New observations on Cretaceous carbonate-siliceous successions in Sahlabad province (Sefid Abeh basin), Eastern Iran

ABSTRACT

The Sahlabad province is located within Sistan ocean in eastern Iran. This province is known for its variety of deposits from Cretaceous to Eocene times. This study is focused on the radiolarian and planktic foraminiferal assemblages during Cretaceous age. Two distinct sections (sections A & B at Kuh-e-Atashkadeh) are reported from ultrabasic rocks, interbedded planktic limestone and red radiolarian siliceous sedimentary rocks. The studied radiolarian assemblages in section A and section B yielded Turonian and Late Aptian ages, respectively. The various species of planktic foraminifera have been used to produce a biozonation through the Turonian to Campanian. Four biozones are recognized from the Upper Turonian to the Lower Campanian in the section A and five biozones are distinguished in the section B. The identification of specimens is based on microscopic observations of thin sections. The definitions of the biozones are given following the works of Caron (1985), Sliter (1989), Premoli Silva and Sliter (1994) and Robaszynski and Caron (1995). The Aptian radiolarian age is the oldest obtained from the red argillaceous chert all this province and has important implications for the rifting/openinig age of Sistan suture zone