Türkiye Jeoloji Bülteni

Abstract: The NW-trending Datça Graben, E-W trending Reşadiye Horst, Gökova and Hisarönü Grabens are the mostimportant morphologic and structural units ofthe SouthwestAnatolia on which, tectonic evolution was controlledby NW-SE, NE-SW and E-W trending faults. The Datça Graben has been started to develop as a halfgraben on theLycean Nappes ofthe central part ofthe Reşadiye Peninsula under the control ofNW-trending southern marginalfault during early Pliocene. Lagoonal-fluvial environment connected with shallow marine has evolved itsevolution as a graben till late Pliocene (late Piacenzian). E-W trending Gökova Graben and Hisarönü Graben,started to develop under the effect of N-S directed extension, ends the development of the Datça Graben. TheGökova Graben is about 140 km long and enlarges from about 5 km to 30 km westward, and activeYali andNisyrosvolcanic centers are located at the western tip ofthe peninsula. E-W trending southern marginal faults of thisgraben and northern marginal faults of the Hisarönü Graben cut the late Pliocene deposits of Datça Graben,forming Reşadiye Horst between these two grabens. This is an important evidence for the development ofGökovaand Hisarönü Grabensstarting from early Quaternary.This region is one of the seismically active regions of the southeast Aegean Sea. The records of historic andinstrumental period shows the presence ofthe strong earthquakes with magnitudes of7.7 (Ms) and intensity ofX,and the effect of important tsunamies in the region. Based on the focal depth and fault plane solutions of theearthquakes (MsS4) occurred in the region between 2000-2006, it is observed that shallow earthquakes associatewith E-W trending normal fault planes, where as the deep earthquakes associate with oblique to strike-slip faultplanes. The concentration of earthquake epicenters in the central and northern part of Gulf of Gökova is animportant evidence for the seismic activity of the central part and northern margin of the Gökova Graben.However, the increase in the density ofdeep focused earthquakes at the south and SW ofReşadiye Peninsula mustbe related with northward subduction along theAegean trench. Based on the earthquakes ofthe historic period andseismic activity ofthe region, we can conclude that the seismic risk and tsunami probability ofthe region is stillvery high.

Abstract: Detailed geological mapping of the western side of Çankırı basin demonstrates that the base of the Neogenesuccession, the Kılçak formation, is found on both sides ofa tectonic sliver. These outcrops are correlated throughtheir lithological descriptions and fossil contents. This finding eliminates the recent tectono-sedimentary modelthat presents the Kılçak formation as a last product of an intercontinental convergence, developed in front ofthethrust sheets of the İzmir-Ankara suture zone. In contrast, our findings support the proposal that the Neogenesuccession in the western margin ofthe Çankırı basin is fragmented by the post Pliocene tectonic sliver, regardedas a neotectonic structure.

Abstract: TheAkgüney copper lead zinc deposit is one ofthe widely occuring and workable deposits in the Eastern BlackSea Region ofTurkey. This deposit consists ofore veinsfound along thefaultzones hosted by hardly altered UpperCretaceaous andesitic rocks. Seven ore veins have been identified and numbered asD-l, D-2, D-3, D-4, D-5, D-6andD-7. These ore veins, excludingD-7, have strikes and dips of N7O-8O0 W, 50-60° NE, while the last one has adip ofE-W, 25° S.The ore veins are cropt out as hardly limonitezed and hematitized quartz veins. Two different ore types weredistinguishedwithin the D-l andD-2 veins which are being mined in the adits. Thefirst one consists ofquartz andfine grainedpyrite, while the second one consists ofquartz, calcite and coarse grained sulfide minerals such as chalcopyrite, galena, sphalerite, fahlor and secondary limonite veinlets in addition to pyrite. The succession ofthese minerals have been identified as: pyrite galena chalcopyrite-Isphalerite chalcopyrite-II(ffahlor)-quartzcalcite.Fluid inclusion data indicate that the oreformingfluids contain CaCl2, MgCl2, NaCl andpossiblyKCl assalts, thesalinity ofthefluids is in the range of24.34 to 13.94 (avr. = 19.0) %NaCl equivalent, and the temperature ofthefluids is in the range of349.0 to 276.0 °C (avr. 307.0 °C) during the crystallization ofthe quartz, going down to211.0 °Cthrough the laterstages ofmineralization.

Abstract: This paperpresents a study ofthe 17 meters high Harmantaşı submarine hill, located 1 mile offshore and at 30meters depth in the north ofthe Saros Gulf, the underwaterspringssurfacing there and theirimpact on seawaterandsediments. Forthispurpose water andsedimentsampleswere taken along lines, and temperature, salinity, pH,DO and organic carbon, total carbonate and heavy metals (Fe, Mn, Cu, Ni, Zn) were analyzed. Also theforaminifertypes were determined.Atsome specificpoints along the 4 linesstudied, underwaterfreshwatersprings arefoundwith the help ofanalyzedwater parameters. The measurement depth being between surface water and mid depth water, and the cyclecurrents having different directions and speeds on the surface, mid and bottom levels, effect the spreading speedanddirection ofthefreshwater.Organic carbon content in surface sedimentsamplesfrom 4 lines, is at acceptable varies between 0,5%-2%. In 41ofthe samples, CaCO3 is measured between 6%-83% and the average is 44%. Especially intensive shell existencein the stations close to the center caused higher concentrations of CaCO3 However at the lower parts ofthesubmarine hill the source ofCaCO3 is more lithogenic. In the stations where an increase in CaCOs isfound, there isa decrease in organic carbon content. Also in the samples with high carbonate contents, sand-sized grainsfromshells are abundant, whereasin the stations with dominant mudsizedgrainsthe organic carbon contents are high.Metal concentrations match well with the average compositions ofsedimentary rocks. General distribution ofthe5measured heavy metals (Cu, Zn, Ni, Mn, Fe) are supporting each other. There is metal increase in some ofthe 42samples studied (for example 1-30, 11-30, IV-70). Whereas, when each metal is elevated within itself, pointaldifferences are clear (for example: in the station 1-60, Ni high, Zn low concentration). Metal contents ofthenorthwestern part ofthe Harmantaşı submarine hill are relatively higher when compared with those from thenortheastern part. Changes in the submarine hill`s morphology are reflected in abundant occurrences ofshelledorganisms at some stations, and differences in speed and direction of currents, influence the accumulation ofinorganic sediments, which determinesthe heavymetal concentration.From the foraminifer species, CaCOt shelled Haurenid types exist abundantly in spring centers and nearby.Farther away, aglutinantshelltextulariidforms are increased.