the gheshlagh bauxite deposit is located 110 km southeast of gorgan. the deposit has been developed as a stratiform horizon with more than 2 km length and a thickness of about 25 m along the contact of ruteh and elika carbonate formations. textural analysis indicates both allochthonous and autochtonous origins for the bauxites. bohemite, diaspore, anatase, rutile, hematite, goethite, kaolinite,...

In the Tethyan realm, leucocratic rocks were recognized as dikes and layers outcropping in ophiolitic of Western Alps, Corsica, Northern Apennines. Several authors have suggested that origin is associated with partial melting cumulate gabbro. Major trace elements composition paragenesis provided information about genetic processes. This research aims at disclosing, for first time, petrographica...

Detailed studies of the deeply metamorphosed Early Precambrian rocks Northern Ladoga region allowed us to distinguish three deformation stages Svecofennian tectogenesis during which there occurred significant structural and compositional transformations "cover (Paleoproterozoic) – basement (Archean)" system. In addition structural-paragenetic analysis, allocate transversal paragenesis in both f...

K^Ar isotopic ages presented by Uysal et al. for illitic clay minerals from drill core samples were interpreted to date the Woodleigh impact event at 359= 4 Ma, allegedly implicating Woodleigh in the Late Devonian mass extinction. However, only very equivocal evidence is presented by Uysal et al. to support a link between clay mineral paragenesis and impact-related features, and the K^Ar ages r...

23 24 Large rounded pyrite grains (>1 mm), commonly referred to as ‘buckshot’ pyrites, are a characteristic feature of 25 the auriferous conglomerates (reefs) in the Witwatersrand and Ventersdorp supergroups. Detailed petrographic 26 analyses of the reefs indicated that the vast majority of the buckshot pyrites are of reworked sedimentary origin, 27 i.e., that the pyrite originally formed in th...