Türkiye Jeoloji Bülteni

Abstract: In this study, it was attempted to determine the petrochcmistry and parent rock characteristics of theGümüşler amphibolites, associatcd with marble and quartzite, from the Niğde metamorplıics by using tlıcirwhole-rock chemical analyses. Amphibolites are associated with a seri es of Pre-Cretaceous supracmstalmetasediınents of the Gümüşler Formation. Massive and variably foliated amphibolites are made up mainlyby plagioclase, hornblende, quartz, diopsite witlı accessory sphene and apatite. Based on trace elementcharacteristics, the amphibolites are suggested to be metaigneous roeks; tuff or less likely basaltic-andesiticlava/sili, which were emplaced between metasediınents. Their parent roeks are subalkalinc basalt andandesite in cnmposition, and are characterisedby high K₂O, Rb, Sr, Ba, K/Rb (-270-550) ratin, and low MgO,Ti,Y, Zr, CaO/Al₂O₃ ratio. Pctrochenıical dataalso suggcstthat the parent roeks of these orthoaınphiboliteswere possibly fonued by fraetionalcrystallization of olivine, clinopyroxene and hornblende.

Abstract: Many maero and miero paleontologic data have been obtainedfrom the Late Cretaceous units ofTurkey. Any ve rleb r at e discovery is unknown since Cretaceous peri od and especialJy under the CretaceousTertiary (C/T) Boundary until ioday. Mosasaurus hoffmanni Mantell, 1829 is thefirst Reptilia vertebratediscovery from the Uppermost Cretaceous level of Türkiye. Mosasaurus hoffmanni was one of the giganticanİmal ofmarines and oceans of ali titnes and the Cretaceous period. Right and lef i maxilla fmgments and their a dozen tooih with left jugal bone of this fossîl are animportant material of this discovety which has beenfound İn the upper sinice of Beyler Dam, near DevrekaniTown of Kastamonu City, These remalns have beenfrom the sandy limestones levels of Campanian-earlymidâle Paleocene Davutlar Formationjust below C/T Boundary in the latesî Maastricllan level. This fossîlhas beenprevîously encoımtere.d in the. United States of America, Belgilim, Nederland, Poland and Bulgaria.Mosasourus hoffmanni found in this study is the youngest mosasaur in thefossü records and, meamvhile thisis thefırstdîscovery in the Western Asia.

Abstract: This study aims at determining sedimentologieal and sedimenter petrographic properties of LateCretaceousagedclasticdepositsthat are widespread in the Eastern Black Sea region.Sedİmenlary roeks exposed in the regkm were deposiied by turbidüy curmnts and characterized as thedistal turbidite. The fota!. îhicknesses of the sequencc range frorn 96 to 750m. Lithqfaci.es are composed ofarecomposite ofpink, green, greenish gray, gmy cohrecl and ıhin- medium-ihick bedded marl and shale; green,greenish gray, gray, brown coloredand îhin-medium-thickbedded, fine, medium, coarsegrainedsandstones. Thefrequently obsen>ed locally interbedded with conglomarete, limestones, elaystones and volcanic material,Sedimentary struclures constiiuteparallel. convolute lamination, graded bedding, had mark and flüte marks.Mineralogîc compo.siti.on of sandstones are auartz, faldispars, lithicfragments, opac mineral, accessorymineral matrix andcemenis. According to mineral ratios in the rock, sandstones are named litharenite-arkose.They are mineralogic immature and texturalty medium mature, The main provenance ofsandsiones weregenerally magmatic are, recycled orogen region a.ndback are subduction complex source. 

Abstract: Mineralogical, petrographical and geochemical features ofLiassic, Upper Cretaceom and Eocenevolcanic roeks in the Torul region, hich aresituatedalongthe transiiîon betmen the Northern and SouthernZones ofEastern Pontides, are investigated.Liassic volcanics are mainly basaltic, basattic andesitic and trachy-cındesitic in composüion. Boşaltcontains labrador (An51.63), olivine and augite, whi.le andesite coniains oligoclase (An27_2s), hornblende andannite (Mg# 0.58-0.67). These volcanics has medium-high K contents, and are tholeiiic to calc-alkaline innature. (La/Lu)N values are between 16.0 and 23.8. SiO2 versus majör and irace element variation plots showgood correlatiom, suggesting sigmficant role of olivine, clinopyroxene, plagioclase and Fe-Ti oxide fractionation during the evolution. The rocks have high LlLE (BA, Kb, Sr) andLREE (La, Ce) but low Ht`SE(Zr, Y, Ti) contents. Trace element distributions show similarities o/N-type MORB sources. Ba/La ratios arebetween 3 and 9, and show similarities ofocean ısland basalt. Ba/Nb, Nb/Th, Th/Y and Nb/Y ratios shasimilarities ofocean ısland basalt, hile KjRb, K/Ba, Sr/Rb, Zr/Nb, Ba/Th, Ba/La, Zr/Rb and Y/Nb ratiosshow similarities of N-type MORB.Upper Cretaceous volcanics are bimodal and, are andesite, dacite and rhyolite in composiüon.Andesite contains andesine (An4l_49), acünoliüc hornblende (Mg# 0.83-0.84), magnesio-hornblende (Mg#0.79) and biotite: dacite contains oligocla.se, sanidine, auartz andannite (Mg# 0.58-0,62): rhyolite containsandesine-oligoclase (An27_i4), guartz, sanidine, biotite and hornblende. (LalLu)N values are between 3.7 and14.7, Increasing in SiO2 versus K2O, Rb, Th, Ba and Nb contents show positive correlation, suggestingsignificant plagioclase, hornblende and Fe-Ti oxide fractionation during the evolution of volcanics. Thesevolcanics enrlchedLlLE elements but depleted HFS elenıenis at the N-type MORB normalhedira.ee elementdiagrams. Negaiive Nb and Ti anomalies shows influence of subduction component during the evolution ofmain magmas. Ba/La ratios are between 15 and 40, and show similarities oftypical ısland are basalt. La/Nb,Ba/Nb, Ba/Th, Rb/Nb, K/Nb, Ba/La, K/Ba, Nb/Th, Zr/Nb and Sm/Nd ratios show similarities of ısland arecalc-alkaline basalt.Eocene volcanics are andesite in composiiion and contain andesine (An4i_44)-oligoclase (An^û.jg),magnesio-hastingsitic hornblende (Mg# 0.72-0.92), magnesio-hastingsitic (Mgtt 0.84-0.91), tschermakitichornblende (Mg4 0.70-0.77), augite (Wo43-44), dlopside (Wo46) and biotite. These volcanics are calcalkaline in character, and has medhım-high K contents. (La/Lu)N values are between 4.6 and 6.9.Fractionation of plagioclase, pyroxene, hornblende and Fe-Ti oxide played an importand role in Eocenevolcanic rocks. Rocks have high LlLE and LREE contents and low HFSE contents. Negaiive Nb and Tianomalies according to the N-type MORB shows influence of subduction component during the evolution ofmain magmas. Ba/l.a rntioz arebelween 43 and 80, andshow similarUi.es of ıslandare basalt. Ba/Nb, Ba/Th.Rb/Nb, K/Nb, Ba/La, K/Rb, Zr/Rb, Sm/Nd and Zr/Ba ratios show similarities of ısland are calc-alkalinebasalt.rDiseguitibriıım tesiures showing magma mixing such as oscülatory zoning, sieve testured andresorbed plagioclase phenoaysts, embayed auartz, breakdown of hornblendes and biotites are commonlyobserved in these rocks. Reverse zoning such as decreasing of anorlhite contents of plagioclase phenocrystsfrom rim to core, decreasing of Mg number of hornblende and pyroxene phenocrysts from rim to core,suggesting of magma mbdng in gechemically. İn addition, basic enelaves observing in Upper Cretaceousdaciles shows signijicant role of magma mingling during the evolution of Torul Volcanics.Assimilation with together fractional crystallisation has signijicant role the evolution of volcanics.High SiO2, La and Ce contents, LlLE enrichment, high K20/Na20 ratios andlow Ti/Yb ratios, and low P2O5concentrations İndlcate interferenceofmain magmas with cruatul materials.Mineralogical, Petrographical andgeochemieal dala indicate that the Torul volcanic rocks evolvedhy the fractional crystallizaüon and magma mixtng ± coniamination/assimilaüon of a parental magmaderived from loer crust and/or metasomatized upper mantle, and the sources of those volcanics areenriched-MORB manile in Liassic, and metasomatised MORB mantle in Upper Cretaceous and Eocene.