The Circum-Mediterranean

Anorogenic Cenozoic Igneous Province

Michele Lustrino1 and Marjorie Wilson2

1 = Dipartimento di Scienze della Terra, Università degli Studi di Roma La Sapienza, P.le A. Moro, 5, 00185 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 Lustrino1 and Marjorie Wilson2

1 = Dipartimento di Scienze della Terra, Università degli Studi di Roma La Sapienza, P.le A. Moro, 5, 00185 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

0

2

4

6

8

38 42 46 50 54 58 62 66 70 74 78SiO (wt%)2

10

12

14

16

18

NaO+KO (wt%)

2

2

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.

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

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100100

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Canary IslandsCanary Islands

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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Canary IslandsCanary IslandsBohemian Bohemian MassifMassif

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmSmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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Canary IslandsCanary IslandsBohemian Bohemian MassifMassifPannonian Pannonian BasinBasin

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmSmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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ple

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Canary IslandsCanary IslandsBohemian Bohemian MassifMassifPannonian Pannonian BasinBasin FrancFranc

ee

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmSmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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Canary IslandsCanary IslandsBohemian Bohemian MassifMassifPannonian Pannonian BasinBasin FrancFranc

eeGermaGermanyny

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmSmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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Canary IslandsCanary IslandsBohemian Bohemian MassifMassifPannonian Pannonian BasinBasin FrancFranc

eeGermaGermanyny SpaiSpai

nn

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmSmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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ple

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Canary IslandsCanary IslandsBohemian Bohemian MassifMassifPannonian Pannonian BasinBasin FrancFranc

eeGermaGermanyny SpaiSpai

nn

Relatively uniform trace Relatively uniform trace element composition.element composition.

Common mantle sources?Common mantle sources?

Hey, this does not mean Hey, this does not mean that there is athat there is a

MANTLE PLUME!MANTLE PLUME!

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmSmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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FrancFranceeGermaGerma

nyny SpaiSpainn

St. HelenaSt. 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.

I think no ! So: handle geochemical data with care.

CsCs

RbRbBaBa

ThThUU

NbNbTaTa

KKLaLa

CeCePbPb

PrPrSrSr

PPNdNd

SmSmZrZr

HfHfEuEu

TiTiGdGd

TbTbDyDy

YYHoHo

ErErTmTm

YbYbLuLu

11

1010

100100

10001000S

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FrancFranceeGermaGerma

nyny SpaiSpainn

St. HelenaSt. Helena

The (obvious) message is:The (obvious) message is:

Geochemical similarities do not imply provenance from similar (common) physical reservoirs but similar petrogenetic processes

Geochemical similarities do not imply provenance from similar (common) physical reservoirs but similar petrogenetic processes

0.5120

0.5122

0.5124

0.5126

0.5128

0.5130

0.5132

0.5134

0.702 0.703 0.704 0.705 0.706 0.707 0.708 0.709 0.7108786Sr/Sr

DMM

EMI

PREMA

EAR

A

HIMU

LVCChUR (0.51264)

EMII

Samples withMgO > 7 wt %

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

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

What does this mean?What does this mean?

Depleted sources = sources that suffered Depleted sources = sources that suffered basaltic melt extraction (Rb more than Sr; basaltic melt extraction (Rb more than Sr; Nd more than Sm).Nd more than Sm).Can this type of source be considered as a Can this type of source be considered as a ““PRIMITIVE, UNDEGASSED, LOWER PRIMITIVE, UNDEGASSED, LOWER MANTLE SOURCEMANTLE SOURCE”?”?

Obviously I guess NOObviously I guess NO

What does this mean?What does this mean?

Depleted sources = sources that suffered Depleted sources = sources that suffered basaltic melt extraction (Rb more than Sr; basaltic melt extraction (Rb more than Sr; Nd more than Sm).Nd more than Sm).Can this type of source be considered as a Can this type of source be considered as a ““PRIMITIVE, UNDEGASSED, LOWER PRIMITIVE, UNDEGASSED, LOWER MANTLE SOURCEMANTLE SOURCE”?”?

Obviously I guess NOObviously I guess NO

How many models have been How many models have been

proposed to explain the origin proposed to explain the origin

of the various districts of the various districts

belonging to the CiMACI belonging to the CiMACI

Province?Province?

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

Thin spot modelThin 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 modelFinger-like mantle plumes model, Most of the European Most of the European Cenozoic volcanic outcrops 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 modelSlab break-off model, To explain the transition of “orogenic” to “anorogenic” igneous activities (e.g., Maghreb, TurkeyMaghreb, Turkey). “Anorogenic” magmatism related to adiabatic decompression of asthenosphere replacing detached lithosphere.

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

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

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

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

Lithospheric modelLithospheric model, (Sardinia)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 Many are the models proposed to explain the origin of CiMACI rocks. These can grouped in: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 None of models can explain the entire range of composition of the CiMACI rocks.composition of the CiMACI rocks.

Many are the models proposed to explain the origin of Many are the models proposed to explain the origin of CiMACI rocks. These can grouped in: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 None of models can explain the entire range of composition of the CiMACI rocks.composition of the CiMACI rocks.

CONCLUSIONS:CONCLUSIONS:

There is no need to invoke the presence of There is no need to invoke the presence of anomalously hot mantle sources (e.g. plumes anomalously hot mantle sources (e.g. plumes coming from deep mantle) to explain the coming from deep mantle) to explain the geographic distribution and geochemistry of the geographic distribution and geochemistry of the CiMACI rocks.CiMACI rocks.

If we adopt a more permissive definition of If we adopt a more permissive definition of “mantle plume”, allowing it to encompass “mantle plume”, allowing it to encompass passivepassive, diapiric upwellings of the upper mantle, , diapiric upwellings of the upper mantle, then we can relate the CiMACI Province then we can relate the CiMACI Province magmatism to multiple upper mantle plumes magmatism to multiple upper mantle plumes upwelling at various times during the Cenozoic.upwelling at various times during the Cenozoic.

CONCLUSIONS:CONCLUSIONS:

To avoid confusion we recommend that such To avoid confusion we recommend that such upper mantle plumes are referred to as diapiric upper mantle plumes are referred to as diapiric

instabilitiesinstabilities..

For details:M. Lustrino and M. Wilson:

The Circum-Mediterranean Anorogenic Cenozoic Igneous Province

Earth-Sci. Rev. (2007) 81, 1-65

For details:M. Lustrino and M. Wilson:

The Circum-Mediterranean Anorogenic Cenozoic Igneous Province

Earth-Sci. Rev. (2007) 81, 1-65

Thanks for your attentionThanks for your attention