Sequence Analysis of a Marine Gilbert-Type Delta, La Miel, Albian Lunada Formation of Northern Spain
- Albina Colella2 and
- David B. Prior3
Published Online: 2 APR 2009
Copyright © 1990 The International Association of Sedimentologists
How to Cite
García-Mondéjar, J. (1990) Sequence Analysis of a Marine Gilbert-Type Delta, La Miel, Albian Lunada Formation of Northern Spain, in Coarse-Grained Deltas (eds A. Colella and D. B. Prior), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303858.ch14
Universita della Calabria, Italy
Atlantic Geoscience Center, Nova Scotia, Canada
- Published Online: 2 APR 2009
- Published Print: 19 OCT 1990
Print ISBN: 9780632028948
Online ISBN: 9781444303858
- Lunada formation;
- Mesozoic Basque-Cantabrian region;
- Peri-Asturian domain, comprising Lower Cretaceous rocks;
- tectonism, controlling La Miel delta;
- short-term sea-level fluctuations, account for origin of sequences;
- Albian tectonic movements
The marine Gilbert-type delta of La Miel, at the base of the Albian Lunada Formation of north Spain, is about 2 km long, 1 km wide and 70 m thick, and consists of sandstones and small quartz-pebble conglomerates. From a section along the axis of the delta, six deltaic and two predeltaic sequences bounded by erosional unconformities have been distinguished. There are several genetic units of deltaic progradation, marine and fluvial aggradation and lateral marine accretion within the sequences, and each genetic unit is made up of one or more facies representing sedimentary environments that range in character from comparatively deep marine (tens of metres) to fluvial. The progradational Gilbert-type units have bottomsets and foresets but rarely topsets; the aggradational units are either shallow marine with corals or fluvial with braided channels; and the marine lateral accretion units are made up of pre-existing facies reworked by tides and waves.
Correlation of the La Miel sequences with others from different outcrops suggests an allocyclic origin for all of them. Short-term, relative sea-level variations, probably tectonically induced, are thought to have been responsible for both the sequences and the genetic units and facies within them. The sequences can be described by sequence stratigraphy (systems tracts) methodology.
The delta of La Miel is considered a part of a major system prograding towards the NW, the Valnera braidplain delta front, made up of several Gilbert-type contemporaneous lobes.