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The early thermal history of the earth

Hanks, Thomas C. and Anderson, Don L. (1969) The early thermal history of the earth. Physics of the Earth and Planetary Interiors, 2 (1). pp. 19-29. ISSN 0031-9201. https://resolver.caltech.edu/CaltechAUTHORS:20140513-133736138

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Abstract

The early thermal history of the Earth is reconsidered with the constraint that core formation occur before the emplacement of the oldest known rock possessing remanent magnetism. The thermal consequences of core formation are such that it must antedate the oldest known surface rock. Arbitrary accretion models are constructed and radioactive abundances are assumed to effect this condition. For all cases, the Earth must accrete in a period of 500 000 years or less (4.5 billion years ago) to fulfill this constraint. Partial melting of silicates upon accretion is implied; core formation and large-scale differentiation of the Earth at that time are a distinct possibility. Several lines of evidence invalidate the chondritic abundances and the terrestrial abundances, calibrated on the basis of present-day heat flow values, as applicable to a homogeneous Earth. These values of U, Th, and K are probably too high. Thermal history models using recent determinations of U, Th, and K from oceanic lherzolites and evidence from continental heat flow imply that the Earth accreted in 200 000 years or less and that large-scale differentiation of the Earth upon accretion seems most likely. The above conclusion vindicates the hot origin hypothesis. One consequence is early enrichment of the radioactive elements in the outer regions of the Earth. The temperatures in the deep interior of the Earth reflect residual accretional energy, including that of core formation, and are not primarily a result of radioactive heating. A Mars model, with the same accretion rate and composition as the Earth model, is colder and undifferentiated due to its smaller mass. Venus is considered to have overall composition and gross thermal history similar to the Earth's.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://www.sciencedirect.com/science/article/pii/0031920169900156PublisherArticle
http://dx.doi.org/10.1016/0031-9201(69)90015-6DOIArticle
Additional Information:© 1969 North-Holland Publishing Company. Received 20 August 1968. Revised 5 December 1968. Contribution 1561, Division of Geological Sciences, California Institute of Technology, Pasadena, California. The calculations were effected on a thermal history program, modified for the results presented here, originally written by R. A. Phinney of Princeton University. The research was supported by the National Space and Aeronautics Administration grant number NGL 05-002-069.
Funders:
Funding AgencyGrant Number
NASANGL 05-002-069
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Other Numbering System NameOther Numbering System ID
Caltech Division of Geological Sciences1561
Issue or Number:1
Record Number:CaltechAUTHORS:20140513-133736138
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140513-133736138
Official Citation:Thomas C. Hanks, Don L. Anderson, The early thermal history of the earth, Physics of the Earth and Planetary Interiors, Volume 2, Issue 1, April 1969, Pages 19-29, ISSN 0031-9201, http://dx.doi.org/10.1016/0031-9201(69)90015-6. (http://www.sciencedirect.com/science/article/pii/0031920169900156)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45726
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:13 May 2014 21:10
Last Modified:03 Oct 2019 06:35

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