Mud-Mounds with Reefal Caps in the Upper Muschelkalk (Triassic), Eastern Spain
- C. L. V. Monty,
- D. W. J. Bosence,
- P. H. Bridges and
- B. R. Pratt
Published Online: 14 APR 2009
Copyright © 1995 The International Association of Sedimentologists
Carbonate Mud-Mounds: Their Origin and Evolution
How to Cite
Calvet, F. and Tucker, M. E. (1995) Mud-Mounds with Reefal Caps in the Upper Muschelkalk (Triassic), Eastern Spain, in Carbonate Mud-Mounds: Their Origin and Evolution (eds C. L. V. Monty, D. W. J. Bosence, P. H. Bridges and B. R. Pratt), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304114.ch10
- Published Online: 14 APR 2009
- Published Print: 17 JUL 1995
Print ISBN: 9780865429338
Online ISBN: 9781444304114
- mud-mounds reefal caps;
- Silicification, producing centimetre-size nodules;
- Platy calcareous algal subfacies;
- massive-tabular and branching;
- dasyclad grainstones;
- bioclastic packstones;
- laminated units
In the Catalan Ranges of north-eastern Spain, distinctive mud-mounds are present in the upper Muschelkalk (Ladinian, Middle Triassic) of the Prades Domain in the La Riba Stratigraphic Unit. The mounds are 5–60 m in height and several hundred metres across. Some mounds are linear structures with a north-east-south-west orientation, parallel to the palaeostrike of the basin and up to 2 km in length. Others are more discrete, isolated mounds, circular in plan view. The mounds, which are completely dolomitized, consist of massive to mottled lime mudstone to packstone, with a peloidal texture. Skeletal grains and ‘Tubiphytes’-type colonial organisms occur locally in the mound-core facies. A grainstone-packstone skeletal-peloidal bank occurs at the base of some mounds, and lenses of coarser skeletal sediment and small patches of ‘Tubiphytes’-microbial crust boundstone are present within the core.
In many cases the mounds developed into reefal complexes with a boundstone facies forming a cap to the mounds, and debris beds and patch reefs developed on the flanks. The reefal facies consists of coral (Thecosmilia) framestone, coral-‘Tubiphytes’-microbial-crust boundstone, ‘Tubiphytes’-microbial crust boundstone, platy algal boundstone, sponge framestone and skeletal-peloidal grainstone-packstone. Marine cements are prominent in the flank and reefal facies and at some localities include former aragonite botryoids and isopachous acicular calcite crusts. Several metres of bedded dasyclad grainstone and peritidal lime mudstone with stromatolites, tepees, vadose pisoids and floe calcite occur on the tops of the larger mud-mound-to-reefal complexes. In some instances clinoforms of mound-top debris prograded several hundred metres in a leeward direction. The intermound facies consists solely of a 0.1–0.5 m thick bioclastic peloidal wackestone-packstone, equivalent to up to 60 m of build-up.
The La Riba mud-mound to reefal complexes evolved during a highstand systems tract on a carbonate ramp and were terminated by a phase of emergence and development of a palaeokarstic surface, which is related to the lowstand systems tract of the succeeding sequence. The La Riba build-ups are some of the best developed in the Muschelkalk of western Europe and are interesting in that they show affinities with some of the Tethyan reefs of the Alpine-Mediterranean area.