About the Cover
ON COVER - A 30-40 cm (12-16 in.) wide shale dyke cross cutting shallow marine sequences, one of over 50 shale dykes, sills and laccoliths exposed in the Jerudong Anticline, Brunei. Shale dykes are rarely exposed structures that form by the injection of highly overpressured mud into hydraulic fractures and faults and may represent the feeder systems for mud volcanoes. Pre-inversion Middle Miocene dykes strike E-W to NE-SW, while Late Miocene-Pliocene inversion related dykes are oriented NW-SE. The rotation in dyke orientation over time reveals a change from a margin-parallel deltaic stress field to NW-SE inversion related stresses and is similar to the stress rotation currently observed in the basin. See "Origin of overpressure and pore pressure prediction in the Baram province, Brunei and "Present-day stress and neotectonics of Brunei: Implications for Petroleum exploration and production" by Tingay et al. in this issue of the Bulletin. Photo by Chris Morley.
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Copyright © 2009 by American Association of Petroleum Geologists (AAPG)
