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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 52 (1968)

Issue: 3. (March)

First Page: 527

Last Page: 527

Title: Operational Classification of Previous HitUnconformitiesNext Hit: ABSTRACT

Author(s): Tom Freeman

Article Type: Meeting abstract


Differences in Previous HitunconformitiesNext Hit suggested by earlier classifications are more fancied than real. The criteria of scale, either areal or temporal, and concordance-discordance do not serve as practical bases for classification. Moreover, the aim of a nomenclature should be to answer the question which is, in the case of Previous HitunconformitiesNext Hit, "what is the evidence?", not "what is the kind?"

Examples demonstrate that evidences for Previous HitunconformitiesNext Hit are: (1) truncation of allochems and stylolites; (2) occurrence of encrusting organisms; (3) cement-supported detritus; (4) cement discontinuities; (5) megascopic erosional relief and bed truncation; and (6) truncation of faults and lithostratigraphic and biostratigraphic units on maps and cross sections.

These evidences fall into the following operational categories: I--petrographic; II--macrographic; and IIIa--lithocartographic and IIIb--biocartographic Previous HitunconformitiesTop.

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