Geochemistry and petrogenesis of the diabase dykes from the Boğazkale region (Çorum, Central Anatolia)

Balcı, Uğur
The Izmir-Ankara-Erzincan (IAE) Suture Belt contains oceanic and continental fragments derived from the northern branch of Neotethys and associated continental entities. In the Boğazkale region (Çorum, Central Anatolia), the pieces of Neotethyan oceanic lithosphere are present in a chaotic manner, and form an ophiolitic mélange. Diabase dykes are observed in the mélange, which cross-cut various rock types of oceanic lithosphere, such as pillow basalts, gabbros and ultramafics. This study aims to investigate the geochemical and petrogenetic features of the diabase dykes, and their importance in the Neotethyan framework. The investigated diabases are mainly made up of plagioclase and a mafic phase, which is clinopyroxene and/or hornblende. According to predominating mafic mineral phase, the diabases can be subdivided into two types as clinopyroxene- and hornblende-diabase. Sub-ophitic textures are common in all clinopyroxene-diabase samples and poikilitic texture in almost all hornblende-diabase samples. Both types are variably modified by low-grade hydrothermal alteration as reflected by the presence of secondary minerals, such as chlorite, epidote, prehnite and actinolite. vi The immobile trace element systematics reveals two chemical types, which seems consistent with the petrographical grouping. Both chemical types display sub-alkaline basalt characteristics. The relationship of MgO with some major and trace elements suggest that fractional crystallization was important in the magmatic evolution of the dykes. One of the major differences between two types is that while Type 2 diabases possess negative Nb anomalies, this feature is not observed in Type 1. In addition, Type 1 diabases are characterized by slight LREE enrichment, whereas Type 2 diabases display flat to slightly LREE-depleted patterns. Type 2 appears to have derived from a depleted asthenospheric mantle source metasomatized by slab-derived fluids/melts. Geochemical signatures of Type 1, on the other hand, require relatively enriched source region and/or small degrees of partial melting. Trace element systematics of Type 2 is consistent with an origin in an oceanic back-arc basin, whereas Type 1 diabases appear to have been generated in a mid-ocean ridge or an oceanic back-arc basin. 40Ar-39Ar radiometric dating on the amphiboles from two Type 2 samples reveals ages of 176.30 ± 0.52 Ma (Toarcian) and 178.82 ± 0.80 Ma (Toarcian), which suggests the presence of an intra-oceanic subduction zone within IAE Ocean during the Early Jurassic.


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In Anatolia, the northern branch of Neotethys is represented by Izmir-Ankara-Erzincan (IAE) Ocean, whose fragments and associated continental entities are preserved in the IAE Suture. However, the traces of this northerly located ocean are not solely bound to the IAE Suture, but can also be found further to the south. The Mersin Melange, situated in southern Turkey, is such a place that preserves the southerly transported remnants of the northern Neotethys. The Mersin Melange essentially displays block-in-m...
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Gediz Graben is a continental extensional basin filled with Neogene sediments. Its margins are controlled by active ~EW-trending fault systems with major system, in terms of total offset and duration of activity, located along the southern margin. The graben evolved as a half graben by the activity of the southern margin during the entire Miocene. Then, the northern margin-bounding structure initiated by PlioQuaternary to form the current configuration of the graben with an inherited asymmetry. The southern...
Preliminary Geochemical Data for the Diabase Dykes from theIzmir-Ankara-Erzincan Suture Belt, Central Anatolia
Balcı, Uğur; Sayıt, Kaan (2017-04-23)
The Izmir-Ankara-Erzincan Suture Belt preserves oceanic and continental fragments originated from the closure of the northern branch of Neotethys. In the Bogazkale area (Central Anatolia), the pieces of the Neotethyan oceanic lithosphere exist in a chaotic manner, forming an ophiolitic mélange. Within the mélange, diabase dykes occur, which are found to cut various types of oceanic lithospheric rocks, including pillow basalts, gabbros and serpentinized ultramafics. We here present the preliminary geochemica...
AKIMAN, O; ERLER, A; GONCUOGLU, MC; Güleç, Nilgün Türkan; GEVEN, A; TURELI, TK; KADIOGLU, YK (1993-12-01)
The closely related assemblage of igneous and metamorphic rocks that lie within a triangular area approximately bounded by the Tuzgolu Fault, the Ecemis Fault and the Izmir-Ankara-Erzincan Suture and between the lines connecting Ankara, Sivas and Nigde is called the Central Anatolian Crystalline Complex (CACC). The granitoids cropping out within the CACC can be divided areally into three groups: (1) a large number of individual small plutons which form an arcuate set and curve from NE-SW to NW-SE and extend...
BODUR, MN; ERGIN, M (Elsevier BV, 1994-07-01)
Six box-cores, one boomerang core and one hundred sixty-six surface sediment samples recovered in the Sea of Marmara were analyzed in an attempt to establish the main controls on distribution and origin of trace metals within the oxic to suboxic basin of this sea.
Citation Formats
U. Balcı, “Geochemistry and petrogenesis of the diabase dykes from the Boğazkale region (Çorum, Central Anatolia),” M.S. - Master of Science, Middle East Technical University, 2018.