical features, especially the Fe-enrichment. Crustal contamination is required by other characteristics as, for example, the negative εNd(T) values and the irregular and sometimes high primary-mantle normalized incompatible trace-element ratios. Al-rich relic material from the formation of the rapakivi granite melt is another source of assimilation. Most probably contaminants are heterogeneous, including undepleted crust (represented, for example, by early Svecofennian and Archaean granitoids), depleted crust (restitic after rapakivi magma extraction), and to some degree the associated rapakivi magma itself. Significant parts of this crust should be Archaean in age.

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