Tectono-Metamorphic Evolution of the Northern Menderes Massif: Evidence from the Horst Between Gördes and Demirci Basins (West Anatolia, Turkey)
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TECTONO-METAMORPHIC EVOLUTION OF THE NORTHERN MENDERES MASSIF: EVIDENCE FROM THE HORST BETWEEN GÖRDES AND DEMİRCİ BASINS (WEST ANATOLIA, TURKEY) A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES OF MIDDLE EAST TECHNICAL UNIVERSITY BY ÇAĞRI BUĞDAYCIOĞLU IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN GEOLOGICAL ENGINEERING SEPTEMBER 2004 Approval of the Graduate School of Natural and Applied Sciences. I certify that this thesis satisfies all the requirements as a thesis for the degree of Master of Science. This is to certify that we have read this thesis and that in our opinion it is fully adequate, in scope and quality, as a thesis for the degree of Master of Science. Examining Committee Members Prof.Dr. Vedat Toprak (METU, GEOE) ___________________ Prof.Dr. Erdin Bozkurt (METU, GEOE) ___________________ Assoc.Prof.Dr. Bora Rojay (METU, GEOE) ___________________ Assoc.Prof.Dr. Kadir Dirik (HU, GEOE) ___________________ Assist.Prof.Dr. İsmail Ömer Yılmaz (METU, GEOE) ___________________ ii I hereby declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work. Name, Last name : Çağrı Buğdaycıoğlu Signature : iii ABSTRACT TECTONO-METAMORPHIC EVOLUTION OF THE NORTHERN MENDERES MASSIF: EVIDENCE FROM THE HORST BETWEEN GÖRDES AND DEMİRCİ BASINS (WEST ANATOLIA, TURKEY) Buğdaycıoğlu, Çağrı M.Sc., Department of Geological Engineering Supervisor : Prof.Dr. Erdin Bozkurt September 2004, 163 pages The Menderes Massif forms a large metamorphic culmination in western Turkey – an extensional province where continental lithosphere has been stretching following Palaeogene crustal thickening. Northern sector of the Massif on the horst between Gördes and Demirci Basins was chosen for structural analysis aimed to study the tectono-metamorphic evolution of the northern Menderes Massif. Within the study area, four groups of rocks are recognized: (1) the metamorphic rocks – orthogneisses and metasediments; (2) pegmatoids; (3) Neogene sedimentary rocks; and (4) Quaternary alluvial sediments. The tectono-metamorphic history of the region involves a regional metamorphism (M1) at upper-amphibolite-facies conditions, coeval with a top-to- the-NNE contractional D1 deformation during the northward backthrusting of Lycian Nappes (Eocene main Menderes metamorphism). Partial anatexis during the latest stages of the M1 was speculated to be the main mechanism for the formation of the migmatites and the granitic magma. Pegmatoid domes and dikes/sills formed during late increments of this phase. iv A second metamorphism (M2) and coeval top-to-the-NNE deformation (D2) took place during the Early Miocene exhumation of the metamorphic rocks along a presently low-angle normal fault in an extensional shear zone at presumably greenschist facies conditions during declining P-T conditions. The latest deformation phase (D3) is high-angle normal faulting due to N–S extension affecting western Anatolia. The E–W grabens dissecting the Massif into northern, central and southern submassifs are the result of this phase, commenced during Pliocene-Pleistocene and gave the western Anatolia much of its present-day shape. The evidence presented supports the idea of episodic two-stage extension in western Turkey. Keywords: Menderes Massif, polydeformation, gneissic dome, episodic two- phase extension, northwestern Turkey. v ÖZ KUZEY MENDERES MASİFİ’NİN TEKTONO-METAMORFİK EVRİMİ: GÖRDES VE DEMİRCİ HAVZALARI ARASINDA KALAN HORSTTAN YENİ BULGULAR (BATI ANADOLU, TÜRKİYE) Buğdaycıoğlu, Çağrı Yüksek Lisans, Jeoloji Mühendisliği Bölümü Tez Yöneticisi : Prof.Dr. Erdin Bozkurt Eylül 2004, 163 sayfa Menderes Masifi, kuzeybatı Türkiye’de Paleojen kıtasal kalınlaşmasını takip eden dönemde gerilme ile yüzeyleyen bölgesel ölçekli en önemli metamorfik parçalardan birini oluşturmaktadır. Kuzey Menderes Masifi’nin tektono-metamorfik evriminin çalışılması amacına yönelik olarak, masifin kuzey kısmının bir parçası olan ve Gördes (Manisa) kasabasının güneybatısında yer alan ve Gördes ve Demirci havzaları arasında kalan horst çalışma alanı olarak seçilmiştir. Çalışma alanında dört kaya grubu yüzeylemektedir: (1) metamorfik kayalar – ortognayslar ve metasedimenterler; (2) pegmatoidler; (3) Neojen sedimenter kayalar; ve (4) Kuvaterner alüvyon sedimanları. Kuzey Menderes Masifi’nin tektono-metamorfik evrimi, üst-ampfibolit fasiyesinde oluşmuş ve Likya Napları’nın kuzeye geri-bindirmesi sırasında oluşan ve kuzeye hareket veren D1 deformasyonuyla eş zamanlı olarak gelişen bölgesel bir metamorfizmaya (M1) sahiptir (Eosen ana Menderes metamorfizması). Çalışma alanındaki migmatitlerin ve granitik magmanın oluşumundaki ana mekanizmanın, M1’in son safhalarında oluşan kısmi ergime olduğu düşünülmektedir. Pegmatoid domları ve daykları/silleri bu fazın en son safhasında oluşmuşlardır. vi Masif, Erken Eosen’de, yeşilşist fasiyesinde ve azalan P-T koşullarında gerçekleşen, ikinci bir metamorfizma (M2) ve eş zamanlı olarak, metamorfik kayaların günümüzde düşük açılı olarak görülen normal fay boyunca yükseldiği, kuzeye hareket veren bir deformasyon (D2) geçirmiştir. Menderes Masifi’ni etkileyen en son deformasyon fazı (D3), batı Anadolu’nun K–G yönlü gerilmesi sırasında oluşan yüksek açılı normal faylanmadır. Masif’i kuzey, orta ve güney ara-masiflere ayıran bütün D–B yönlü grabenler, Pliyosen-Pleyistosen’de başlayan ve batı Türkiye’ye bugünkü yapısını kazandıran bu deformasyon sonucu oluşmuştur. Sunulan bulgular batı Türkiye’deki iki aşamalı gerilme hipotezini desteklemektedir. Anahtar Kelimeler: Menderes Masifi, polideformasyon, gnays domu, iki aşamalı gerilme, kuzeybatı Türkiye. vii ACKNOWLEDGMENTS I am greatly indebted to Prof.Dr. Erdin Bozkurt for his guidance, continuous encouragement and interest, constructive discussions, critically reviewing and editing of the manuscript, and supervision throughout every stage of this study. Without him, this thesis could have never been completed. I am grateful to Assist.Prof.Dr. Hasan Sözbilir for his help during the field studies and Ökmen Sümer for his guidance during İzmir journey. Many thanks to Prof.Dr. Vedat Toprak, Assoc.Prof.Dr. Bora Rojay, Assist.Prof.Dr. Nuretdin Kaymakcı, and Assist.Prof.Dr. Mehmet Lütfi Süzen for their interest on the progress of the thesis and their endless offers for help during the preparation of this thesis and my M.Sc. education. I ought to thank all examining committee members whose comments, critics and advice improved the text a lot. I am also grateful to my friend Serhat Demirel for his valuable help, productive and provocative discussions and suggestions during the petrographic studies in the laboratory and his friendship and encouragement during the preparation of this thesis. The technical assistance of Orhan Karaman during the preparation of thin sections from oriented samples for petrographic and microstructural analyses is gratefully acknowledged. I would like to thank to all my friends, especially Gence Genç, Başak Şener, Alper Fulat, and Çağıl Kolat, who were with me during the stressful final preparation stages of the thesis, for their invaluable encouragement. Last, but not the least, I offer my grateful thanks to my family, my mom, dad and brother, for their unlimited patience, unwavering support and encouragement in this study and all through my life. This research was funded by METU Research Foundation grant BAP- 2002-03-09-02. viii TABLE OF CONTENTS PAGE PLAGIARISM . iii ABSTRACT . iv ÖZ . vi ACKNOWLEDGMENTS . viii TABLE OF CONTENTS . ix LIST OF TABLES . xii LIST OF FIGURES . xiii CHAPTERS 1. INTRODUCTION . 1 1.1. Definition of the Problem . 1 1.2. Purpose and Scope . 7 1.3. Location of the Study Area . 9 1.4. Methods of Study . 11 1.5. Established Background Geology of Western Turkey . 12 1.5.1. The Menderes Massif . 14 1.5.1.1. Metamorphism . 16 1.5.1.2. Magmatism . 20 1.5.1.3. Deformation . 22 1.5.2. Current Problems . 26 1.6. Previous Studies: the Gördes Region . 30 2. STRATIGRAPHY . 38 2.1. Introduction . 38 2.2. The Metamorphic Rocks . 41 2.2.1. Orthogneisses . 41 2.2.2. Metasediments . 51 ix 2.2.2.1. Migmatites . 51 2.2.2.2. Kyanite-Garnet-Biotite-Muscovite-Albite-Quartz Schists . 59 2.2.2.3. Quartz-Muscovite-Garnet Schists . 63 2.3. Pegmatites . 65 2.4. Neogene Sedimentary Rocks . 71 2.5. Quaternary Alluvial Sediments . 76 3. STRUCTURAL GEOLOGY . 77 3.1. Introduction . 77 3.2. Deformational Phases . 77 3.3. D1 Deformation . 78 3.3.1. F1 Folding . 85 3.3.2. Microstructural Features of Deformed Grains in Orthogneisses . 85 3.3.3. Shear-sense Indicators . 94 3.4. D2 Deformation . 94 3.4.1. Detachment Faulting . .101 3.4.2. F2 Folding . .101 3.5. D3 Deformation . .104 3.5.1. Kınık-Mestanlı Area . .104 3.5.2. Yardere Area . .110 3.5.3. Dikilitaş Area . .112 4. DISCUSSION AND CONCLUSION . .115 4.1. Introduction . .115 4.2. Metamorphism . .115 4.2.1. M1 Metamorphism . .115 4.2.2. M2 Metamorphism . .120 4.3. Deformation . .121 4.3.1. D1 Deformation . .121 4.3.2. F1 Folding . .123 4.3.3. D2 Deformation . .124 4.3.4. F2 Folding . .127 4.3.5. D3 Deformation . .129 x 4.4. Significance of D2 and D3 Deformations . .130 4.5. Migmatization, Partial Anatexis and Intrusion of Pegmatoids . .132 4.6. Relationships among Migmatization, Crustal Melting, Extension and Intrusion . .134 4.7. Is the Horst Between Gördes and Demirci Basins A Gneissic Dome?