Elliott T. Burden

Basin evolution in western Newfoundland: New insights from hydrocarbon exploration

The Humber zone is the most external zone of the Appalachian orogen in western Newfoundland. It records multiphase deformation of the Cambrian-Ordovician passive margin and of the Ordovician to Devonian foreland basins by the Taconian, Salinian, and Acadian orogenic events. The recent phase of exploration drilling has provided new evidence for structural, stratigraphic, reservoir, and source rock maturation models of western Newfoundland. The first well, Port au Port 1, supported the hypothesis that the Round Head thrust had an earlier extensional history prior to the Acadian compressional inversion that created the present-day structural high of the Port au Port Peninsula. The well tested a small anticline formed in a footwall shortcut fault of the Round Head thrust. The second well, Long Point M-16, was drilled at the northern tip of Long Point to test a triangle zone identified by previous workers. This well demonstrates that the frontal monocline at the western edge of the triangle zone is elevated by a stack of imbricate thrusts composed of rocks of the Taconian allochthon and compressional basement-involved faults that have uplifted the Cambrian-Ordovician carbonate platform. The structural model developed in the Port au Port area with the aid of these wells has been extended throughout the Humber zone in western Newfoundland. Changes in structural style illustrated by regional cross sections suggest that prospective trap geometries are only developed in the southern and central parts of the region. The reservoir model proposed invokes exposure and karsting of the footwalls of extensional faults formed as the carbonate platform collapsed during a Middle Ordovician hiatus, the St. George unconformity. Structural relief became more pronounced as extensional collapse continued through the Middle Ordovician. (Begin page 394) These structurally high fault footwalls became the foci for dolomitizing and mineralizing fluids that used major faults as fluid conduits during the Devonian. Fluids deposited sulphide ores and created zebra and sparry dolomite and some sucrosic hydrothermal dolomites in the St. George Group and the Table Point Formation. The reservoir model, maturity and source rock data, and the structural models have been combined with seismic and onshore surface geology. This enables the prospectivity of the western Newfoundland Cambrian-Ordovician play trend to be evaluated for further exploration.

PALYNOLOGY AND MICROPALEONTOLOGY OF THE CLAM BANK FORMATION (LOWER DEVONIAN) OF WESTERN NEWFOUNDLAND, CANADA

Abstract Sandstone and siltstone samples collected from the lowest part of the Clam Bank Formation in western Newfoundland contain a distinctive monospecific conodont assemblage of Ozarkodina remscheidensis eosteinhornensis and O. remscheidensis ssp., confidently dated as Late Ludlow through Lochkovian. Palynomorph assemblages of terrestrial spores, acritarchs, chitinozoans, scolecodonts and plant fragments are relatively abundant and diverse in the lower 250 m of this formation. Taxa include the cryptospore genera Cymbohilates, Acontotetras, Hispanaediscus, Laevolancis, and Tetrahedraletes, spore genera Ambitisporites, Aneurospora, Apiculiretusispora, Emphanisporites, Retusotriletes, Synorisporites, Vermiverruspora, and a new species Stellatispora fahraeusi. Acritarchs include the taxon Triangulina sanpetrensis and chitinozoa include Angochitina chlupaci. Palynomorphs indicate a Lochkovian age, corresponding with the Apiculiretusispora sp. E zone from Europe. In well preserved samples from this section, ...

Palynology of cretaceous and tertiary strata, Northeast Baffin island, Northwest Territories, Canada: Implications for the history of rifting in Baffin bay

Abstract Palynomorphs from outliers of the Quqaluit and Cape Searle formations in half‐grabens off northeast Baffin Island are examined in order to elucidate the history of rifting and sedimentation. Two distinctive assemblages, herein called the Gemmatriletes clavatus ‐ Cicatricosisporites potomacensis Zone (GC Zone) and the Trivestibulopollenites betuloides‐Pesavis parva Zone (TP Zone) are recognized. The lower part of the GC Zone in the lower part of the Quqaluit Formation consists of a low diversity assemblage of long ranging schizaealean spores and gymnosperm pollen; a late Neocomian and Aptian age is suggested from this assemblage. In addition to the name bearing species, the upper part of the GC Zone in the upper Quqaluit Formation contains a diverse spore and pollen assemblage, including Camarozonotriletes ambigens, Cicatricosisporites crassiterminatus, Appendicisporites matesovae, Foveogleicheniidites confossus, Tappanispora sp. cf. Tigrisporites verrucatus, Foveotricolpites sphaeroides, Tricolpi...