Selected Publications

Abstract:   This study investigates the lowermost Arenigian siliciclustic deposits of the
Roquebrun area, eastern Montagne Noire (France). The whole sequence
consists of cyclically arranged shallow marine to peritidal shales and sandstones.
Based on lithology and sedimentary textures, six lithofacies types are
distinguished in this paper: A) sandy noduliferous shale, B) sandy shales with
thin crossbedded sandstone beds, C) hummocky cross bedded sandstones with
thin shale interbeds, D) anialgamated hummocky cross stratified quartzarenites,
E) thin-bedded shale-/sandston ititercalations with wave ripples, linsen
And flaser bedding, and  F) shales and.siltstones with sparse quartzarenite
beds. Three alternative facies rnodels are discussed: I . offshore bar model:
open shelf (Lithofacies A to C), wit intercalated sequence of off'shore bar
deposits (D and E) surrounded by restricted marine interbar deposits (F); 2.
tectonic rise model: clastic ramp-/ barrier shoreline facies sequence from open
shelf mud (A) and distal tempestite . facies (B) through proximal terripestite
(C)/ shoreface (D) to shorelirie (E) and lagoorznl deposits (F). This second
modlel implies nearby emergent area which is assumed to represent a local tectonic
uplift in this part vf the lower Ordoviciatz Gorndwana shelf; 3. sequence
stratigraphic model: continental margin / shelf break fizcies sequerzce with
interccilated peritidal lowstand deposits. The depositional environments of litho-
,faicies A to F, respectively, are interpreted in the same way as in the previous
model, but the coastal deposits of lithofacies D to F are proposed to rim the
exposed Gondwana shelf cluring sea level lowstand The present field data do
not allow to make a clear clecisiorz between these models. Front a sedimentologic
point of view, the first model seems to be the least probable. In any of these
models, a short-term relatice sea level fal l during the time of deposition is indicated
Syndepositional tectonic activity is indicatecl by increased accumularional rates of
the early Arenigiarz deposits and can be inferred from the abrupt cessation of
sandy input near the top of the sequence.

Keywords:   Noffke, Shale, Sandstone, Arenigian, Lithofacies, Continental margin sedimentation, Tempestite, Heerault (Roquebrun area) ,Montagne Noire

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