An Early to Middle Miocene Magnetostratigraphy From the Ebro Basin (NE Spain)
Abstract
The Ebro Basin represents the last stage of evolution of the south-pyrenean foreland, which formed since the late Cretaceous as a result of northwards subduction and collision between the Iberian and the European plates. The basin evolved into a land-locked configuration by the latest Eocene when continued compression led to closing of its NW marine gateway. Filling of the basin continued from late Eocene to the late Middle Miocene, leading to the accumulation of a thick sequence of alluvial and lacustrine sediments. In the middle-to-late Miocene the basin opened towards the Mediterranean and river incision cut through the complete Eocene to Miocene sedimentary succession. Nearly undeformed Early to Middle Miocene units crop out extensively in the central parts of the basin and have delivered a long and continuous magnetostratigraphic record. Considering the time resolution achievable with magnetostratigraphy, the numerous studies on the sedimentary sequences of the Ebro Basin provide compelling evidence for stratigraphic completeness and relatively steady sedimentation over the Oligocene-Miocene time interval. The perfect match with the geomagnetic polarity time scale provides a robust and high resolution chronology for the late stages of basin infill, allowing cyclostratigraphic analysis to be made as well as correlation with the various records of regional to global climate change. Noticeably, the Early- Middle Miocene boundary corresponds in the central Ebro Basin with a remarkable and sharp transition from a marly-gypsiferous to a carbonate unit. It represents a significant environmental change from a dry period dominated by a hipersaline water body to a wetter period with rapid installation of an areally extensive carbonate lake. Magnetostratigraphic data indicates that this period of lacustrine expansion is simultaneously recorded in other basins of the Iberian Plate and corresponds to the climatic optimum of the Langhian stage that preceeded the middle Miocene global cooling.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2007
- Bibcode:
- 2007AGUSMGP52A..08G
- Keywords:
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- 1520 Magnetostratigraphy;
- 1535 Reversals: process;
- timescale;
- magnetostratigraphy;
- 9605 Neogene