• journal_title：AAPG Bulletin
• Contributor：Robert M. Sanford ; Frederico W. Lange
• Publisher：American Association of Petroleum Geologists (AAPG)
• Date：1960-
• Format：text/html
• Language：en
• journal_abbrev：AAPG Bulletin
• issn：0149-1423
• volume：44
• issue：8
• firstpage：1316
• section：Articles

The northeast-southwest-trending Parana structural basin attained its present form in the upper Paleozoic. The stratigraphic sequence includes (in addition to Silurian tillites and pre-Silurian metamorphic and crystalline rocks devoid of interest from the standpoint of petroleum possibilities) lower Devonian sandstones and bituminous shales, lower Pennsylvanian glacial deposits with marine intercalations, upper Pennsylvanian and Permian marine sandstones and shales, and Triassic eolian sandstone. A widespread cover of upper Triassic-Jurassic basaltic lavas, over 1,500 meters thick in places, renders most geophysical and geologic exploration methods ineffective. The zone of contact between the Devonian shales and overlying Itarare sandstone, in which oil seeps on both the Andean and eastern basin flanks are assumed to originate, is considered the most favorable objective for exploratory drilling.