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Volume n° 2 - from B16 to B33 B16 B16 - Leaders: R. Bourrouilh, L. Moen-Maurel, J. Muñoz, A. Teixell Field Itinerary DAY 1 Pau Welcome to the fi eld trip and the Pyrenees By R. Bourrouilh, L. Moen-Maurel, J. Muñoz And A. Teixell. Briefi ng and introduction to the Field Trip. Stop 1.1: Panorama of the Pyrenees : fi gure 1.1. I. A transect of the northern pyrenees By R. Bourrouilh* and L. Moen-Maurel**, *Laboratoire CIBAMAR, Université de Bordeaux 1, Avenue des Facultés, 33405 Talence Cedex, France, e-mail : r.bourrouilh@cibamar.u-bordeaux1.fr ** TOTAL, 64018 Pau Cedex, France, e-mail : laure.moen-maurel@total.com DAY 2 from Pau to Oloron Sainte Marie Stop 2.1: Le Tucq : the North-Pyrenean margin and the Upper Cretaceous fl ysch : fi gures 2.1 a, 2.1 b, 2.1 c, 2.1d Introduction: the South Aquitaine margin developed as a passive rifted margin during the opening of the Bay of Biscay. The N-Pyrenean rifted basins were created and fi lled by syn-rift Lower Cretaceous black shales. During Cenomanian (-96 Ma), rifted basins merged in a long and narrow furrow or the N-Pyrenean basin or trough, which was rapidly fi lled up by synrift and drift calcareous Cretaceous Flysch. However, the area underwent compressional tectonics as recently as 80 Ma ago, during the Late Cretaceous and the furrow rapidly retreated westwards, from 80 Ma to today, forming, up to now, the modern Bay of Biscay. The North-Pyrenean fl ysch sedimentation, can reach 7 km in thickness. The section studied in this Stop pertains to Upper Cretaceous-Paleocene sedimentation (but the KT limit is now covered by road work) which is coeval with the closure of the basin, and the westward progradation of the silici-clastic Paleocene sedimentation. Access: the Stop is on the D 934, on the right side of the road, just at the locality “Le Tucq”. The outcrop section is located in the curve of the road (fi gure 1.1a) and the measured section (fi gure 2.1b, Tucq section and 2.1c, Guillampeau section) along the side of the adjacent car track. Structural and sedimentological landscape: the D Figure 1.1 - Geological view of the Pyrenees, from the Boulevard des Pyrenees, Pau.
WESTERN PYRENEES FOLD-AND-THRUST-BELT: GEODYNAMICS, SEDIMENTATION AND PLATE BOUNDARY RECONSTRUCTION FROM RIFTING TO INVERSION B16 Figure 2.1a - Flysch section at Guillampeau, top is on the right. 934 crosscuts the Upper Cretaceous fl ysch. The curve of the river, as well as that of the road are provoked by the top of the Upper Cretaceous fl ysch, containing large white mudstone mudfl ows, as well as reworked Triassic (fi rst diapiric) gravity slabs mass-fl ows, silici-clastic mass fl ows etc. In the landscape, the curve is marked by an old chalk oven, and prolonged by a smooth wooded cliff. Along the western side of the road two fi eld sections have been measured in the gently north-dipping turbiditic and mass-fl ow sequences with internal slumps (Bourrouilh, Montagné and Doyle, 1993, unpublished data). The fi rst one, or the Tucq section is just on the curve of the road, in front of the Tucq restaurant, but is now covered by road work (fi gure 2.1b): The Upper-Cretaceous to Paleocene section is 27 m thick and represents a mixed silici-clasticcarbonate sedimentation. Five sedimentary units can be distinguished. On the four basal units, the sedimentation is mainly constituted by successive silici-clastic mass-fl ow deposits, reworked mudstones Figure 2.1ca - measured section 1 at Guillampeau, from R.Bourrouilh et al., 1993, unpub. data. Figure 2.1b - measured section at Le Tucq, from R.Bourrouilh et al., 1993, unpub. data. and anoxic mud clasts, and by silici-clastic Boumatype turbidites. Measured sedimentary fold axes are, successively, from bottom to top : N 60°, dip 35°E (unit 2, lower part), N 83°, dip 10° SE (small slump, unit 3), N 175° (large slump, unit 3), N 90° to 110° (clast, base of unit 4), N 115°, dip 25°N, (base of unit 5), N 115°, dip 22° N-NE. However, carbonate gravity sedimentation comes back again and forms unit 5, considered the base of a large carbonate mud-fl ow. Figure 2.1cb - measured section 2 at Guillampeau, from R. Bourrouilh et al. 1993, unpub. data. 21 - B16 Volume n° 2 - from B16 to B33
Page 1 and 2: Field Trip Guide Book - B16 Volume
Page 3 and 4: Volume n° 2 - from B16 to B33 32 n
Page 5 and 6: WESTERN PYRENEES FOLD-AND-THRUST-BE
Page 21: WESTERN PYRENEES FOLD-AND-THRUST-BE
Page 37 and 38: the North- WESTERN PYRENEES FOLD-AN
Page 67 and 68: Back Cover: Itinerary of the fi eld

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