Bosquejo estratigráfico de la región de El Tranco Pontones-Santiago de la Espada (Zona prebética, provincia de Jaén

Some results obtained in the El Tranco-Santiago de la Espada area, located in the Sierras de Cazorla y Segura (Prebetic Zone), are shown in this note. The established series are described and related the one the other. Several importants lacunas and the presence of an intramiocene unconformity are pointed out. A geological scheme are included

Estructuras sedimentarias primarias

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Coastal sedimentary environments and sea-level changes

A detailed knowledge of the 3-D arrangement and lateral facies relationships of the stacking patterns in coastal deposits is essential to approach many geological problems such as precise tracing of sea level changes, particularly during small scale fluctuations. These are useful data regarding the geodynamic evolution of basin margins and yield profit in oil exploration. Sediment supply, wave-and tidal processes, coastal morphology, and accommodation space generated by eustasy and tectonics govern the highly variable architecture of sedimentary bodies deposited in coastal settings. But these parameters change with time, and erosional surfaces may play a prominent role in areas located towards land. Besides, lateral shift of erosional or even depositional loci very often results in destruction oflarge parts ofthe sediment record. Several case studies illustrate some commonly found arrangements offacies and their distinguishing features. The final aim is to get the best results from the sedimentological analysis of coastal units. [RESUMO] o conhecimento detalhado do arranjo tridimensional e das relayoes laterais de facies nos depositos costeiros sao essenciais para definir, corn precisao, as variayoes do nivel do mar, em especial as flutuayoes de pequena escala. Estas fornecem dados uteis para 0 reconhecimento da evoluyao geodinamica das margens das bacias bem como para a pesquisa e explorayao de petroleo. 0 acarreio sedimentar, os processos ondulatorios e de mares, a morfologia costeira e 0 espayo de acomodayao gerado pela eustasia e pela tectonica sao os responsaveis pela arquitectura muito variavel dos corpos sedimentares depositados em arnbientes costeiros. Todavia, estes parametros variam no tempo, e as superficies de erosao podem ter papel importante nas areas proximas do continente. Alem disso, a deslocayao lateral da erosao ou mesmo lacunas sedimentares conduzem, corn frequencia, a destruiyao de parte significativa do registo sedimentar. Apresentam-se exemplos que ilustram alguns arranjos frequentes de facies e os seus parametros caracteristicos corn vista a obter os melhores resultados na analise sedimentologica das unidades costeiras

Sedimentary structures gerenated on the foreshore by migrating ridge and runnel systems on microtidal and mesotidal coasts of S. Spain

The migration of ridge and runnel systems on mícrotidal coasts is a rather simple process starting with the formation of a rídge at the uppcr shoreface after storms and its mígration landwards until it welds onto fue berm. This results in an ideal sequence of structures which ineludes (from bottom to top): cross-laminated sands (runnel facies); cross-bedded sands with local discontinuity surfaces (ridge facies); and even-laminated sands (berm facies). Larger tidal tange and higher wave activity on mesotidal coasts induce a mote differentiated pattern. At early stages of accretion, the ridge is covered at high tide and éxposed at low tide. Swash accumulates a secondary bar of coarse sediment during low water that is removed snd incorporated in the slip face of the ridge by avalanching during rising tídes. At high tide, large amounts of finer sedíment are brought by waves and deposíted on top of the rídge and in the slip face, generating fining-upward sequences. Erosional low-angle discontinuity surfaces develop during falling tides. Within the runnel, longshore currents are strong enough to build up small megaripples with crests roughly normal to the shoreline and waves induce wave ripples with crests more or less parallel to the shoreline. At later stages of accretion, the ridge is submerged mainly during spring high tide. After the runnel has been filled up, a vertical growth of the new berm occurs associated with finíng-upward sequences due to decreasing energy and shoreward shíftíng of swash zones, during the transition from neap to spring tides. The resulting ideal sequence of sedimentay structures is larger and better differentiated han those described for microtidal and tideless coasts

Coastal sedimentary environments and sea-level changes

A detailed knowledge of the 3-D arrangement and lateral facies relationships of the stacking patterns in coastal deposits is essential to approach many geological problems such as precise tracing of sea level changes, particularly during small scale fluctuations. These are useful data regarding the geodynamic evolution of basin margins and yield profit in oil exploration. Sediment supply, wave-and tidal processes, coastal morphology, and accommodation space generated by eustasy and tectonics govern the highly variable architecture of sedimentary bodies deposited in coastal settings. But these parameters change with time, and erosional surfaces may play a prominent role in areas located towards land. Besides, lateral shift of erosional or even depositional loci very often results in destruction of large parts of the sediment record. Several case studies illustrate some commonly found arrangements of facies and their distinguishing features. The final aim is to get the best results from the sedimentological analysis of coastal units

Presentación de "Paleogeografía de la Meseta Norte durante el Terciario"

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Ambientes sedimentarios y facies

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Las "sand waves" calcareníticas del Río Alías (Mioplioceno de la Cuenca de Níjar, Almería)

Las calcarenitas marinas someras del Plioceno del Río Alías se depositaron en un umbral que separaba dos cuencas marinas. Alli migraban distintas formas de fondo movidas por corrientes de deriva, de dirección E-W y sentidos cambiantes, generadas por las tormentas y vientos dominantes en la regió

Sedimentación costera cíclica en Sorbas (Messiniense, SE de España)

Shifts of the shoreline in the Late Messinian Sorbas Member can be correlated with oscillations of the precession index and eccentricity curves. Close inspection reveals three orders of sea level oscillations with variable amplitudes. The first order, with amplitudes of tens of meters,correlates well with oscillations in the Precession Index curve. The second order of fluctuations, with metric amplitudes, fits well in a millennial/submillennial periodicity. The smaller-scaled third order fluctuations,with amplitudes around 0.5 m, are assigned to decadal periodicity. Comparison with examples in SE Spain indicates that the two pervasive smaller scale periodicities persisted since the Late Miocene in Western Mediterranean, independent of the dominant orbital forcing (precession vs. orbital eccentricity).Los cambios costeros registrados en el Miembro Sorbas (Messiniense Terminal) pueden correlacionarse con oscilaciones de las curvas del Índice de Precesión y la excentricidad. Se reconocen tres órdenes de cambios del nivel del mar con magnitudes distintas.Las de primer orden (amplitud: decenas de metros) corresponden a oscilaciones de la curva del índice de precesión.Las de segundo orden (amplitud métrica), encajan en un patrón milenario. Las de tercer orden,con amplitud 0.5 m,se asimilan a periodicidad decenal. Diversos ejemplos muestran que las dos periodicidades menores persisten en el Mediterráneo occidental desde el Messiniense, independientemente del parámetro orbital dominante (precesión o excentricidad).Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)Universidad Complutense de MadridMinisterio de Educación, Cultura y Deporte (MECD)pu