About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 68 (1984)

Issue: 4. (April)

First Page: 508

Last Page: 508

Title: Sedimentation on an Early Proterozoic Continental Margin: Gowganda Formation (Huronian), Elliot Lake Area, Ontario, Canada: ABSTRACT

Author(s): Andrew D. Miall

Abstract:

Eight continuous cores up to 150 m (500 ft) long and spaced an average of 200 m (650 ft) apart plus nearby outcrops, yield a detailed insight into the composition and architecture of an ancient continental-margin sequence.

Continental glaciers provided an abundant supply of coarse debris but, apart from rainout deposits from floating ice, played little or no part in Gowganda sedimentation. The basal 50 m (165 ft) of the Gowganda Formation represents a continental-slope depositional system. It consists mainly of gravelly and sandy sediment gravity flow deposits, interbedded with minor rain-out units of diamictite, and argillite containing dropstones. Ten types of sediment gravity flow are distinguished. An overlying submarine-channel depositional system, 10-50 m (30-165 ft) thick, consists of pelagic argillites containing dropstones and showing deformation structures. These are interbedded with well-sorted channel-fill sandstones. A submarine point bar 4.5 m (15 ft) thick demonstrates a meandering channe geometry. This channel-fill sequence probably formed during a period of high sea level and reduced sediment supply, possibly reflecting retreat of the ice. The subsurface sequence is completed by a blanket of massive rain-out diamictites up to 55 m (180 ft) thick, and a younger slope sequence of sediment gravity flow diamictites and sandstones.

The complex architecture of this formation reflects the interplay of numerous depositional and erosional processes that are now known to occur on continental margins. The traditional submarine-fan models may have no relevance to this type of continental margin, with its numerous sediment sources and frequent changes in sea level.

End_of_Article - Last_Page 508------------

Copyright 1997 American Association of Petroleum Geologists