Abstract
An Eocene mud‐mound outcrops within a shallow‐water carbonate‐siliciclastic shelf sequence located close to the southern (foreland) margin of the Pateogene southern Pyrenean foreland basin. Outcrops are approximately perpendicular to the shoreline and permit a shore‐to‐basin reconstruction of palaeoenvironments.
The small (less than 2.5 m thick and less than 120 m wide) carbonate mud‐mound overlies deltaic sandstones. The main lithologies within the mound are nodular wackestones and nummulitic marls. Seaward and central areas are characterized by wackestones arranged in aggradational and progradational convex‐up beds. Branching corals are scattered within the mound but are not preserved as a framework. The shoreward margin is characterized by wackestones (with corals) which are repeatedly cut by scour surfaces. Scour surfaces are infilled with nummulite marls and bedded wackestones with scattered corals. These interfinger with the mound‐core wackestones. Each marl and bedded wackestone is overlain by retrogradational wackestones of the mound.
Bioclastic grains include coral, foraminifera, mollusc, bryozoan and coralline algal debris, which, together with detrital quartz, are set in a micritic matrix. The matrix is composed of low‐Mg calcite micrite and microspar with minor dolomite and quartz with no identifiable microbial/algal filaments. There are no indications of early cementation of the micrite, early cavities or early cements. The muds appear to have been mainly generated as biodetrital grains which were physically deposited. Corals show neomorphism or a mouldic porosity and spar infill.
The occurrence of presumed storm‐generated erosional scours and marls on the shoreward side indicate that this was also the windward margin. The mound therefore had the same environmental setting, size and composition as the Recent biodetrital mounds of Florida Bay.
The small (less than 2.5 m thick and less than 120 m wide) carbonate mud‐mound overlies deltaic sandstones. The main lithologies within the mound are nodular wackestones and nummulitic marls. Seaward and central areas are characterized by wackestones arranged in aggradational and progradational convex‐up beds. Branching corals are scattered within the mound but are not preserved as a framework. The shoreward margin is characterized by wackestones (with corals) which are repeatedly cut by scour surfaces. Scour surfaces are infilled with nummulite marls and bedded wackestones with scattered corals. These interfinger with the mound‐core wackestones. Each marl and bedded wackestone is overlain by retrogradational wackestones of the mound.
Bioclastic grains include coral, foraminifera, mollusc, bryozoan and coralline algal debris, which, together with detrital quartz, are set in a micritic matrix. The matrix is composed of low‐Mg calcite micrite and microspar with minor dolomite and quartz with no identifiable microbial/algal filaments. There are no indications of early cementation of the micrite, early cavities or early cements. The muds appear to have been mainly generated as biodetrital grains which were physically deposited. Corals show neomorphism or a mouldic porosity and spar infill.
The occurrence of presumed storm‐generated erosional scours and marls on the shoreward side indicate that this was also the windward margin. The mound therefore had the same environmental setting, size and composition as the Recent biodetrital mounds of Florida Bay.
| Original language | English |
|---|---|
| Title of host publication | Carbonate Mud‐Mounds |
| Subtitle of host publication | Their Origin and Evolution |
| Editors | C L V Monty, D W J Bosence, P H Bridges, B R Pratt |
| Publisher | Wiley |
| Chapter | 15 |
| Pages | 421-437 |
| Number of pages | 17 |
| ISBN (Electronic) | 9781444304114 |
| ISBN (Print) | 9780865429338 |
| DOIs | |
| Publication status | Published - 17 Jul 1995 |