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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 63 (1979)

Issue: 3. (March)

First Page: 514

Last Page: 514

Title: Depositional Sequence in Subarctic Sandy Beach Face, Central Labrador: ABSTRACT

Author(s): Gerald E. Reinson, Peter S. Rosen

Article Type: Meeting abstract

Abstract:

Beach-face deposits on the strand-plain coast near Michael River, Labrador, contain four distinct units. The basal unit 1 (60 cm thick) is a graded sequence of well-mixed sand and gravel near the bottom and medium-grained laminated sand at the top. It is disconformably overlain by unit 2 (20 cm thick) which consists of fine to medium-grained sand with contorted and disrupted laminations and small pods of loosely packed sand. Unit 3 (25 cm thick) is a chaotic gravel and sand sequence devoid of sedimentary structures, whereas the uppermost unit 4 (20 cm thick) consists of well-laminated, fine to medium-grained sand.

The stratigraphic sequence is interpreted as follows. Unit 1 represents the normal berm accretionary phase of late summer 1977, and unit 2, the foreshore accretionary phase during early winter. In early winter, the wetted beach surface begins to freeze and a deposit of interlaminated sand and ice forms under the continuous action of swash-backwash. This deposit is later deformed, owing to volume reduction and loading, during thawing. Small sediment-laden ice blocks, which are washed up and incorporated into the accreting laminated sequence, are represented by porous sand pods when the ice medium melts. Unit 3 is the remnant of ice-rafting and ice-push deposits which accumulated during ice breakup in spring 1978, whereas unit 4 records the normal foreshore swash-backwash accretionary p ase of early summer 1978. The fact that freeze and breakup events are recorded within a complete yearly cycle of beach-face accretion indicates that such events could be preserved in the rock record under rapidly aggrading summer-beach conditions similar to those at Michael River.

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