0000000000049501
AUTHOR
Juan Usera
Geographical and bathymetric distribution of foraminiferal assemblages from the Alboran Sea (western Mediterranean)
A total of 176 surface sediment samples, recovered in the Alboran Sea by the oceanographic vessel Vizconde de Eza during the 2002 and 2003 campaigns, were analysed for their foraminiferal content. Planktonic and benthic foraminifera were picked up, studied and classified. In addition, a series of diversity indices were calculated. An attempt was made to correlate diversity (Fisher alpha index) with longitude, latitude and depth. Planktonic assemblages are strongly dominated by the species Globorotalia inflata (d’Orbigny) together with Globigerina bulloides d’Orbigny. Correlation analysis show only a weak relation between planktonic foraminiferal diversity and both longitude and distance to …
Middle Miocene foraminifera from Canals (Valencia, western Mediterranean). Biostratigraphic and palaeoenvironmental aspects
The age and the palaeoenvironmental conditions of the tap marls outcroppings near the locality of Canals in the south of the Valencia Province (E Spain) are discussed. Based on the planktonic foraminifera assemblages, mainly the species Globorotalia praemenardii , these tap marls are dated as Serravallian in age (middle Miocene). The analysis of the foraminiferal assemblages suggests a relatively well-ventilated uppermiddle bathyal environment, with only a moderate oxygen deficiency throughout most of the studied section. The rather cool waters indicated by the planktonic foraminifera (e.g. Globigerina bulloides ) are compatible with the decreasing temperatures trend during the middle Mioce…
Biochronological and paleoenvironmental interest of foraminifera lived in restricted environments: application to the study of the western Mediterranean holocene
As a consequence ofthe Flandrian transgression, numerous littoral lakes were f since roughly 6000 BP in the western Mediterranean coast. This kind of environment is colonized, among other groups, by specialized forms of foraminifera. Some species arose in the Upper Tertiary, some others in the Pleistocene and others are exclusively Holocene. Two kinds ofenvironment are proposed in the colonization: one with very low salinity waters where agglutinated test species prevail and another one with brackish waters, dominated by calcareous test species. In addition, Trichohyalus aguayoi can be considered as an acmezone within the Holocene. We propose a cenozone formed by the following assemblage: A…
Electrochemical characterization of natural gold samples using the voltammetry of immobilized particles
The application of the voltammetry of immobilized particles for characterizing natural gold samples from different geological settings and dating vein deposits is described. This is based on recording characteristic electrochemical oxidation signatures of gold and silver following the attachment of metal sub-microsamples to graphite electrodes. Keywords: Electrochemistry, Gold, Mineralogy, Placer deposits, Vein deposits, Nuggets
Palaeoenvironments and Quaternary foraminifera in the Elx coastal lagoon (Alicante, Spain)
Abstract During the Quaternary, different palaeoenvironments characterised the Elx coastal lagoon (‘Albufera d'Elx’) located in the easternmost sector of the Betic Ranges (SE Spain). Micropalaeontological and sedimentological analysis of three drilled cores allowed characterization of different sedimentary environments, including alluvial, restricted lagoon, lagoon with marine connection, shoreface, foreshore, backshore, swamp, washover fan, and back-barrier flat. A model of the evolution of this region during Marine Isotope Stage (MIS) 7 is proposed, based on chronostratigraphic correlation between the cores. Up to six transgressive episodes can be recognised, mostly represented by calcare…
Una fauna de foraminíferos en el Mioceno continental de la localidad de Buñol (provincia de Valencia)
A fauna of benthonic forarninifera was found in the continental Miocene from Buñol (Valencia, Spain). This fauna was considered as autochthonous, Two species were identified: <i>Rosalina douvillei</i>(CUSHMAN) and <i>Quinqueloculinai seminula</i> (LINNÉ). A few number of planktonic individuals were found. These individuals were refered to the species <i>Globorotalia</i> cf. <i>mayeri</i> CUSHMAN & ELLISOR. The paleoenvironmental characteristics of this outcrops, taken into account the information obtained from benthonic foraminifera, and the bioestratigraphic data obtained from planktonic foraminifera are discussed.<br><br>En e…
Maximum flood area during MIS 1 in the Almenara marshland (Western Mediterranean): Benthic foraminifera and sedimentary record
The sedimentological and micropaleontological analysis of three mechanical cores in the marshland of Almenara (Valencian Community, Spain) has allowed the reconstruction of the Holocene evolution of this wetland. The cold and dry 8.2-ka event might be represented in Almenara by a massive carbonate precipitation bed, upon which mid- and late-Holocene sediments were subsequently deposited. The direct influence of sea-level changes has been recorded in the two cores (S-4 and S-5) located near the marsh barrier, at 400–450 m from the current coastline. The maximum flood area during MIS 1 (last 11,600 years) is represented in these cores by sediments indicative of different littoral subenvironm…
Benthic foraminifera and environmental changes in the Quaternary of the western Mediterranean coast: the core of Xeraco, Valencia, Spain
The evolution of the benthic foraminiferal assemblages from a 60 m core drilled in the Quaternary lagoon of Xeraco (Valencia, Spain) is studied. Two moments of warm climate, high sea-level and maximal marine influence in the lagoon have been identified. The first one at the base of the core, punctuated by highly frequent changes during the Upper Pleistocene, and the other one in the upper end of the series during the Holocene. The presence of a middle core section with low diversity and a nearly total absence of marine foraminifers is interpreted as a regressive interval of cold climate conditions linked to a glacial stage.
Mid-Holocene and historical palaeoecology of the Albufera de València coastal lagoon
espanolLa laguna costera de la Albufera de Valencia es uno de los mayores lagos oligohalinos de la Peninsula Iberica. Fuertemente contaminada y amenazada por planeamientos de desarrollo urbanistico, fue finalmente protegida como Parque Natural en 1986, con el fin de preservar la cubeta y sus ambientes aledanos, los cuales consisten fundamentalmente en arrozales y un bosque sobre la barra arenosa costera. Los planes de restauracion se centran en recuperar la calidad del agua y la cobertura de macrofitos sumergidos que ocupaban la mayor parte de la laguna en los anos 50. Hasta la publicacion de algunos trabajos recientes, se conocia bien poco de la historia paleoambiental esta zona humeda. Co…
Study of the morphological affinity between two species of benthic foraminifera from restricted environments: Rosalina douvillei (Cushman, 1928) and Trichohyalus aguayoi (Bermúdez, 1935)
A biometric comparison is carried out on selected tests of the foraminiferal species Rosalina douvillei (Cushman, 1928) and Trichohyalus aguayoi (Bermudez, 1935). The Rosalina douvillei specimens were recovered from the marginal marine Oligocene/Miocene site of Russingen (Mainz Basin, Germany), the lacustrine beds of the lower Miocene site of Bunol (Valencian Community, Spain) and the middle/ upper Miocene site of Fuendetodos (Aragon, Spain). The Trichohyalus aguayoi tests were collected in the current coastal lagoon of Torreblanca and recovered from Holocene cores sampled in the Peniscola marsh and in the coastal lagoon of l’Albufera de Valencia, all them in the Valencian Community (Spain)…