Abstract

This paper presents a depositional model for a temperate, low-energy carbonate ramp based on descriptive studies of five areas around the Balearic Islands of Mallorca and Menorca. This low-energy ramp differs significantly from other present-day temperate carbonate platforms that are primarily high-energy open shelves. It is characterized by the following lithofacies (from shore to basin): (1) lagoon, (2) barrier island, (3) shallow subtidal, (4) inner ramp, (5) middle ramp, and (6) distal ramp. Subaqueous carbonate dunes are present near slope breaks off Menorca and Cabrera, but they are not representative of the entire ramp. Balearic ramp sediments differ in composition, texture, biology, and degree of cementation from those on modern low-energy, tropical ramps. Balearic ramp carbonates lack ooids and peloids, hermatypic coral buildups, and calcareous green algae (except in one restricted bay where Halimeda is relatively common). Red algal sands and gravels extend to depths of up to 90 m, and are coarser than their strandplain-equivalent lime sands. Skeletal allochems consist of the bryomol-rhodalgal association, marine cementation is rare, and the carbonate fraction of deep-water muds is mainly Mg-calcitic and calcitic in composition. Aragonite is rare. Except for the red alga Peyssonnelia, which is composed of aragonite, it is neither a dominant skeletal constituent nor common as a cement. The Mediterranean Sea off Mallorca and Menorca is a low-energy, temperate, oligotrophic, clear-water environment. The depositional model for the region is an isolated platform configured as a homoclinal ramp. Ancient counterparts of the Balearic ramp are present in the Neogene of the Mediterranean Tethys and the Paratethys, and though the constituents of fossil assemblages vary with time, the biota of the Balearic ramp, such as bryozoans, red algae, echinoderms, and mollusks, ranges from the Paleozoic Era to the present. Echinodermal bryomols passing to basinal muds on carbonate ramps are particularly characteristic of the Early Carboniferous in North America and Europe. This suggests that the Balearic Islands temperate ramp may be more representative of some ancient carbonate sequences than either temperate, high-energy, open shelves or tropical ramps in the present oceans.

First Page Preview

First page PDF preview
You do not currently have access to this article.