The Circum-Mediterranean Anorogenic Cenozoic Igneous Province Michele Lustrino 1 and Marjorie Wilson 2 1 = Dipartimento di Scienze della Terra, Università degli Studi di Roma La Sapienza, P.le A. Moro, 5, Roma 2 = Institute of Geophysics and Tectonics, School of Earth and Environment, Leeds University, Leeds, LS2 9JT, UK The Circum-Mediterranean Anorogenic Cenozoic Igneous Province Michele Lustrino 1 and Marjorie Wilson 2 1 = Dipartimento di Scienze della Terra, Università degli Studi di Roma La Sapienza, P.le A. Moro, 5, Roma 2 = Institute of Geophysics and Tectonics, School of Earth and Environment, Leeds University, Leeds, LS2 9JT, UK

CiMACI Province = Circum Mediterranean Anorogenic Cenozoic Igneous We have reviewed more than 8000 whole rock analyses of Cenozoic igneous rocks from Canaries to Turkey and from Libya to Germany CiMACI Province = Circum Mediterranean Anorogenic Cenozoic Igneous We have reviewed more than 8000 whole rock analyses of Cenozoic igneous rocks from Canaries to Turkey and from Libya to Germany

How to discriminate an “anorogenic” from an “orogenic” igneous rock? Mmmhh… Not an easy task. Why? A magma should never be defined from a geodynamic point of view. How to discriminate an “anorogenic” from an “orogenic” igneous rock? Mmmhh… Not an easy task. Why? A magma should never be defined from a geodynamic point of view.

Es.: Mt. Etna, Hyblean Mts., Pantelleria, etc. Are these “anorogenic” (or “intra-plate”) volcanoes? Are all the “orogenic” geochemical features of Aeolian Islands related to crustal contamination of the sources? Is the “orogenic” feature of the Italian lamproites related to coeval tectonic setting? Es.: Mt. Etna, Hyblean Mts., Pantelleria, etc. Are these “anorogenic” (or “intra-plate”) volcanoes? Are all the “orogenic” geochemical features of Aeolian Islands related to crustal contamination of the sources? Is the “orogenic” feature of the Italian lamproites related to coeval tectonic setting?

What about K-rich and leucite-bearing magmas? Not only the Roman Comagmatic Province (potassic to ultrapotassic) There are also K-rich (leucititic) “anorogenic” rocks at Calatrava (central Spain), Eifel (Germany), Bohemian Massif. Also in Sardinia (Montiferro) there are analcime-bearing basanites. What about K-rich and leucite-bearing magmas? Not only the Roman Comagmatic Province (potassic to ultrapotassic) There are also K-rich (leucititic) “anorogenic” rocks at Calatrava (central Spain), Eifel (Germany), Bohemian Massif. Also in Sardinia (Montiferro) there are analcime-bearing basanites.

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle Canary Islands

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle Canary Islands Bohemian Massif

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle Canary Islands Bohemian Massif Pannonian Basin

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle Canary Islands Bohemian Massif Pannonian Basin France

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle Canary Islands Bohemian Massif Pannonian Basin France Germany

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle Canary Islands Bohemian Massif Pannonian Basin France Germany Spain

Ba/Nb Sample/Primitive Mantle Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Canary Islands Bohemian Massif Pannonian Basin France Germany Spain Relatively uniform trace element composition. Common mantle sources? Hey, this does not mean that there is a MANTLE PLUME!

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle France Germany Spain St. Helena Does anybody of you belive to the existence of a single mantle plume coming from St. Helena to Germany on the basis of geochemical similarities? I think no ! So: handle geochemical data with care.

Ba/Nb Cs Rb Ba Th U Nb Ta K La Ce Pb Pr Sr P Nd Sm Zr Hf Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Sample/Primitive Mantle France Germany Spain St. Helena The (obvious) message is: Geochemical similarities do not imply provenance from similar (common) physical reservoirs but similar petrogenetic processes

Virtually all the primitive CiMACI rocks are derived from a source DEPLETED in terms of Sr-Nd isotopic ratios

What does this mean? Depleted sources = sources that suffered basaltic melt extraction (Rb more than Sr; Nd more than Sm). Can this type of source be considered as a “PRIMITIVE, UNDEGASSED, LOWER MANTLE SOURCE”? Obviously I guess NO What does this mean? Depleted sources = sources that suffered basaltic melt extraction (Rb more than Sr; Nd more than Sm). Can this type of source be considered as a “PRIMITIVE, UNDEGASSED, LOWER MANTLE SOURCE”? Obviously I guess NO

How many models have been proposed to explain the origin of the various districts belonging to the CiMACI Province?

Deep mantle plume Eifel Deep mantle plume, coming from lower mantle (proposed to explain the origin of the Eifel magmatic field in Germany)

Thin spot model Thin spot model, Two variations of this model are known: one considers that the stem of the plume is centred below the Canary Islands, whereas the second considers that the stem is centred beneath Iceland.

Finger-like mantle plumes modelMost of the European Cenozoic volcanic outcrops Finger-like mantle plumes model, Most of the European Cenozoic volcanic outcrops would be linked to a single upper mantle reservoir (the European Asthenospheric Reservoir; EAR) located between the 410 and the 660 km discontinuities.

Slab break-off model Maghreb, Turkey Slab break-off model, To explain the transition of “orogenic” to “anorogenic” igneous activities (e.g., Maghreb, Turkey). “Anorogenic” magmatism related to adiabatic decompression of asthenosphere replacing detached lithosphere.

Slab break-off coupled with the thin spot modelVeneto Slab break-off coupled with the thin spot model, (Veneto area). This model explains the paradox of existence of igneous activity with “anorogenic” geochemical characteristics in an active subduction-related setting.

Fossil plume model IsraelJordanSicily Channel Fossil plume model The prolonged and geochemically uniform Mesozoic/Cenozoic igneous activity in Israel, Jordan and Sicily Channel is related to the derivation from a common reservoir represented by an ancient fossil plume head unable to penetrate thick lithosphere.

Passive rift modelTurkey, Jordan, Israel, Syria and Germany) Passive rift model, (Turkey, Jordan, Israel, Syria and Germany). Magmatism is triggered by adiabatic decompression of the asthenosphere reactivated by lithospheric thinning.

Slab-window modelMt. Etna and Ustica) SE Spain and Maghrebian Africa Slab-window model, (Mt. Etna and Ustica). Magmatism related to an asthenospheric window between a continental and an oceanic plate. For SE Spain and Maghrebian Africa: subduction of oceanic lithosphere caused continental-edge delamination of the subcontinental lithosphere associated with sublithospheric mantle upwelling

Lithospheric modelSardinia) Lithospheric model, (Sardinia). Most of the middle Miocene- Quaternary volcanic activity of Sardinia is related to decompression melting of a variably metasomatized lithospheric mantle.

Many are the models proposed to explain the origin of CiMACI rocks. These can grouped in: 1) 1)Models that require active upraise of asthenospheric mantle (or even deeper sources) (  mantle plumes); 2) 2) Models that requires lithospheric extension (or detachment and delamination processes) to induce decompression melting and passive upraise of asthenospheric and lithospheric melts. None of models can explain the entire range of composition of the CiMACI rocks. Many are the models proposed to explain the origin of CiMACI rocks. These can grouped in: 1) 1)Models that require active upraise of asthenospheric mantle (or even deeper sources) (  mantle plumes); 2) 2) Models that requires lithospheric extension (or detachment and delamination processes) to induce decompression melting and passive upraise of asthenospheric and lithospheric melts. None of models can explain the entire range of composition of the CiMACI rocks. CONCLUSIONS:

There is no need to invoke the presence of anomalously hot mantle sources (e.g. plumes coming from deep mantle) to explain the geographic distribution and geochemistry of the CiMACI rocks. If we adopt a more permissive definition of “mantle plume”, allowing it to encompass passive, diapiric upwellings of the upper mantle, then we can relate the CiMACI Province magmatism to multiple upper mantle plumes upwelling at various times during the Cenozoic. If we adopt a more permissive definition of “mantle plume”, allowing it to encompass passive, diapiric upwellings of the upper mantle, then we can relate the CiMACI Province magmatism to multiple upper mantle plumes upwelling at various times during the Cenozoic. CONCLUSIONS: To avoid confusion we recommend that such upper mantle plumes are referred to as diapiric instabilities.

For details: M. Lustrino and M. Wilson: The Circum-Mediterranean Anorogenic Cenozoic Igneous Province Earth-Sci. Rev. (2007) 81, 1-65 Thanks for your attention