A new ammonoid fauna from the Carnian (Upper Triassic) Kasimlar Formation of the Taurus Mountains (Anatolia, Turkey)

Abstract

We describe a new ammonoid fauna from the Taurus Mountains of southern Turkey. The Carnian ammonoid fauna from As ßa giyaylabel is presented for the first time. Ammonoids were obtained from limestone to marl beds of an approximately 35-m-thick section, which presents the rare opportunity to investigate ammonoid faunas across the Lower-Upper Carnian boundary. Intense sampling near the village of As ßa giyaylabel led to the recognition of a new Lower Carnian (Julian 2) to Upper Carnian (Tuvalian 1) ammonoid fauna from the Kasimlar Formation. The genus Kasimlarceltites gen. nov. is reported for the first time from the Taurus Mountains, which represents the main faunal element and occurs as huge mass occurrence (n ≫ 1 million). Kasimlarceltites krystyni gen. et sp. nov., Klipsteinia disciformis sp. nov. and Anasirenites crassicrenulatus sp. nov. occur within the Lower Carnian Carbonate member (Units A-B) of the Kasimlar Formation from the Taurus Platform Units. Ammonoids described from the marls of the Tuvalian Marlstone member were deposited during a major, Tethyan-wide climate crisis -the so-called Carnian crisis -characterized by a demise of carbonate platforms. Based on the biostratigraphic relevance of certain ammonoid taxa described herein, the age of the analysed parts of the Kasimlar Formation is Julian 2 to Tuvalian 1. The discovery of the new ammonoid assemblages from As ßa giyaylabel substantiates the significance of Upper Triassic faunas within the Taurus Mountains and facilitates the correlation with faunal assemblages from other regions in the Tethyan Realm. The ammonoid fauna and facies indicate a general deepening from open-platform margins, over deeper shelf settings down to an open marine-influenced basinal environment. The tentative habitat for Kasimlarceltites gen. nov. is a shallow platform environment to upper mid-ramp.

Susceptibility and radiometry data used for stratigraphic correlations: case study on Upper Triassic beds in Turkey

“…The Julian/Tuvalian boundary (¼Lower/Upper Carnian boundary) is also clearly observable at AS I, as demonstrated by detailed facies analyses and ammonoid-biostratigraphic investigations (Lukeneder et al 2012, Lukeneder & Lukeneder 2014. Correlatable sections in the vicinity of AS I represent similar sediment sequences, with somewhat different thickness.…”

“…Samples did not receive any special preceding preparation; 152 radiometry measurements were performed in sediments of the Kartoz and Kasımlar Formations at AS I; 155 at AS IV; 81 at KA I; 132 at KA II; and 33 at KA IV. Data were subsequently compared with facies analyses and biostratigraphic data of AS I (Lukeneder et al 2012;Lukeneder & Lukeneder 2014) as well as with sections from nearby localities (AS IV, KA I -II & IV).…”

“…2). The whole 33 m of the Kasımlar log represents a maximum time interval of 1.89 -5.5 Ma (Ogg 2012;Lukeneder & Lukeneder 2014). This big difference in absolute values reflects an extreme divergence of two different chronostratigraphic models used for the absolute durations of the Upper Triassic (Ogg 2012).…”

“…The Kartoz Formation is only marginally represented by the lowermost 1.7 m of the log; this reflects a shallow palaeowater environment (massive limestone-bearing in situ reefs, megalodont bivalves, gastropods, sponges). The Kasımlar Formation, in turn, is represented by at least 33 m, bearing the Carbonate member (Julian 2), the Marlstone member and the Shale member (Tuvalian 1; Lukeneder et al 2012, Lukeneder & Lukeneder 2014Fig. 2).…”

“…Allochthonous biogenic material, for example, thick-shelled bivalves, gastropods and plasticlasts within the pelagic limestones, indicate episodic input of thin (several millimetres-thick) coarse-grained sediment layers from different source areas (proved by the microfacies; see Table 1) of the foreslope or shallow marine ramp (Lukeneder et al 2012). The general deepening of the carbonate ramp at AS I is demonstrated by both the ammonoid biostratigraphy (Lukeneder & Lukeneder 2014) and the facies analysis (Lukeneder et al 2012).…”