Nd and Sr isotopic characterization of the Wrangellia terrane and implications for crustal growth of the Canadian cordillera
- Univ. of Arizona, Tucson (USA)
- Geological Survey of Canada, Vancouver, British Columbia (Canada)
Nd and Sr isotopic data are reported from samples of most of the major lithologic units of the Wrangellia terrane exposed on Vancouver Island and the Queen Charlotte Islands. Initial {epsilon}{sub Nd} values range from +1.0 to +7.3 and initial {sup 87}Sr/{sup 86}Sr ratios range from 0.70323 to 0.70481. These ratios are similar to those of modern island arcs and demonstrate the unevolved, juvenile nature of this terrane. These data indicate that Wrangellia probably resided in an intra-oceanic environment until its accretion to North America. Nd crustal residence ages for clastic sedimentary rocks of Wrangellia (mean T{sub CR} = 0.77 {plus minus} 0.33 Ga, T{sub DM} = 0.57 {plus minus} 0.35 Ga) are much closer to their stratigraphic ages than is the case for the ages of many other Phanerozoic sedimentary rocks, thus providing strong evidence for Phanerozoic crustal addition to North America. Early Proterozoic crustal components cannot comprise more than about 6% of Wrangellia; therefore the terrane consists of {approximately}94% new, mantle-derived crust. The amount of new crust in Wrangellia is very similar to the amount determined for two other large Cordilleran terranes, Alexander and Stikine. The accretion of juvenile terranes to a continent appears to be an important mechanism of crustal growth.
- OSTI ID:
- 6285928
- Journal Information:
- Journal of Geology; (USA), Journal Name: Journal of Geology; (USA) Vol. 98:5; ISSN JGEOA; ISSN 0022-1376
- Country of Publication:
- United States
- Language:
- English
Similar Records
Kilbuck terrane: Oldest known rocks in Alaska
Calcareous nannofossil biostratigraphy of Chititu Formation, Wrangellia terrane, Alaska
Related Subjects
580000* -- Geosciences
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
BETA DECAY RADIOISOTOPES
CANADA
CONTINENTAL CRUST
EARTH CRUST
ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
ISLANDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPE DATING
ISOTOPE RATIO
ISOTOPES
NEODYMIUM ISOTOPES
NORTH AMERICA
NUCLEI
OCEANIC CRUST
OROGENESIS
RADIOISOTOPES
ROCKS
SEDIMENTARY ROCKS
STABLE ISOTOPES
STRONTIUM 86
STRONTIUM 87
STRONTIUM ISOTOPES