Isotopic mapping of age provinces in Precambrian high-grade terrains: Sri Lanka

Journal Article · Thu Sep 01 04:00:00 EDT 1988 · J. Geol.; (United States)

DOI:https://doi.org/10.1086/629256· OSTI ID:6765069

Milisenda, C C; Liew, T C; Hofmann, A W; Kroener, A

Nd model ages of amphibolite- and granulite-grade rocks in Sri Lanka form a simple region pattern that broadly correlates with mappable geological units, and is in effect an isotopic map of the island's basement. The granulite-grade units of the Highland Group and Southwest Group have model ages of 2.2-3.0 Ga indicating derivation mainly from late Archean sources. They are bounded to the east and west by late Proterozoic gneisses of the Vijayan Complex with model ages of 1.1-2.0 Ga. The isotopic data identify three distinct crustal provinces and are not consistent with earlier suggestions that the Vijayan gneisses are retrograde equivalents of the Highland granulites. Sri Lanka is not a direct continuation of the Archean Dharwar Craton of southern India. Identification of Vijayan-type juvenile crustal terrains in other Gondwana fragments may play a key role in determining the precise attachment of southern India-Sri Lanka in eastern Gondwana.

• Research Organization: Max-Planck Institut fuer Chemie, Mainz (West Germany)
• OSTI ID: 6765069
• Journal Information: J. Geol.; (United States), Journal Name: J. Geol.; (United States) Vol. 96:5; ISSN JGEOA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
AGE ESTIMATION
ASIA
BASEMENT ROCK
CONTINENTAL CRUST
DEVELOPING COUNTRIES
EARTH CRUST
ELEMENTS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GNEISSES
ISLANDS
ISOTOPE DATING
MAPPING
METALS
METAMORPHIC ROCKS
NEODYMIUM
PLATE TECTONICS
PRECAMBRIAN ERA
RARE EARTHS
ROCKS
SRI LANKA
TECTONICS