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Title: | Stratigraphy and Sedimentology of the Triassic at St. Martins and Lepreau, New Brunswick |
Authors: | Nadon, Gregory C. |
Advisor: | Middleton, G.V. |
Department: | Geology |
Publication Date: | Oct-1981 |
Abstract: | <p>Two small Triassic basins in southern New Brunswick were examined. The eastern basin, centered approximately 30 km east of Saint John, consists of three formations. The lower unit, renamed the Honeycomb Point Formation, resting unconformably on Carboniferous sediments, consists of redbeds and sandstones and was deposited on a semi-arid alluvial fan with flow predominently eastward. Some of the sands were reworked into small dune fields migrating to the southwest.</p> <p>The lower redbeds are unconformably overlain by the roundstone conglomerates and coarse-grained, gray-green, trough crossbedded sandstones of the Quaco Formation. These sediments were deposited by a large braided river which initially flowed northward but which was later deflected toward the northeast by the growth of alluvial fans.</p> <p>In the western end of the basin the Echo Cove Formation overlies the Quaco conglomerate. It can be divided into four members, all of which represent alluvial fan deposition. The members are partially time transgressive but are characterized by different facies, paleocurrent directions and climates.</p> <p>Pollen analysis of sandstones from the upper portion of the Fownes Head Member indicates a mid-Late Carnian age for the sediments.</p> <p>The Lepreau Formation outcrops along the coast approximately 70 km west of Saint John. It was subdivided into three members. The lower member consists of breccias (predominantly granite) which laterally interfinger with fine to medium grained massive sandstones deposited on a semi-arid alluvial fan. These are unconformably overlain by a complex series of conglomerates, medium and coarse-grained sandstones and red shales. This unit is gradationally overlain by breccias forming a thickening and coarsening upward sequence.</p> <p>Regional plate tectonic studies of the initial rifting of the Atlantic show graben formation controlled by four major transform fault systems. The postulated presence of a mantle hot spot along the Kelvin Fracture Zone and the associated doming of the region may have been in part responsible for the northward dipping paleoslope indicated by the Quaco Formation. Palynological studies of the Triassic basins on the continental United States and Eastern Canada show that while the grabens formed along more or less the same zone of structural weakness, they did so as two separate systems. Those in the United States began in South Carolina in the Mid to Late Carnian and gradually opened northwards. Those in Canada also began in the Mid to Late Carnian, however, because of structural weaknesses in the crust caused by the closing of the Proto-Atlantic, the basins opened toward the northeast.</p> |
Description: | Title: Stratigraphy and Sedimentology of the Triassic at St. Martins and Lepreau, New Brunswick, Author: Gregory C. Nadon, Location: Thode |
URI: | http://hdl.handle.net/11375/19807 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Nadon_Gregory_C_1981_10_master.pdf | Title: Stratigraphy and Sedimentology of the Triassic at St. Martins and Lepreau, New Brunswick, Author: Gregory C. Nadon, Location: Thode | 60.69 MB | Adobe PDF | View/Open |
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