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Tectonic and climatic controls on the sequential arrangement of an alluvial fan/fan‐delta complex ( M ontserrat, E ocene, E bro B asin, NE S pain)
Author(s) -
GómezPaccard M.,
LópezBlanco M.,
Costa E.,
Garcés M.,
Beamud E.,
Larrasoaña J. C.
Publication year - 2012
Publication title -
basin research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.522
H-Index - 83
eISSN - 1365-2117
pISSN - 0950-091X
DOI - 10.1111/j.1365-2117.2011.00532.x
Subject(s) - geology , paleontology , magnetostratigraphy , alluvial fan , structural basin , subsidence , tectonic subsidence , tectonics , sequence stratigraphy , delta , transgressive , sequence (biology) , sea level , facies , oceanography , aerospace engineering , engineering , biology , genetics
A magnetostratigraphy‐based chronological framework has been constructed in the E ocene sediments of the M ontserrat alluvial fan/fan‐delta complex (southeast E bro B asin), in order to unravel forcing controls on their sequential arrangement and to revise the tectonosedimentary history of the region. The palaeomagnetic study is based on 403 sites distributed along an 1880‐m‐thick composite section, and provides improved temporal constraints based on an independent correlation to the geomagnetic polarity time scale. The new chronological framework together with sequence stratigraphy and geohistory analysis allow us to investigate the interplay between factors controlling the sequential arrangement of the Montserrat complex at the different temporal scales and to test for orbitally driven climate forcing. The results suggest that the internal stacking pattern in transgressive and regressive sequences sets within the more than 1000‐m‐thick M ilany C omposite M egasequence can be explained as the result of subsidence‐driven accommodation changes under a general increase of sediment supply. Composite sequences (tens to hundreds of metres thick) likely reflect orbitally forced cyclicity related to the 400‐kyr eccentricity cycle, possibly controlled by climatically induced sea‐level fluctuations. This study also provides new insights on the deformational history of the area, and shows a correlation between (tectonic) subsidence and forelimb rotation measured on basin‐margin deformed strata. Integration of subsidence curves from different sectors of the eastern E bro B asin allows us to estimate the variable contribution of tectonic loads from the two active basin margins: the C atalan C oastal R anges and the P yrenees. The results support the presence of a double flexure from L ate L utetian to L ate B artonian, associated with the two tectonically active margins. From L ate B artonian to E arly P riabonian the homogenization of subsidence values is interpreted as the result of the coupling of the two sources of tectonic load.