Middle Cambrian to Lower Ordovician faunas from the Chingiz Mountain Range, central Kazakhstan

• The middle Cambrian to Lower Ordovician back-arc sedimentary succession studied in the Kol'denen River and in the Zerbkyzyl Mountains of the central Chingiz Mountain Range is composed predominantly of siltstones, sandstones and volcaniclastic rocks with rare beds of micritic carbonates, black shales and cherts. Fossil assemblages including conodonts, lingulate brachiopods, arthropods, sponges and probable Tasmanites cysts were recorded both from the carbonate and chert beds showing that richly diverse marine environments existed directly adjacent to the volcanic arcs. The Kol'denen River localities contain a diverse upper Cambrian paraconodont assemblage of the open-sea affinity. The representatives of Rossodus, Cordylodus, Drepanodus and Variabiloconus, having an almost pandemic distribution and characteristic of basinal facies, dominate the Lower Ordovician conodont fauna. The Cambrian-Ordovician boundary transition is characterized by chert production that was more likely caused by a local productivity increase than by general changes in palaeooceanographic and palaeogeographical conditions.

Subject headings

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geology (hsv//eng)

Keyword

biostratigraphy

conodonts

siliceous deposits

upper Cambrian

Lower Ordovician

central Kazakhstan

Historical geology and palaeontology

Historisk geologi och paleontologi

Historical Geology and Paleontology

Historisk geologi och paleontologi

Publication and Content Type

ref (subject category)

art (subject category)