Triassic pelagic deposits of Timor: palaeogeographic and sea-level implications


Serval ID
Article: article from journal or magazin.
Triassic pelagic deposits of Timor: palaeogeographic and sea-level implications
Palaeogeography, Palaeoclimatology, Palaeoecology
Martini R., Zaninetti L., Villeneuve M., Cornee J.J., Krystyn L., Cirilli S., De Wever P., Dumitrica P., Harsolumakso A.
Publication state
Issued date
In West Timer, Triassic deposits are found in the Parautochthonous
Complex, as well as in the Allochthonous series of Sonnebait. A detailed
biostratigraphic investigation integrating field observations and facies
analysis, allowed the reconstruction of a synthetic lithostratigraphic
succession for the Upper Triassic, a stratigraphic transition from
Carnian shales to Upper Norian-Rhaetian limestones is also shown by this
study. The fossil content predominantly originates from an open marine
environment; lithostratigraphic Units A-E are dated on the basis of
radiolaria and palynomorphs, and Unit H, on ammonites and conodonts. The
presence of pelagic bioclasts, together with normal grading, horizontal
laminations, and current ripples, is indicative of a distal slope to
basin environment. The ammonite rich condensed limestone of Unit H was
deposited on a `pelagic carbonate plateau' exposed to storms and
currents. The organic facies have been used as criteria for
biostratigraphy, palaeoenvironmental interpretation, and sequence
stratigraphy. The palaeontological analysis of the Triassic succession
of West Timer is based on the investigation of radiolaria and
palynomorphs, in the marls and limestones of Units A-E, and also on
ammonites and conodonts in the condensed limestone of Unit H. Units A
and B are Carnian (Cordevolian) in age, based on the occurrence of the
palynomorph Camerosporites secatus, associated with `Lueckisporites' cf.
singhii, Vallasporites ignacii, Patinosporites densus and
Partitisporites novimundanus. Unit C is considered as Norian, on the
basis of a relatively high percentage of Gliscopollis meyeriana and
Granuloperculatipollis rudis. Unit D contains significant palynomorphs
and radiolaria; the organic facies, characterized by marine elements, is
dominated by the Norian dinocysts Heibergella salebrosacea and
Heibergella aculeata; the radiolaria confirm the Norian age. They range
from the lowermost Norian to the lower Upper Norian. Unit E also
contains radiolaria, associated in the upper part with the well-known
marker of the Upper Norian, Monotis salinaria. For Unit E, the
radiolaria attest to a Lower to Upper Norian age based on the occurrence
of Capnodoce and abundant Capnuchosphaera; the upper part is Upper
Norian to Rhaetian based on the presence of Livarella valida. Finally,
the blocks of condensed limestone with ammonites and conodonts of Unit H
allowed the reconstruction of a synthetic stratigraphic succession of
Upper Carnian to Upper Norian age. Our stratigraphic data lead to the
suggestion that the Allochthonous complex, classically interpreted as a
tectonic melange of the accretionary prism of the island Arc of Banda.
is a tectonically dismembered part of a Triassic lithostratigraphic
succession. (C) 2000 Elsevier Science B.V. All rights reserved.
Create date
14/12/2012 9:31
Last modification date
20/08/2019 15:20
Usage data