Silurian conodonts from the "Orthoceras limestones" (Tafilalt and Tindouf basins, NW Africa)

RON MARTÍN, M.; VOLDMAN, G.G.; GARCÍA LÓPEZ, S.

Fourth International Conodont Symposium, Cuadernos del Museo Geominero

Instituto Geológico y Minero de España

Año: 2017; p. 99 - 104

In contrast to the low to mid latitude Silurian conodont faunas from peri-Gondwanan Europe and Laurentia, little is known about the Silurian conodont faunas from the widespread cold-water limestones that developed in northern Gondwana. Few researchers have addressed the Silurian conodont faunas from NW Africa, where predominantly shale deposits expand with very uniform facies throughout scattered outcrops for several hundreds of kilometers, many of them affected by territorial disputes. Based on published and unpublished reports of 40 stratigraphic sections, García López et al. (1996) analysed the main lithological features and conodont associations from a vast area of northern Gondwana, extending from northern France to the west?central Sahara. They recognized four pulses of limestone depositionduring the early Llandovery, late Llandovery ? early Wenlock, latest Wenlock ? Ludlow, and Pridoli. The second two limestone packages are characterized by condensed outer shelf nautiloid and scyphocrinoid limestones and are distinct markers for regional correlation studies (Destombes et al., 1985; Lubeseder, 2008).The broad siliciclastic character of the Silurian sedimentary succession and the diff cult working conditions in some regions of NW Africa resulted in that most of the conodont information from this area is obtained from spot samples. In the present contribution, we analyze two new conodont samples obtained from the ?Orthoceras limestones? in the Taf lalt Basin (Eastern Anti-Atlas, Morocco) and the southern fl ank of the Tindouf Basin (W Sahara) (Fig. 1). Taking into account the recent conodont studies from NW Africa (e.g.,Sarmiento et al., 1997; Benfrika, 1999; Benfrika et al., 2007; Männik et al., 2011; Lubeseder, 2008; Corriga et al., 2014), they allow us to improve the knowledge on the Silurian conodont faunas and shed light into the episodic development of condensed limestone levels in northern Gondwana.