Complex sedimentology and palaeohabitats of Holocene coastal deserts, their topographic controls, and analogues for the mid-Cretaceous of northern Iberia

Abstract

Desert coasts in plate margins contain one of the most variable sedimentary records in terms of facies and stacking patterns. Reliefs in these basins together with massif palaeogeography and palaeotopography strongly control the spatial distribution of facies belts and complex lateral facies changes between very different coeval subenvironments, leading to mixtures of sedimentary particles with variable composition.

Biodiversity of ecosystems in an arid setting: The late Albian plant communities and associated biota from eastern Iberia

“…However, there are no reasons to believe that arid and semi-arid ecosystems from the Cretaceous were less complex than their modern counterparts, such as the Namib and Kalahari deserts [ 126 , 127 ]. The presence of palynological assemblages of varying composition in marine-influenced intervals is otherwise expected, given the taphonomic, palynological and palaeobotanical constraints [ 14 , 128 – 131 ], and indicates the existence of mosaic vegetation types in the area with conifer-forests along the Tethyan coasts ( Fig 16 ). The vegetation of this region was strongly conditioned by both the influence of the sea and the desert and other factors such as palaeowildfires, as the abundant charcoal occurrence in the Spanish Cretaceous amber-bearing deposits indicates [ 40 , 132 ].…”

“…The record of highly variable fossil remains and amber with biological inclusions suggest the presence of an ecosystem structurally framed by multi-tiered vegetation [ 14 , 28 , 34 – 36 ] sustaining complex arthropod communities ( Table 2 ). Terrestrial ecosystems of such complexity might seem surprising for deposits associated with a desert system.…”

“…The diversity of angiosperm pollen types and their varying abundance pattern ( S2 Appendix ) suggest that producers had distinct ecophysiologies allowing them to colonise not only moister habitats and, probably, water-logged, if not aquatic, environments [ 12 , 35 , 152 – 154 ] but also well-drained and/or dry edaphic settings. Originally associated with moist environments [ 155 ], angiosperms may have already radiated into more arid settings by the late Albian, as their presence in deposits associated with the desert system could suggest [ 14 ]. It is likely that the representation of flowering plants in pre-Cenomanian ecosystems is underestimated owing to morpho-functional and taphonomic biases (i.e., low production and dispersal of entomophilous pollen [ 156 ]).…”

“…The distinctiveness of the western European flora has been recognised for a long time and several biogeographic provinces have been named on the basis of the nature of the fossil assemblages (i.e., palynological and megaremains [ 8 , 9 ]). The increased attention to the time-interval is justified by the rising of the dominance of the flowering plants in many ecosystems [ 10 – 13 ] including arid environments [ 14 ]. During the later part of the Early Cretaceous, SW Europe has been described as one of the probable migratory routes of angiosperms originating from a northern Gondwanan centre of radiation [ 15 ].…”

“…In Iberia, the eastern coastal margin consisted of a complex set of depositional environments comprising multifaceted vegetation types including conifer forests [ 14 , 25 ]. Palaeobotanical studies of ancient desert successions (see i.e.…”