Publication Type:

Journal Article

Authors:

Long, D. G. F.

Source:

Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, National Research Council of Canada, Ottawa, ON, Canada, Volume 44, Number 3, p.413-431 (2007)

ISBN:

0008-4077

Keywords:

Anticosti Island, Ashgillian, basins, bioclastic sedimentation, Canada, carbonate rocks, clastic rocks, climate forcing, cycles, depositional environment, eastern canada, Ellis Bay Formation, field studies, foreland basins, Hirnantian, hummocky cross-stratification, limestone, lithostratigraphy, Llandovery, loading, Lower Silurian, marine environment, Merrimack Group, micrite, orbital forcing, Ordovician, paleogeography, Paleozoic, planar bedding structures, quebec, Rhuddanian, sea-level changes, Sedimentary rocks, sedimentary structures, sedimentation, shelf environment, Silurian, storm environment, structural controls, subsidence, tempestite, thrust sheets, tropical environment, Upper Ordovician

Abstract:

Following partial closure of the northern Iapetus Ocean along the Newfoundland segment of the St. Lawrence Promontory, subsidence along the Anticosti Platform was influenced by residual thermal subsidence, renewed tectonic loading by thrust sheets to the south, and sediment loading. Basement subsidence, calculated by removing the effects of sediment loading, was between 2 and 5 cm/ka in the Caradocian, increasing to 8.6 cm/ka in the Pusgillian and Cautleyan, and reaching a maximum of 17.7 cm/ka in the Rawtheyan, during deposition of the Princeton Lake and Vaureal Formations. A marked decline in subsidence, beginning in the Hirnantian and continuing into the Early Silurian, may reflect decoupling of thrust loads to the south, although a further stage of thrust loading may have occurred in the Aeronian during deposition of the lower part of the Jupiter Formation. Storm frequency curves, produced using tempestite abundance, thickness, and grain size through more than a kilometre of carbonate strata on Anticosti Island, allow recognition of long period, 3rd-order trends. These are in part similar to local sea-level trends deduced from direct interpretation of sedimentary structures, but depart significantly from paleontological-based sea-level curves. Shorter period 4th-order cycles appear to be related to orbital eccentricity with periods of 100 and 400 ka. These may reflect periods with falling sea levels, increasing storm activity, or enhanced sediment flux to the middle and outer shelf.

Notes:

GeoRef, Copyright 2018, American Geological Institute.<br/>2007-075883<br/>Princeton Lake Formation<br/>Vaureal Formation