RT Journal Article
T1 Variable style of transition between Palaeogene fluvial fan andlacustrine systems, southern Pyrenean foreland, NE Spain
A1 Sáez, Alberto
A1 Anadón, Pere
A1 Herrero Fernández, María Josefa
A1 Moscariello, Andrea
AB Two Palaeogene fluvial fan systems linked to the south-Pyrenean margin arerecognized in the eastern Ebro Basin: the Cardona–Su´ ria and Solsona–Sanau¨ jafans. These had radii of 40 and 35 km and were 800 and 600 km2 in arearespectively. During the Priabonian to the Middle Rupelian, the fluvial fansbuilt into a hydrologically closed foreland basin, and shallow lacustrinesystems persisted in the basin centre. In the studied area, both fans are part ofthe same upward-coarsening megasequence (up to 800 m thick), driven byhinterland drainage expansion and foreland propagation of Pyrenean thrusts.Fourteen sedimentary facies have been grouped into seven facies associationscorresponding to medial fluvial fan, channelized terminal lobe, nonchannelizedterminal lobe, mudflat, deltaic, evaporitic playa-lake andcarbonate-rich, shallow lacustrine environments. Lateral correlations definetwo styles of alluvial-lacustrine transition. During low lake-level stages,terminal lobes developed, whereas during lake highstands, fluvial-dominateddeltas and interdistributary bays were formed. Terminal lobe deposits arecharacterized by extensive (100–600 m wide) sheet-like fine sandstone bedsformed by sub-aqueous, quasi-steady, hyperpycnal turbidity currents.Sedimentary structures and trace fossils indicate rapid desiccation and subaerialexposure of the lobe deposits. These deposits are arranged incoarsening–fining sequences (metres to tens of metres in thickness)controlled by a combination of tectonics, climatic oscillations and autocyclicsedimentary processes. The presence of anomalously deeply inciseddistributary channels associated with distal terminal lobe or mudflatdeposits indicates rapid lake-level falls. Deltaic deposits form progradationalcoarsening-upward sequences (several metres thick) characterized by channeland friction-dominated mouth-bar facies overlying white-grey offshorelacustrine facies. Deltaic bar deposits are less extensive (50–300 m wide)than the terminal lobes and were also deposited by hyperpycnal currents,although they lack evidence of emergence. Sandy deltaic depositsaccumulated locally at the mouths of main feeder distal fan streams andwere separated by muddy interdistributary bays; whereas the terminal lobesheets expand from a series of mid-fan intersection points and coalesced toform a more continuous sandy fan fringe.
PB Blackwell Publishing Ltd
SN 0037-0746
YR 2007
FD 2007
LK https://hdl.handle.net/20.500.14352/50350
UL https://hdl.handle.net/20.500.14352/50350
LA eng
DS Docta Complutense
RD 16 abr 2025