Evolution of a Fault-Controlled, Deep-Water Sub-Basin, Tabernas, SE Spain

Abstract

The Neogene Tabernas Basin, SE Spain, provides important evidence at outcrop for the interplay between tectonic deformation of the sea floor, slope instability and turbidity current behaviour. Dextral-oblique strike-slip faults and associated folds propagated along the basin axis to deform the palaeo-sea floor, creating structurally-controlled depressions in which turbidity currents were trapped and ponded. EW-trending syn-depositional faults define a narrow sub-basin that subsided asymmetrically as a negative flower structure. The sub-basin contains an expanded succession (>300 m of ponded turbidite sheets, debrites and slumps) along its northern margin flanked by the principal fault strand defined by a wide zone of sheared and calcite-veined marl. A narrower fault zone with a smaller displacement marks the southern margin of the sub-basin and the fill close to it is thin with internal discordances, evidence of local failure and southward thinning of sandstone sheets. Both northern and southern faults ‘died’ at the same stratigraphic level and were overstepped by basin floor turbidites showing evidence of weaker and longer-range topographic confinement. As turbidites healed and aggraded out of the sub-basin to progressively onlap the southern margin of the basin, major gravity failures occurred emplacing thick (>100 m) mass-transport complexes. The first initially reworked the southern part of the sub-basin fill together with the early onlap wedge, the second remobilised the onlap wedge, and the third records failure of the upper part of the slope well above the wedge. The first two were toe-confined failures, the third and furthest travelled was confined by basin axis topography. All three failures are lateral to or directly overlain by ‘megabed’ sheets on the basin floor, implying either a common trigger (earthquakes) or slope instability following reflection of large volume flows. Tabernas turbidites highlight the role of basin tectonics (as opposed to up-dip supply and sea level fluctuations) in directly impacting on deep-water processes and stratigraphy. Small deep-water transtensional sub-basins opened up along long transfer faults accommodating regional extension.

The provenance of a turbidite system within a tectonically active wrench basin: Insights from heavy mineral characteristics of Miocene sandstones in the Tabernas Basin, south‐east Spain

“…Variations in provenance-sensitive parameters are shown in Figures 6 and 7. The GZi-ATi plots show that the great F I G U R E 3 Composite stratigraphic column for the Tabernas Basin, modified after Haughton (2000), Hodgson and Haughton (2004), Kleverlaan (1989a) and Baudouy et al (2021). majority of samples have similar characteristics, with extremely high GZi and generally low ATi.…”

“…The Verdelecho Formation is capped by the El Gordo Megabed (Figure 4E,F), which is a seismite feature that extends across the basin from Buho Canyon in the north to Cerro Pedro 10 km to the south (Figure 2), with additional less voluminous megabeds at higher stratigraphic levels. Baudouy et al (2021) refer to the Molinos Formation and equivalents as Phase 1, the Sartenella Formation as Phase 2, the Loma de Los Baños Formation as Phase 3 and the Verdelecho plus El Gordo Megabed as Phase 4 (Figure 3). In this paper, the lithostratigraphic nomenclature of Haughton (2000) and Hodgson and Haughton (2004) is followed, but the Solitary Channel is separated from the remainder of the Sartenella Formation in view of its depositional history (Pickering et al, 2001) and the discrepancies concerning its inferred palaeoflow direction.…”

“…The data set covers the Sartenella sandstones (undifferentiated), the Solitary Channel, the Verdelecho Formation and the El Gordo Megabed, as well as the underlying Molinos Formation redbeds and modern stream sediments draining the two possible source areas (Sierra de los Filabres and Sierra Alhamilla). Heavy mineral F I G U R E 2 Geological map of the Tabernas Basin showing locations of sites discussed in the text and samples used in the heavy mineral provenance study, adapted from Kleverlaan (1987) and Baudouy et al (2021). Locations 4A through F refer to illustrations of sedimentological elements shown in Figure 4.…”

“…Geological map of the Tabernas Basin showing locations of sites discussed in the text and samples used in the heavy mineral provenance study, adapted from Kleverlaan (1987) and Baudouy et al. (2021). Locations 4A through F refer to illustrations of sedimentological elements shown in Figure 4.…”

“…These deepwater sediments are frequently visited on educational field trips, especially by geologists investigating potential hydrocarbon reservoir analogues. Extensive sedimentological, stratigraphic and structural studies of the basinal succession (Kleverlaan, 1987(Kleverlaan, , 1989a(Kleverlaan, , 1989bCronin, 1995;Haughton, 2000;Pickering et al, 2001;Hodgson & Haughton, 2004;Koopmans, 2012;Baudouy et al, 2021) have led to the identification of two lobe systems, informally the termed Sandy System (Sartenella Formation) and Muddy System (the confined Loma de Los Baños Formation and the unconfined Verdelecho Formation), a channel unit within the Sartenella Formation (Solitary Channel) and a basin-wide seismite (El Gordo Megabed). Nevertheless, there remains some doubt over the provenance of the sandstones and of the stratigraphic relationships between the lobe and channel systems.…”