Pyrolysis of organic matter in the Nabae subbelt, Shimanto accretionary complex, southwest Japan
Published:January 01, 1993
J. P. Hibbard, D. K. Larue, 1993. "Pyrolysis of organic matter in the Nabae subbelt, Shimanto accretionary complex, southwest Japan", Thermal Evolution of the Tertiary Shimanto Belt, Southwest Japan: An Example of Ridge-Trench Interaction, Michael B. underwood
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A Rock-Eval pyrolysis study of the Nabae subbelt, the Oligocene-Miocene portion of the Cretaceous to Miocene Shimanto accretionary complex on Shikoku Island, southwest Japan, has yielded ambiguous data concerning the character of the organic component of rocks in the subbelt. The poor data are attributed to the high level of organic maturity in the subbelt. This high organic maturity has been interpreted to be the result of an episode of spreading ridge subduction in the local area. Total organic carbon (TOC) ranges from less than 1 to 30%; average TOC in all stratigraphic units is >0.5%, suggesting that the Nabae subbelt may have been a good hydrocarbon source prior to the thermal disturbance. Several organic-rich samples, some with high hydrogen index values, in spite of high thermal maturation, may indicate local preservation of type II organic matter.