<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Relative sea level fluctuations during the Frasnian generated two shallow-marine, mixed siliciclastic-carbonate successions in the Devonian Asturo-Leonese Basin. Each system represents a third-order sequence-stratigraphical unit deposited in the same basin during comparable extreme greenhouse conditions without nearby fluvial entry points. Depositional control on the siliciclastic and carbonate distribution was driven by relative sea level fluctuations, basin geometry, availability of sand and the way sediment was distributed by shelf currents. Early Variscan flexural bending of the continental crust changed the basin shape from a shelf with a gradual profile and low dip (early Frasnian) towards a shelf with a steep depositional dip (late Frasnian). Shelf distribution changed from along-shelf transport (early Frasnian) towards offshore-directed gravity flows (late Frasnian). As a consequence, siliciclastic-carbonate distribution changed from a predominance of skeletal carbonate in the proximal shoreface – foreshore area and siliciclastic predominance distally (early Frasnian), to a distribution pattern with proximal shoreface skeletal carbonates, offshore muddy carbonates and a siliciclastic zone in between where gravity flows distributed the siliciclastic sediment down dip (late Frasnian).</p></abstract>

Relative sea level fluctuations during the Frasnian generated two shallow-marine, mixed siliciclastic-carbonate successions in the Devonian Asturo-Leonese Basin. Each system represents a third-order sequence-stratigraphical unit deposited in the same basin during comparable extreme greenhouse conditions without nearby fluvial entry points. Depositional control on the siliciclastic and carbonate distribution was driven by relative sea level fluctuations, basin geometry, availability of sand and the way sediment was distributed by shelf currents. Early Variscan flexural bending of the continental crust changed the basin shape from a shelf with a gradual profile and low dip (early Frasnian) towards a shelf with a steep depositional dip (late Frasnian). Shelf distribution changed from along-shelf transport (early Frasnian) towards offshore-directed gravity flows (late Frasnian). As a consequence, siliciclastic-carbonate distribution changed from a predominance of skeletal carbonate in the proximal shoreface – foreshore area and siliciclastic predominance distally (early Frasnian), to a distribution pattern with proximal shoreface skeletal carbonates, offshore muddy carbonates and a siliciclastic zone in between where gravity flows distributed the siliciclastic sediment down dip (late Frasnian).

Facies patterns and depositional processes in two Frasnian mixed siliciclastic-carbonate systems in the Cantabrian Mountains, northwest Spain

Jan Sluijtersstraat 7, 3443 HP Woerden, the

Geologos

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Relative sea level fluctuations during the Frasnian generated two shallow-marine, mixed siliciclastic-carbonate successions in the Devonian Asturo-Leonese...

Facies patterns and depositional processes in two Frasnian mixed siliciclastic-carbonate systems in the Cantabrian Mountains, northwest Spain

Published Online: May 16, 2020

Page range: 1 - 23

Received: Sep 25, 2018

Accepted: Jan 08, 2020

DOI: https://doi.org/10.2478/logos-2020-0001

Keywords
mixed systems, sequence stratigraphy, depositional controls, Upper Devonian, Asturo-Leonese Basin

© 2020 Gerard B.S. van Loevezijn et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Facies patterns and depositional processes in two Frasnian mixed siliciclastic-carbonate systems in the Cantabrian Mountains, northwest Spain

Published Online: May 16, 2020

Page range: 1 - 23

Received: Sep 25, 2018

Accepted: Jan 08, 2020

DOI: https://doi.org/10.2478/logos-2020-0001

Keywordsmixed systems, sequence stratigraphy, depositional controls, Upper Devonian, Asturo-Leonese Basin

© 2020 Gerard B.S. van Loevezijn et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
mixed systems, sequence stratigraphy, depositional controls, Upper Devonian, Asturo-Leonese Basin