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|Title:||AN ANALYSIS OF CARDIUM FORMATION EVENT STRATIGRAPHY|
|Authors:||Bartlett, John Jeremy|
|Abstract:||<p>Analysis of the sedimentary facies, early diagenesis and micropaleontology of event stratigraphy within the transgressive phase of the Cardium Formation indicates that changes of sea level occur during extremely short timespans possibly as short as 10,000 years. These rapid sea level changes produce either erosive or gradational boundaries between stratigraphic sequences. These boundaries termed Horizons.</p> <p>Quantitative consideration of the foraminiferal population below, at and above these Horizons indicates that there was probably very little pause during the change in sea level; no unusual accumulations of biogenic debris occur. The foraminifera indicate that the waterbody was turbid and very likely diluted by fresh water. The resulting environmental stress persisted throughout Cardium time over a topographic 'bench' shorewards of the maximum extent of the regressive shoreline.</p> <p>Fresh water dilution and possible increased organic supply encouraged the formation of synsedimentary siderite. Its ubiquitous occurence at the Horizons examined may indicate a short pause in sedimentation prior to renewed transgression, but the possibility of rapid sideritization makes this hypothesis unprovable.</p> <p>Although subtle, some of the burrowing and cementation patterns characteristic of carbonate hardgrounds appear in the ubiquitously erosional fifth Horizon. The other Horizons are too gradational to show such behaviour.</p> <p>All Horizons show rapid sedimentological changes. Erosion in one location may appear as a correlative conformity in another. Their behaviour indicates rapid changes in water depth.</p> <p>As a whole the Cardium Formation probably represents a shoreline response to Late Turonian eustatic sea level change which was further influenced by shorter term tectonically induced sea level changes. With the exception of the fifth Horizon, the Horizons probably all formed subaqueously without a pause in sedimentation. Apart from changes from erosive to gradational contacts, Horizon behaviour is the same across the area studied.</p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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