Nb–Ta mineralization in Ti-oxide minerals from the Bagolyhegy Metarhyolite Formation (Bükk Mountains, NE Hungary)

The foliated low-grade metamorphic rocks of the Triassic Bagolyhegy Metarhyolite Formation, mainly of pyroclastic origin, host post-metamorphic quartz-albite veins containing abundant tourmaline and occasionally rutile/ilmenite. The study of the Ti-oxide-mineralized veins with SEM-EDX revealed an unusual mineral assemblage comprising fine-grained Nb–Ta-bearing oxides (columbite-tantalite series, fluorcalciomicrolite and other Nb–Ti–Y–Fe-REE-oxide minerals) intergrown with Nb-rich polymorphs of TiO2 (anatase, rutile), ilmenite and zircon enriched with hafnium. This high field strength elements (HFSE)-bearing paragenesis is unexpected in this lithology, and was not described from any formation in the Paleozoic-Mesozoic rock suite of the Bükk Mountains (NE Hungary) before. The host metavolcanics are significantly depleted in all HFSE compared to the typical concentrations in felsic volcanics and the mineralized quartz-albite veins have even lower Ti–Nb–Ta concentration than the host rock, so the mineralization does not mean any enrichment. From proximal outcrops of the Triassic Szentistvánhegy Metavolcanics, potassic metasomatized lenses with albite-quartz vein fillings containing rutile/ilmenite are known. We studied them for comparison, but they only contain REE mineralization (allanite-monazite-xenotime); the Nb–Ta-content of Ti-oxide minerals is undetectably low. LA-ICP-MS measurements for U–Pb dating of Hf-rich zircon of the Nb–Ta-rich mineral assemblage gave 71.5 ± 5.9 Ma as lower intercept age while dating of allanite of the REE mineralized quartz-albite veins gave 113 ± 11 Ma as lower intercept age. The REE-bearing vein fillings formed during a separate mineralization phase in the Early Cretaceous, while the Nb–Ta mineralization was formed by post-metamorphic alkaline fluids in the Late Cretaceous., controlled by fault zones and fractures.

Geological map of Athens Metropolitan Area, Attica (Greece): A review based on Athens Metro ground investigation data

The ground investigations for the construction of Athens Metro –including over 60.000 m of sampling boreholes and geological mapping of the underground tunnel face–, planned and carried out under the supervision of ATTIKO METRO S.A., offer important geological data that enrich and locally modify our knowledge for the geology of Athens Metropolitan Area (AMA). On the basis of these data, this paper presents the Geological Map of AMA as well as a revised tectonostratigraphic scheme for the area and geological profiles along several sections of the Athens Metro lines. The geological map is a synthesis of the geological data obtained from the ground investigations with the already published geological maps and includes a Mesozoic rock assemblage as well as the Neogene-Quaternary Athens Basin. The following basic conclusions can be drawn from the interpretation of these data: (a) The Athens Unit, the basement of AMA, is divided into four formations (from bottom to top), the Lower Athens Schist, the Upper Athens Schist, the Athens Sandstone-Marl Series and the Crest Limestone. (b) Ultrabasic rocks (serpentinite) constitute the basement of Athens Unit. (c) Serpentinite bodies at the eastern border of Athens Basin, have undergone almost complete metasomatism to listwanite along their tectonic contacts with Alepovouni Marble on top and Kessariani Dolomite at their base. (d) The limestone outcrops at the western border of Athens Basin (e.g., Karavas hill) form tectonic windows of Pelagonian Upper Cretaceous limestone underneath the Athens Schist and not klippen of Crest Limestone on top of it. The revised geological map also includes the Attica-Evia Fault, which is the dominant structure of the broader area, locally mapped by two sampling boreholes across the planned metro line 4.

WELL AND OUTCROP CORRELATION IN THE EASTERN PART OF AKIMEUGAH BASIN, PAPUA: MESOZOIC PLAY POTENTIAL

Mesozoic sediments are the main objective for hydrocarbon exploration in the eastern part of Akimeugah Basin, Papua. However, little information is currently available on paleogeography and subsurface distribution of the Mesozoic rock unit. This study analyzed Mesozoic rock unit from outcrops at Wamena and surrounding area to wells data in the eastern part of Akimeugah Basin, Papua. Outcrop and well correlation was made to interpret paleogeography of Mesozoic unit. This study was using existin 2D seismic and passive seismic tomography data to determine the distribution of Mesozoic rock unit in the subsurface and its hydrocarbon potential. The Mesozoic rock unit in the eastern part of Akimeugah Basin is divided into four formations based on their lithological characteristic. Respectively from old to young, Kopai, Woniwogi, Piniya and Ekmai Formation. The depositional environment of Mesozoic rock unit in the southern part of the study area is shore/tidal to shelf and basin fl oor in the northern part. Three Mesozoic potential plays in the studied area are divided into 1) Central Range Mountains thrust-fold belt play, 2) Akimeugah low land thrust-fold belt play and 3) Tanah Merah pinch-out play. The results presented in this paper are expected to be a guide for further hydrocarbon exploration in the study area. Mesozoic sediments are the main objective for hydrocarbon exploration in the eastern part of Akimeugah Basin, Papua. However, little information is currently available on paleogeography and subsurface distribution of the Mesozoic rock unit. This study analyzed Mesozoic rock unit from outcropsat Wamena and surrounding area to wells data in the eastern part of Akimeugah Basin, Papua. Outcrop and well correlation was made to interpret paleogeography of Mesozoic unit. This study was using existing 2D seismic and passive seismic tomography data to determine the distribution of Mesozoic rock unit in the subsurface and its hydrocarbon potential. The Mesozoic rock unit in the eastern part of Akimeugah Basin is divided into four formations based on their lithological characteristic. Respectively from old to young, Kopai, Woniwogi, Piniya and Ekmai Formation. The depositional environment of Mesozoic rock unit in the southern part of the study area is shore/tidal to shelf and basin fl oor in the northern part. Three Mesozoic potential plays in the studied area are divided into 1) Central Range Mountains thrust-fold belt