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Stratigraphy of Palaeocene phosphate pelagic stromatolites (Prebetic Zone, SE Spain)

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Chacón Pichaco, Beatriz and Martín Chivelet, Javier (2008) Stratigraphy of Palaeocene phosphate pelagic stromatolites (Prebetic Zone, SE Spain). Facies, 54 . pp. 361-376. ISSN 0172-9179

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Official URL: http://link.springer.com/journal/10347



Abstract

The hemipelagic domain of the ancient southern
continental margin of Iberia is home to a strongly condensed
pelagic succession (6–15 cm thick) characterized by
the presence of phosphate stromatolites. This succession,
probably generated in the slope of the continental margin,
records a period of some 9 Ma, corresponding to the latest
Maastrichtian to Late Thanetian interval. A microstratigraphical
analysis allows for characterizing and biostratigraphically
dating six successive developmental stages in
the succession, which outline the main environmental evolution
of the depositional setting. The Wrst of them determined
the generation of a submarine hardground during the
latest Maastrichtian to earliest Danian interval. The other
Wve are represented by Wve successive microstratigraphical,
unconformity-bounded, genetic units, respectively Early–
Middle Danian, Late Danian–Early Selandian, intra-Selandian,
Late Selandian–Early Thanetian, and Middle–?Late
Thanetian in age. The three oldest units are characterized
by the accretion of phosphate stromatolites, favoured by
very low rates of pelagic sedimentation and by a microbially
mediated extra input of phosphate. The two youngest
units are dominated by carbonate deposition, which has
always taken place at very low rates. Condensed sedimentation
was abruptly interrupted at the end of the Palaeocene
(?latest Thanetian), when the condensed succession and its
hosting substrate were gravitationally slumped and redeposited
at the base of the slope in the form of a megadebris
Xow that can be now observed in Sierra de Aixorta
(Alicante, SE Spain). The Aixorta pelagic phosphatic stromatolites
are among the youngest ever described, and their
existence suggests that the oceanographic conditions necessary
for their development prevailed during most of the
Palaeocene, but disappeared during the Late Selandian,
never to return.


Item Type:Article
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The original publication is available at www.springerlink.com

Subjects:Sciences > Geology > Stratigraphic geology
ID Code:20331
Deposited On:08 Mar 2013 10:51
Last Modified:11 Dec 2018 08:42

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