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A) Oolite with muscovite schist core and micritic calcite shell in sandstone of Series I. B) Pebble of limestone with foraminifera. C) Pebble of limestone with radiolaria and algae. D) Pebble of chert with radiolaria. E) Pebble of metabasalt with plagioclases with ophitic texture. F) Oolitic limestone: ooids cemented with sparitic calcite (B-F in conglomerates from Series II).
Source publication
In Attica, from the Miocene through the Quaternary, successive generations ofdetachment faults caused exhumation and denudation ofAlpine HP rocks and -later on -formation of sedimentary basins. The Mesogea low angle detachment fault separates the HP rocks exposed at the southern flank ofthe PenteLi Mt from the Late -post-Late Miocene Mesogea basin....
Contexts in source publication
Context 1
... consist of quartz, illite, smectite, calcite and dolomite. The sandstones contain rock fragments mainly of muscovite -oxychlorite schists, marbles and quartzites, as well as grains of quartz, albite, more rarely epidote and blue amphibole. Oolites show clasts of quartz, marble, or muscovite schists in the core and shells of micritic calcite (Fig. 4A) indicating deposi- tion in a shallow, near the shore lacustrine environment. Clasts and oolites are cemented with sparitic calcite (50-70 µm grain size). In metapelites and calc-schists of Penteli Mt, muscovite- oxychlorite schists are common. The presence of such clasts in the sandstones of Series I suggests that at the time of their ...
Context 2
... sediments occur showing a rhythmic alternation in the lithological succession. c: Unconsolidated or loosely consolidated conglomerates. They consist of well-rounded spherical to ellipsoidal pebbles, 2 to 6 cm in size, and a sandy matrix. Dominant are: (i) Pebbles of light grey to white coloured micritic limestones (frequently rich in microfossils (Figs. 4b, 4c), sparitic, oolitic limestones and limestones with spheroidal SiO 2 ...
Context 3
... Pebbles of red to greenish cherts mostly full of radiolaria (Fig. 4d). (iii) Pebbles of sandstones possibly derived from the Eocene-Oligocene "Molasse" sediments with clasts of quartz, plagioclase, microcline, biotite, muscovite, garnet, chromite, rutile, and composite grains of chlorite-muscovite schist indicating provenance from magmatic, metamorphic and ul- tramafic rocks, similar to those of the ...
Context 4
... derived from the Eocene-Oligocene "Molasse" sediments with clasts of quartz, plagioclase, microcline, biotite, muscovite, garnet, chromite, rutile, and composite grains of chlorite-muscovite schist indicating provenance from magmatic, metamorphic and ul- tramafic rocks, similar to those of the Pelagonian zone. (iv) Pebbles of metabasalt (diabase Fig. 4e) consisting of augite, plagioclase, magnetite, and of chlorite, calcite and pumpellyite being alteration products of magmatic minerals. Only in upper parts of series II, in the Voula hill (star in Fig. 3), a conglomerate predominantly contains pebbles of chert, metabasalt and of chloritoid bearing chlorite-muscovite schist. As in the ...
Context 5
... interlayers occur. They vary in thickness from 2 up to 20 meters ( Fig. 3) are grey to light brownish and very hard with a flinty fracture. The third limestone inter- layer (from the bottom to the top) is oolitic. Oolites consist of coarse-grained sparitic calcite (10- 20 µm in size) cemented with isometric calcite crystals 40-50 µm in size (Fig. 4F). This indicates precipitation/recrystallization of calcite in shallow, quite warm water environment. Iron hydroxide impregnation coloured the matrix calcite ...
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Citations
... The blocks consist of calcite marbles and light greenish grey phengite orthogneisses (Voula hill), dolomitic marble with metabasite intercalations (Petrokorifi hill) and calcite and dolomitic marble (Pyrina hills). Minerals in orthogneisses (albite, microcline, phengite, and quartz) and metabasites (actinolite, magnesiohornblende, epidote , clinozoisite, and albite) indicate that these blocks derive from the LTU from the Penteli area (Mposkos et al., 2007). Notably, the gravity-sliding blocks from the Pyrina hill are 5 km distant from the foot of the Penteli Mt. in line with horizontal transport along the PADF continuing after the Pliocene. ...
In seismically active regions, active low-angle detachment faults are probably more frequent as is commonly thought and may play an important but still underestimated role in the evolution of landforms and basins. We investigate the tectonically active region of Attica (Greece) in the Aegean back arc as a model region to show how basins and mountain ranges commonly thought to be formed by movements on high-angle normal faults in fact reflect the surface expression of displacements on yet undetected, deep-seated, active low-angle normal detachment faults. Inferences are made based on an integrated study of Attica linking the petrology of clastic sediments with geomorphology and structures, and including few new palynological data. From the Miocene to Recent, three sets of normal detachment fault systems were successively active. Shear zones of the 1st (Early Miocene) stage emplaced rocks of the Attic Cycladic high-P metamorphic belt (AC-HP-belt) from depth corresponding to greeschist facies conditions in the brittle, upper crust. In the 2nd stage the WNW dipping Attica low-angle normal detachment fault system between the AC-HP-belt and the un-or weakly metamorphosed rocks of the sub-Pelagonian Zone (SPZ) was active. Clastic sedimentation started in the Late Miocene, during the 2nd stage. Late Miocene and Early Pliocene clastic sediments reveal that during the 2nd stage many areas that presently expose the AC-HP-belt were still covered by the overlying SPZ. Also, now uplifted areas such as the Parnitha mountain range that currently undergo strong erosion were then the sites of sedimentary sinks. The 3rd stage (Late Pliocene through Recent) is associated with dramatic changes in the morphology and recurring steepening of the relief. Reversal of the Parnitha area from the site of deposition into the site of erosion is associated with deposition of coarse conglomerates to the SE of the Parnitha Mt. and S of the Penteli Mt. Sediments of the 3rd stage reflect activity of the here newly described, SSE-dipping Penteli—Athens low-angle detachment fault (PADF) system formed at a high angle to the Attica detachment fault. The outcome of this study is that the present-day geomorphology is to a high degree related to the operation of the PADF system. Steep fault bounding the Athens and Mesogea basins as well as the mountain ranges (Parnitha, Penteli, Hymittos mounts) belongs to its breakaway zone or root into the PADF. Ongoing tectonic movements related to this fault system were responsible for the 1999 Athens (Mw = 6.0) earthquake. We particularly discuss how the PADF may continue into greater depth, the translation magnitude, and how the PADF fits into the wider kinematic framework of the Aegean region.
The Lavrion carbonate-hosted Pb-Ag-Zn deposit in southeast Attica, Greece, consisted of significant non-sulfide ore bodies. The polymetallic sulfide mineralization was subjected to supergene oxidation, giving rise to gossan. The principal non-sulfide minerals of past economic importance were smithsonite, goethite and hematite. The supergene mineral assemblages occupy secondary open spaces and occur as replacement pods within marble. Calamine and iron ore mainly filled open fractures. X-ray diffraction and scanning electron microscopy of samples of oxidized ore indicate complex gossan mineralogy depending on the hypogene mineralogy, the degree of oxidation and leaching of elements, and the local hydrologic conditions. Bulk chemical analysis of the samples indicated high ore-grade variability of the supergene mineralization. On multivariate cluster analysis of geochemical data the elements were classified into groups providing evidence for their differential mobilization during dissolution, transport and re-precipitation. The mode of occurrence, textures, mineralogy and geochemistry of the non-sulfide mineralization confirm that it is undoubtedly of supergene origin: the product of influx into open fractures in the country rock of highly acidic, metal-rich water resulting from the oxidation of pyrite-rich sulfide protore. Dissolution of carbonates led to opening of the fractures. Mineral deposition in the supergene ore took place under near-neutral to mildly acidic conditions. The supergene dissolution and re-precipitation of Fe and Zn in the host marble increased metal grades and separated iron and zinc from lead, thereby producing economically attractive deposits; it further contributed to minimization of pollution impact on both soil and ground water.
