WOO, KYUNG SIK, Department of Geology, Kangweon National Univ., Chuncheon, Kangweondo, Korea; and CLYDE H. MOORE, Geology Department, Louisiana State Univ., Baton Rouge, LA

ABSTRACT: Carbonate Diagenetic Histories and Implications for Dolomite Recrystallization of the Mungok and Yonghung Formations, Yeongweol, Kangweondo, Korea

Carbonate diagenetic histories of the Mungok and Yonghung Formations were investigated using coordinated textural, isotopic and elemental data. The Mungok and Yonghung Formations are mostly composed of tidal flat deposits and show numerous cycles due to subsidence and eustatic sea-level change.

The Mungok and Yonghung Formations show different paragenetic sequences during relatively early diagenetic histories from shallow marine to shallow burial. The Mungok Formation is paragenetically characterized by radiaxial fibrous calcite cementation, framboidal pyritization, syntaxial overgrowth and equant calcite cementation, chertification, and idiotopic dolomitization in the matrix of flat pebble conglomerate, stromatolitic limestone, and chert. The Yonghung Formation is shown by penecontemporaneous dolomitization, syntaxial overgrowth and equant calcite cementation, chertification, and idiotopic dolomitization in burrows and chert.

In the intermediate to deep burial diagenetic environments, however, both formations show similar paragenetic sequences. Most of the xenotopic dolomite formed before stylolitization. Cementation and/or replacement byequant and prismatic calcite, saddle dolomite, and quartz in vein and pyritization terminated the diagenetic history.

Dolomite recrystallization can be observed texturally in the idiotopic dolomite found in the matrix of flat pebble conglomerate and stromatolite (cryptalgal laminite) by means of cathodoluminescence and back-scattered image of scanning electron microscope. Elemental data by electron microprobe show that the recrystallized part of the idiotopic dolomite are much higher in Fe than unrecrystallized part.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.