Untitled

Funder

Organizational Unit

Publications

Publication . Estevens, Mário; Ávila, Sérgio P.

Os Açores são bem conhecidos pela sua rica fauna de cetáceos actuais. Menos conhecida, no entanto, é a ocorrência de fósseis de baleias do Neogénico superior em Santa Maria, a única ilha deste arquipélago vulcânico com registo sedimentar significativo. Este trabalho consiste numa revisão do escasso registo fóssil de cetáceos de Santa Maria, incluindo as ocorrências históricas há muito citadas na literatura, bem como outras mais recentes, ainda não publicadas. Todas as 10 ocorrências presentemente reconhecidas provêm do Complexo do Touril, uma unidade sedimentar essencialmente marinha que foi datada, no conjunto, do Messiniano-Zancliano (» 6.0-4.8 Ma). Além de alguns restos menos completos, tentativamente atribuídos apenas a Cetacea indet., os espécimes mais significativos pertencem a grupos maioritariamente pelágicos, que vivem tipicamente em águas oceânicas profundas e abertas (Mesoplodon sp. e ? Balaenopteridae indet.). Na iminência de mais descobertas, os cetáceos do Neogénico superior dos Açores podem vir a revelar-se bastante importantes no estabelecimento de correlações paleobiogeográficas no âmbito do Atlântico Norte, quer devido à localização estratégica do arquipélago quer devido à raridade, nesta região, das associações de cetáceos conhecidas deste intervalo estratigráfico.

2007Journal article

Open access

Neogene Shallow-marine Paleoenvironments and preliminary strontium isotope chronostratigraphy of Santa Maria Islands, Azores

Publication . Kirby, Michael X.; Jones, Douglas S.; Ávila, Sérgio P.

The fossils of Santa Maria Island in the Azores archipelago represent one of the few shallow-marine communities of Neogene age between Europe and North America. Before the evolutionary and biogeographic implications of these fossils can be understood, however, their associated depositional environments and geologic ages must be determined. Here we present preliminary results from sedimentary facies analysis and strontium isotope chronostratigraphic analysis of sediments and fossils from two localities on Santa Maria Island that provide a window into shallow-marine environments and communities within the mid-Atlantic Ocean during the Neogene. Pedra-que-Pica on the southeastern corner of Santa Maria contains strata of fine-grained lithic calcarenite, coquina, and fine- to medium-grained lithic wacke that represent a regressive sequence from transition-zone to foreshore environments. The second locality at Pedreira do Campo on the southwestern-side of Santa Maria contains limestone and fine- to coarse-grained lithic arenite that represent a regressive sequence from shallow bank to shoreface-foreshore environments. Strontium isotopic results from Pedra-que-Pica and Pedreira do Campo indicate that these localities contain fossils that range from late Miocene to late Pliocene in age. Three molluscs collected from the coquina at Pedra-que-Pica have an average 87Sr/86Sr composition of 0.709018±0.000008 that represents an average estimated age of 5.51±0.21 Ma. Three pectinid bivalves collected from the limestone at Pedreira do Campo show a wide range in 87Sr/86Sr ratios, from 0.708885 to 0.709078, which represent estimated ages from 10.03 to 2.24 Ma, respectively. These results help to place the shallow-marine communities of Santa Maria Island into a geologic context that will aid our understanding of how these communities relate to the broader evolutionary and biogeographic history of the Atlantic basin during the Neogene.

2007Journal article

Open access

Illustrated checklist of the infralittoral molluscs off Vila Franca do Campo

Publication . Martins, António M. de Frias; Borges, José P.; Ávila, Sérgio P.; Costa, Ana C.; Madeira, Patrícia; Morton, Brian

A list of the molluscan species dredged during the 3rd International Workshop of Malacology and Marine Biology is presented. Positive identification has not been possible for a number of taxa. However, almost all species are illustrated so as to provide a practical guide to the species which may occur as beach drift and others which naturally range up into the intertidal. The distribution of the species at the various collecting stations is also presented as a table organized by depth, and identifying where specimens were collected alive or, in the case of bivalves, with both valves attached.

2009-09Journal article

Open access

The marine fossils from Santa Maria Island. An Historical overview

Publication . Madeira, Patrícia; Kroh, Andreas; Martins, António M. de Frias; Ávila, Sérgio P.

In the Azores, Santa Maria is the only island with a sedimentary cover in a nine island volcanic system. This southeast most island of the archipelago has a rich fossil record, dated to the Late Miocene-Early Pliocene and to the Pleistocene. Palaeontological investigations on the island started in the late nineteen century. Nevertheless, through the next 150 years, the number of publications and thus the attention given to the fossil record of Santa Maria shows considerable fluctuation over time. From the beginning, the Miocene-Pliocene outcrops, more numerous in the island, focused the attention of the scholars. Recently, however, the interest has shifted to the Pleistocene outcrops. Data obtained from these outcrops has been used extensively in the interpretation and discussion of the Azorean geological genesis and evolution, particularly of Santa Maria, the oldest island of the archipelago. However, its role in the interpretation and discussion of the origin and subsequent evolution of insular marine communities has been meagre. The checklists produced for Santa Maria’s fossiliferous outcrops, account for a large spectrum of represented animal groups. Workers have focused their attention on the molluscs, being the group best represented in the fossil record. Data on other animal groups is still scarce, particularly in case of the Pleistocene outcrops. The fossiliferous beds of Santa Maria are far from being an exhausted matter and further research in the Island should be considered.

2007Journal article

Open access