Field Trips

1107

FIELD TRIPS: FT-1

THE GEOLOGY OF THE HAYMANA (ANKARA) REGION: JURASSIC-CRETACEOUS STRATIGRAPHY AND THE CRETACEOUS-TERTIARY BOUNDARY

One-day geological field trip

28th April 2018 Saturday, 08.30-17.00

The participation is limited to 40 people, picnic lunch in the field, price: xx TL

 

Field trip leaders: Aral Okay1, Demir Altıner2 and Sevinç Özkan-Altıner2

1İTÜ Avrasya Yerbilimleri Enstitüsü ve Maden Fakültesi, Jeoloji Müh. Bölümü, Maslak 34469 İstanbul okay@itu.edu.tr

2ODTÜ, Jeoloji Müh. Bölümü, 06880 Ankara

 

Jurassic Bilecik Limestone and the overlying Campanian – Maastrichtian flysch in the core of the Haymana anticline.

The Jurassic – Tertiary stratigraphy of the Ankara region is best observed in the Haymana region.  Recent studies have shown the presence of an Upper Jurassic to Upper Cretaceous limestone succession in the core of the Haymana anticline1.  This limestone sequence consists of four formations, which are separated by unconformities.  These are: Upper Jurassic – Lower Cretaceous (Kimmeridgian – Berriasian) shallow marine limestones, Lower Cretaceous (Berriasian) pelagic limestones, middle Cretaceous (Albian – Cenomanian) pelagic limestone and calciturbidite and Upper Cetaceous (Turonian – Santonian) red pelagic limestones.  These carbonate-rich formations are unconformably overlain by a thick continuous clastic succession ranging from Campanian to Eocene.  This thick clastic series, which constitute the Haymana Basin, the Cretaceous-Tertiary boundary is recently precisely located and studied2.

The Jurassic – Cretaceous stratigraphy in the core of the Haymana anticline and the Cretaceous-Tertiary boundary in the clastic succession will be shown and discussed during the field trip.  The field trip will involve up to one hour long walks.  A picnic lunch will be eaten in the field.

1Okay, A.I., Altıner, D., 2016, Carbonate sedimentation in an active margin: Cretaceous history of the Haymana region, Pontides. International Journal of Earth Sciences, 105, 2013–2030.

2Esmeray-Senlet, E., Özkan-Altiner, S., Altiner, D., Miller, K.G., 2015, Planktonic foraminiferal biostratigraphy, microfacies analysis, sequence stratigraphy, and sea-level changes across the Cretaceous–Paleogene boundary in the Haymana basin, Central Anatolia, Turkey.  Journal of Sedimentary Research, 85, 489–508.

 

FIELD TRIPS: FT-2

GEOLOGY OF THE BEYPAZARI TRONA FIELD, ANKARA, TURKEY

One-day geological field trip

28th April 2018 Saturday, 08.30-17.00

The participation is limited to 40 people, picnic lunch in the field, price: Not determined yet.

 

Field trip leaders: Cahit HELVACI

Dokuz Eylül Üniversitesi, Jeoloji Mühendisliği Bölümü, Tınaztepe Yerleşkesi, 35160 Buca İzmir, Turkey, e-mail:cahit.helvaci@deu.edu.tr

Overlooking Beypazarı Town, Beypazarı monoclinal folds in the background.

The Beypazarı district is a large area of volcano-sedimentary rocks in the interior of central Anatolia, situated ~100 km northwest of Ankara. Trona, lignite, and bituminous shale occur in the lower part, and Na-sulfate and gypsum occur in the upper part of the sedimentary sequence of the Beypazarı Miocene basin.

The trona deposit, located 250–300 m below the topographic surface, was discovered incidentally in the summer of 1982 by the general directorate of the Mineral Research and Exploration (MTA) while carrying out a drilling project on lignite deposits. Proven trona reserves are 210 million metric tonnes, and total reserves are estimated as 240 million metric tonnes. The Beypazarı trona deposit is the world’s second largest trona deposit after the Green River deposit, Wyoming, USA. In addition, there are ~400 million metric tonnes of lignite, 340 million metric tonnes of bituminous shale, and 1 million metric tonnes of Na-sulfate in the Beypazarı basin.

The trona deposit located north of Zaviye village is associated with shale in lower part of the Hırka Formation and alternates with bituminous shale and claystones. Based on borehole data, it is estimated that the areal extent of the trona deposit is ~8 km2. The trona beds were deposited as two lensoidal bodies within a 70–100 m thick zone in the lower part of the shale unit. A total of 33 trona beds are known: 16 in the lower trona lens and 17 in the upper lens. The total thickness of the lower trona horizon ranges from 40 to 60 m, and the total thickness of the upper trona horizon is ~40 m. The interval between the lower and the upper trona horizons varies from 30 m to 35 m.

The most likely sources of Na for the formation of the trona and other sodium-carbonate salts were thermal springs, the tuffs interbedded with the sediments, and the extensive Neogene volcanic rocks interfingering with sedimentary rocks in the northeastern part of the basin.

REFERENCES

Helvacı, C., Natural Soda Deposits and their Economic Importance. Geological Bulletin of Turkey, 33(3), 49-58.

Helvacı,C., 2010, Geology of the Beypazarı trona field, Ankara, Turkey. Mid-congress Field Exursion Guide Book, Tectonic Crossroads: Evolving Orogens of Eurasia-Africa-Arabia 4–8 October 2010, Ankara, Turkey.

Helvacı, C., 1998, The Beypazarı trona deposit, Ankara province, Turkey. In: Proceedings of the First International Soda Ash Conference (John R. Dyni and Richard W. Jones, editors) Volume II. Wyoming State Geological Survey Public Information Circular 40, Laramie, 67-103.

 

FIELD TRIPS: FT-3

PALEOCENE-EOCENE STRATIGRAPHY, FOSSIL ASSOCIATIONS AND BIOSTRATIGRAPHY OF THE HAYMANA BASIN, ANKARA

One-day geological field trip

28 th April 2018 Saturday, 8.30-18.00

The participation is limited to 20 people, picnic lunch in the field, price will be announced later

Field trip leaders: Ercan Özcan1, Attila Çiner2, Şükrü Acar3, Güner Ünalan3, Aynur Hakyemez3

1İTÜ Maden Fakültesi Jeoloji Müh. Bölümü, Maslak 34469 İstanbul, ozcanerc@itu.edu.tr

2İİTÜ Avrasya Yerbilimleri Enstitüsü, Maslak 34469 İstanbul

3MTA Genel Müdürlüğü, Jeoloji Etütleri Dairesi, Çankaya 06800 Ankara

Paleocene-Eocene sedimentary sequence of the Haymana Basin displays remarkable vertical and lateral facies changes. Between Haymana and Polatlı, Palecene deposits are characterized by continental clastics (Kartal Formation), shallow-marine limestone (Çaldağ Formation) and deep-marine shales (Yeşilyurt Formation) (Ünalan et al., 1976). The Upper Paleocene- Lower Eocene deposits are made up of algal limestone, marl and shale beds (Kırkkavak Formation), that pass to deep-marine conglomerate-sandstone-marl-shale intercalations with debris flows (Ilgınlıkdere and Eskipolatlı formations). A regional shallowing is marked by the deposition of continental conglomerates and sandstones (Beldede Formation), and shallow-marine limestone (Çayraz Formation) that laterally grade to siliciclastic turbidites (Yamak Formation).

Field aspects of the lower part of the Lower Eocene Çayraz Formation and overlying planktonic foraminiferal marls near Çayraz village, north of Haymana, Ankara.

We aim to introduce a- larger bentic foraminiferal levels in the upper part of the Campanian-Maastrichtian sequence of the Haymana Formation (Özcan and Özkan-Altıner, 1997), b-shallow marine Kırkkavak Formation overlying the Kartal Formation near Karahamzalı village Haymana (Özcan et al., 2001) and c-highly fossiliferous lower part of the Çayraz Formation and overlying pelagic marls near Çayraz village (Çiner et al., 1996; Sirel, 1998; Özcan, 2002).

Çiner, A., Deynoux, M., Ricou, S., Koşun, E., 1996, Cyclicity in the Middle Eocene Çayraz carbonate formation, Haymana basin, Central Anatolia, Turkey. Palaeogeography, Palaeoclimatology, Palaeoecology, 121, 313-329.

Özcan, E., 2002, Cuisian orthophragminid assemblages (Discocyclina, Orbitoclypeus, Nemkovella) from Haymana- Polatlı basin (central Turkey): biometry and description of two new taxa. Eclogae Geologicae Helvetiae, 95, 75-97.

Özcan, E., Özkan-Altıner, S., 1997, Late Campanian- Maastrichtian evolution of orbitoidal foraminifera in Haymana Basin succession. (Ankara, Central Turkey). Revue de Paleobiologie, 16, 271-290.

Özcan, E., Sirel, E., Özkan-Altıner, S. Çolakoğlu, S., 2001, “Late Paleocene Orthophragminae (Foraminifera) from the Haymana– Polatlı Basin (Central Turkey) and description of a new taxon, Orbitoclypeus haymanaensis”. Micropaleontology, 47, 339-357.

Sirel, E., 1998, “Foraminiferal description and biostratigraphy of the Paleocene- Lower Eocene shallow-water limestones and discussion on the Cretaceous- Tertiary boundary in Turkey”, General Directorate of the Mineral Research and Exploration Monography Series, No:2.

Ünalan, G., Yüksel, V., Tekeli, T., Gönenç, O., Seyirt, Z.,  Hüseyin, Z., 1976, Haymana-Polatlı yöresinin (GB Ankara) Üst Kretase- Alt Tersiyer stratigrafisi ve paleocoğrafik evrimi. Türkiye Jeoloji Bülteni, 19, 159-176.

 

FIELD TRIPS 4: FT-4

ABORTED DUE TO HEALTH PROBLEM

ON THE DEFINITION OF ANKARA OPHIOLITIC MÉLANGE IN ANKARA REGION

A day geological field trip

April 28, 2018. Saturday, 09.00-18.00

Moderate walks. Picnic lunch in the field. The participation is limited to 20 people. price will be announced later.

Field trip coordinator: Bora Rojay1

1METU, Department of Geological Eng., 06800 Ankara, brojay@metu.edu.tr

The importance and the meaning of the Ankara ophiolitic mélange (“Ankara mélange”; Bailey ve McCallien, 1950; 1953) in the tectonic evolution of the Neotetis is increased with the newly, introduced age datings done on oceanic fragments. This will lead to changes in our understanding in the evolution of Tethys Ocean. Knowing this, the components of the Ankara ophiolitic mélange and the basins on top –Orhaniye basin as the example- will be introduced and Ankara ophiolitic mélange terminology will be discussed during the field trip.

The field trip will start from north of Ankara with Orhaniye basin and some basement rocks tectonically overlain by Ankara ophiolitic mélange with its components at 10.00 am. Afterwards the northwest to southeast thrusting of the Triassic limestone blocky sequence (Karakaya Unit) onto Ankara ophiolitic mélange will be seen in Elmadağ region (west of Ankara). Then along a section from Kılıçlar to Kızılırmak valley (west of Ankara) the components like pillow lavas alternating radiolarites, intensely deformed radiolarites, ophiolitic breccias, serpentinezed and intensely deformed peridotites and sheared matrix of the Ankara ophiolitic mélange will be seen. 13.00 Lunch break. After the break, the overthrusting of Ankara ophiolitic mélange onto overturned Late Cretaceous-Paleogene sequences will be seen along Kızılırmak valley. During the second half of the field trip, the tectonic elements of Ankara ophiolitic mélange, like pillow basalts, radiolarites, ophiolitic-radiolarian breccias, bio-volcaniclastic detrital limestones, and diabase-gabbro dykes cross-cutting all of these rocks will be seen in Kalecik region. 17.00 tea break at Baykuş gorge. Back to Ankara.

Figure 1. Tectonic elements of Ankara region and distribution of Ankara ophiolitic mélange (modified from Geological map of Turkey, 1:500 000 scaled MTA map) and NW-SE geological section.

Some References
Bailey, E. B. and Mc.Callien, W. J., 1953. Serpentine lavas, the Ankara Mélange and the Anatolian Thrust. Phil. Trans. Royal Soc. Edinburgh, 62/2, 403-442.

Bailey, E.B. and McCallien, W.J., 1950. The Ankara Mélange and the Anatolian Thrust. MTA Bull., 40, 17-21.

Festa, A., Pini, G.A., Dilek, Y., and Codegone, G., 2010. Mélanges and mélange-forming processes: a historical overview and new concepts, International Geology Review, 52:10-12, 1040-1105.

Koçyiğit, A., Özkan, S. and Rojay, B. 1988. Examples from the Forearc Basin Remnants at the Active Margin of Northern Neo – Tethys; Development and Emplacement Ages of the Anatolian Nappe, Turkey. METU Jour. of Pure and Applied Sci., 21, 1-3 183-210.

Norman, T. N., 1973, On the structure of Ankara Mélange. Proceedings of the Symposium on the 50th Anniversary of Turkish Republic. MTA Publ., 78-94.

Raymond, L.A., 1984. Classification of mélanges. In Mélanges: Their nature, origin and significance (ed; Raymond, L.A.). Geol. Soc. Am. Bull. Spec. Paper 198, 7-20.

Rojay, B., 2013. Tectonic evolution of the Cretaceous Ankara Ophiolitic Mélange during the Late Cretaceous to pre-Miocene interval in Central Anatolia, Turkey. Journal of Geodynamics. 65, 66-81.

 

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