Marsaglia, Kathleen M.1, Michela Arnaboldi2, Richard N.
Hiscott3, Thomas K. Pletsch4, Alastair Robertson5, Masaaki
Shirai6, Richard C. Wilson7, Anna Engstrom8, Gianreto
Manatschal9, Therese Shryane10, R. Mark Leckie11, Ocean Drilling Program Leg 210 Scientific
(1) California State University Northridge, Northridge, CA
(2) Department of Geological Sciences University of Michigan, Ann Arbor, MI
(3) Earth Sciences Department Memorial University of Newfoundland, St. John's, NF
(4) Technical Mineralogy and Sedimentology Section Bundesanstalt fur Geowissenschaften und Rohstoffe, Hannover, Germany
(5) Department of Geology and Geophysics University of Edinburgh, Edinburgh, United Kingdom
(6) Ocean Research Institute University of Tokyo, Tokyo, Japan
(7) Department of Earth Sciences The Open University, Milton Keynes, United Kingdom
(8) Department of Geology and Geochemistry Stockholm Universitet, Stockholm, Sweden
(9) Centre de Geochimie de la Surface Ecole et Observatoire des Sciences de le Terre, Strasbourg, France
(10) Galway Geofluids Research Centre National University of Ireland, Galway, Ireland
(11) Department of Geosciences University of Massachusetts, Amherst, MA
(12) N/A, N/A,
ABSTRACT: Results from Recent Deep-Water Drilling in the Newfoundland Basin, East of Hibernia Field
Ocean Drilling Program (ODP) Site 1276 was drilled in 4549 meters water depth in the Newfoundland Basin approximately 360 km east of Hibernia Field, off Canada. It records the post-rift burial of irregular basement topography. Below a cased, uncored depth of 800 meters, 933 m of lower Oligocene to uppermost Aptian(?)-lower Albian sedimentary rocks were cored (~85% recovery). Drilling terminated in diabase sills coincident with a prominent seismic reflector (U) previously hypothesized to correlate with the Avalon Unconformity.
The stratigraphy at Site 1276 is similar to that drilled on the conjugate Iberian margin. Background hemipelagic mudrocks and interbedded coarser gravity-flow deposits form the bulk of the succession at Site 1276. They include debris flows, turbidites, and muddy viscous gravity-flow deposits that range in composition from siliciclastic sandstones and mudrocks to carbonate grainstones and marlstones. Most gravity-flow deposits contain significant biogenic carbonate, whereas most of the interbedded hemipelagic sediments are non-calcareous, reflecting deposition below the carbonate compensation depth.
The Albian-Cenomanian section is characterized by moderately enriched total organic carbon (TOC) content (max. of ~10% TOC), low hydrogen indices (HI < 100), C/N ratios averaging ~20, and a positive correlation between C/N and TOC, suggesting a strong influence of terrestrially derived organic matter. Finely laminated, discrete organic-rich "black shales" with higher TOC are present. Two such intervals may correspond with Oceanic Anoxic Events 1b and 2; they have HI > 150, characteristic of marine organic matter and have S2 up to 25 mgHC/g, indicating that they originally had petroleum-generating potential.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.