RT Journal Article
T1 Fluvial architecture as a response to two-layer lithospheric subsidence during thePermian and Triassic in the Iberian Basin, eastern Spain
A1 López Gómez, José
A1 Arche, Alfredo
A1 Vargas Hernández, Henar María
A1 Marzo Carpio, Mariano
AB The stratigraphy of a sedimentary basin is mainly the result of the long-term response of a depositionalsurface to prolonged subsidence. However, the real nature of interrelations between fluvial architecture andsubsidence is still unknown. Herein, we present new data on these relationships by combining the results ofdetailed sedimentological field work with data acquired through automated forward modelling andbackstripping for the alluvial Permian and Triassic sediments of the SE Iberian Ranges. Using thismethodology, we determined tectonic subsidence of the basin by means of backstripping analysis and crustand lithospheric mantle stretching factors (δ and β, respectively) using forward modelling technique. Resultsindicated that a configuration of two individual and independent layers during lithospheric subsidence foreach tectonic phase fit better for this time of the studied basin evolution than the assumption of subsidencedue to a single layer spanning the whole lithosphere.For this study, we simplified fluvial geometries as two main types: isolated (I) and amalgamated (A), withsubtypes in each case. Different order bounding surfaces (b.s.) were distinguished in the field, although weonly selected those affecting the whole basin under study. These included those b.s. of clear tectonic origin,ranging from individual basin boundary-fault pulses produced over periods of approximately 1 My to thosearising from major tectonic events, such as the beginning of extension in the basin, causing major changes inbasin geometry over periods of 3–5 My.The comparison of δ and β values and fluvial geometries for each identified tectonic phase in the basinevolution, revealed some possible relationship between subsidence and fluvial geometry: Sections showingthe most varied fluvial architectural geometries, including ribbon and nested forms, were related to higherβ and δ stretching factors values indicating tectonic phases of greater stretching and subsidence. When bothstretching factors were similar and close to 1, fluvial geometry was basically reduced to amalgamatedgeometry type. Wider ranging of fluvial geometries was associated with stages of basin development inwhich crust and upper mantle activities differed, that is, showing larger differences of β and δ stretchingfactors values. The related slope changes are proposed as the main surface control of fluvial styles.Combination of subsidence with other possible controlling factors such as avulsion rate, climate or budget ofsediments, gives rise to the definitive alluvial architecture of a basin.
PB Elsevier
SN 0037-0738
YR 2010
FD 2010
LK https://hdl.handle.net/20.500.14352/42470
UL https://hdl.handle.net/20.500.14352/42470
LA eng
DS Docta Complutense
RD 1 may 2024