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The Late Mesozoic and Cenozoic Tectonic Evolution of Western and Central Anatolia Revealed through the Central Sakarya and Cankiri Basin
Campbell, Clay Franklin
Campbell, Clay Franklin
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Abstract
This dissertation describes the tectonic development of Western and Central Anatolia from late-Cretaceous to recent times from the viewpoint of the sedimentologic, structural, and geochemical record of the Central Sakarya and Çankırı Basin. The first question I want to answer was “How many subduction zones facilitated intercontinental collision between the Pontides and Anatolide Tauride Block?” This question arose through seemingly contradictory geologic and kinematic datasets. Kinematic datasets demonstrate ~750 km of supra-subduction zone extension occurred from ca. 105–95 Ma whilst magmatism remained in the Black Sea region, supporting a scenario where two subduction zones facilitated intercontinental collision between Pontides and Anatolide-Tauride Block. However, although well exposed in Eastern and Central Anatolia, the presence of an additional accretionary wedge and magmatic arc have yet to be identified south of the Central Sakarya Basin located in western Anatolia, supporting the presence of a single intra-oceanic subduction system. Thus, to test the double vs. single subduction models, we reviewed the tectonic evolution of the Central Sakarya Basin and collected a supplementary zircon Hf dataset from late Cretaceous-Eocene basin levels. Our results demonstrate the majority of the sedimentary rocks within the lower levels of the Central Sakarya Basin were sourced from the İzmir-Ankara Suture Zone and are defined by a single, isotopically juvenile late Cretaceous detrital zircon age peak, 5–10 Myr older than biostratigraphic age determinations. Similarly, higher levels of the Central Sakarya Basin record a rapid, ~5 Myr shift to isotopically evolved Hf values during uplift of the İzmir-Ankara accretionary prism, which occurred ~10 Myr prior to the earliest estimates for intercontinental collision at ~75 Ma. As such, paleocurrent indicators, the absence of Pontide-affinity Paleozoic and Neoproterozoic detrital zircons, a juvenile to evolved isotopic shift in late Cretaceous detrital zircons, lag times, and premature uplift of the accretionary wedge in Western Anatolia are best explained by subduction of an intra-oceanic arc along the southern Pontide margin. In this light, I conclude that similar to Central and Eastern Anatolia subduction zones were located within the Neotethyan Ocean and along the southern margin of the Pontides prior to collision with the Anatolide-Tauride Block at ~75 Ma. The differences in along strike preservation history is a question that remains to be answered. The second question I want to answer was “How did Anatolia evolve with regards to the protracted late-Cretaceous to recent times collisions between the Pontides, Anatolide-Tauride Block, and African Continent?” This question arose through an influential article published in Nature Communications in 2017 that described how crustal thickening and the symmetric distribution of mantle sourced volcanic centers within the Central Anatolian Plateau supported a scenario where rapid foundering of a 160 km thick by 280 km wide region of lithospheric mantle drove > 1 km of rapid uplift around ~10 Ma. However, modest erosion rates throughout Cenozoic times and the absence of such a large anomaly in solid earth tomography are largely contradictory to foundering as the singular process that drove uplift of the Central Anatolia Plateau. In order to reconcile these observations, I focused on the northern Çankırı Basin region and the southern Konya Basin - Tuz Gölü depression within the Central Anatolian Plateau. By leveraging topographic datasets from modern plateau analogs in conjunction with local geologic and geochemical datasets I found that significant uplift in the northern Çankırı Basin region occurred via a small-scale ~150 km diameter crustal foundering event from 36.5–31.5 Ma. In contrast, ca. 1–2 km uplift of the southern Konya Basin - Tuz Gölü depression occurred from 10–8 Ma. I attribute the fault-bounded, internally drained, low relief elliptical region encompassing the Konya Basin and Tuz Gölü depression to reflect the recent growth and foundering of multiple smaller ~100 km diameter foundering events. In this light, I propose that small scale foundering events associated with modest magnitudes of uplift ( 1 km of rapid uplift around ~10 Ma. However, modest erosion rates throughout Cenozoic times and the absence of such a large anomaly in solid earth tomography are largely contradictory to foundering as the singular process that drove uplift of the Central Anatolia Plateau. In order to reconcile these observations, I focused on the northern Çankırı Basin region and the southern Konya Basin - Tuz Gölü depression within the Central Anatolian Plateau. By leveraging topographic datasets from modern plateau analogs in conjunction with local geologic and geochemical datasets I found that significant uplift in the northern Çankırı Basin region occurred via a small-scale ~150 km diameter crustal foundering event from 36.5–31.5 Ma. In contrast, ca. 1–2 km uplift of the southern Konya Basin - Tuz Gölü depression occurred from 10–8 Ma. I attribute the fault-bounded, internally drained, low relief elliptical region encompassing the Konya Basin and Tuz Gölü depression to reflect the recent growth and foundering of multiple smaller ~100 km diameter foundering events. In this light, I propose that small scale foundering events associated with modest magnitudes of uplift (< 1km/Myr) resulted in the formation of the Central Anatolian Plateau interior from late Eocene–recent times.
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Date
2022-12-31
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University of Kansas
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Keywords
Geology, Anatolia, Detrital zircon, Drip Tectonics, Hf isotopes, Incipient Collision