Search

Copyright of Ameghiniana is the property of Argentine Paleontological Association / Asociacion Paleontologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The elemental content—mainly trace elements—of samples from two boreholes (PLN, CM) with evidence of tsunamiites, located in the Doñana National Park (SW Spain), were studied. The geochemical variations of the REE, LILE, HFSE, and other elements (Al, Ti, S, Na, Br, Sc, Co, Cr) were interpreted according to the mineralogy present in the samples. The results obtained show the geochemical complexity of the estuarine paleoenvironments, in this case with the existence of three Holocene-age tsunamigenic deposits (around 4.25, 3.56 and 2.2–2 kyr BP). The statistical analysis of the samples' geochemistry, by means of linear correlation and factor analysis, made it possible to differentiate two associations. The first is representative of an inherited mineralogy (REE-Y-Rb-Sr-Cs-Th-U-Hf-Al-Ti-Co-Cr-Sc); the second includes elements (Br-Na) linked to mineral formation under evaporite conditions (halite). The trace element geochemistry of sediments thus becomes an excellent tool to identify tsunamiites in the studied zone, especially those elements that are clear proxies for marine incursions (Na, Br, Sr) and high energy events (Hf, Ti). The parent area of the provenance of the materials is mainly of felsic composition. [ABSTRACT FROM AUTHOR]

Portus was the main port of imperial Rome from the 2nd century AD to the 5th century AD, with an inner, hexagonal port (Trajan basin) and an outer port (Claudius basin) linked by a channel bounded by quays. Six sedimentary facies have been differentiated in the geological analysis of a core extracted in this channel, basically composed of poorly classified bioclastic muds typical of restricted environments, accumulations of Posidonia oceanica (Linnaeus) Delile, 1813 and a final anthropic fill. The subfossil record of bivalves, foraminifera and ostracods is characteristic of Mediterranean brackish environments (lagoons, estuaries, deltas) with significant environmental stress, due to changes in the physical-chemical parameters and probably the periodic dredging of this seaway during a period of about 300 years. The presence of "Neptune balls" points to the development of probable stormy periods that deposit these unique structures in the internal areas of this historic port. [ABSTRACT FROM AUTHOR]

The malacological analysis of the Cañada Honda shell midden (Tinto-Odiel estuary, SW Spain) has allowed an approximation of the palaeo biodiversity of this sector during the Mesolithic. During this period, the progressive marine transgression caused the flooding of this estuary, coinciding with an initial intensive capture of the bivalves Lutraria and Ruditapes decussatus in the northern and southern sector of this site, respectively. In a second phase, Ruditapes decussatus was the main collected species in all sectors. This last period coincided with some diversification in catches, still dominated by Ruditapes decussatus but with significant proportions of Cerastoderma edule. This stage witnessed a progressive sedimentary filling of the estuary and the creation of marshes and barrier islands. The almost total fragmentation of the specimens would imply that the surface of this shell midden was exposed for a long time while in use. In addition, an occasional charring of some molluscs has been detected. The main molluscs of this site are also the most abundant in other later shell middens (∼cal 5.2–4 kyr BP), indicating an important perpetuation of the collecting and/or eating habits in this environment. All the species determined in them are also currently found in this estuary and its surroundings, where they are also captured. [ABSTRACT FROM AUTHOR]

The Roman port of Portus was the most important in the Mediterranean during the imperial period (27 BC–476 AD). It was made up of an outer port or Claudius basin and an inner hexagon or Trajan's port, joined by the Canale di Imbocco. The archaeobotanical record obtained in a continuos sediment core taken in this channel is made up of 19 types of plant macroremains, with a predominance of fibers of the seagrass Posidonia oceanica L., replaced by fluvial sediments in the upper part of the core. Seeds, fruits and thorns of aquatic species from marine or brackish waters, halophyte species, edible species, freshwater riparian vegetation and remains of charcoal and wood also appear regularly. According to the inferred palaeoenviromental evolution of this core, Portus was an area of fluvial-marine interaction during the Roman Empire, with brackish water conditions interrupted by stormy periods deduced from the record of P. oceanica. The archaeobotanical and sedimentary evolution points to a restriction of marine contributions and a final implantation of a fluvial environment. In this evolution, a specific interval with abundant charcoal and caryopses of Triticum could correspond to a fire, which was followed by a possible period of greater construction activity linked with large fragments of wood. • Fibers and Neptune balls of Posidonia oceanica dominated the filling of Portus. • The archaeobotanical record indicates an evolution from an initial marine domain to a final fluvial/anthropic phase. • High abundance of Neptune balls are tentatively correlated with stormy periods. • The joint presence of charcoal, caryopses of Triticum and larger wood fragments is associated with a fire. [ABSTRACT FROM AUTHOR]

In recent decades, numerous studies have focused on the paleoenvironmental reconstruction of coastal areas, with special emphasis on the detection of tsunami layers. These multidisciplinary investigations usually do not study the mineralogy of the environment as well as the underlying or overlying layers.This paper analyzes the whole-rock mineralogy and clay minerals contained in seven short cores obtained in the Doñana National Park (SW Spain) and deposited during the 5.000–1.500 cal. yr BP interval.The main purpose is to deduce the paleoenvironments from which the sedimentary facies present in them were formed and an approximation to the transport mechanisms involved in their formation. Results of X-ray diffraction analysis indicate that the main minerals are phyllosilicates, quartz and calcite, with smectites and illite being the most abundant phyllosilicates. According to the whole-rock mineralogy and additional statistical procedures (correlation, cluster analysis), the main source of quartz is the erosion of Doñana spit, while the Guadalquivir river, its tributaries and the old lagoon have contributed mainly with smectite-rich phyllosilicates. On the contrary, waves, tides and high-energy events introduced illite and bioclasts in an old lagoon from the nearby shallow marine sectors. Consequently, the mineralogical analysis is revealed as an interesting tool for palaeoenvironmental reconstruction in this area, since it varies between different sedimentary environments. In addition, the combined study of whole-rock and clay mineralogy detects the tsunami layers and the provenance of their sediments in the studied cores. Unlabelled Image • The mineralogy is a powerful tool to reconstruct sedimentary sources. • In the Roman Lacus Ligustinus, phyllosilicates and smectites were supplied by the Guadalquivir River. • The mineralogy of the outer lagoonal area was controlled by the Doñana spit. • High-energy events caused the introduction of bioclastic quartz-rich sands. • Illite was introduced from the adjacent shelf to the innermost lagoonal zones. [ABSTRACT FROM AUTHOR]