The role of clinopyroxene in the chemical evolution of Earth s mantle

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1 The role of clinopyroxene in the chemical evolution of Earth s mantle Costanza Bonadiman Earth Sciences Departmente- University of Ferrara, Italy

magma ocean In the Beginning Core Core Bulk Silicate Earth < 10 Ma 10-30 Ma

2 magma ocean In the Beginning Core Core Bulk Silicate Earth < 10 Ma Ma Undifferentiated Earth End of terrestrial accreation Today Hadean Eon bybp Archean Eon bybp

International Stratigraphic Commission, 2007 Phanerozoic Eon 0.

3 International Stratigraphic Commission, 2007 Phanerozoic Eon bybp Proterozoic Eon bybp Archean Eon bybp Hadean Eon byBP

4 Model for the crystallization of a terrestrial magma ocean (Caro et al., 2005, Wood et al., 2006) Residual melt (protocrust) F(melt) < 1% CaO = 0.35 wt% Highly depleted upper mantle 5-7 wt% cpx (30-60 My) Sequence of crystallization F(melt)= 18% F(melt)= 25% F(melt)= 27% F(melt)= 100% 15 GPa 22 GPa 24.5 GPa 136 GPa CaO = 0.95 wt% CaO = 2.55 wt% 73% crystallized CaO = 3.5 wt% (based on Sm, Nd, Lu and Hf mineral/melt partition coefficients) Uppermost mantle 57% ol, 14% gt, 29% cpx Upper transition zone 57% Ring, 43% Maj Lower transition zone 57% Ring, 38% Maj, 5% CaPv Lower manle 79-75% MgPv 16% FP 5-9% CaPv BSE phase proportions

5 The most common rock type of the mantle is peridotite, but eclogite (garnet + clinopyroxene) and pyroxenite are also represented

Average Peridotite Modes Olivine: 68-82 % Orthopyroxene: 10-25%

6 Average Peridotite Modes Olivine: % Orthopyroxene: 10-25% Clinopyroxene : 5-21% Plagioclase: < 5%; Spinel: <3% Garnet 5-10% M. Wilson, 1989

garnet Mg 3 Al 2 Si 3 0 12 olivine All silicate minerals have the same fundamental building block - the silica tetrahedron.

The simplest way for silicate minerals to achieve electrical neutrality is by bonding with positively charged ions (cations) such as Fe2+, Ca2+, Mg2+, Na+ and K+.

7 garnet Mg 3 Al 2 Si olivine All silicate minerals have the same fundamental building block - the silica tetrahedron. It consists of 4 oxygens ions surrounding the smaller silicon ion. The silica tetrahedron is a complex ion (SiO4-4 ) with a charge of -4. The simplest way for silicate minerals to achieve electrical neutrality is by bonding with positively charged ions (cations) such as Fe2+, Ca2+, Mg2+, Na+ and K+. (Mg, Fe) 2 Si0 4 Silica tetrahedra may link together to form singlechains, double-chains, and sheets by sharing oxygen ions between them. orthopyroxene (Mg,Fe) 2 Si clinopyroxene CaMgSi Ca 2 (Mg,Fe) 5 Si ( OH) 2 KMg 3 (Si 3 Al)O 10 (F,OH) 2 amphibole phlogopite

8 Mantle xenoliths, Subei Basin- China

9 Upper mantle peridotite olivine clinopyroxene spinel orthopyroxene 2 mm Cape Verde harzburgite

10 Upper mantle peridotite olivine clinopyroxene garnet orthopyroxene 2 mm Kimberly, South Africa

11 Slave, gt-xenoliths (Kopylova and Caro, 2004)

12 Slave, gt-xenoliths (Kopylova and Caro, 2004)

13 From the Archean Cr-diopside is stable from the lower part of the upper mantle(up to 550 km) to the Moho discontinuity. It represents one of the best tools for recording mantle compositional variations related to depletion and enrichment processes over a large time span Mantle xenoliths Diamond Peridotitic inclusions

14 Th, U in mantle minerals Olivine: U: --; -5 (ppb); Th: ---;7 (ppb) Orthopyroxene: U <4- <10 (ppb); Th 4-15 (ppb) our data set + GERM Garnet: U: (ppm) 2- (ppm); Th: (ppm) Clinopyroxene: U <0.012 (ppm) 6 (ppm); Th < (ppm) our data set

15 D min/melt cpx/melt * opx/melt ol/melt sp/melt gt/melt * Th U E -7 1 E E -7 1 E Ionov et al., 2002 and references therein * Calculated and discussed with Alberto Zanetti (IGG-CNR, Pavia. Italy)

Globe Map showing the locations of samples considered in the study Global distribution of continental cratons different in age as indicated in the fields.

16 Globe Map showing the locations of samples considered in the study Global distribution of continental cratons different in age as indicated in the fields. Age provinces: Archons, >2.5 Ga; Protons, 2.5 to 1.0 Ga; and Tectons, <1 Ga. (From Haggerty, 1999). subcontinental Lithospheric Mantle SCLM Off craton mantle

17 Al2O3 clinopyroxenes Ca- pyroxene CI1 and CV3 chondrite Phanerozoic 6 Proterozoic 4 2 craton (Archean) TiO

18 Solid inclusion in diamonds (Peridotitic types) Slave this study Kimberlite pipe this study Cpx data base Liaoning Province (China) 5 ultramafic inclusions (Wang & Gasparik, 2000) Sub-craton lithospheric mantle (kimberlite-lamproite host lavas) Kaapvaal Craton 189 garnet lherzolites PMP-gp this study 90 spinel lherzolites PMP-sp this study Slave Craton 326 individual grains Slave this study Ukrainian Shield 41 grains from placers Priazovje this study Off-craton lithospheric mantle (alkaline basic host lavas) Eastern Siberia 5 garnet lherzolites Vitim Glaser et al., 1999; Ionov, 2003 Subei basin (Eastern China) 28 gt + 38 sp lherzolites China Xu et al., 2000, this study Patagonia 12 garnet lherzolites Pali Aike Kempton et al., 1999, this study Off-craton shallow continental lithospheric mantle (alkaline basic host lavas) Antartica 15 spinel lherzolites Ant Coltorti et al., 2004 Southeastern Australia 127 spinel lherzolites SEAU this study Veneto Volcanic Province (Italy) 30 spinel lherzolites VVP Beccaluva et al., 2001; (this study) Sardinia (Italy) 32 spinel lherzolites Sardinia Beccaluva et al., 2001; (this study) San Carlos (Arizona) 15 spinel lherzolites San Carlos this study Scotland Main Land 13 spinel lherzolites Streap this study (Bonadiman et al., 2008) Orkneys (Scotland) 21 spinel lherzolites Rinibar this study (Bonadiman et al., 2008) Olot, Calatrava (Spain) 8 spinel lherzolites Olot this study Kapfenstein (Austria) 12 spinel lherzolites Kap this study

19 Cr 2 O 3 craton-gt-lherzolites gt-peridotites, Ramsay & Tompkins, 1994 clinopyroxenes Priazovje-Ukranian Plateau Slave Kaapvaal-gt gt-lh China gt-lh Pali-Aike gt-lh Vitim Kaapvaal -sp Archean mantle sp-lherzolites and off-craton gt-lherzolites, Ramsay & Tompkins, 1994 (2002) field sp-lherzolites and off-craton gt-lherzolites SEAU sp-lh Lessini sp-lh San Carlos sp-lh Sardinia sp-lh Streap (Scotland-main land) sp-lh Rinibar(Orkneys) pd cox inclusion diamond Cpx CI1 and CV3 chondrites Phanerozoic and proterozoic mantle 0.5 eclogite, megacrysts and cognate crystals (Nimis, 2002) Al 2 O

20 Primary clinopyroxenes (no evidences of metasomatic reactions) 100 Zr/Y Phanerozoic off-craton (gt) Archean craton 10 SPC-gt Proterozoic Scotland 1 diamond incl SPC-sp off-craton (sp) Phanerozoic Zr ppm

21 Cpx in diamond inclusions* Primary Clinopyroxenes (no evidences of metasomatic reactions) 100 off-craton (sp) Phanerozoic cpx/ C1 chondrite 10 1 off-craton (gt) Phaneorozoic 0.1 craton Archean (+ Scotland- Proterozoic) La1 Ce Sr Nd Zr Sm Eu Ti Gd Dy Y Er Yb *Data from GEMOC lab.

22 Scotland Proterozoic mantle CN2 FN4 GN5 Patagonia Kutch(India) Comores cpx/c1chondrite Cs Rb Ba Th U Nb La Ce Pr Sr Nd Zr Hf Sm Eu Ti Gd Tb Dy Y Ho Er Tm Yb Lu Bonadiman et al., 2008

23 10 1 Archean Proterozoic-Phanerozoic U cpx (ppm) Th cpx (ppm)

24 Archean Off-craton Phanerozoic FTIR determinations Bonadiman et al., (2009) Intra platexenoliths (sp-lherzolite) from Colorado Plateau large province: Li et al. (2008); Nushan and Hannouba mantle xenoliths: Yang et al. (2008b); mantle wedge xenoliths from Kilbourne Hole (New Mexico), Washington State and Mexico: Peslier et al. (2002) and Peslier & Luth (2006); cratonic mantle xenoliths (gt-, sp-lherzolite and one eclogite) from South Africa and Colorado Plateau: Bell & Rossman (1992); and Grant et al. (2007).

25 Archean Phanerozoic Bonadiman et al., 2009

26 Kaapvaal cratonic mantle Peslier et al., 2010

Evolution of the lithospheric mantle Garnet peridotites are interpreted as metasomatised metasomatic refertilization, related to the intrusion of mafic melts represented by the eclogites and

27 Evolution of the lithospheric mantle Garnet peridotites are interpreted as metasomatised metasomatic refertilization, related to the intrusion of mafic melts represented by the eclogites and pyroxenites. This refertilization process has added Fe, Ca and Al to the peridotites, crystallizing garnet and clinopyroxene at the expense of olivine and orthopyroxene. Really two separate trend?? Griffin et al., 2009

28 Special thanks to Bill Griffin (GEMOC, Department of Earth and Planetary Sciences Macquarie University, Australia) for major and trace element analyses of diamond peridotite inclusions and clinopyroxene individual grains from Kaapvaal Craton Slave Craton Ukrainian Shield

The mantle metasomatism: diversity and impact What the mantle xenoliths tell us?

The mantle metasomatism: diversity and impact What the mantle xenoliths tell us? Mantle metasomatism Physical and chemical processes that are implemented during the flow of magmas and / or fluids within