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Late Holocene estuarine phosphogenesis in Raglan Harbour, New Zealand
Author(s) -
CULLEN DAVID J.,
CHALLIS G. A.,
DRUMMOND G. W.
Publication year - 1990
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.1990.tb01829.x
Subject(s) - geology , harbour , holocene , radiocarbon dating , intertidal zone , oceanography , carbonate , quaternary , shore , coring , estuary , bay , paleontology , geochemistry , archaeology , drilling , geography , mechanical engineering , materials science , computer science , engineering , metallurgy , programming language
A unique instance of Holocene estuarine phosphogenesis has been investigated in Raglan Harbour, on the west coast of North Island, New Zealand. Nodular calcareous concretions, which formed within surficial estuarine muds between 6500 and 3600 years BP, were superficially impregnated by carbonate fluorapatite between 3600 and 1600 years BP. The phosphatized nodules lie beneath a late Quaternary shore platform, which is reinforced by a mass of intertwined bioturbation structures and tubular rootlet casts impregnated by limonite and goethite. Large polygonal cracks, indicative of a desiccatory regime, are locally conspicuous on the platform surface and in the immediately subjacent muds. The phosphogenesis in Raglan Harbour is here related to an episode of lowered sea‐level, during which a paludal environment succeeded the estuarine, to be followed, in turn, by a positively and interlude. The subsequent rise of sea‐level to its present position over the last 1600 years or so has reinstated the shore platform in its present intertidal situation.