Mapeamento da ilha da Trindade, Atlântico Sul

The area chosen for this study is the island of Trinidade, which is located 1167 km off the Brazilian coast, in parallel Victory at 20 ° 30'S and 29 º 19'W, being the most easterly point of our continent. The isolation of oceanic island of Trinidade leaves no noticeable that she is part of a large submarine volcanic chain oriented east-west lineament known as Vitória- Trindade. Along with the island of Martin Vaz, who is Federal Territory is administered by the Navy of Brazil. Both correspond to Source alkaline volcanic islands. The area of the island of Trinidad has approximately 10 km2. Geologically consisting ankaratritic spills, spills tannbuschiticos, volcanic tuff spills analcite-ankaratrite, phonolite spills, spills nefelinite, pyroclastics, spills grazinite, tinguaitos, olivine-analcitito, calcarenite dunes and wind according to Almeida (1961). The island has its base on the ocean floor, at 5,800 m depth. It is the only place still recognizes preserved volcanic necks and plugs, as well as remnants of a volcano in Brazil. Magmatism occurred here a sodium alkali-silica subsaturated where his wrist was last 50,000 years according to Almeida (1961). It is a place with restricted access due to their distance from the coast, his contribution and hard to be an exclusive area of the Navy. On the island with peaks occur up to 620 meters high, and its rugged mountainous terrain and difficult access to very specific points, as the peak of Desire, peak Fazendinha, Monument and other points on the island. Because of its location far from the coast, its small infrastructure, difficulty of landing and restricted access by sea, the island of Trinidad offers no possibility of tourism, being a military outpost, and scientific basis of great importance, which conduct research in area of marine biology, oceanography, geology and others

Carbonate cements in contemporaneous beachrocks, Jaguaribe beach, Itamaracá island, northeastern Brazil: petrographic, geochemical and isotopic aspects

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Deformational evolution of a Cretaceous subduction complex: Elephant Island, South Shetland Islands, Antarctica

New structural data from Elephant Island and adjacent islands are presented with the objective to improve the understanding of subduction kinematics in the area northeast of the Antarctic Peninsula. on the island, a first deformation phase, D-1, produced a strong SL fabric with steep stretching and mineral lineations, partly defined by relatively high pressure minerals, such as crossite and glaucophane. D-1 is interpreted to record southward subduction along an E-W trench with respect to the present position of the island. A second phase, D-2, led to intense folding with steep E-W-trending axial surfaces. The local presence of sinistral C'-type sheer bands related to this phase and the oblique inclination of the L-2 stretching lineations are the main arguments to interpret this phase as representing oblique sinistral transpressive shear along steep, approximately E-W-trending shear zones, with the northern (Pacific) block going down with respect to the southern (Antarctic Peninsula) block. The sinistral strike-slip component may represent a trench-linked strike-slip movement as a consequence of oblique subduction. Lithostatic pressure decreased and temperature increased to peak values during D-2, interpreted to represent the collision of thickened oceanic crust with the active continental margin. The last deformation phase, D-3, is characterised by post-metamorphic kink bands, partially forming conjugate sets consistent with E-W shortening and N-S extension. The rock units that underlie the island probably rotated during D-3, in Cenozoic times, together with the trench, from an NE-SW to the present ENE-WSW position, during the progressive opening of the Scotia Sea. The similarity between the strain orientation of D-3 and that of the sinistral NE-SW Shackleton Fracture Zone is consistent with this interpretation. (C) 2000 Elsevier B.V. B.V. All rights reserved.

Early Miocene bivalves from the Cape Melville Formation, King George Island, West Antarctica

Seven species of marine bivalves, including six new taxa, are described from the Cape early Miocene Melville Formation which crops out on the Melville Peninsula, King George Island, West Antarctica. The bivalve assemblage includes representatives of the families Nuculidae, Ennucula frigida sp. nov., E. musculosa sp. nov.; Malletidae, Neilo (Neilo) rongelii sp. nov.; Sareptidae, Yoldia peninsularis sp. nov.; Limopsidae, Limopsis psimolis sp. nov.; Hiatellidae, Panopea (Panopea) sp. cf. P. regularis; and Pholadomyoida (Periploma acuta sp. nov.). Species studied come from four sedimentary sections measured in the upper part of the unit. Detailed morphologic features of nuculoid and areoid species are exceptionally well preserved and allow for the first time reconstruction of muscle insertions as well as dentition patterns of Cenozoic taxa. Known geological distribution of the species is in agreement with the early Miocene age assigned to the Cape Melville Formation. The bivalve fauna from Cape Melville Formation is the best known from Antarctic Miocene rocks, a time of complex geologic, paleogeographic and paleoclimatic changes in the continent. The new fauna introduces new taxonomic and palaeogeographic data that bear oil the question of opening of sea gateways and distribution of Cenozoic biota around Antarctica.

Karyotype of the invasive species Pterois volitans (Scorpaeniformes: Scorpaenidae) from Margarita Island, Venezuela

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)