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Application of Sr and O isotope relations to the petrogenesis of the alkaline rocks of the Red Hill complex, New Hampshire, USA

Contributions to Mineralogy and Petrology

By:
and
DOI: 10.1007/BF00371061

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Abstract

The Red Hill ring complex in central New Hampshire is composed of apparently cogenetic syenites, nepheline-sodalite syenite, and granite. The ages and petrogenetic relations among five of the six recognized units have been investigated by rubidiumstrontium and oxygen isotope analysis of whole rocks and separated minerals. Whole-rock samples from three syenite units are consistent with a single Rb-Sr isochron which gives an age of 198??3 m.y. and an initial (87Sr/86Sr)o ratio of 0.70330??0.00016 (??2 sigma; ??=1.42?? 10-11y-1). However, Sr isotope data for two other units, nepheline syenite and granite, are not consistent with this isochron but rather indicate higher initial ratios which range from 0.7033 to about 0.707. Whole-rock O isotope analyses give ??18O values which range from+6.2 to+9.3??? Sr and O isotope analyses on mineral separates indicate that observed whole-rock variations in (87Sr/86Sr)o are primary and are not due to any secondary process. The fact that the isotope systematics correlate with rock type, suggests that crustal interaction is likely to have played a significant role in the development of this over-and undersaturated association. Such process(es), while still not fully delineated, could be of fundamental importance to the genesis of associations of critically undersaturated and oversaturated intrusives. The data support the idea that interaction between magmas and crustal materials strongly influenced the compositional relations of similar complexes elsewhere including those of the White Mountain magma series. ?? 1977 Springer-Verlag.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Application of Sr and O isotope relations to the petrogenesis of the alkaline rocks of the Red Hill complex, New Hampshire, USA
Series title:
Contributions to Mineralogy and Petrology
DOI:
10.1007/BF00371061
Volume
65
Issue:
2
Year Published:
1977
Language:
English
Publisher:
Springer-Verlag
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Contributions to Mineralogy and Petrology
First page:
213
Last page:
225