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Devonian chitinozoan biozones of Western Gondwana

Grahn Y.

Acta Geologica Polonica

2005

Vol. 55, no. 3

211-227

A formal Devonian chitinozoan biozonation for western Gondwana is proposed. This palaeogeographic province corresponds to South America, and was located in medium to high latitudes during the Devonian. Devonian chitinozoans are known from northern Argentina, Bolivia, Brazil and eastern Paraguay. Altogether 230 localities (including wells and outcrops) are included in this study, and 171 species have been encountered. One new species, Angochitina praedensibaculata, is described. A biozonation based on the first occurrence of critical chitinozoan species is introduced. Thirteen biozones are defined: the Angochitina praedensibaculata, Angochitina strigosa, Urochitina loboi, Ramochitina magnifica, Ancyrochitina pachycerata, Ancyrochitina parisi, Alpenachitina eisenacki, Ramochitina stiphrospinata, Fungochitina microspinosa - Ancyrochitina taouratinensis, Hoegisphaera glabra, Urochitina bastosi - Sommerochitina langei, Fungochitina fenestrata and Fungochitina ultima zones.These biozones are compared with known spore zones from the same area, and chitinozoan biozones on a global basis.

Integrated correlation of Late Silurian (Pridoli s.l.) - Devonian chitinozoans and miospores in the Solimoes Basin, northern Brazil

Grahn Y., Łoboziak S., Melo J.

Acta Geologica Polonica

2003

Vol. 53, nr 4

283-300

Chitinozoans from the Late Silurian (Pridoli s.l.) and Devonian, and miospores from the Middle and Late Devonian, have been investigated from the Solimoes Basin in northern Brazil. Of the 37 chitinozoan species encountered, 16 are retained in open nomenclature, because of an insufficient number of well-preserved specomens, and Ramochitina jutaiense is newly described. Three or four miospore zones have been recognized: the LE - LN and VH zones of late to latest Famennian age, and a poorly characterized interval not older than the AP zone of latest Emsian - early Eifelian age. A regional chitinozoan biozonation, consisting of six zones, is proposed for the investigated interval. These zones are, from the oldest to the youngest: concurrent range zone of Ancyrochitina ancyrea and Ancyrochitina aff. A libyensis (Pridoli s.l.); interval range zone of Angochitina filosa (early Lochkovian); concurrent range zone of Urochitina loboi and Ramochitina jutaiense sp.nov. (late Lochkovian); concurrent range zone of Ancyrochitina arirambaense and Alpenachitina eisenacki (Eifelian s.l. - early Givetian); interval range zone of Angochitina mourai (Frasnian - middle Famennian); and total range zone of Fungochitina ultima (late Famennian).