PANEL OF ROCKS

Vilalba Series slate

  • Minerals: Chlorite, muscovite, sericite (+- quartz).
  • Period: Precambrian (Late Proterozoic).
  • Struture: Core of O Seo anticline.
  • Sedimentary environment: Turbidite fans.

Vilalba Series phylite

  • Minerals: Chlorite, muscovite (+- sericite, quartz).
  • Period: Precambrian (Late Proterozoic).
  • Struture: Core of O Seo anticline. The Cadomian cycle comprises between 2000 and 2500 metres of slate, schist and metasandstone with a fine intercalation of gneisses and amphibolites, which are partially visible on the surface between Seoane do Courel and Noceda.
  • Sedimentary environment: Turbidite fans.

Lower cándana quartzite

  • Minerals: Quartz (+- muscovite, biotite).
  • Period: Lower Cambrian
  • Struture: Inverted limb of O Seo anticline. Formed by 30 to 150 meters of metasandstone, quartzite and slate, with conglomerate rock near the base.
  • Sedimentary environment: Turbidite fans.

Cándana group marble limestone

  • Minerals: Calcite, dolomite (+- muscovite).
  • Period: Lower cambrian.
  • Struture: Normal limb of O Seo anticline. The limestones (calcium carbonates) are in this case of grey tones. They occur together with yellowish dolomites (calcium and magnesium carbonates).
  • Sedimentary environment: Shallow marine continental shelf.

Cándana Group schists

  • Minerals: Quartz, muscovite (+- sericite, biotite).
  • Period: Lower Cambrian
  • Struture: Seoane-Oencia, grey and greenish slate with interbedded metasandstone, quartzite, limestone and dolostone.
  • Sedimentary environment: Shallow marine continental shelf.

Vegadeo Formation limestone

  • Minerals: Lower-middle Cambrian
  • Period: Lower-middle Cambrian.
  • Struture: Sucession monocline Seoane-Oencia. TheVegadeo Formation is made up of between 20 and 250 meters of marbleized dolostone and limestone. Three sequences can be observed in this formation (lower, middle and upper), formed in coastal areas, featuring carbonate tidal flats and ramps with archaeocyatha.
  • Sedimentary environment: Shallow water tidal flats.

Vilamea Beds Slate

  • Minerals: Chlorite, muscovite, sericite (+- quartz).
  • Period: Upper Cambrian-Lower Ordovician.
  • Struture: Seoane-Oencia “sucesión monoclinal” or normal lim of the Sil syncline. The Vilamea beds comprise more than 250 m of grey slate, occasionally ampelitic, with fine beds of light metasandstone, as well as trilobite fossils.
  • Sedimentary environment: Carbonate ramp on shallow marine continental shelf.

Seceda Beds marble limestone

  • Minerals: Calcite (+- quartz, muscovite, sericite).
  • Period: Lower devonian (Lochkovian).
  • Struture: O Courel core syncline. Seceda Formation are made up of around 50 m. of slate with chloritoid, quartzite, sandy slate and marbleized limestone with crinoids, branchiopoda, bryozoa, tabulate coral and conodonts.
  • Sedimentary environment: Shallow marine continental shelf.

Folgoso formation slate with chloritoid

  • Minerals: Sericite, chlorite, muscovite (+- quartz, graphite, pyrite)
  • Period: Wenlock-Ludlow Silurian.
  • Struture: O Courel syncline. The Folgoso Formation comprises approximately 450 m. of black chloritoid and ampelitic blach shale, partially interbedded with quartzite, sandy slate and limestone. It also features graptolite, cephalopod and conodont fossils. The base of these rocks is a unconformity, the result of a period of erosion without sedimentation.
  • Sedimentary environment: Contintenal platform, distal facies.

Aquiana Formation limestone

  • Minerals: Calcite (+- quartz, sericite, muscovite).
  • Period: Upper Ordovician
  • Struture: Normal limb of O Courel syncline. Comprising up to 20 m. of banded and unconformed marbleized dolostones and limestone (in other words, sediment was formed following a period of erosion) that feature crinoids and other fossils.
  • Sedimentary environment: Shallow carbonatemarine continental shelf.

Ferruginous breccia of Pardellán or Peites Bed

  • Minerals: Quartz, chlorite, sericite, hematite, limonite, goethite.
  • Period: Upper Ordovician.
  • Struture: Normal limb of O Courel syncline. Breccia formed by angular stones cemented with iron oxides and other minerals, probably associated with the karstification of the limestone of La Aquiana Formation.
  • Sedimentary environment: Karst formed within an emerged marine carbonate platform.

Diabase

  • Minerals: Plagioclase, amphibole, pyroxene (+- quartz, chlorite).
  • Period: Cretaceous.
  • Struture: O Courel syncline / Seoane-Oencia “sucesión monoclinal”. A dense network of dykes up to 10 m. width, showing green and yellowish colours in weathered surfaces and spherical parallelepipedal or columnar disjuntion.
  • Forming environment: Palaeozoic rock with magma intrusion.

Luarca Formation slate

  • Minerals: Chlorite, muscovite, sericite, quartz.
  • Period: Middle Ordovician.
  • Struture: Inverted limb of O Courel syncline. Geological formation made up mainly of less than 1000 meters of single-tone black or greyish-blue slate.
  • Sedimentary environment: Muddy shallow marine continental shelf.

Ferruginous metasandstone of Rubiá beds.

  • Minerals: Quartz, iron oxide.
  • Period: Middle Ordovician.
  • Struture: Normal limb of O Courel syncline. Alternating beds of quartzite, metasandstone and slate includede in the “Transition beds” located in the upper section of the Armorican Quartzite.
  • Sedimentary environment: Shallow marine continetal shelf with iron-rich sediments.

Armorican Quartzite

  • Minerals: Quartz (+- muscovite, chlorite).
  • Period: Lower Ordovician.
  • Struture: Normal limb of O Courel syncline. Formed by thick white or grey quartzite with finely interbedded metasandstones and slate, featuring traces of trilobites and other ichnofossils.
  • Sedimentary environment: Shallow sandy marine continental shelf.

Soldón beds slate

  • Minerals: Chlorite, muscovite, sericite, quartz.
  • Period: Lower Ordovician
  • Struture: Normal limb of O Piornal anticline. Comprising black and grey slate with abundant interbedded beds of metasandstone.
  • Sedimentary environment: Shallow marine continental shelf.

Soldón beds quartzite

  • Minerals: Quartz (+- muscovite, chlorite).
  • Period: Lower Ordovician.
  • Struture: Normal limb of O Piornal anticline. Made up of sandstone and quartzin beds ranging from decametric to metric thickness, and slate with sandy layers.
  • Sedimentary environment: Shalllow marine continental shelf.

Glaciomarine diamictite

  • Period: Upper Ordovician.
  • Struture: Sil syncline. Slate with small carbonate pebbles that became datached from icebergs floating in the ocean. These rocks are stateigrapphically layered between the slate of the Luarca and Folgoso formations.
  • Sedimentary environment: Shallow marine continental shelf with stones detached from icebergs.

San Clodio Series metagreywacke.

  • Minerals: Fragments rocks formed by quartz, chlorite, muscovite and sericite rocks.
  • Period: Lower Carboniferous (Serpukhovian).
  • Struture: Variscan synorogenic sequence of the core of the Sil syncline. These are the most recent Palaeozoic metamorphic rocks in the Geopark made up of metagreywacke, slate, lydite (radiolarite) and microconglomerates with traces of plants and ichnofossils. The San Clodio Series was deposited in a sedimentary basin as a result of the deformation process 324 million years ago during the Variscan orogeny.
  • Sedimentary environment: Turbidite fans.

San Clodio Series limestone

  • Minerals: Calcite.
  • Period: Lower Carboniferous (Serpukhovian).
  • Struture: Variscan synorogenic sequence of the core of the Sil syncline. Interbedded limestone in the San Clodio Series.

San Clodio Series lydite

  • Minerals: Siliceous minerals.
  • Period: Lower carboniferous (Serpukhovian).
  • Struture: Variscan synorogenic sequence of the core of the Sil syncline. This is a siliceous rock like flint, with a conchoidal fracture, although it is darker in tone due to the presence of organic matter.
  • Sedimentary environment: Turbidite fans with siliceous skeletons formed by marine organisms.

Conglomerate Rock, traditionally know as “Pedra Cabaleira”.

  • Minerals: Quartz and iron oxide.
  • Period: Neogene Cenozoic (Pliocene).
  • Struture: Sil syncline. Formed by rounded to subangular quartzite and slate pebbles and cobbles resulted from the erosion of O Courel mountains, creating alluvial fans within sedimentary basins that date back more than a million years.
  • Sedimentary environment: Alluvial fans.

Folgoso Formation ampelite slate

  • Minerals: Sericite, chlorite, muscovite (+- quartz, graphite, pyrite)
  • Period: Upper Silurian (Wenlock-Ludlow).
  • Struture: Sil syncline. Black carbonaceous slate with a thickness of around 50 m., located under 400 m. of black slate with chloritoid.
  • Sedimentary environment: Deep marine continental shelf.

“Ollo de Sapo” Formation porphyroid

  • Minerals: Feldspar, quartz (+- biotite, chlorite).
  • Period: Late Cambrian-Lower Ordovician.
  • Struture: Vilachá Anticline. Rock that extends from the north of Galicia to the north of Guadalajara, being covered by Mesozoic and Cenozoic rocks of the Duero Basin. The rock was formed mainly by the metamorphism of volcanic and sedimentary rock from the erosion of igneous rocks. The geopark is home of the fine-grained variety from, the Ollo de Sapo Formation with interbedded metapelite and quartzite.
  • Sedimentary environment: Continental shelf with abundant magma intrusions.

Capas dos Montes slate

  • Minerals: Chlorite, muscovite, sericite (+- quartz).
  • Period: Lower Ordovician
  • Struture: Vilachá anticline. Composed of some 300 meters of black and grey slate with interbedded ampelite and metasandstone. The base commonly features quartzite and micro-conglomerate rocks.
  • Sedimentary environment: Shallow marine continental shelf.

Slate with andalusite. Contact metamorphism

  • Minerals: Andalusite, chlorite, sericite, quartz & biotite.
  • Period: Late carboniferous early permian.
  • Struture: Sil syncline. Andalusite formed by contact metamorphism in the aureole created by two-micas granite of A Rúa.
  • Forming environment: Contact metamorphism aureole in Palaeozoic rocks.

Late muscovite-biotite granite of the Variscan Orogeny

  • Minerals: Quartz, feldspar, biotite (+- muscovite, chlorite).
  • Period: Late Carboniferous-early Permian.
  • Struture: Sil syncline. Two mica Variscan granite post-tectonic to Variscan orogeny.
  • Forming environment: Palaeozoic rocks with magma intrusions.