Sandy mixed terrigenous/calcareous drift deposits off New Zealand as a model for petroleum exploration

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Author(s): Nolasco, Jasmyn; Marsaglia, Kathleen M.; Bailey, Claire; Bender-Whitaker, Carrie; Jaeger, John; Villasenor-Joquera, Tania
Author Affiliation(s): Primary:
California State University Northridge, Department of Geological Sciences, Northridge, CA, United States
University of Florida, United States
Volume Title: 2014 AAPG annual convention & exhibition; abstracts volume; Ideas and innovation; fuel for the energy capital
Source: Abstracts: Annual Meeting - American Association of Petroleum Geologists, Vol.2014; AAPG 2014 annual convention & exhibition, Houston, TX, April 6-9, 2014. Publisher: American Association of Petroleum Geologists and Society for Sedimentary Geology, Tulsa, OK, United States
Note: In English
Summary: Sandy contourite drifts have been promoted as potential petroleum reservoir facies but their compositional variation, particularly in the terrigenous fraction, remains understudied. Scientific ocean drilling on the Canterbury Margin of eastern South Island, New Zealand is yielding new insights. Here the drift history extends back into the Miocene, but we have focused our work on the ≈300 m-thick mid-Pliocene to Pleistocene (<3 my) section that was continuously cored at ODP (Ocean Drilling Program) Site 1119. Sand detrital modes of very fine and fine sand fractions from 19 unconsolidated core samples (38 thin sections) were determined based on counts of 400 points using the Gazzi-Dickinson method and a detailed bioclast classification scheme. Very fine sand fractions contain an average of 25% bioclastic debris, with bioclasts making up 51% of the fine sand fraction. Foraminifera are the dominant bioclasts, with pelagic more common than benthic varieties. The average proportions of monocrystalline quartz, plagioclase and potassium feldspar are similar in the very fine and fine sample sets (average QmKP of ≈25:12:63 each). In contrast, the very fine sand fractions have, on average, higher lithic (QFL%L of 16 vs. 3%), mica (Totalgrain%M of 11 vs. 5%), and dense mineral (Totalgrain%D of 9 vs. 3%) content as compared with the fine sand fractions. Stratigraphic sections correlated by previous workers with younger clinoform drape (Unit I) and older mounded drift (Unit II) seismic facies showed no distinct compositional differences in their sand fractions. The composition of Site 1119 drift sand is, however, distinctly different from modern onshore river sand. Common metamorphic lithic fragments and chlorite grains suggest a southern Otago schist provenance, however the high proportion of Ca-plagioclase, a non-schist mineral phase, requires a contribution from Torlesse Group or Cenozoic volcanic rocks. Previous workers have linked grain size variation of the silt fraction in this drift deposit to glacial processes resulting from tectonic uplift along the nearby Alpine Fault plate boundary; this may help explain the compositional mix. We are also comparing and contrasting the Site 1119 drift sand compositions with those from along-strike slope-clinoform and shelf facies recovered at Integrated Ocean Drilling Program Expedition 317 sites to the south, in order to place the Site 1119 results in a larger, more detailed source-to-sink context.
Year of Publication: 2014
Research Program: ODP Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 29 Economic Geology, Energy Sources; Australasia; Biofacies; Canterbury Basin; Cenozoic; Clastic rocks; Clastic sediments; Contourite; Drift; Facies; Foraminifera; Invertebrata; Leg 181; Microfossils; Mineral composition; Models; Neogene; New Zealand; ODP Site 1119; Ocean Drilling Program; Otago Schist; Pacific Ocean; Petroleum; Petroleum exploration; Pleistocene; Pliocene; Protista; Quaternary; Reservoir rocks; Sand; Sedimentary rocks; Sediments; South Island; South Pacific; Southwest Pacific; Terrigenous materials; Tertiary; Torlesse Supergroup; West Pacific
Coordinates: S444520 S444520 E1722336 E1722336
Record ID: 2015095221
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States