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100 _aSousa, Carlos
_951345
245 _aHolocene evolution of a barrier island system, Ria Formosa, South Portugal /
260 _bSage,
_c2019.
300 _aVol 29, issue 1, 2019 : (64-76 p.).
520 _aHolocene evolution of the Ria Formosa barrier island system was studied through the examination of a large subsurface dataset acquired from 191 boreholes and five seismic refraction profiles. Two boreholes with total depths of 26 and 16.5 m were selected for a multi-proxy detailed laboratory analysis, including mean grain size distribution, organic matter (OM) content, color variation, shell identification, and benthic foraminifera assemblages. Selected cores are thought to be representative of the identified depositional sub-basins. Subsurface age data from 16 AMS 14C dated samples were plotted against depth and resulted in a coherent age model of sedimentary infill. The system evolution was largely controlled by sediment availability, accommodation space, and Holocene sea level rise, first at a rapid rate of 7 mm/yr from 10 kcal yr BP to 7.25 kcal yr BP, followed by a slowdown to 1.1 mm/yr until present. A conceptual model for the origin and Holocene evolution of the Ria Formosa barrier island system implies three main steps, leading to the present system geomorphology: (1) marine flooding of incised palaeovalleys by the rapid transgression of palaeovalleys in the early Holocene; (2) development of a proto-barrier island chain perched on Pleistocene detritic headlands and steeper interfluve areas during the early to middle Holocene; and (3) full development of the barrier islands chain and enclosing of the coastal lagoon, followed by the maturation of the system with subsequent siltation and salt marsh expansion from the middle Holocene until present. The onset of barrier system formation dates back to ca. 8 kcal yr BP, predating previously proposed age.
650 _abarrier island system,
_951346
650 _aHolocene,
_950806
650 _a palaeoenvironmental reconstruction,
_951347
650 _a palaeosurface model,
_951348
650 _aRia Formosa,
_951349
650 _asea level rise
_951350
700 _aBoski, Tomasz
_951351
700 _aPereira, Laura
_951352
773 0 _012756
_916504
_dLondon: Sage Publication Ltd, 2019.
_tHolocene/
_x09596836
856 _uhttps://doi.org/10.1177/0959683618804639
942 _2ddc
_cART
999 _c12761
_d12761