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U‐Pb dating of a remagnetized Paleozoic limestone
Author(s) -
DeWolf Charles P.,
Halliday Alex N.
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/91gl01278
Subject(s) - paleozoic , geology , calcite , ordovician , diagenesis , carbonate , paleomagnetism , carboniferous , deposition (geology) , carbonate rock , geochemistry , paleontology , mineralogy , sedimentary rock , sediment , structural basin , materials science , metallurgy
The Upper Ordovician Trenton Group of New York State is one of a number of Appalachian limestones which yields paleomagnetic poles suggesting disturbance in the late Paleozoic. Calcite fractions dissolved from samples of the Trenton Limestone define a 238 U‐ 206 Pb age of 454±8 Ma (MSWD=12.8) in excellent agreement with 40 Ar− 39 Ar and U‐Pb ages for the deposition of the underlying Diecke Bentonite. This requires that the U‐Pb system in the calcite has been preserved since deposition and early diagenesis. If late Paleozoic remagnetization of this limestone was induced by fluids, these fluids did not interact with significant amounts of carbonate. The apparent robustness of the U‐Pb system, and the large spread in µ values (18.17–118.8), offers potential precision of ±1 Ma in determining the Paleozoic time scale.