Elvio Pinto Bosetti

Remarks on sequence stratigraphy and taphonomy of the Malvinokaffric shelly fauna during the KAČÁK Event in the Apucarana Sub-basin (Paraná Basin), Brazil

The Eifelian–Givetian (Middle Devonian) transition constituted an important paleoenvironmental event for the Malvinokaffric Realm in the Apucarana Sub-basin (Paraná Basin). This study highlights integration between taphonomy and sequence stratigraphy, and four depositional sequences are identified during the transition. In Sequence 1, the presence of a typical normal-sized Malvinokaffric fauna is recorded. In the transgressive systems tract (TST) of Sequence 2, no benthic fossils are present, and this is interpreted as a stratigraphic marker of an event of significant paleoenvironmental change (KAČÁK Event). In Sequence 3, the TST has abundant bioclasts, which become rarer toward the top of the section, i.e., within the transgressive systems tract. The original habitat of this autochthonous to parautochthonous fauna was a low-energy environment between the fair weather wave base and the storm wave base of the Devonian epicontinental sea. In the highstand systems tract of this sequence, the presence of normal-sized Pennaia paulianna and lingulids demonstrates the return of more ambient conditions. Sequence 4 is of Carboniferous age. Its limit is a second-order sequence boundary recording a lowstand systems tract formed by a fluvial depositional system. The low diversity and the disappearance of taxa are not the result of a taphonomic bias, but reflect the post-KAČÁK Event.

The North American geologist Walter Karl Link and oil exploratory research at Petrobras (1954–1960)

The necessity of petroleum and the challenges related to oil exploration in Brazil caused the country in 1953 to create Petrobras, the Brazilian oil company, and to hire a foreigner work force. The company hired the North American geologist, Walter Karl Link (1902–1982), to be the head of the Department of Exploration, one of the most important and promising departments of Petrobras. In that position, Link faced not just countless technical difficulties but also personal ones during the six years (1954–1960) that he worked for the company. The aim of this article is to demonstrate how the Department of Exploration contributed to the consolidation of Petrobras over the six year period and how Petrobras became a model for other companies.