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25-631: The Iberian plate came into existence during the Cadomian Orogeny of the late Neoproterozoic, about 650–550  Ma , on the margin of the Gondwana continent, involving the collisions and accretion of the island arcs of the central Iberian plate , Ossa-Morena plate , South Portuguese plate . The three plates have never separated substantially from each other since that time. In the Mesozoic, Late Jurassic Africa started moving east, and

50-677: A submarine fan . There are also acid and basic volcanics interbedded. Some authors believe that there was an unconformity during the Brioverian succession, as there are phtanite stones in the upper parts believed to be eroded from the lower parts, but this is still inconclusive. Cadomian magmatism has been dated in the intrusions and volcanics as 690 to 500 million years ago . Foliated quartz diorite occur at Baie de St Brieuc, at Coutances , La Hague, Guernsey , Alderney and Sark . These are only roughly dated 700 to 580 million years ago . The last magmatism identified

75-756: A plate boundary extending westward from the Bay of Biscay. When motion along this boundary ceased, a boundary linking extension in the Kings Trough to compression along the Pyrenees came into existence. Since the late Oligocene , the Iberian plate has been moving as part of the Eurasian plate, with the boundary between Eurasia and Africa situated along the Azores–Gibraltar fracture zone . Continued rotation of

100-509: A similar way to the Andes . Sediments deposited on the continental margin were pushed up onto the continent, at the same time as intrusions of calc-alkaline magmas occurred. The pre Cadomian basement rocks consist of Orosirian or Paleoproterozoic Icart gneiss dated at close to 2,018  million years ago . These are exposed on Guernsey and at Cape La Hague in Normandy . This

125-856: Is in the geologic timescale the last age or uppermost stage of the Miocene . It spans the time between 7.246 ± 0.005 Ma and 5.333 ± 0.005 Ma (million years ago). It follows the Tortonian and is followed by the Zanclean , the first age of the Pliocene . The Messinian overlaps the Turolian European Land Mammal Mega Zone (more precisely MN 12 and 13) and the Pontian Central European Paratethys Stage. It also overlaps

150-591: Is termed the Icartian succession. Near Trégor the gneiss in the Cadomian Perros-Guirec complex has been U-Pb dated to 1,790  million years ago . Sark also has a gneiss basement. Vidal et al. studied Strontium isotope ratios and concluded that the basement is not widely present below the Cadomian orogeny, and Rabu et al. argued that the existing surface gneiss are fragments detached from

175-543: Is the Jersey Dyke Swarm from 425  million years ago . Partial melting has resulted in migmatites . These form belts named after Saint-Malo , Dinan , and St Cast in north-east Brittany. The Rance valley has a metamorphic sequence including phyllites , amphibolite , metatexites , and diatexites which have melted into granite . Leucogranites and anatectic granites have been derived from sediments melting. East Brittany and Lower Normandy contains

200-512: The Alpine Tethys opened. Subsidence related to this caused deep deposits of sediments on the east and some sediment remnants in pop downs in central parts of Spain. Two stages of rifting occurred in the east, one from Later Permian to Triassic, and the second from Late Jurassic to early Cretaceous. On the south side deposits of carbonates and clastic sediments formed a shelf in shallow water during late Triassic and Liassic times. This

225-640: The magma poor opening of the Atlantic Ocean . The Hercynian Foldbelt is mostly buried by Mesozoic and Tertiary cover rocks to the east, but nevertheless outcrops through the Iberian Chain and the Catalan Coastal Ranges. Cadomian Orogeny The Cadomian Orogeny was a tectonic event or series of events in the late Neoproterozoic , about 650–550 Ma , which probably included the formation of mountains. This occurred on

250-897: The African craton. However it is possible that a basement of gneiss exists at depth below Normandy and Brittany. This gneiss was formerly known as Pentevrian. However it is now known that the Pentevrian type rocks do not predate the Cadomian orogeny, and this name is no longer appropriate for the Icart Gneiss. The Brioverian sequence of rocks was deposited during or before the Ediacaran period 750 to 540 million years ago . Most of these sediments are mudstone , siltstone or sandstone , but there are also some conglomerate , phtanites ( quartzite cemented with lime) and contaminated limestone . These seem to be deposited in

275-616: The Atlantic Ocean opening started between Ireland and Greenland . This left the Bay of Biscay as a failed rift. The rotation of Iberia and its relation to the formation of the Pyrenees has been difficult to decipher with certainty. Detailed aeromagnetic measurements from the sea floor offshore of the Grand Banks of Newfoundland show that Iberia moved as part of the African plate from late Cretaceous to mid- Eocene time, with

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300-788: The Iberian plate in the early Miocene once again separated the Iberian plate from Eurasia opening the Betic Corridor , a strait of water connecting the Mediterranean Sea with the Atlantic Ocean . As the Iberian plate rotated, it closed the Betic Corridor approximately 5.96 million years ago during the Messinian period of the Miocene, precipitating the Messinian Salinity Crisis , a period when

325-516: The Italian city of Messina on Sicily , where the Messinian evaporite deposit is of the same age. The base of the Messinian is at the first appearance of the planktonic foram species Globorotalia conomiozea and is stratigraphically in the middle of magnetic chronozone C3Br.1r. The Global Boundary Stratotype Section and Point for the Messinian is located in a section at Oued Akrech, near

350-734: The Mancellian batholith which consists of intrusions of granodiorite and granite. These other plutons are derived from fractionally crystallized mantle melts. At the Baie de St Brieuc and near Coutances in Manche and Trégor region there are pillow lavas , basalt erupted under water. A later stage of acid volcanics in the form of andesite and rhyolite have been erupted on Brioverian sediments on Jersey at 533  million years ago , and at St Germain-le-Gaillard in Lower Normandy. In

375-731: The Mediterranean Sea evaporated partly or completely. The core of the Iberian Peninsula consists of a Hercynian cratonic block known as the Iberian Massif. On the northeast this is bounded by The Pyrenean fold belt , and on the southeast it is bounded by the Betic Foldchain . These twofold chains are part of the Alpine belt . To the west, the peninsula is delimited by the continental boundary formed by

400-506: The North Armorican Massif was put together from a series of terranes 540  million years ago , their joins are the shear zones. The terranes are known as St Brieuc, St Malo and Mancellian terranes. Deformation in this model is caused by oblique subduction and is strike-slip, but not crustal thickening. The migmatite belts would then be explained by high heat flow in marginal basins. Messinian The Messinian

425-643: The Tregor region there are units called Tuffs de Tréguier and Ignimbrites de Lézardrieux . The southern edge of the Gulf of Saint-Malo between Tregor and Cancale shows the deformational structures of the Cadomian Orogeny. These are East-west to North East trending upright folding. Schistosity is developed parallel to the axial plane of the folds. Prehnite-pumpellyite facies to mid- amphibolite facies have been produced by metamorphism . Movement

450-736: The break-up of Pangea, in the early Cretaceous, the Bay of Biscay started opening around 126 Ma and completed by 85 Ma. This created the Biscay Abyssal Plain , and parted the Iberian plate from the Trevelyan Escarpment . During this time Iberia rotated anticlockwise relative to Eurasia. This caused the subduction of the Ligurian Basin onto the eastern side. This formed the Betic nappe stack . After 85 Ma

475-436: The late Huayquerian and early Montehermosan South American Land Mammal Ages , and falls inside the more extensive Hemphillian North American Land Mammal Age . During the Messinian, around 6 million years ago, the Messinian salinity crisis took place, which brought about repeated desiccations of the Mediterranean Sea . The Messinian was introduced by Swiss stratigrapher Karl Mayer-Eymar in 1867. Its name comes from

500-523: The margin of the Gondwana continent, involving one or more collisions of island arcs and accretion of other material at a subduction zone . The precise events, and geographical position, are uncertain, but are thought to involve the terranes of Avalonia , Armorica and Iberia . Rocks deformed in the orogeny are found in several areas of Europe, including northern France, the English Midlands , southern Germany, Bohemia , southern Poland and

525-564: The southwest Iberian Peninsula . The name comes from Cadomus , the Latin name for Caen , northern France. L Bertrand gave the orogeny its name in 1921, naming it after Cadomus the Gaulish name for Caen in Normandy . He defined the end as being marked by Lower Palaeozoic red beds. The interpretation is that the belt was formed as oceanic crust subducted below the Armorica land mass in

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550-492: The structural grain in the Cadomian Orogeny. There are two overall models for the formation of the Cadomian Orogeny. Firstly by Jean-Pierre Brun & P. Bale that compression to the south west of a volcanic arc and back arc basin onto the edge of the continent at the St Malo and Mancellian regions 590  million years ago formed the orogeny. Crustal thickening took place afterwards. Secondly P. J. Treloar considers that

575-424: The western margin. The Iberian Abyssal Plain , off the west coast of Portugal and Spain, formed 126 Ma. This separated Newfoundland 's Grand Banks , with Galicia Bank and Flemish Cap being split at 118 Ma. By Early Cretaceous , 110 Ma rifting occurs on west and north west edges. During the time of the supercontinent Pangea , the Iberian plate was joined to Armorica (Northern France). During

600-681: Was concentrated in shear belts such as at St Cast . The movement on the belts was sinistral and horizontal. During the orogeny the migmatite belts of north east Brittany were formed. Baie de St Brieuc and St Malo migmatites were deformed with the typical structure. After the orogeny, continental sediments were washed on top of the deformed Cadomian rocks. They include conglomerate and sandstone in Brittany, Jersey and Alderney. The Cap Frehel red beds are dated at 472  million years ago . These post orogeny deposits were dumped from braided stream channels. The basins for these sediments followed

625-479: Was rifted in Toarcian times (Early Jurassic 190 Ma). Active rifting was complete by 160 Ma. After this thermal subsidence occurred till the end of Cretaceous. During this time rifting separated North America from Africa forming a transform zone. In the late Triassic and early Jurassic there were two stages of rifting involving extension and subsidence on the western margin of Iberia. It also extended

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