Friday, March 29, 2013

Significant Climate Change From Bajocian to Bathonian Jurassic in Negev

Jurassic flora of the Negev Desert: Plant taphonomy, palaeoecology and palaeogeographic inference


1. Valentin Krassilov (a)
2. Alex Berner (b)
3. Sophia Barinova (a)


a. Institute of Evolution, University of Haifa, Mount Carmel, Haifa 31905, Israel

b. Israel Institute of Technology, Haifa, 32000, Israel


Jurassic fossil plants of Makhtesh Ramon, the northern Negev, are collected from the Early Bajocian paralic Inmar Formation conformably overlain with the marine Mahmal Formation, which contains ammonite markers of the Middle–Upper Bajocian age. Plant remains occur in the thin ferruginous layers traceable all over the questa exposures, composed of re-deposited sand at the base and the fine-grained ferro-alumosilicate lamella on top. Plants are preserved as ferruginous molds of leafy shoots and reproductive material, buried by turbid run-over sand flows and embedded in the back-wash clayey deposits as calcified plant debris. On account of their peculiar taphonomy and elementary composition, the fossiliferous horizons are interpreted as tsunamites. The coastal plant assemblages are endemic at the syntaxonomic level, with Gondwana affinities extended to insular landmasses north of the Tethys. The abundance of bennettitalean plants and the inferred proximity of Araucaria-like brachyphylls gives the Bajocian Inmar flora a thermophilic paratropical aspect, while the Bathonian flora of Sinai is of a more temperate aspect, suggesting a major mid-Jurassic climate change.

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