Age and petrogenesis of the Diana Complex, Adirondack Mountains, New York
- Miami Univ., Oxford, OH (United States). Dept. of Geology
- Univ. of Leeds (United Kingdom). Dept. of Earth Sciences
U-Pb zircon data show that the Diana Complex was emplaced 1152[plus minus]12 Ma ago along the Carthage-Colton Mylonite Zone (CCMZ), that marks the boundary between the Adirondack Highlands and the Lowlands. The tectonic setting of the Complex is uncertain because granitoid plutons of the same age were emplaced under syntectonic conditions in the Lowlands, while in the Highlands the same plutons have been viewed as anorogenic. Deformation focused on the CCMZ is reflected in whole-rock Rb-Sr isochron age of 1038[plus minus]97 Ma for the Complex. This resetting is typical of granitoid plutons within a 10 km-wide zone across the CCMZ, but is absent outside this zone elsewhere in the Lowlands. Although the chemical continuity of the Complex with Adirondack mafic rocks of the same presumed age demonstrates that crystal fractionation from a basic parent was a likely origin for the Complex, it is probable the magmas were modified by crustal assimilation. For example, the initial [sup 87]Sr/[sup 86]Sr[sub 1152] values for the Complex (0.7042[plus minus]3) are higher than the same ratios for Adirondack mafic rocks (0.7033[plus minus]6), and one zircon fraction lies to the right of the discordia defined by the other four analyzed fractions. The nature and age of the assimilant may be constrained by a metasedimentary xenolith with a whole-rock Rb-Sr isochron age of 1318[plus minus]15 Ma. Changes in TiO[sub 2] and P[sub 2]O[sub 5] abundances and La/Yb values indicate that the crystallization of both accessory (e.g., Fe-Ti oxides, apatite and zircon) and silicate phases were important in the fractionation of the Diana Complex syenites.
- OSTI ID:
- 5770124
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
Evidence for syntectonic intrusion of plutons in the Bear Mountains fault zone, California
Late proterozoic-early Paleozoic crust in the Hermitage flexure, Newfoundland Appalachians: U/Pb ages and tectonic significance
Related Subjects
580000* -- Geosciences
ACTINIDES
ADIRONDACK MOUNTAINS
AGE ESTIMATION
ALKALI METALS
ALKALINE EARTH METALS
APPALACHIAN MOUNTAINS
CHEMISTRY
CRYSTALLIZATION
DEVELOPED COUNTRIES
ELEMENTS
GEOCHEMISTRY
GEOLOGY
IGNEOUS ROCKS
ISOTOPE DATING
LEAD
METALS
MINERALOGY
MINERALS
MOUNTAINS
NEW YORK
NORTH AMERICA
PETROGENESIS
PETROLOGY
PHASE TRANSFORMATIONS
PLUTONIC ROCKS
ROCKS
RUBIDIUM
SILICATE MINERALS
STRONTIUM
TECTONICS
URANIUM
USA
ZIRCON