Albian syndepositional block rotation and its geological consequences, Basque–Cantabrian Basin (western Pyrenees)

Abstract

Stratigraphic, structural, palaeocurrent and palaeomagnetic analyses of Upper Albian deep-water deposits in and around the Deba block (Northern Iberia) are presented. Results indicate an anticlockwise vertical-axis rotation of this block by 35 • during a maximum time span of c. 1 Ma (Late Albian intra-C. auritus ammonite Subzone). This Albian syndepositional block rotation is interpreted to be the consequence of the coeval activity of conjugate major sinistral strike-slip faults and minor (antithetic) dextral strike-slip faults, which border the Deba block. On the base of conservative estimations, a minimum block-rotation rate of 35 • Ma −1 and a sinistral strike-slip rate of 1.2 km Ma −1 are calculated. As a consequence of the interaction of the rotated Deba block with adjacent nonrotated blocks, its corners experienced coeval transpressive (NW and SE corners) and transtensional deformations (SW and, possibly, NE corners). At the transtensional SW corner, two domal highreflective seismic structures have been recorded and interpreted as high-level magmatic laccoliths. These magmatic intrusions triggered the development of a mineralizing hydrothermal system, which vented to the Late Albian seafloor warm to hot hydrocarbon-rich fluids. Vented hydrocarbon was generated from Albian organic-rich sediments by contact alteration with hydrothermal fluids.

Provenance of quartz-rich metamorphic tectonite pebbles from the “Black Flysch” (W Pyrenees, N Spain): An EBSD and detrital zircon LA–ICP-MS study

“…Longitudinal and traverse syn-sedimentary faults (e.g. : García-Mondéjar et al, 1996;Agirrezabala and Dinarés-Turell, 2013) promoted complex lithostratigraphic and facies relationships, lateral thickness changes, basin floor topographic variations and individualization of sub-basins and depocenters connected to northern and southern deltaic-slope sedimentary systems (Agirrezabala, 1996;Badillo et al, 1983;García-Mondéjar et al, 1985;Robles et al, 1988;Robles, 1991, 1995). Pillow-lavas and submarine volcanoclastic deposits interbedded in the medium-to upper part of the succession have a paleontologically constrained late middle Albian age (base of the Hysteroceras varicosum Zone; López-Horgue et al, 2009).…”

The Early Aptian volcanic episode of Gutiolo (N Spain): Expression of the Bilbao Rift Fault Zone

“…During the late Albian, magmatic eruptions occurred both in the Bilbao and Gernika‐Elgoibar fault zones and persisted into the Late Cretaceous. The Gernika‐Elgoibar Fault, located at the southern European margin, was subjected to sinistral transtension and transpression movements, as proposed in Agirrezabala and García‐Mondéjar () for the Middle Albian, García‐Mondéjar () for the Aptian and Albian, Agirrezabala et al () for the late Albian, Iriarte () for the Late Cretaceous, and Agirrezabala and Dinarès‐Turell () for the late Albian. These movements are not compatible with maintenance of the Iberian Plate without SE translation, as proposed by Roca et al ().…”

Syndepositional forced folding and related fluid plumbing above a magmatic laccolith: Insights from outcrop (Lower Cretaceous, Basque-Cantabrian Basin, western Pyrenees)

“…High-amplitude seismic structures recorded along the northern margin of the basin have been interpreted as high-level magmatic sills and laccoliths (Agirrezabala and Dinarès-Turell, 2013;. Above these buried intrusions, Albian outcrops of hydrocarbonderived authigenic carbonates and clastic dikes indicate the expulsion to the paleoseabed of thermogenic methane and oil formed by contact metamorphism of organic-rich host sediments (Agirrezabala et al, 2008Agirrezabala, 2009).…”