Implications for the evolution of continental crust from Hf isotope systematics of detrital zircons in Archean sandstones
Thesis/Dissertation
·
OSTI ID:5369895
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
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ATLANTIC OCEAN
CANADA
CHEMICAL COMPOSITION
CHEMISTRY
COMPARATIVE EVALUATIONS
CONTINENTAL CRUST
DEVELOPED COUNTRIES
EARTH CRUST
EVALUATION
FEDERAL REGION VIII
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC MODELS
HAFNIUM ISOTOPES
ISLANDS
ISOTOPE DATING
ISOTOPE RATIO
ISOTOPES
MICHIGAN
MINERALS
MONTANA
NEWFOUNDLAND
NORTH AMERICA
ORIGIN
PRECAMBRIAN ERA
ROCKS
SANDSTONES
SEAS
SEDIMENTARY ROCKS
SEDIMENTS
SILICATE MINERALS
SURFACE WATERS
USA
WYOMING
ZIRCON
580000* -- Geosciences
AGE ESTIMATION
ATLANTIC OCEAN
CANADA
CHEMICAL COMPOSITION
CHEMISTRY
COMPARATIVE EVALUATIONS
CONTINENTAL CRUST
DEVELOPED COUNTRIES
EARTH CRUST
EVALUATION
FEDERAL REGION VIII
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC MODELS
HAFNIUM ISOTOPES
ISLANDS
ISOTOPE DATING
ISOTOPE RATIO
ISOTOPES
MICHIGAN
MINERALS
MONTANA
NEWFOUNDLAND
NORTH AMERICA
ORIGIN
PRECAMBRIAN ERA
ROCKS
SANDSTONES
SEAS
SEDIMENTARY ROCKS
SEDIMENTS
SILICATE MINERALS
SURFACE WATERS
USA
WYOMING
ZIRCON