%0 Journal Article
%A Alonso Zarza, Ana María
%A Calvo Sorando, José Pedro
%T Palustrine sedimentation in an episodically subsiding basin:the Miocene of the northern Teruel Graben (Spain)
%D 2000
%@ 0031-0182
%U https://hdl.handle.net/20.500.14352/59021
%X Lacustrine deposits form most of the sedimentary record accumulated throughout the Miocene in the northernpart of the Teruel Graben, a landlocked basin situated in NE Spain. Three main stratigraphic units ( Units I–III )spanning Late Vallesian to Late Turolian in age, are distinguished in the area. The two former units comprise mainlycarbonate lacustrine deposits that were deposited in a palustrine or a more permanent but shallow lacustrine setting,the latter being related mainly to periods of lake expansion under more humid and cooler climatic conditions. Incontrast, deposition of Unit III, characterised by gypsiferous lacustrine sediments in central parts of the basin, reflectsthe influence of source rocks of evaporitic nature (Upper Triassic formations) that were emplaced by diapiric upliftin the eastern margin during the Middle Turolian. Carbonate lake sediments belonging to Units I and II consist offour main lithofacies associations: (a) distal–alluvial lake margin deposits; (b) lacustrine carbonates and pedogenicallymodified lacustrine carbonates; (c) carbonate fill channels; and (d) organic-rich marlstone and carbonate (marshes).Lithofacies association (a) shows typically a sequential arrangement formed, from bottom to top, of red mudstone,carbonate palaeosols and biomicrite beds (sequence type 1a). These sequences are interpreted as a result of slow butcontinuous aggradation of the floodplain areas and subsequent rise of the water table, probably reflecting equilibriumbetween subsidence and sedimentation. Lithofacies association (b) consisting of biomicrite beds passing upward intopalaeosols (sequence type 1b) is thought to be caused by marked pulses of tectonic subsidence that created theaccommodation space required for fast development of a carbonate lake. Carbonate fill channels, showing erosivelower surfaces dig out on previous channels, marsh deposits and/or lacustrine carbonates, exhibit well-developedprismatic structure at their bed tops. The sequential arrangement suggests similar tectonic constrains than theenvisaged for lithofacies 1b. The comparison of depositional styles of the lake systems with the palaeoclimaticevolutionary pattern of the basin throughout the Miocene indicates that the combined effect of tectonism, climateand source rock played a major role in the stratigraphic framework of the basin during this period.
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