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The Middle Jurassic eastern margin of the Iberian platform system (eastern Spain). Palaeogeography and biodispersal routes of ammonoids.

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Fernández López, Sixto Rafael and Gómez Fernández, Juan José (2004) The Middle Jurassic eastern margin of the Iberian platform system (eastern Spain). Palaeogeography and biodispersal routes of ammonoids. Rivista italiana di paleontologia e stratigrafia , 110 (1). pp. 151-162. ISSN 0035-6883

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Official URL: http://www.rivistaitalianadipaleontologia.it/



Abstract

From a sedimentological and palaeogeographical point
of view, in the eastern margin of the Iberian platform system, Middle
Jurassic deposits are represented by a thick pile of carbonates with minor
marls interbedded. Different facies, within the Tortosa, Aragonese
and Castilian platforms, pertain to two categories: internal platform
and external platform facies. A system of extensional faults was the
major factor determining the differentiation of several shallow, carbonate,
epicontinental platforms. The so-called Iberian Basin was a
shallow intracratonic platform system, in which a relatively deep extensional
basin (the Catalan Basin) started to be differentiated during
the late Bajocian. In the eastern part of this faulted platform system,
the occurrence of a listric fault, dipping towards the east, conditioned
the development of a late Bajocian differentiated subsident area named
the Tortosa Platform.
From a palaeobiogeographical point of view, the ammonite fossil
assemblages of the Iberian platforms are composed of Sub-Mediterranean
taxa. At the eastern margin of the Iberian platform system,
the appearance and distribution of shells of ammonoids were taphonomically
and ecologically controlled by regional changes of relative
sea level. A Sub-Mediterranean zonation can be recognized, although
most of the ammonites shells correspond to adult individuals arrived
by necroplanktic drift from more open-marine or oceanic areas. The
following criteria are relevant in recognizing the maximum deepening
episodes in the Iberian platform system: colonization (including ontogenic
development) of open-marine taxa, immigration of oceanic taxa
and development of endemic species. In terms of Sequence Stratigraphy,
the development of expanded, external platform sections in the Tortosa
Platform during the Garantiana Biochron (late Bajocian) is noteworthy.
During this episode, the Iberian platform system reached the
maximum bathymetric values and acted as a biogeographical dispersal
area for some taxonomic groups of ammonoids between the Western
Tethys and the Proto-Atlantic.


Item Type:Article
Uncontrolled Keywords:Facies, Carbonate platform, Condensed section, Deepening/shallowing cycle, Extensional basin, Palaeobiogeography, Dispersal route, Proto-Atlantic, Western Tethys
Subjects:Sciences > Geology > Paleontology
ID Code:23085
Deposited On:09 Oct 2013 11:27
Last Modified:11 Dec 2018 08:42

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