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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 49 (1965)

Issue: 3. (March)

First Page: 359

Last Page: 359

Title: Locating the Source of Sands in Flysch Troughs: ABSTRACT

Author(s): Daniel J. Stanley

Article Type: Meeting abstract


Field characteristics of sand units are stressed in most flysch studies. Megascopic properties of lithology, stratification, and sedimentary structures are essential for interpretation of depositional environments and directions of sediment transport within mobile belts. Problems related to the source of sands, however, cannot be solved by field work alone.

In certain studies, two of the most important questions concerning source remain unanswered:

(a) What was the nature of the parent-rocks exposed in the source area?

(b) Where was the source area with respect to the site of flysch accumulation?

Petrographic examination of sands on a regional scale is required to help solve these fundamental problems. Heavy mineral studies are particularly useful in providing paleogeographic information. Heavy mineral assemblages display a lack of diversity (small number of mineral species) in almost all flysch formations where they have been examined. These assemblages are invariably mature to supermature (high percentages of resistant minerals). Sands containing assemblages of this type were probably derived from terrains already lacking a diversity of minerals. Thus, sands in many flysch troughs were largely derived from older clastic formations (re-sedimentation or "cannibalization" process) exposed within or adjacent to the mobile belt.

Furthermore, the distribution patterns of light and heavy mineral fractions vary laterally in these formations indicating the presence of local sediment sources along mobile belts. Petrography serves as a check on the relative importance of lateral versus longitudinal transportation of sands in flysch troughs.

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Copyright 1997 American Association of Petroleum Geologists