Geochemical and isotopic data of meta-gabbroic dikes in Alaşehir area in the Menderes Massif, Western Turkey: Evidence for the Early Cambrian back-arc rifting?

2018-06-02
Gürsu, Semih
Köksal, Serhat
Möller, Andreas
Stratigraphic feature of undated garnet-bearing meta-gabbroic dikes cross-cutting basement rocks of meta-pelitic successions in the Alaşehir areas (Central Menderes Massif - CMM) are still in debate and are distinct from the eclogitic meta-gabbroic dikes, garnet amphibolites and biotite rich meta-gabbroic dikes cross-cutting Neoproterozoic basement rocks (meta-tonalites/meta-granodiorites and meta-granites) that crop out in the Birgi, Tire and Çine areas of the CMM. The garnet-bearing meta-gabbro dikes in the Alaşehir areas have low Nb (0.6 to 4.9 ppm), low Th (0.2 to 0.5 ppm), low Zr (10.1 to 54.6 ppm), low to moderate Y (8.4 to 15.1 ppm), Ti (2518 t 6175 ppm), Zr/Yb (13.33 to 41.31 ), Ti/Zr (57.05 to 346.86), Y/Zr (0.23 to 0.98) ratios. They are highly depleted in LREE and display flat patterns in MREE and HREE compared to the eclogitic meta-gabbroic dikes, garnet amphibolites, biotite rich meta-gabbroic dikes of the Late Neoproterozoic basement rocks. Nb, Zr, Ti contents with Nd/Sm and La/Yb ratios compared to La/Yb and Eu/Eu* indicate distinct enrichment of the garnet-bearing meta-gabbroic dikes (Alaşehir areas) relative to the eclogitic meta-gabbroic dikes, garnet amphibolites and biotite rich gabbroic dikes (Birgi, Tire and Çine areas). The low Nb, low Th, low Zr contents, and high Ti/Zr and low Zr/Yb ratios in the garnet-bearing meta-gabbroic dikes (Akşehir areas) compared to the eclogitic meta-gabbroic dikes, biotite rich meta-gabbroic dikes indicates that they may have been derived from melting of mafic lower crustal sources. Variable ɛ Nd(540) (-2.9 to +1.9) and 147Sm/144Nd ratios (0.1320 to 0.2277) of the garnet-bearing meta-gabbroic dikes in Alaşehir areas indicate extensive mixing of a mafic lower crustal source with depleted mantle during their formation. Apparent crustal residence Nd model ages (TDM) determined using the two-stage model of Liew and Hofmann (1988) range from 1.08 - 1.47 Ga, also indicating mixing of older sources with depleted mantle. We suggest that Andean-type subduction was followed by lithospheric thinning of the continental crust, resulting in an initial stage of back-arc basin formation in the peri-Gondwanan crust during the Late Neoproterozoic. The biotite-rich meta-gabbroic dikes may have been generated during the initial stage of this rifting, whereas garnet-bearing meta-gabbroic dikes (Alaşehir areas) may have been generated later during the mature stage of continental rifting in the Early Cambrian. Similar tectonic scenarios have been suggested for other peri-Gondwanan terranes in Europe, the Middle East, and eastern Asia.

Suggestions

GEOCHEMICAL CHARACTERISTICS OF GRANITOIDS ALONG THE WESTERN MARGIN OF THE CENTRAL ANATOLIAN CRYSTALLINE COMPLEX AND THEIR TECTONIC IMPLICATIONS
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...
Afyon zonu örtü birimlerinin yaşı ve tektonikönemi u pb kırıntılı zirkon jeokronolojisi
Bozkurt, Erdin (TMMOB Jeoloji Mühendisleri Odası; 2016-04-11)
Afyon Zone in the Anatolide-Tauride block is represented by a Pan-African metamorphic basement and unconformably overlying lower Triassic-lower Tertiary low-grade metamorphic cover rocks. The cover sequences commences with a thick basal metaconglomerate. It comprises two distinct lithologies, characterized by quartz pebbles and carbonate pebbles, and grades into a wine red-purple-reddish-gray-mottled metaclastic sequence, made up of a sandstone-shale-mudstone and quartzite alternation. The grain size decrea...
Deformation History of the Haymana Basin Structural Records of Closure Collision and Subsequent Convergence Indentation Events at the North Central Neotethys Central Anatolia Turkey
Gülyüz, Erhan; Özkaptan, Murat; Kaymakcı, Nuretdin (null; 2016-04-22)
Gondwana(Tauride Platfrom and Kırşehir Block) and Eurasia (Pontides) derived continental blocks bound the Haymana basin, in the south and north, respectively. Boundaries between these blocks are signed by İzmirAnkara-Erzincan and debatable Intra-Tauride Suture zones which are straddled by the Haymana Basin in the region. In this regard, deformation recorded in the upper Cretaceous to middle Eocene deposits of the basin is mainly controlled by the relative movements of these blocks. Therefore, understanding ...
Neotectonics of East Anatolian Plateau (Turkey) and Lesser Caucasus: implication for transition from thrusting to strike-slip faulting
Kocyigit, A; Yilmaz, A; Adamia, S; Kuloshvili, S (2001-01-01)
The east Anatolian plateau and the Lesser Caucasus are characterised and shaped by three major structures: (1) NW-and NE-trending dextral to sinistral active strike-slip faults, (2) N-S to NNW-trending fissures and /or Plio-Quaternary volcanoes, and (3) a 5-km thick, undeformed Plio-Quaternary continental volcanosedimentary sequence accumulated in Various strike-slip basins. In contrast to the situation in the east Anatolian plateau and the Lesser Caucasus, the Transcaucasus and the Great Caucasus are chara...
Petrogenesis and tectonic setting of Cadomian felsic igneous rocks, Sandikli area of the western Taurides, Turkey
Guersu, Semih; Goencueoglu, M. Cemal (Springer Science and Business Media LLC, 2006-09-01)
In the Sandikli (Afyon) region, western Taurides, the Late Proterozoic rocks of the Sandikli basement complex are composed of low-grade meta-sedimentary rocks (Guvercinoluk Formation) intruded by felsic rocks (Kestel Cayi Porphyroid Suite, KCPS). The KCPS is a deformed and highly sheared, dome-shaped rhyolitic body with a granitic core. Quartz porphyry dikes intrude both the slightly metamorphic igneous and the sedimentary rocks of the basement complex. Both the quartz porphyries and rhyolites were converte...
Citation Formats
S. Gürsu, S. Köksal, and A. Möller, “Geochemical and isotopic data of meta-gabbroic dikes in Alaşehir area in the Menderes Massif, Western Turkey: Evidence for the Early Cambrian back-arc rifting?,” presented at the GEOBONN 2018, (2 - 06 Eylül 2018), Bonn, Almanya, 2018, Accessed: 00, 2021. [Online]. Available: http://www.geobonn2018.de/assets/geobonn_2018_abstracts_12092018.pdf.