Juvenile Middle Proterozoic crust in the Adirondack Highlands, Grenville province, northeastern North America

Journal Article · Fri Feb 01 00:00:00 EST 1991 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1991)019<0119:JMPCIT>2.3.CO;2· OSTI ID:5679698

Daly, J S ^[1]; McLelland, J M ^[2]

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1. University College Dublin (Ireland)
2. Colgate Univ., Hamilton, NY (USA)

Nd isotope data indicate that minimal amounts of significantly older crust have contributed to the genesis of the oldest (ca. 1.3-13.5 Ga) plutons in the Adirondack Highlands. These are magmatic arc tonalites with positive initial {epsilon}{sub Nd} values and Sm-Nd depleted mantle model ages (t{sub DM}) that are within 70 m.y. of the time of their crystallization. Granitoids of the anorthosite-mangerite-charnockite-granite suite, dated at 1,156-1,134 Ma, as well as the 1,100-1,050 Ma plutons, associated with the Ottawan phase of the Grenvillian orogenic cycle, also have positive initial {epsilon}{sub Nd} values and t{sub DM} ages similar to the tonalites. Derivation of both groups of granitoids by crustal melting of the magmatic arc is consistent with the available isotopic and geochemical data. Juvenile late Middle Proterozoic crust that formed during or just prior to the Grenville cycle appears to dominate the southwestern Grenville province as well as the Grenville inliers to the south. In contrast, most of the contiguous Grenville province in Canada comprises largely reworked older crust.

• OSTI ID: 5679698
• Journal Information: Geology; (USA), Vol. 19:2; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC FORMATIONS
AGE ESTIMATION
GEOCHEMISTRY
NORTH AMERICA
CANADA
CONTINENTAL CRUST
CRYSTALLIZATION
GEOLOGY
ISOTOPE DATING
ISOTOPE RATIO
MOUNTAINS
NEODYMIUM ISOTOPES
OROGENESIS
PLUTONIC ROCKS
PRECAMBRIAN ERA
SAMARIUM ISOTOPES
USA
CHEMISTRY
EARTH CRUST
GEOLOGIC AGES
IGNEOUS ROCKS
ISOTOPES
PHASE TRANSFORMATIONS
RARE EARTH ISOTOPES
ROCKS
580000* - Geosciences