Geomorphic and geological constraints on the active normal faulting of the Gediz (Alaşehir) Graben, Western Turkey.

The Gediz (Alaşehir) Graben is located in the highly tectonically active region of Western Turkey. Extension due to regional geodynamic controls has resulted in a broadly two-phase evolution of the graben; firstly, low-angle normal faulting relating to the exhumation of the Menderes Massif metamorphic core complex took place between 16 - 2.6 Ma. Secondly, high-angle normal faulting initiated ~ 2 Ma forming the Gediz and other E-W trending grabens in the region. Here we quantify the throw rate along the fault array over the last 2.6, 2 and 0.7 Ma using structural and geological constraints, along with analysis of topographic relief as a proxy for footwall uplift. We derive, for the first time, time averaged rates of fault motion from 0.4 mm/yr to 1.3 mm/yr along the strike of the Gediz Graben, with variation in throw-rate associated with the geometry of individual fault strands. Patterns in throw-rate along strike of the graben bounding fault array also suggest that the fault segments have become linked during the last 2.6 - 2 Ma, possibly at 0.8 – 0.7 Ma. Furthermore, these data suggest that an earthquake occurring along the graben bounding fault could have a maximum predicted Mw of 6.3 - 7.6

Normal fault growth and linkage in the Gediz (Alasehir) Graben, Western Turkey, revealed by transient river long-profiles and slope-break knickpoints

The Gediz (Alaşehir) Graben is located in the highly tectonically active and seismogenic region of Western Turkey. The rivers upstream of the normal fault-bounded graben each contain a non-lithologic knickpoint, including those that drain through inferred fault segment boundaries. Knickpoint heights measured vertically from the fault scale with footwall relief and documented fault throw (vertical displacement). Consequently, we deduce these knickpoints were initiated by an increase in slip rate on the basin-bounding fault, driven by linkage of the three main fault segments of the high-angle graben bounding fault array. Fault interaction theory and ratios of channel steepness suggest that the slip rate enhancement factor on linkage was a factor of 3. We combine this information with geomorphic and structural constraints to estimate that linkage took place between 0.6 Ma and 1 Ma. Calculated pre- and post-linkage throw rates are 0.6 and 2 mm/yr respectively. Maximum knickpoint retreat rates upstream of the faults range from 4.5 to 28 mm/yr, faster than for similar catchments upstream of normal faults in the Central Apennines and the Hatay Graben of Turkey, and implying a fluvial landscape response time of 1.6 to 2.7 Myr. We explore the relative controls of drainage area and precipitation on these retreat rates, and conclude that while climate variation and fault throw rate partially explain the variations seen, lithology remains a potentially important but poorly characterised variable

pattern in the eastern Mediterranean

Sedimentologic and stable isotopic studies in the cal basin-fill provide new insights on the late NeogeneQuaternary climatic pattern in the eastern Mediterranean. Long-term subsidence and terrestrial sedimentation in the basin beginning in the late Miocene are recorded in alluvial fan and fluvial deposits overlain by Pliocene palustrine carbonates. An erosional unconformity separates the Pleistocene siliciclastic and calcrete deposits above as a single sedimentary unit resting on top of floodplain fines and restricted to the basin center.The stable isotopic analysis of the palustrine carbonates and pedogenic calcretes displays a wide range of -7.98 < delta O-18 < -6.38%. and -8.89 < delta O-18 < -7.06 parts per thousand, respectively) and the lack of significant delta O-18-delta C-13 covariance (r = 0.59 and 024) may indicate subhumid conditions or significant diagenetic alteration. The delta C-13 values of these carbonates (-7.71 <delta C-13 < 4.08%. and 9.15 <delta C-13 < 6.17 parts per thousand, respectively), organic delta C-11 data from calcretes (-27.88 and 24.57% average value: 26.53%.), and floral remains indicate that the landscapes were dominated by C3 forest plants. (C) 2013 Elsevier B.V. All rights reserved

fluvio-deltaic sequence of the Denizli Basin (SW Turkey)

The late Pliocene-early Pleistocene Tosunlar succession (Denizli Basin, southwestern Turkey) represents fluvial-dominated delta environments at the margins of a brackish long-lived lake. Two main facies associations are documented: (i) a delta front facies association, with a distal (DF1) and proximal (DF2) deposits; and (ii) a delta plain facies association that contains distributary channel (DPI) and interdistributary swamp (DP2) deposits.The stable isotopic analysis of the mollusc faunas exhibit a narrow range of values (-4.68 < delta O-18 < + 021%. and + 0.43 < delta C-13 < +3.27%., respectively) and the very poor delta O-18-delta C-13 correlation (r = -0.16) may indicate hydrologically open lake and significant diagenetic alteration. The mollusc faunas and their stable isotope ratios show a biogeographically isolated brackish lake system under semiarid climatic conditions. Under special environmental conditions the endemic faunal composition remained constant which is very unusual for a (semi-) isolated long-lived lake setting. (C) 2015 Elsevier B.V. All rights reserved

basins

The Cal Basin formed in the late Miocene as an orogen-top rift hosting terrestrial sedimentation. The initial array of alluvial fans in a half-graben basin was replaced by an axial meandering-river system during the late Tortonian. Palaeomammal taxa indicate a mid-Turolian age of the deposits and a grass-dominated steppe ecosystem. Isotopic data from pedogenic carbonates indicate a warm, semiarid to arid climate. Subhumid to humid climatic conditions prevailed in the Pliocene, with a palustrine environment and savannah-type open ecosystem, recording a regional response to the marine flooding that terminated the Messinian 'salinity crisis' in the Mediterranean. Pleistocene saw re-establishment of a fluvial system in the basin with the development of an open steppe ecosystem in warm, semiarid to arid climatic conditions. The sedimentary facies analysis of the basin-fill succession, combined with biostratigraphic data, render the basin a regional reference and help to refine the Neogene tectono-climatic history of SW Anatolia. (C) 2012 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved

(Denizli Basin, Southwestern Anatolia, Turkey)

The chemical and isotopic properties of thermal waters (Kamara and Cizmeli) and cold springs from the Venice Geothermal Field (YGF), in southwestern Anatolia, Turkey are investigated in order to establish a conceptual hydrogeochemical-hydrogeological model. These thermal waters derive from Menderes metamorphic rocks and emerge along normal faults; they are commonly used for heating of greenhouses and bathing facilities. Discharge temperatures of thermal waters are 32 degrees C to 57 degrees C (mean 51 degrees C) for Kamara and 35 degrees C to 68 degrees C (mean 47 degrees C) for Cizmeli, whereas deep groundwaters are 15 degrees C to 20.1 degrees C (mean 17 degrees C) and shallow groundwaters ware 12 to 16 degrees C (mean 15 degrees C). Kamara and Cizmeli thermal waters are mostly of Na-Ca-HCO3-SO4 type, whereas deep groundwaters are Ca-Mg-HCO3 and Mg-Ca-HCO3 types and shallow groundwaters are mainly Mg-CaSO4-HCO3 and Ca-Mg-HCO3 types.In the reservoir of the geothermal system, dissolution of host rock and ion-exchange reactions changes thermal water types. High correlation in some ionic ratios (e.g. Na vs. Cl, K vs. Cl, HCO3 vs. Cl) and high concentrations of some minor elements (e.g., As, Sr, B, Cl, F) in thermal waters likely derive from enhanced water-rock interaction. Water samples from YGF have not reached complete chemical re-equilibrium, possibly as a result mixing with groundwater during upward flow. Geothermal reservoir temperatures are calculated as 89-102 degrees C for Kamara and 87-102 degrees C for Cizmeli fields, based on the retrograde and prograde solubilities of anhydrite and chalcedony. Based on the isotope and chemical data, a conceptual hydrogeochemical-hydrogeological model of the YGF has been constructed. Very negative delta O-18 and delta H-2 isotopic ratios (Kamara: mean of 8.43 parts per thousand and 56.9 parts per thousand, respectively and Cizmeli: mean of -7.96 parts per thousand and - 53.7 parts per thousand, respectively) and low tritium values (<1 TU) reflect a deep circulation pathway and a meteoric origin. Subsequent heating by conduction in the high geothermal gradient setting (resulting from regional crustal thinning) drives geothermal waters upwards along faults and fractures that act as hydrothermal pathways. Positive delta C-13 ratios (+9.45 parts per thousand for Kamara and +7.28 parts per thousand for cizmeli) indicate a metamorphic origin of thermal waters. Negative carbon isotope ratios (-8.40 parts per thousand) found in the cold groundwaters are linked to exchange in freshwater carbonates of the Sazak Formation. (C) 2015 Elsevier B.V. All rights reserved

(Denizli Basin, Southwestern Anatolia, Turkey)

The chemical and isotopic properties of thermal waters (Kamara and Cizmeli) and cold springs from the Venice Geothermal Field (YGF), in southwestern Anatolia, Turkey are investigated in order to establish a conceptual hydrogeochemical-hydrogeological model. These thermal waters derive from Menderes metamorphic rocks and emerge along normal faults; they are commonly used for heating of greenhouses and bathing facilities. Discharge temperatures of thermal waters are 32 degrees C to 57 degrees C (mean 51 degrees C) for Kamara and 35 degrees C to 68 degrees C (mean 47 degrees C) for Cizmeli, whereas deep groundwaters are 15 degrees C to 20.1 degrees C (mean 17 degrees C) and shallow groundwaters ware 12 to 16 degrees C (mean 15 degrees C). Kamara and Cizmeli thermal waters are mostly of Na-Ca-HCO3-SO4 type, whereas deep groundwaters are Ca-Mg-HCO3 and Mg-Ca-HCO3 types and shallow groundwaters are mainly Mg-CaSO4-HCO3 and Ca-Mg-HCO3 types.In the reservoir of the geothermal system, dissolution of host rock and ion-exchange reactions changes thermal water types. High correlation in some ionic ratios (e.g. Na vs. Cl, K vs. Cl, HCO3 vs. Cl) and high concentrations of some minor elements (e.g., As, Sr, B, Cl, F) in thermal waters likely derive from enhanced water-rock interaction. Water samples from YGF have not reached complete chemical re-equilibrium, possibly as a result mixing with groundwater during upward flow. Geothermal reservoir temperatures are calculated as 89-102 degrees C for Kamara and 87-102 degrees C for Cizmeli fields, based on the retrograde and prograde solubilities of anhydrite and chalcedony. Based on the isotope and chemical data, a conceptual hydrogeochemical-hydrogeological model of the YGF has been constructed. Very negative delta O-18 and delta H-2 isotopic ratios (Kamara: mean of 8.43 parts per thousand and 56.9 parts per thousand, respectively and Cizmeli: mean of -7.96 parts per thousand and - 53.7 parts per thousand, respectively) and low tritium values (<1 TU) reflect a deep circulation pathway and a meteoric origin. Subsequent heating by conduction in the high geothermal gradient setting (resulting from regional crustal thinning) drives geothermal waters upwards along faults and fractures that act as hydrothermal pathways. Positive delta C-13 ratios (+9.45 parts per thousand for Kamara and +7.28 parts per thousand for cizmeli) indicate a metamorphic origin of thermal waters. Negative carbon isotope ratios (-8.40 parts per thousand) found in the cold groundwaters are linked to exchange in freshwater carbonates of the Sazak Formation. (C) 2015 Elsevier B.V. All rights reserved

Anatolia, Turkey)

The Karahayt Geothermal Field (KGF) is located at the northern margin of the Denizli Basin in SW Anatolia (Turkey) where thermal waters discharge along the Quaternary normal fault segments locally displaced by conjugate transfer faults. Major and trace element contents and stable isotopes (delta O-18, delta H-2, delta H-3 and delta C-13) of the KGF thermal and cold waters were analyzed in order to determine their origin and evolution and reservoir temperatures. Two main thermal waters, indicated as being fed by steam-heated aquifers, are recognized: (1) Ca-HCO3 and (2) Ca-SO4 types. All thermal waters have shown non-equilibrium chemical conditions, indicating mixing processes. According to the delta O-18 (-9.14 to -8.07) and delta H-2 (-59.50 to -51.80) data, the KGF thermal waters are meteoric in origin and originated from precipitation in the northern piedmont of Yenice Horst with elevation of 900 m asl. Various geothermometers yield the reservoir temperatures of 80-130 degrees C. A conceptual flow model for the KGF was suggested as follows: the thermal waters were derived from a regional flow system with high recharge areas and deep circulation depth. The NW- and NE-trending conjugate fault segments (the Pamukkale Fault Zone) serve as features of hydraulic channelling, magmatic heat source and fluid convection in the extensional settings. This fault system is characterized by migration of a large amount of CO2-rich gas from the deep geothermal reservoir. Consequently, the KGF is characterized by a fault-hosted geothermal system affected by magmatism and active extensional tectonics, the same as other geothermal fields in this crustal extensional setting