Spatial patterns of erosion and landscape evolution in a bivergent metamorphic core complex revealed by cosmogenic 10Be: The central Menderes Massif (western Turkey)

In extensional provinces with low-angle normal faulting (such as the Aegean region), both tectonic processes and erosion induce landscape change, but their interaction during the evolution of topography and relief accompanying continental extension has rarely been addressed. Here we present local and catchment-wide 10Be erosion rates that document the spatial pattern of erosion in the central Menderes Massif, a metamorphic core complex consisting of two asymmetric mountain ranges (Bozdağ and Aydın) bound by detachment faults and active grabens. Catchment-wide erosion rates on the northern flank of the Bozdağ Range are rather low (40–110 mm/k.y.) but reach values of >300 mm/k.y. on the steep southern escarpment—a pattern that reflects both topography and bedrock lithology. In the Aydın Range, erosion rates are generally higher, with mean erosion rates of ∼190 and ∼260 mm/k.y. on the northern and southern flank, respectively, and more variable along strike. In both ranges, erosion rates of ridge crests derived from amalgamated clasts are 30–90 mm/k.y. The difference between local and catchment-wide erosion rates indicates that topographic relief increases in most parts of the massif in response to ongoing fault-related uplift and concomitant river incision. Our findings document that tectonic processes exert a significant control on landscape evolution during active continental extension and are reflected in both the topographic signature and the spatial pattern of erosion. In the Menderes Massif, rock susceptibility to weathering and erosion is a dominant factor that controls the erosional contribution to rock exhumation, which varies spatially between ∼10% and ∼50%

High-K volcanism in the Afyon region, western Turkey: from Si-oversaturated to Si-undersaturated volcanism

Volcanic rocks of the Afyon province (eastern part of western Anatolia) make up a multistage potassic and ultrapotassic alkaline series dated from 14 to 12 Ma. The early-stage Si-oversaturated volcanic rocks around the Afyon city and further southward are trachyandesitic volcanic activity (14.23 ± 0.09 Ma). Late-stage Si-undersaturated volcanism in the southernmost part of the Afyon volcanic province took place in three episodes inferred from their stratigraphic relationships and ages. Melilite– leucitites (11.50 ± 0.03 Ma), spotted rachyandesites, tephryphonolites and lamproites (11.91 ± 0.13 Ma) formed in the first episode; trachyandesites in the second episode and finally phonotephrites, phonolite, basaltic trachyandesites and nosean-bearing trachyandesites during the last episode. The parameter Q [normative q-(ne + lc + kls + ol)] of western Anatolia volcanism clearly decreased southward with time becoming zero in the time interval 10–15 Ma. The magmatism experienced a sudden change in the extent of Si saturation after 14 Ma, during late-stage volcanic activity of Afyon volcanic province at around 12 Ma, though there was some coexistence of Si-oversaturated and Si-undersaturated magmas during the whole life of Afyon volcanic province

K-richterite-olivine-phlogopite-diopside-sanidine lamproites from the Afyon volcanic province, Turkey

Middle Miocene volcanic activity in the Afyon volcanic province (eastern part of Western Anatolia) is characterized by multistage potassic and ultrapotassic alkaline volcanic successions. The volcanism is generally related to the northward subduction of the African plate beneath the Eurasian Plate. In Afyon, the Middle Miocene volcanic products consist of melilite leucitite, tephriphonolite, trachyte, basaltic-trachyandesite, phonolite, phonotephrite, tephriphonolite and lamproite rocks. Near-surface emplacement and relatively quiescent subaerial eruptions of lamproitic magma produced different emplacement forms such as dome/plug-shaped bodies and lava flows, showing variation in volume and texture. The mineralogical constituents of the lamproites are sanidine, olivine (77 < Mg no. < 81), phlogopite (74 < Mg no. < 78), K-richterite, clinopyroxene (74 < Mg no. < 78), with accessory apatite, calcite and opaque minerals. Afyon lamproites resemble Mediterranean-type Si-rich lamproites. Their compositional range is 50-52 wt % SiO(2), 4-8 wt % MgO, and they display a typical lamproitic affinity. Chondrite-normalized REE patterns exhibit enrichment in LREE relative to HREE ((La/Yb)(CN) = 15.3-17.0). They show extreme enrichment in LILE relative to primitive mantle values and troughs of Nb and Ti. The lamproites give a range of high initial (87)Sr/(86)Sr ratios and low (143)Nd/(144)Nd ratios. The geochemical and isotopic characteristics suggest that lamproitic magma is derived from highly metasomatized mantle. The enrichment history may include metasomatic events related to subduction, as in other active orogenic areas of the Mediterranean

Mechanism of emplacement and origin of the Ildir lava dome in the Karaburun Peninsula, western Anatolia (Turkey)

The Karaburun Peninsula, which is considered to be a part of the Anatolide-Tauride Block, is situated between western Anatolia and the eastern part of the Aegean Sea, in a post-collisional extensional environment, and is located within the Izmir-Balikesir Transfer Zone. The Paleozoic - Mesozoic basement rocks of the peninsula are cut and covered by Miocene volcanic successions, comprising mostly andesitic lavas and volcanoclastic deposits that interfinger with detrital lacustrine deposits. A NW-SE elongated andesitic exogenous composite lava dome structure (major axis is 4 km and minor axis is 1 km) was identified and dated to be 16.39 +/- 0.34 Ma in age. It cuts and covers the Algal andesitic pyroclastic and epiclastic deposits of the Ildir peninsula. Internal structures and igneous fabrics indicate a composite exogenous lava dome structure with short distance lava flows over a flat floor of Algal ignimbrite. Emplacement of this Ildir composite lava dome was controlled by fissure-like volcanic activity along multiple fault lineaments as a result of extensional duplex negative palm-tree lineaments which are related to the Miocene NW-SE directed sinistral strike-slip transtensional fault zone of the Karaburun peninsula. Comparison of the andesitic Ildir lava dome to all volcanic rocks of the Karaburun peninsula implies that the parental (more mafic) magma which formed the lava dome was generated by partial melting of a highly contaminated mantle source which had been modified by subduction-derived fluid/melt components. The Ildir melts were subsequently differentiated by fractional crystallization and crustal assimilation processes in the crust

Coeval Shoshonitic-ultrapotassic dyke emplacements within the Kestanbol Pluton, Ezine - Biga Peninsula (NW Anatolia)

The Biga Peninsula, in the north-western part of Western Anatolia, is part of the Sakarya Zone of the Western Pontides and the tectonically overlying Ezine group. The basement rocks are intruded by the early Miocene Kestanbol Pluton and early to middle Miocene calc-alkaline to shoshonitic-ultrapotassic volcanic successions related to postcollisional continental extension. The Kestanbol Pluton mainly comprises monzonite and granodiorite and is cut by shoshonitic-ultrapotassic tephriphonolite dykes. Ar-40-Ar-39 ages of biotite (21.22 +/- 0.09 Ma) and leucite (22.21 +/- 0.07 Ma) crystals indicate that tephriphonolite dyke emplacement was coeval with the intrusion of the Kestanbol Pluton during the early Miocene (21.5 +/- 1.6, 22.8 +/- 0.2 Ma). The geochemical features of the tephriphonolite dykes suggest a phlogopite-bearing mantle source which may originate from a previously metasomatised subcontinental lithospheric mantle source. This mantle source shows the imprints of carbonate-reach oceanic sediment recycling and crustal material contamination processes, which evolved during northward subduction and closure of the northern branch of the Neo-Tethys Ocean beneath the Sakarya zone during the late Cretaceous to Eocene