Geological setting and genesis of the Eastern Avalon high alumina belt

Hayes, John P. (1996) Geological setting and genesis of the Eastern Avalon high alumina belt. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (11MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The eastern Avalon High-alumina belt is an alteration system of Precambrian age, hosted by the Johnnies Pond formation. The Johnnies Pond formation is a newly recognized unit and is separated from the Harbour Main group which was previously thought to be the only major volcanic unit on the eastern Avalon Peninsula. Detailed mapping demonstrates the presence of a major regional unconformity between the Conception Group and the Johnnies Pond formation. The remaining volcanic rocks in the Harbour Main group conformably underlie the Conception Group. The Holyrood Granite is pre-Conception in age and clearly intrudes both the Johnnies Pond Formation and foliated hornblende diorite of the Foxtrap diorite, which is interpreted to be the oldest unit on the Avalon Peninsula on the basis of structural relationships. -- The eastern Avalon High-alumina belt is marked by the development of silicification, sericitization and pyrophyllitization within the rhyolitic ash-flow tuffs of the Johnnies Pond Formation. The earliest alteration in the zone involved silicification, presumably proximal to pyrophyllitization at depth, subsequently overprinted by fracture hosted sericite and pyrophyllite. Early silicification is accompanied by pyritization which locally contains anomalous gold. The alteration system and the redistribution of rock components were likely controlled by dissolution mechanisms and kinetically inhibited precipitation of less soluble hydrous aluminosilicates producing amorphous reaction products which subsequently recrystallize to pyrophyllite.

Actions (login required)

View Item