About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 901

Last Page: 901

Title: Miocene Reef at Baixo, Porto Santo (Eastern Atlantic): ABSTRACT

Author(s): Maya W. Best

Article Type: Meeting abstract


In the eastern Atlantic Ocean, living hermatypic scleractinian corals which contain zooxanthellae are found only on the Cape Verde archipelago and the volcanic islands in the Gulf of Guinea. In the same region, the islands of Madeira and Porto Santo, with its outliers Baixo and Cima, yield similar hermatypic scleractinian corals of Miocene age. Porto Santo is almost entirely volcanic, but coral reefs were established there in the Miocene. Recent study has revealed interesting facts regarding the reef's paleoecology and stratigraphy.

The environment of the Porto Santo reefs in Miocene time appears to be similar to that of reefs which colonized the submarine slopes of Krakatoa (West Java) seven years after its great eruption. In that example, the corals suffered much from tephra deposition on the sea floor. The Baixo locality, however, is situated at the outermost fringe of the Porto Santo volcano. It is conceivable that this spot was less affected by tephra deposition than other localities, so that the Baixo coral fauna is far more diverse than any other Porto Santo locality. So far, nine hermatypic and nine ahermatypic coral genera have been found in this fossil reef. Two hermatypes have branching colonies (Pocillopora and Stylophora), one is ramose or massive (Porites), and the other six (Acanthastrea, Montastre , and the Haliastrea group) are massive reef constructors. Pocillopora, originally described as a tabulate coral by Mayer in 1864, is the most important coral of the Baixo reef. The presence of these reef-building corals in the eastern Atlantic in the Miocene also sheds new light on the evolution and paleozoogeography of the Tethyan coral fauna, especially after the Tethys Ocean was severed by tectonic movement in the late Miocene.

End_of_Article - Last_Page 901------------

Copyright 1997 American Association of Petroleum Geologists