Bulletin of the Mineral Research and Exploration (BMRE)
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NEOTECTONIC CHARACTERISTICS OF BEŞPINAR-HAVZA SEGMENT OF NORTH ANATOLIAN TRANSFORM FAULT ZONE
No full textMINERALOGICAL-PETROGRAPHICAL STUDIES AND GENESIS OF THE KARALAR (GAZİPAŞA, ANTALYA) GALENITE-BARITE MINERALIZATION
No full textTHE METAMORPHISM AND THE RELATIONSHIP BETWEEN INFRA AND SUPRASTRUCTURES OF THE BİTLİS MASSIF – TURKEY
No full textThe infrastructure of the massive consists essentially of amphibolites, gneisses and micaschists intruded by a biotite granite and the successive hololeucocratic phase. The mantling rocks of the suprastructure comprise metapelitic rocks unconformably underlying metacarbonates dated as Middle Devonian- Mesozoic. The infra-suprastructure boundary is interpreted as a surface of transgressive overlap. The rocks of infra and suprastructure are involved in isoclinal folds with ductile deformation along most of the boundary conclusively suggesting in situ position of the suprastructure during the Alpine deformation. The shear planes are discontinous, en echelon and run independently of the infra-suprastructure boundary. A uniform sequence of Palaeozoic rocks, which is not intruded by the granites of the infra-structure, together with the infra-suprastructure boundary being a sedimentary contact, are conclusive evidence for the existence of a Precambrian event. Eradication of Precambrian paragenesis occurs in the flanks of major folds where a complete Alpine zoning exists from very low grade to anatectic conditions as exemplified by the Kesandere section in contrast to the preservation of Precambrian parageneses in the unsheared competent rocks of the infrastructure of the hinge areas. There is no gap in physical conditions with regard to a single episode of deformation. The gap occurring between the infra and the suprastructure is due to different physical conditions of Precambrian and Alpine deformations. Retrograde effects are presumably due to an Alpine imprint on the Precambrian parageneses, whereas they are attributed to a continuous process of deformation with contemporaneous uplift and progressive diminution of physical conditions in the case of imprint on early Alpine parageneses. The interpretation herein presented in relation to nature of infra and suprastructure boundary and metamorphism of Bitlis massive is consistent, for all aspects, with the regional geologic data showing that it is the deformed Alpine passive margin of the Arabian plate
ORIGIN AND PETROLOGY OF EKECİKDAĞ GRANITOID IN WESTERN CENTRAL ANATOLIAN CRYSTALLINE MASSIF
No full textA belt formed by a number of granitoid intrusions is situated at the western part of the Central Anatolian Crystalline Massif. One of the granitoid intrusion at the southwest of the belt crops out between Aksaray and Ortaköy and is called Ekecikdağ. Ekecikdağ granitoid, which is composed of monzogranites and granodiorites. intruded both the metamorphic and ophiolitic host rocks. Ekecikdağ granitoid is differentiated into following subunits with respect to their petrographical and chemical composition: Borucu granodiorite-monzogranite, Sinandi microgranite, Hisarkaya porphyribc granite, Kalebalta teucogranite and aplite granite. All these subunits are genetically related to each other. Borucu granodiorite-monzogranite represents the main magmatic phase whereas aplite granite the latest. Ekecikdağ granitoid has a calcalkaline character and show aluminocafemic trend. It has features which favour both I and S types of granite. Enclaves observed in granitoid is thought to be xenoliths derived from pre-existing gabbroic rocks during the emplacement of the granitic magma. The geochemical data suggest a post-collisional tectonic setting and a continental crustal source for Ekecikdağ granitoid. In regard to regional data, during Upper Cretaceous, the existence of an ensimatic arc to the north of the Central Anatolian Crystalline Massif is suggested. It is also proposed that collision and obduction of this ensimatic are on to the Central Anatolian continental crust caused crustal thickening and increase in the geothermal gradient in the region. This gave rise to the partial melting of the continental crust and to the formation of a granitic magma
AN EXAMPLE TO SEPIOLITE FORMATION IN VOLCANIC BELTS BY HYDROTHERMAL ALTERATION: KIBRISCIK (BOLU) SEPIOLITE OCCURRENCE
No full textGeological, mineralogical and chemical properties of a sepiolite occurrence, located in the south of Kıbrıscık township of Bolu Province, north central Turkey, have been investigated in detail, and new mineralogical data have been obtained. Differing from the sedimentary sepiolite deposits, mostly associated with the carbonate/evaporite sequences, Kıbrıscık sepiolite occurs in the Köroğlu (Gallatian) Volcanic Belt and has formed by the hydrothermal alteration of the vitric tuff unit of Middle Miocene aged Deveören Volcanites. The mineral, which shows a similar XRD pattern to sepiolite, gives DTA and IR patterns with close resemblance to those of palygorskite, in addition to its chemical composition with rather high alumina content. There are indications of monoclinal symmetry, determined by XRD, and it is thought to be possible that the material represents a new mineral phase
