Papers by Mehmet Ali Gücer
The Dodurga Pluton is located within the Central Pontides (northern Türkiye) and, has a SW-NE elo... more The Dodurga Pluton is located within the Central Pontides (northern Türkiye) and, has a SW-NE elongation, and consists of granodiorite and dacite porphyry. Previous studies have suggested that this pluton is Triassic in age, and its whole-rock geochemical systematics are consistent with those from adakitic magmatic occurrences rather than the classic arc granitoid suite. This study reports the first time in-situ/whole-rock radiogenic isotopic (Sr, Nd and Pb) and mica/amphibole Ar-Ar age data to evaluate better its petrogenetic-geodynamic evolution and chemical nature of mantle source(s). Unlike previous data, combined new in-situ zircon U-Pb yield Late Cretaceous crystallization ages of 84.2±0.9 Ma and 86.9±0.9 Ma, and Ar-Ar age data along with apatite fission track measurements suggest magma cooling extending to 82.3±0.4 Ma and 85.4±0.4 Ma, respectively. The apatite fission track (AFT) dating results also reveal that this pluton was buried at a depth of 2.5-3 km following a fast-cooling period during Late Cretaceous and cooled/exhumed over ~2 km during the Middle-Late Miocene (15-10 Ma) in a slow cooling phase. The overall data reported here suggest that the Dodurga Pluton represents melts derived from an enriched/metasomatized mantle source that interacted with lower crustal mafic rocks in an active continental margin as a result of northward subduction of the northern branch of the Neotethys Ocean.
Yerbilimleri, 2024
The early Cenozoic magmatism in the Eastern Sakarya Zone (NE Turkey) provides significant insight... more The early Cenozoic magmatism in the Eastern Sakarya Zone (NE Turkey) provides significant insights into the regional tectonomagmatic evolution. Adakite-like intrusive/extrusive rocks have been widely observed from the Late Paleocene to the Plio-Quaternary period in the region. In the study area, Early Eocene adakitic andesites are observed in outcrop areas smaller than 10 km2 and they contain abundant microgranular enclaves. This study presents petrochemistry data of the enclaves and discusses petrological relationships with the host rock. The enclaves, with more basic composition compared to the parent rocks, are observed in ranging from a few to 20 cm in size. They are microlithic to porphyritic in texture and mainly composed of plagioclase, hornblende, clinopyroxene, orthoclase and opaques. Both petrographic and petrochemical characteristics indicate that they are of basaltic and basaltic andesite and may have derived from a sub-alkaline magma. Major and trace element variations indicate that fractional crystallization was effective, and plagioclase, pyroxene, hornblende, magnetite and apatite fractionation played an important role. Similar trace element distributions of enclaves and host rocks may indicate interaction processes while mixing of felsic and mafic magmas. Similarly, REE models of the rocks, indicated hornblende fractionation played an important role in their evolution, whereas plagioclase fractionation was less effective. Petrochemical data suggest that the parent magma of the enclaves was produced by the partial melting of oceanic basalts under amphibole eclogite facies conditions during the initial stages of the extensional tectonic regime just after the complete closure of the northern Neotethys Ocean.
Journal of Asian earth sciences, Mar 1, 2024
Turkish Journal of Earth Sciences
in the eastern part of the Pontides (NE Türkiye) are accommodated in the Pontide paleomagmatic ar... more in the eastern part of the Pontides (NE Türkiye) are accommodated in the Pontide paleomagmatic arc and the eastern part of the Pontides Metallogenic Belt containing numerous various deposits. Fe-skarn mineralization around the Arnastal Plateau (Gümüşhane-Türkiye) is fragmentary in this area, which is covered with plants (grasses, flowers, etc.). Thus, it was attempted to describe the subsurface structures and Fe mineralization using an interpretation of the available geological and existing magnetic data in this area. Granitoid and volcano-sedimentary series (Upper Cretaceous) outcrop in the study area. These volcanosedimentary series consist of limestone, sandy limestone, marl, andesite, quartz andesite, basalt, and their equivalent pyroclastics. They include a thin layer of the red limestone (Upper Cretaceous) and olistolith recrystallized limestones (Jurassic-Lower Cretaceous). Zigana granitoid, intruding into all of these rocks, is high-K calc-alkaline and metaluminous and is classified as quartz monzonite, monzogranite, granite, and syenogranite as a result of its modal composition. Contact pyrometasomatic mineralization occurs in between the limestone and granitoids in the Arnastal Plateau. In addition to petrographic and mineralogical studies, magnetic methods were applied to an area of approximately 10 km 2 to find any covered Fe deposits. Magnetic susceptibility values measured on the outcropped rocks ranged from 1 to 34 (10-7 SI) for limestone, 78 to 3750 (10-7 SI) for basalt, and 105 to 3946 (10-7 SI) for granitoids. It is considered that these ranges express the alteration (physical or chemical) of the rocks, their homogeneity, and the lack or presence of Fe minerals. The magnetic survey was conducted along a study area measuring 12,075 m long with 25 and/or 50 m station spacing. Processing of the magnetic data revealed the presence of eight buried Fe ores that could represent either massive or disseminated mineralization between the Sarıtaş and Kurtdere plateaus. Magnetite ore bodies may be present from the surface to a depth of approximately 15-25 m inside the limestone. In addition to the identification of new magnetite ore mineralization or bodies, a new geological map was designed by determining probable formation boundaries with this magnetic survey.
Journal of Asian Earth Sciences , 2024
The pre-Jurassic tectonic evolution of the Central Pontides in northern Turkey is still poorly un... more The pre-Jurassic tectonic evolution of the Central Pontides in northern Turkey is still poorly understood due to the lack of detailed geochemical and geochronological data from the basement units. Therefore, this study reports for the first time combined whole rock geochemistry, trace element data and U-Pb ages for detrital zircons, and Ar-Ar geochronological data from the metasedimentary rocks of the Devrekani Massif, Geme Complex, and the Serveçay Unit to better understand their provenance, depositional age characteristics, and tectonic evolutions. The detrital zircon U-Pb data of metasedimentary units from the Devrekani Massif, Geme Complex, and the Serveçay Unit yield ca. 191, 185 and 298 Ma maximum depositional ages (youngest age peaks), respectively. The Devrekani Massif is dominated by Permo-Carboniferous-aged detrital zircons (67 %), whereas Neoproterozoic and Devonian-aged detrital zircons are more common in the Geme Complex (47 %) and the Serveçay Unit (53 %). These distinct age distributions clearly indicate that the Devrekani Massif may has been deposited in a dissimilar location compared to the Geme Complex and the Serveçay Unit. Furthermore, in contrast to the Devrekani Massif, the source area of the metasedimentary rocks from the Geme Complex is comparable with that of the Serveçay Unit. Lastly, the obtained detrital zircon U-Pb and mica Ar-Ar ages suggest that the Devrekani Massif and the Geme Complex were deposited and metamorphosed during the Early and Middle Jurassic, respectively. The Serveçay Unit was deposited and metamorphosed in the Permian.
Geological Magazine
Magmatic activity in the Sakarya Zone, an important segment of the Alpine orogenic belt, continue... more Magmatic activity in the Sakarya Zone, an important segment of the Alpine orogenic belt, continues intermittently from the middle Carboniferous to Miocene. In this study, we provide geochronological and geochemical data from the Dağdibi Pluton in the eastern Sakarya Zone to present some inferences on the source region and petrogenesis of the middle Eocene magmatism. U–Pb zircon geochronology from two granodiorite samples gives middle Eocene ages of 44.75 ± 0.92 and 45.01 ± 0.59 Ma. The pluton is mainly composed of K-feldspar, plagioclase, quartz, Mg-hornblende/actinolite, Fe–Ti oxides and small amounts of biotite, and secondary chlorite and epidote. Parental magma of the intrusive rocks has a high-K calc-alkaline affinity with metaluminous character. The oxygen fugacity values vary between −18 and −17. The rocks show slightly radiogenic 87Sr/86Sr(i) (0.704845–0.705726) ratios and ϵNdi values between −0.96 and +0.52. Pb–Pb isotope ratios are typical for those of the lower continental...
Coğrafi Bilimler Dergisi
İnsanlık tarihinde olduğu gibi insanın yaşamında önemli gelişmelere sebep olan madenlere ihtiyaç ... more İnsanlık tarihinde olduğu gibi insanın yaşamında önemli gelişmelere sebep olan madenlere ihtiyaç giderek artmaktadır. Tarih çağlarına da isim veren madenler, insanoğlunun yaşamını sürdürebilmesi için gerekli bir hammadde kaynağı olmuştur. Günümüzde madenler, ülke ekonomilerini direkt etkileyen faktörlerin başında gelmektedir. Altın, tarihi çok eskilere dayanan bir maden olup özellikle son yıllarda artan talep ve buna bağlı olarak yeni altın kaynaklarının aranması giderek önem kazanmıştır. Türkiye, farklı jeolojik özellikte altın yatakları ve 431 tonluk Merkez Bankası rezervi ile Dünyada %2’lik bir payla zengin bir ülke konumundadır. Ayrıca son yıllarda altın madenciliğinin gelişmesine bağlı olarak Türkiye’de altın arama çalışmaları yoğun bir şekilde devam etmekte olup 2021’de yıllık altın üretimi 39 ton seviyelerine çıkmıştır. Ülkemizde Ege ve Marmara Bölgeleri ile Doğu Karadeniz Bölümü’nde altın madenciliğinin yoğunlaştığı belirlenmiştir. Altın madenciliğinin yoğun olarak yapıldığı...
The Guleman Ophiolite is located in the southeast of Turkey and mainly consists of harzburgites a... more The Guleman Ophiolite is located in the southeast of Turkey and mainly consists of harzburgites and dunites hosting economically viable chromitite bodies, and lesser amounts of cumulate and isotropic gabbro, diabase dykes, pyroxenite and locally plagiogranite. This study reports the combined whole-rock geochemical and radiogenic isotope (Sr and Nd) data for gabbro and diabase dykes, and in-situ zircon U-Pb geochronological data for plagiogranite and gabbro from the Guleman Ophiolite. Two different geochemical groups were determined based on immobile minor and trace elements, and radiogenic isotope characteristics of gabbro and diabase dykes investigated here. The first group is represented by boninites and displays highly depleted elemental patterns compared to NMORB, and spoon-shaped rare earth element profiles. Contrarily, the second group resembles back-arc basin basalts and is characterized by NMORB-like rare earth element patterns associated with negative Nb anomalies. The boninitic samples are characterized by less radiogenic 143 Nd/ 144 Nd (i) (0.51229 to 0.51267; ƐNd = − 4.8 to +2.7) and more radiogenic 87 Sr/ 86 Sr (i) (0.70549 to 0.70758) isotope compositions compared to the back-arc basin basalt-like samples (143 Nd/ 144 Nd (i) = 0.51289 to 0.51296; ƐNd = +7.0 to +8.4; 87 Sr/ 86 Sr (i) = 0.70496 to 0.70629), indicating derivation from distinct and/or heterogeneous mantle source regions within a supra-subduction zone. The LA-ICP-MS zircon U-Pb analyses yielded concordant late Cretaceous ages for gabbro (82 ± 2.9 Ma) and plagiogranite (79.9 ± 0.8 Ma) samples. The overall geochemical, isotopic and geochronological data presented here suggest that the Guleman Ophiolite consists of forearc and initial back-arc spreading sections of oceanic crust, which may have been formed in an intra-oceanic subduction zone within the Berit Ocean (northern branch of the southern Neo-Tethyan ocean). Moreover, the generation of continental arc magmatism (i.e. Baskil and Esence Granitoids) was well-documented on the active margin of the Malatya-Keban Metamorphics to the north. Therefore the closure of this oceanic basin should have resulted in multiple coeval northward subduction events during the late Cretaceous.
Gümüşhane Üniversitesi Fen Bilimleri Enstitüsü Dergisi
Bu çalışmada, Doğu Pontidler’ in Kuzey Zonunda Trabzon ili sınırlarında Köprüyanı mevkiindeki Fe-... more Bu çalışmada, Doğu Pontidler’ in Kuzey Zonunda Trabzon ili sınırlarında Köprüyanı mevkiindeki Fe-Cu skarn cevherleşmesinin; jeolojisi, petrografisi, cevher mikroskobisi özellikleri ve mineral kimyası içeriklerinin belirlenmesi amaçlanmıştır. Köprüyanı cevherleşme sahasında, aktinolit, tremolit, pirit, kalkopirit, manyetit ve malakit mineralleri ile kırık çatlak zonları boyunca gelişmiş limonitleşme, hematitleşme kloritleşme ve epidotlaşma türü alterasyonlar gözlenmektedir. Manyetit minerallerinin genellikle kalkopirit, pirit ve granat ile birlikte bulunduğu, TiO2 içeriklerinin çok düşük (%0.02-1.02) olduğu buna karşılık FeOt içeriklerinin ise %83.13-92.00 arasında değiştiği belirlenmiştir. Manyetit ile beraber bulunan ve ekzoskarn zonunda yer alan kalkopirit minerallerinin Cu içeriğinin %33.50-43.27 ve Fe içeriği %29.84-39.11 arasında değiştiği belirlenmiştir. Epidot minerallerinin Al içeriklerinin yüksek (2.06-2.46), Mn içeriklerinin düşük (0.01-0.03) ve Fe+3 içeriklerinin ise nisp...
Bu çalışmada, Doğu Pontidler' in Kuzey Zonunda Trabzon ili sınırlarında Köprüyanı mevkiindeki Fe-... more Bu çalışmada, Doğu Pontidler' in Kuzey Zonunda Trabzon ili sınırlarında Köprüyanı mevkiindeki Fe-Cu skarn cevherleşmesinin; jeolojisi, petrografisi, cevher mikroskobisi özellikleri ve mineral kimyası içeriklerinin belirlenmesi amaçlanmıştır. Köprüyanı cevherleşme sahasında, aktinolit, tremolit, pirit, kalkopirit, manyetit ve malakit mineralleri ile kırık çatlak zonları boyunca gelişmiş limonitleşme, hematitleşme kloritleşme ve epidotlaşma türü alterasyonlar gözlenmektedir. Manyetit minerallerinin genellikle kalkopirit, pirit ve granat ile birlikte bulunduğu, TiO2 içeriklerinin çok düşük (%0,02-1.02) olduğu buna karşılık FeO t içeriklerinin ise %83,13-92,00 arasında değiştiği belirlenmiştir. Manyetit ile beraber bulunan ve ekzoskarn zonunda yer alan kalkopirit minerallerinin Cu içeriğinin %33,50-43,27 ve Fe içeriği %29,84-39,11 arasında değiştiği belirlenmiştir. Epidot minerallerinin Al içeriklerinin yüksek (2.06-2.46), Mn içeriklerinin düşük (0.01-0.03) ve Fe +3 içeriklerinin ise nispeten yüksek (0.59-0.96) olduğu belirlenmiştir. Al bakımından zengin olan epidotların türünün ise klinozoisit olduğu tespit edilmiştir. Granat türleri ağırlıklı olarak andradit ve grossularandradittir. Cevher mikroskobisi ve mineral kimyası çalışmaları kapsamında derlenen verilere bağlı olarak, Köprüyanı cevherleşmesinin Fe-Cu skarn tipinde olduğu ve bölgede var olan skarn cevherleşmelerinin parajenez, süksesyon ve mineral kimyası verileri ile benzerlik gösterdiği sonucuna ulaşılmıştır.
Proceedings 74. Geological Congress of Turkey, 2022
Since the initial recognition of crystalline basement rocks in
Safranbolu-Karadere area by Arpat ... more Since the initial recognition of crystalline basement rocks in
Safranbolu-Karadere area by Arpat et al (1978), their detailed age, source
areas and the palaeogeographic setting were a matter of debate. The
basement rocks in this area and also in a number of other outcrops of the
Istanbul-Zonguldak Terrane mainly consist of medium grade
quartzofeldspatic schists, quartzites, ortho- and paragneisses,
amphibolites/metagabbros together with slightly metamorphic granites,
aplites-pegmatites. The crystalline basement is disconformably overlain
by early Tremadocian (earliest Ordovician) graptolitic black shales. In the
Karadere area the metamorphic paragneisses in the host rocks of para and
ortho origin is garnet-biotite- muscovite. The metabasic rocks are
characterised by hornblende –epidote-chlorite. The intruding felsic
igneous rocks display blasto-milonitic textures and include only white
mica and chlorite as metamorphic minerals. Geochemically, the
metasedimentary host rocks display characteristic features of passive
margin rocks derived from a continental arc source. The felsic and mafic
orthogneisses/amphibolites are of granitic and gabbroic origin,
respectively. In tectonomagmatic discrimination diagrams they all plot in
volcanic arc field. Concordant LA ICP MS ages of detrital zircons
(n=285) from the paragneisses range from 2 Ga to 600 Ma, where 84% of
the ages range between 1.2 and 1.8 Ga (Mesoproterozoic). The youngest
detrital zircons (4%) in these rocks are 685 Ma (Cryogenian) in age. The
concordia age of the sampled granitic orthogneisses, on the other hand, is
604+/-2 Ma indicating to mid Ediacaran magmatism. The youngest ages
obtained from the paragneisses are Ar-Ar ages of 530-53 Ma indicating to
a metamorphic event during the earliest Cambrian. The new data contrasts
with the previous studies where the “metagranites” were dated as 590-560
Ma and attributed to a pan-African magmatic event. The zircons from the
“metasediments” in previous studies yielded a range of 1870-710 Ma with
a maxima at 890-710 Ma, suggesting derivation from an Afro-Arabian
source. Our new ages from the zircon populations found in the
paragneisses suggest derivation from a provenance dominated by
Mesoproterozoic continental arc type igneous rocks and deposition in a
continental margin not earlier than the mid Neoproterozoic. During the
late Neoproterozoic (ca 600Ma), the continental margin is once again in
close vicinity of the Cadomian Arc and was intruded by the arc magmatic
rocks. The age pattern of the pre-Cadomian paragneisses of Karadere on
the density-probability diagram is markedly different from NE
Africa-derived terranes but display similarities to the basement rocks of
both Avalonian and Amazonian terranes.
International Conference on Applied Engineering and Natural Sciences (ICAENS 2022), 2022
International Anatolian Congress on Multidisciplinary Scientific Research, 2022
Congress Program IMPORTANT, PLEASE READ CAREFULLY ❖ To be able to attend a meeting online, login ... more Congress Program IMPORTANT, PLEASE READ CAREFULLY ❖ To be able to attend a meeting online, login via https://zoom.us/join site, enter ID "Meeting ID or Personal Link Name" and solidify the session. ❖ The Zoom application is free and no need to create an account. ❖ The Zoom application can be used without registration. ❖ The application works on tablets, phones and PCs. ❖ The participant must be connected to the session 5 minutes before the presentation time. ❖ All congress participants can connect live and listen to all sessions. ❖ Moderator is responsible for the presentation and scientific discussion (question-answer) section of the session. Points to Take into Consideration-TECHNICAL INFORMATION Make sure your computer has a microphone and is working. You should be able to use screen sharing feature in Zoom. Attendance certificates will be sent to you as pdf at the end of the congress. Requests such as change of place and time will not be taken into consideration in the congress program. Before you login to Zoom please indicate your name surname and hall number, exp.
International Anatolian Congress on Multidisciplinary Scientific Research, 2022
Congress Program IMPORTANT, PLEASE READ CAREFULLY ❖ To be able to attend a meeting online, login ... more Congress Program IMPORTANT, PLEASE READ CAREFULLY ❖ To be able to attend a meeting online, login via https://zoom.us/join site, enter ID "Meeting ID or Personal Link Name" and solidify the session. ❖ The Zoom application is free and no need to create an account. ❖ The Zoom application can be used without registration. ❖ The application works on tablets, phones and PCs. ❖ The participant must be connected to the session 5 minutes before the presentation time. ❖ All congress participants can connect live and listen to all sessions. ❖ Moderator is responsible for the presentation and scientific discussion (question-answer) section of the session. Points to Take into Consideration-TECHNICAL INFORMATION Make sure your computer has a microphone and is working. You should be able to use screen sharing feature in Zoom. Attendance certificates will be sent to you as pdf at the end of the congress. Requests such as change of place and time will not be taken into consideration in the congress program. Before you login to Zoom please indicate your name surname and hall number, exp.
TURKISH JOURNAL OF EARTH SCIENCES, 2020
The study area is located in the eastern part of the Sakarya Zone called the eastern Pontide (Bla... more The study area is located in the eastern part of the Sakarya Zone called the eastern Pontide (Black Sea Region), North Turkey. It is formed of rocks from the Late Cretaceous epoch, such as those in the metallogenic province in the eastern part of the Black Sea region (Figure 1; Table 1). This eastern Black Sea (Pontide) metallogenic province lies along an E-W line in the region and developed as an island arc from the Jurassic to the Miocene during the subduction of the Tethyan oceanic crust under the Sakarya Zone (Şengör and Yılmaz, 1981). Volcanic activity in the Pontides began during the Liassic. Basic rock formation during this period occurred in a rift environment, which developed on a Precambrian to Paleozoic basement (Schnieder et al., 1988; Arslan et al., 1997), forming volcanic rocks that are predominantly felsic. Felsic rocks are followed in an upward sequence by Late Cretaceous to Eocene volcanic and granitoid rocks. Intensively altered, they host numerous massive sulfide, vein type, skarn and clay deposits (
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Papers by Mehmet Ali Gücer
Safranbolu-Karadere area by Arpat et al (1978), their detailed age, source
areas and the palaeogeographic setting were a matter of debate. The
basement rocks in this area and also in a number of other outcrops of the
Istanbul-Zonguldak Terrane mainly consist of medium grade
quartzofeldspatic schists, quartzites, ortho- and paragneisses,
amphibolites/metagabbros together with slightly metamorphic granites,
aplites-pegmatites. The crystalline basement is disconformably overlain
by early Tremadocian (earliest Ordovician) graptolitic black shales. In the
Karadere area the metamorphic paragneisses in the host rocks of para and
ortho origin is garnet-biotite- muscovite. The metabasic rocks are
characterised by hornblende –epidote-chlorite. The intruding felsic
igneous rocks display blasto-milonitic textures and include only white
mica and chlorite as metamorphic minerals. Geochemically, the
metasedimentary host rocks display characteristic features of passive
margin rocks derived from a continental arc source. The felsic and mafic
orthogneisses/amphibolites are of granitic and gabbroic origin,
respectively. In tectonomagmatic discrimination diagrams they all plot in
volcanic arc field. Concordant LA ICP MS ages of detrital zircons
(n=285) from the paragneisses range from 2 Ga to 600 Ma, where 84% of
the ages range between 1.2 and 1.8 Ga (Mesoproterozoic). The youngest
detrital zircons (4%) in these rocks are 685 Ma (Cryogenian) in age. The
concordia age of the sampled granitic orthogneisses, on the other hand, is
604+/-2 Ma indicating to mid Ediacaran magmatism. The youngest ages
obtained from the paragneisses are Ar-Ar ages of 530-53 Ma indicating to
a metamorphic event during the earliest Cambrian. The new data contrasts
with the previous studies where the “metagranites” were dated as 590-560
Ma and attributed to a pan-African magmatic event. The zircons from the
“metasediments” in previous studies yielded a range of 1870-710 Ma with
a maxima at 890-710 Ma, suggesting derivation from an Afro-Arabian
source. Our new ages from the zircon populations found in the
paragneisses suggest derivation from a provenance dominated by
Mesoproterozoic continental arc type igneous rocks and deposition in a
continental margin not earlier than the mid Neoproterozoic. During the
late Neoproterozoic (ca 600Ma), the continental margin is once again in
close vicinity of the Cadomian Arc and was intruded by the arc magmatic
rocks. The age pattern of the pre-Cadomian paragneisses of Karadere on
the density-probability diagram is markedly different from NE
Africa-derived terranes but display similarities to the basement rocks of
both Avalonian and Amazonian terranes.
Safranbolu-Karadere area by Arpat et al (1978), their detailed age, source
areas and the palaeogeographic setting were a matter of debate. The
basement rocks in this area and also in a number of other outcrops of the
Istanbul-Zonguldak Terrane mainly consist of medium grade
quartzofeldspatic schists, quartzites, ortho- and paragneisses,
amphibolites/metagabbros together with slightly metamorphic granites,
aplites-pegmatites. The crystalline basement is disconformably overlain
by early Tremadocian (earliest Ordovician) graptolitic black shales. In the
Karadere area the metamorphic paragneisses in the host rocks of para and
ortho origin is garnet-biotite- muscovite. The metabasic rocks are
characterised by hornblende –epidote-chlorite. The intruding felsic
igneous rocks display blasto-milonitic textures and include only white
mica and chlorite as metamorphic minerals. Geochemically, the
metasedimentary host rocks display characteristic features of passive
margin rocks derived from a continental arc source. The felsic and mafic
orthogneisses/amphibolites are of granitic and gabbroic origin,
respectively. In tectonomagmatic discrimination diagrams they all plot in
volcanic arc field. Concordant LA ICP MS ages of detrital zircons
(n=285) from the paragneisses range from 2 Ga to 600 Ma, where 84% of
the ages range between 1.2 and 1.8 Ga (Mesoproterozoic). The youngest
detrital zircons (4%) in these rocks are 685 Ma (Cryogenian) in age. The
concordia age of the sampled granitic orthogneisses, on the other hand, is
604+/-2 Ma indicating to mid Ediacaran magmatism. The youngest ages
obtained from the paragneisses are Ar-Ar ages of 530-53 Ma indicating to
a metamorphic event during the earliest Cambrian. The new data contrasts
with the previous studies where the “metagranites” were dated as 590-560
Ma and attributed to a pan-African magmatic event. The zircons from the
“metasediments” in previous studies yielded a range of 1870-710 Ma with
a maxima at 890-710 Ma, suggesting derivation from an Afro-Arabian
source. Our new ages from the zircon populations found in the
paragneisses suggest derivation from a provenance dominated by
Mesoproterozoic continental arc type igneous rocks and deposition in a
continental margin not earlier than the mid Neoproterozoic. During the
late Neoproterozoic (ca 600Ma), the continental margin is once again in
close vicinity of the Cadomian Arc and was intruded by the arc magmatic
rocks. The age pattern of the pre-Cadomian paragneisses of Karadere on
the density-probability diagram is markedly different from NE
Africa-derived terranes but display similarities to the basement rocks of
both Avalonian and Amazonian terranes.