Implications for the evolution of continental crust from Hf isotope systematics of detrital zircons in Archean sandstones

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5369895

Stevenson, R K

The fractionation of zircons by sedimentary processes into continental margin sandstone deposits results in a biased preservation of pre-existing continental crust in the form of zircon in those sequences. This provides a unique opportunity to distinguish between the contrasting theories of episodic growth versus constant volume of continental crust over geologic time through Hf isotope ratios of detrital zircons. {sup 176}Hf/{sup 177}Hf ratios were determined for detrital zircon fractions from 2.6-3.0 Ga old sedimentary sequences from the Canadian Shield, North Atlantic, Wyoming, and Kaapvaal Cratons. The data strongly suggest inheritance of pre-3.0 Ga zircons only in areas where pre-3.0 Ga old crust exists today, and imply that the quantity of continental crust prior to 3.0 Ga ago was not much greater in extent than the pre-3.0 Ga crust exposed today. Small amounts of continental crust prior to 3.0 Ga ago and rapid addition of continental crust between 2.5 and 3.0 Ga ago are consistent with the episodic growth theory of crustal evolution.

• Research Organization: Arizona Univ., Tucson, AZ (United States)
• OSTI ID: 5369895
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL CRUST
GEOLOGIC MODELS
ORIGIN
ZIRCON
GEOCHEMISTRY
ISOTOPE DATING
ATLANTIC OCEAN
CHEMICAL COMPOSITION
COMPARATIVE EVALUATIONS
HAFNIUM ISOTOPES
ISOTOPE RATIO
MICHIGAN
MONTANA
NEWFOUNDLAND
PRECAMBRIAN ERA
SANDSTONES
SEDIMENTS
WYOMING
AGE ESTIMATION
CANADA
CHEMISTRY
DEVELOPED COUNTRIES
EARTH CRUST
EVALUATION
FEDERAL REGION VIII
GEOLOGIC AGES
ISLANDS
ISOTOPES
MINERALS
NORTH AMERICA
ROCKS
SEAS
SEDIMENTARY ROCKS
SILICATE MINERALS
SURFACE WATERS
USA
580000* - Geosciences