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Absolute ages of mu...
Absolute ages of multiple generations of brittle structures by U-Pb dating of calcite
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- Hansman, Reuben J. (author)
- Stockholms universitet,Institutionen för geologiska vetenskaper
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Albert, Richard (author)
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Gerdes, Axel (author)
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- Ring, Uwe (author)
- Stockholms universitet,Institutionen för geologiska vetenskaper
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(creator_code:org_t)
- 2018
- 2018
- English.
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In: Geology. - 0091-7613 .- 1943-2682. ; 46:3, s. 207-210
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Subject headings
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- Direct dating of brittle structures is challenging, especially absolute dating of diagenesis followed by a series of superimposed brittle deformation events. We report 22 calcite U-Pb ages from tectonites and carbonate host rocks that date 3 diagenetic and 6 brittle deformation events. Results show that U-Pb dating of calcite fibers from these structures is compatible with overprinting relationships. Ages indicate that diagenesis occurred between 147 +/- 6 Ma and 103 +/- 34 Ma, and was followed by top-to-the-south, layer-parallel shearing due to ophiolite obduction at 84 +/- 5 Ma (2 sigma errors). Sheared top-to-the- northeast, layer-parallel veins were dated as 64 +/- 4 Ma and are interpreted to have developed during postobduction exhumation. After this event, a series of strike-slip structures, which crosscut and reactivated older faults due to northwest-southeast horizontal shortening, were dated as 55 +/- 22 Ma and 43 +/- 6 Ma. Eight ages from strike-slip faults and thrusts resulting from northeast-southwest shortening range from 40.6 +/- 0.5 Ma to 16.1 +/- 0.2 Ma. The youngest ages are from minor overprinting fibers ranging in age between 7.5 +/- 0.9 Ma and 1.6 +/- 0.6 Ma. Our results show that U-Pb dating of calcite fibers can be successfully used to constrain a complicated succession of brittle deformation structures that encompasses two orogenies and an intervening extension period.
Subject headings
- NATURVETENSKAP -- Geovetenskap och miljövetenskap (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences (hsv//eng)
Keyword
- Geology
- geologi
Publication and Content Type
- ref (subject category)
- art (subject category)
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