Crust Formation and Plate Motion in the Early Archean
Mounting evidence for voluminous continental crust formation in the early Archean involving intracrustal melting and selective preservation of granitoid rocks suggests that initial crust formation and growth were predominantly by magmatic underplating in plumegenerated Iceland-type settings. Collisi...
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American Association for the Advancement of Science (AAAS)
1992
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craaas:10.1126/science.256.5062.1405 2024-09-15T18:04:08+00:00 Crust Formation and Plate Motion in the Early Archean Kröner, A. Layer, P. W. 1992 http://dx.doi.org/10.1126/science.256.5062.1405 https://www.science.org/doi/pdf/10.1126/science.256.5062.1405 en eng American Association for the Advancement of Science (AAAS) Science volume 256, issue 5062, page 1405-1411 ISSN 0036-8075 1095-9203 journal-article 1992 craaas https://doi.org/10.1126/science.256.5062.1405 2024-07-25T04:00:51Z Mounting evidence for voluminous continental crust formation in the early Archean involving intracrustal melting and selective preservation of granitoid rocks suggests that initial crust formation and growth were predominantly by magmatic underplating in plumegenerated Iceland-type settings. Collision of these early islands to give rise to larger blocks is suggested by extensive horizontal shortening in both supracrustal and granitoid assemblages. Preservation of early Archean high-grade gneisses that were once at depths of 20 to 30 kilometers implies that these blocks developed thick, subcrustal roots despite high mantle heat flow. Rigid continental plates must have existed since at least 3.5 billion years ago, and greenstone belts (composed of mixed metavolcanic and metasedimentary sequences intruded by granitoid plutons) probably developed on or near these microcontinents. Paleomagnetic data with good age control from at least one ancient craton suggest that plate motion was at normal minimum average velocities of about 17 millimeters per year with respect to the poles during the period 3.5 billion to 2.4 billion years ago. If this is true on a global scale, Archean plate motion was not faster than in later geologic times. Article in Journal/Newspaper Early Islands Iceland AAAS Resource Center (American Association for the Advancement of Science) Science 256 5062 1405 1411 |
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Open Polar |
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AAAS Resource Center (American Association for the Advancement of Science) |
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craaas |
language |
English |
description |
Mounting evidence for voluminous continental crust formation in the early Archean involving intracrustal melting and selective preservation of granitoid rocks suggests that initial crust formation and growth were predominantly by magmatic underplating in plumegenerated Iceland-type settings. Collision of these early islands to give rise to larger blocks is suggested by extensive horizontal shortening in both supracrustal and granitoid assemblages. Preservation of early Archean high-grade gneisses that were once at depths of 20 to 30 kilometers implies that these blocks developed thick, subcrustal roots despite high mantle heat flow. Rigid continental plates must have existed since at least 3.5 billion years ago, and greenstone belts (composed of mixed metavolcanic and metasedimentary sequences intruded by granitoid plutons) probably developed on or near these microcontinents. Paleomagnetic data with good age control from at least one ancient craton suggest that plate motion was at normal minimum average velocities of about 17 millimeters per year with respect to the poles during the period 3.5 billion to 2.4 billion years ago. If this is true on a global scale, Archean plate motion was not faster than in later geologic times. |
format |
Article in Journal/Newspaper |
author |
Kröner, A. Layer, P. W. |
spellingShingle |
Kröner, A. Layer, P. W. Crust Formation and Plate Motion in the Early Archean |
author_facet |
Kröner, A. Layer, P. W. |
author_sort |
Kröner, A. |
title |
Crust Formation and Plate Motion in the Early Archean |
title_short |
Crust Formation and Plate Motion in the Early Archean |
title_full |
Crust Formation and Plate Motion in the Early Archean |
title_fullStr |
Crust Formation and Plate Motion in the Early Archean |
title_full_unstemmed |
Crust Formation and Plate Motion in the Early Archean |
title_sort |
crust formation and plate motion in the early archean |
publisher |
American Association for the Advancement of Science (AAAS) |
publishDate |
1992 |
url |
http://dx.doi.org/10.1126/science.256.5062.1405 https://www.science.org/doi/pdf/10.1126/science.256.5062.1405 |
genre |
Early Islands Iceland |
genre_facet |
Early Islands Iceland |
op_source |
Science volume 256, issue 5062, page 1405-1411 ISSN 0036-8075 1095-9203 |
op_doi |
https://doi.org/10.1126/science.256.5062.1405 |
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Science |
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256 |
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5062 |
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1405 |
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1411 |
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1810441631425363968 |