Palinspastic Reconstruction Versus Cross‐Section Balancing: How Complete Is the Central Taurides Fold‐Thrust Belt (Turkey)?

Abstract

In many fold‐thrust belts, cross section–derived shortening estimates are significantly lower than predicted based on plate convergence. This has led to controversial hypotheses that shortening may be largely underestimated due to wholesale underthrusting (convergence without shortening) below far‐traveled continent or ocean‐derived nappes. The Late Cretaceous‐Eocene Taurides fold‐thrust belt (southern Turkey) may contain a highly incomplete shortening record of convergence likely caused by wholesale underthrusting. To estimate this underthrusting, we calculate convergence across the belt using a map‐view palinspastic reconstruction that takes into account major rotations of tectonic units during their accretion. We use paleomagnetic and fault kinematic analysis, timing of accretion, and Africa‐Eurasia convergence to constrain our reconstruction. Our paleomagnetic results confirm an ~40° clockwise vertical axis rotation of the Geyikdağı nappe that forms the core of the belt, which we interpret is accommodated by a lateral gradient in underthrusting on faults structurally above and below the Geyikdağı nappe. We reconstruct ~400–450 km of convergence across the Taurides during their accretion. We compare this predicted convergence to shortening calculated from balanced cross sections, in which we reconstruct a minimum of 154‐km shortening: 57 km within far‐traveled nappes, 70‐km thrusting of far‐traveled nappes over the Geyikdağı nappe, and 27‐km shortening within the Geyikdağı nappe. Shortening in the Taurides created a significant nappe stack, but the majority of convergence was accommodated by wholesale underthrusting with barely a trace at the surface, including ~160 km of convergence by rotation of the belt, and 90–130 km related to missing Africa‐Eurasia convergence.

Benthic foraminifera from the Albian shallow-marine limestones in the Geyik Dağı area (Central Taurides), southern Turkey

“…The Maastrichtian to Lutetian cherty pelagic limestones (Kuşca Limestone) also occur in a separate tectonic slice of the Yıldızlı Dağ Unit (Özgül, 1997). On the other hand, McPhee et al (2018) called the same rock assemblages the Geyikdağı nappe, which was deformed by a thin-skinned thrust fault imbricate system that affected the uppermost Mesozoic carbonates and by a deeper thrust duplex system that incorporates Ordovician and older basement rocks. During field work in the Geyik Dağı area, we have observed two carbonate successions of different paleoenvironmental settings separated by faults: one of them contains orbitolinid and rudistid bioclastic limestones of Cenomanian age (cf.…”

“…The Cretaceous platform carbonates in the Geyik Dağı area represent a part of the so-called L'Axe Calcaire du Taurus (Ricou et al, 1975), Anatolide-Tauride Carbonate Platform (ATCP) (Şengör and Yılmaz, 1981), Taurus Carbonate Platform (Koçyiğit, 1981), Menderes-Taurus Platform (Görür and Tüysüz, 2001), Menderes Carbonate Platform (Vlahović et al, 2005). Most previous works on the Geyik Dağları range aim to explain its complex geological and tectonic evolution (e.g., Özgül, 1976, 1997; McPhee et al, 2018), except for Özer and Kahrıman (2019), in which Cenomanian canaliculate rudists were documented. In the Anamas-Akseki area, which is the continuation of the Geyik Dağları range to 65 km northwest, there are few studies on the detailed biostratigraphy and facies of the Cretaceous platform carbonate sequences (e.g., Martin, 1969; Monod, 1977; Altıner et al, 1999; Solak et al, 2017, 2019; Solak, 2019).…”

Thermal history of the western Central Taurides fold-thrust belt: Implications for Cenozoic vertical motions of southern Central Anatolia

“…The Aladağ and Bolkardağı nappes, and overlying Bozkır nappes, were thrust at least 70 km southwestward over the Geyikdağı nappe, as shown by tectonic windows and klippen (McPhee et al, 2018a). McPhee et al (2018aMcPhee et al ( , 2018b observed that the Geyikdağı nappe is internally deformed and interpreted a thin-skinned style of thrusting based on widespread flat-on-flat thrust contacts, tectonic windows and re-entrants, and klippen. This thrusting produced the Derebucak thrust imbricate toward the foreland (west) and a duplex that is enveloped by the Seydişehir anticline toward the hinterland (east) (Fig.…”

“…Structural constraints suggest the Beydağları platform was underthrusted below the Geyikdağı nappe by a minimum of a few kilometers in Eocene time (McPhee et al, 2018a). On the other hand, palinspastic restorations that incorporate paleomagnetic constraints suggest up to some tens of kilometers of Eocene underthrusting (McPhee et al, 2018b).…”

“…The Central Taurides comprise a Late Cretaceous to late Eocene forearc fold-thrust belt, which formed in the upper plate of the Cyprus and Antalya subduction zones (McPhee et al, 2018a(McPhee et al, , 2018b. The Central Anatolian Plateau interior corresponds to a Late Cretaceous to middle Eocene backarc extensional province (Gürer et al, 2018b) that was active during the formation of the Taurides forearc foldthrust belt, and is characterized by a kilometer-high average elevation, low topographic relief, and an extensive internal drainage system.…”