Tubular structures of northern Wairarapa (New Zealand) as possible examples of ancient fluid expulsion in an accretionary prism: evidence from field and petrographical observations
Published:January 01, 2003
Béatrice Ledésert, Christophe Buret, Frank Chanier, Jacky Ferrière, Philippe Recourt, 2003. "Tubular structures of northern Wairarapa (New Zealand) as possible examples of ancient fluid expulsion in an accretionary prism: evidence from field and petrographical observations", Subsurface Sediment Mobilization, P. Van Rensbergen, R. R. Hillis, A. J. Maltman, C. K. Morley
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The Cape Turnagain area is located on the inboard portion of the Hikurangi subduction margin, on the northern Wairarapa coast of the North Island of New Zealand. A 4.5 km long coastal section of sea cliffs of Mio-Pliocene sediments contains numerous tubular carbonate-rich concretions. Their morphology and petrographical observations suggest they were possibly formed by fluid flows of carbonate-rich water through a silty sediment. These tubular concretions could be fossil fluid expulsion structures similar to dewatering chimneys described offshore in New Zealand. The external diameter of the concretions observed in situ reaches 60 cm and internal canal up to...
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Subsurface Sediment Mobilization
Sedimentary facies in the subsurface are usually interpreted from a epositional/stratigraphical perspective: the depositional layering is generally considered to remain undisturbed, except in a few settings. But, there is growing evidence that subsurface sediment mobilization (SSM) is more widespread than previously thought, as new observations arise from the ever-increasing resolution of subsurface data. Many examples are from hydrocarbon provinces but studies elsewhere, for example in preparation for the underground storage of hazardous waste, have yielded unexpected examples. Although until now the different aspects of SSM, including soft sediment deformations, sand injections, shale diapirs, mud volcanoes, etc, have been separated, the new discoveries emphasize their inter-connection, regardless of scale, depth, location, grain size or trigger mechanism. This volume integrates the different aspects of sediment mobilization in the subsurface and their structural consequences, allowing a more generaland a more coherent view of the subject.