No Slide Titleearth.lzu.edu.cn/hdupf/fil/201807/201807261532576025118849.pdf · Magmatism in Ocean...

大家下午好！

牛耀龄 (Yaoling Niu)

Earth Scie

nces

英国杜伦大学（Durham University）地球科学系教授

兰州大学“中组部千人计划”特聘教授

岩浆的起源，演化与全球构造（地幔动力学过程）

Magmatism in Ocean Basins and Mantle Dynamics

– A petrologic and geochemical approach




1. Basic concept of magma generation and evolution

有关岩浆成因和演化的一些基本概念

2. Some petrologic and geochemical perspectives of

mantle plumes, ocean ridges, plume-ridge interactions

and mantle convection

岩石学和地球化学观: 地幔柱、洋中脊、地幔柱-洋中脊相互作用、地幔对流动等

如果大家对我讲的内容感兴趣的话，

我建议你们考虑加盟兰州大学，读研

究生、做博士后、教书、育人：

我保证你们会从事同样有趣的研究，

但比我站得更高，看得更远, 贡献更大！

用岩石地球化学方法探讨大洋岩浆活动和地幔动力学过程


– A Petrologic and Geochemical Approach

Yaoling Niu (牛耀龄）

1. Introduction – Basic Concept of Magma Generation and Evolution

2. Ocean Ridge Magmatism – New Perspectives from Global MORB Data

3. Ocean Island magmatism – New Perspectives from Global OIB Data

4. Plume-Ridge Interactions – A petrologic/geochemical perspective

2011.10 西安“全国岩石学与地球动力学年会会前讲座”

6. Mesozoic/Cenozoic lithosphere thinning & volcanism in eastern China: A

special consequence of plate tectonics

5. MORB Geochemistry and Continental Crust Growth

1. Introduction – Basic Concept of Magma Generation

and Evolution

2011.10 西安“全国岩石学与地球动力学年会会前讲座”

Stone, S. & Y.L. Niu, 2009. Origin of compositional trends in clinopyroxene of

oceanic gabbros and gabbroic rocks: A case study using data from ODP Hole

735B, Journal of Volcanology and Geothermal Research, 184, 313-322.

Niu, Y.L. & M.J. O’Hara, 2009. MORB mantle hosts the missing Eu (Sr, Nb,

Ta and Ti) in the continental crust: New perspectives on crustal growth, crust-

mantle differentiation and chemical structure of oceanic upper

mantle, Lithos, 112, 1-17.

Niu, Y.L., 2005. Generation and evolution of basaltic magmas: Some basic

concepts and a hypothesis for the origin of the Mesozoic-Cenozoic volcanism

in eastern China,Geological Journal of China Universities, 11, 9-46.

Niu, Y.L., T. Gilmore, S. Mackie, A. Greig & W. Bach, 2002. Mineral

chemistry, whole-rock compositions and petrogenesis of ODP Leg 176 gabbros:

Data and discussion, In Natland, J.H., Dick, H.J.B., Miller, D. J., and Von

Herzen, R. P. (Eds.), Proceedings of the Ocean Drilling Program, Scientific

Results, 176,doi:10.2973/odp.proc.sr.176.011.2002, 60pp.

References:

34

K

Vp

sV

Vs = 0 if 100% melt present

Vs with melt

Melt, if any, is insignificant in the mantle

because of Vs > 0

Magma generation:

shallow process < 200 km

Smithsonian Institution, Global Volcanism Program

• The largest mountain belt on Earth, ~ 55,000 km long, circling the globe

• The very site where ocean crust, > 66% surface of the solid Earth, is being

constantly created.

The global ocean ridge system

Map adapted from NOAA

Smithsonian Institution, Global Volcanism Program

Convergent Plate

Boundary

(Mariana, Tonga)

Island ArcMid-Ocean Ridge Ocean Island

Continental Margin Arc

Intraplate/Divergent

Plate Boundary

(East Africa, CFB of Deccan)

Rift

Divergent Plate

Boundary

(EPR, MAR)Intraplate

(Hawaii, Reunion)

Convergent Plate

Boundary

(Andes in South America)

Two basic processes of magmatic rocks:

1. Magma generation: Solid Melt

2. Magma evolution: Melt Solid

Temperature

Pre

ssu

re

0% 100%

Subsolidus

(100% solid)

A

Solid + Liquid

B

Superliquidus

(100% melt)

C

Partial Melting

Melting of a Rock

Temperature

Pre

ssu

re

A

B -DP

Mechanisms of melt generation: (1) Decompression (-DP, e.g., MOR, hotspots/plumes)

Partial Melting

DPH2O

(3) Addition of H2O (and alkalis) (DPH2O, e.g., Arcs/subduction zones)

DT

(2) Heating (DT, e.g., crustal melting for granite/granitoid due to basaltic

magma heating or possibly internal heating due to K-U-Th heat

accumulation)

Pressu

re

(kb

ars)

110090070050015001000

0

5

10

15

20

25

Melts + solidSolid

Hydrous (H2O-saturated) solidi

of crustal rocks

Temperature (°C)

Gran

ite

Tonolite Basalt0

50

100

150

Melts + Solid

Dep

th(k

m)

Dry

Solid

us

CO

2 -H2 O

Solid

us

Solid

Wet (CO2+H2O-saturated) solidus

of mantle peridotite

Temperature (°C)

Mechanisms of melt generation:

1. Decompression (-DP, e.g., MOR, hotspots/plumes)

2. Heating (DT, e.g., crustal melting for granite/granitoid due

to basaltic magma heating or possibly internal heating due

to K-U-Th heat accumulation)

3. Addition of H2O (and alkalis) (DPH2O, e.g., Arcs/subduction

zones)

4. Compression (DP, rare, but perhaps some carbonatite, post-

collisional granitoids etc.)

Source Rock (lherzolite)

Petrological Consequence of Partial Melting

Applicable to other systems: “fusible melt” and “refractory residue

PM

Residue - Refractory: high Mg/Fe, low SiO2

(Harzburgite)

Melt - fusible: low Mg/Fe, high SiO2

(Picrite or picritic basalt)

Partial melting “transforms” one single rock into two rocks:

(1) different compositions & (2) different physical properties

• plagioclase (low P)

• spinel (medium P)

• garnet (high P)

• amphiboles

• phlogopite

• baddeleyite

• sulfides etc.

Ol

Opx Cpx

Orthopyroxinite Clinopyroxinite

Dunite

Harzburgite

Websterite

Olivine

Orthopyroxenite

Wehrlite

Olivine

Websterite

Lherzolite

(Pyrolite)

Ferile Peridotite

Ol

Opx Cpx

Dunite

Har

zburg

ite

Lherzolite

(Pyrolite)

Residual

Peridotites

Fertile & residual peridotite

Lherzolite = Harzburgite + basalt

Experimentally Established Mineral Compositional Systematics in

Peridotite Melting Residues

F (wt. %) - Extent of melting or melt extraction

Mg# = Mg/[Mg +Fe2+] in whole rock Mg# -Oliv, Opx (Cpx if present)

Al2O3 -Opx (Cpx if present) Cr# = Cr/[Cr +Al] -Spinel

Magma generation at divergent plate boundaries:

Mid-ocean ridges

Back arc spreading centers

Continental rift systems

Global ocean ridges, backarc basins and 4 major Cenozoic Continental rifts: Rio Grande, Lake Baikal, East African and Rhinegraben

Rhinegraben

Rio Grande

Lake Baikal

East

African

Temperature P

ress

ure

A

B -DP

DT




accumulation)


Partial Melting

DPH2O

Mid-Ocean Ridges

Plate separation-induced passive upwelling

decompression melting for MORB

Melting region1

2Cold thermal

boundary layer

Solidu

s

Temperature

Pre

ssu

re

Conductive

Co

nve c

tive

(adiab

at)

Melt p

ath

1

2

Magma generation at convergent plate boundaries:

Oceanic-oceanic subduction - Island Arcs

Oceanic-continental subduction - Continental Arcs

Continent-continent collision zones

Oceanic-oceanic

(Mariana, Tonga etc. in western Pacific

Oceanic-Continental

(Andes, South America)

Continental-Continental collision

(Himalaya, Tibetan Plateau)

Temperature P

ress

ure

A

B -DP

DT




accumulation)


Partial Melting

DPH2O

Island Arcs & Continental Magmatic

Arcs

Subducting-slab dehydration-induced mantle wedge melting

Magmatism at transform fault zones:

No volcanisms, but a few

“leaky transforms” with transtensional tectonics:

Garrett Transform (13°S EPR, Hékinian et al., 1995; Niu & Hékinian, 1997)

Siqueiros Transform (9°N EPR, Perfit et al., 1997)

Raitt Transform (60°S PAR, Castillo et al., 1998)

The fact that volcanism is either absent or very rare in the transform fault systems is consistent with

the fact that (1) there is no excess heat there available for asthenospheric mantle melting; (2) there is

no excess water available to trigger melting; and (3) the strike-slip dominated plate motions does not

create gravitational void for large scale asthenospheric upwelling and decompression. Having said

that, limited volcanisms have indeed been found in some leaky transforms such as the Garrett

transform [Hékinian et al., 1995; Niu & Hékinian, 1997], Raitt transform [Castillo et al., 1998], and

Siqueiros transform [Perfit et al., 1996] in the Pacific. These transforms are however tectonically

transtensional in nature where such extension induced passive upwelling and melting is evident not

only from the erupted basalts but also the morphology and orientations of the volcanic ridges.

GN-10

GN-2 13°30'

111°112°

13°30'

Pacific Plate

NAZCA Plate

-R

idge-R

idge

-R

idge

GN-12GN-11

GN-15

GN

-14

GN

-03

GN

-04

GN-13

3750

3750

3000

3000CENTRAL BASIN

Magma generation within plates:

Mantle plumes/hotspots

Hotspots/seamount chains

Continental Flood Basalts/Oceanic plateaus

LIPs - Large Igneous Provinces

Convergent Plate

Boundary

(Mariana, Tonga)

Island ArcMid-Ocean Ridge Ocean Island

Continental Margin Arc

Intraplate/Divergent

Plate Boundary

(East Africa, CFB of Deccan)

Rift

Divergent Plate

Boundary

(EPR, MAR)Intraplate

(Hawaii, Reunion)

Convergent Plate

Boundary

(Andes in South America)

Hawaiian Islands

Hawaiian-Emperor Chain

Jason Morgan‘s 1971

Plume Model

• Upwelling from thermal

boundary layer at the

base of the mantle

From Geological Society

Decompression melting of

large plume head - LIPs

Decompression melting of narrow plume tail - seamount chains

Campbell, I.H. & R.W. Griffiths, Implications of mantle plume structure for

the evolution of flood basalts, Earth Planet. Sci. Lett., 99,79-93, 1990.

Davies, G.F, A case for mantle plumes, Chinese Science Bulletin, 50, 1541-1554, 2005.

(In the same issue: Foulger, G.R, Mantle plumes: Why the current scepticism? Chinese

Science Bulletin, 50, 1555-1560, 2005.)

Farnetani, C.G., H. Samuel, Beyond the thermal plume paradigm, Geophys. Res. Lett., 32,

L07311, doi:07310.01029/02005GL022360, 2005

Thermochemical plumes

Temperature P

ress

ure

A

B -DP

DT




accumulation)


Partial Melting

DPH2O

From Davidson, J., W. E. Reed & P. M. Davis, Exploring Earth, Prentice Hall, 1997]

Core

Plate tectonics is driven by the

“Cold” thermal boundary layer

atop the mantle - cooling plates

Mantle plumes are derived from the

hot Earth’s interiors – perhaps at the

basal “Hot” thermal boundary layer

(CMB?)

After Davidson, J., W. E. Reed & P. M. Davis, Exploring Earth, Prentice Hall, 1997]

Core

Ba Th U La Pr Pb Sm Hf Gd Tb Ho Er YbRb Nb Ta Ce Sr Nd Zr Eu Ti Dy Y Tm Lu

Prim

itiv

e M

an

tle N

orm

ali

zed OIB

MORB

1

10

100

• Incompatible element-depleted MORB

source must be shallow.

• Incompatible element-enriched plume

sources for OIB must come from hot

deep interiors.

Such distinctions

Plumes–hot–deep-enriched OIB

vs.

Ridges–cold–shallow–depleted MORB

Plate tectonics is driven by the

“Cold” thermal boundary layer

atop the mantle - cooling plates

Mantle plumes are derived from the

hot Earth’s interiors – perhaps at the

basal “Hot” thermal boundary layer

(CMB?)

1000 1100 1200 1300 1400 1500 1600 1700

0

20

40

60

10

30

50

Pre

ssu

re (

kb

ars

)

Temperature (°C)

Solidus

Solidus

Adiabat, 1.8°C/kbar, of

upwelling mantle

(subsolidus)

Adiabat, 6°C/kbar, of

decompression melting

mantle (supersolidus)

Melting Reactions

• plagioclase (low P)


• garnet (high P)

• amphiboles

• phlogopite

• baddeleyite

• sulfides etc.

Ol

Opx Cpx


Dunite

Harzburgite

Websterite

Olivine

Orthopyroxenite

Wehrlite

Olivine

Websterite

Lherzolite

(Pyrolite)

Ferile Peridotite

Ol

Opx Cpx

Dunite

Har

zburg

ite

Lherzolite

(Pyrolite)

Residual

Peridotites

Melting Reactions

Magmas produced by

Incongruent, NOT congruent, melting

That is, in order to generate melt, one or two

minerals will be created simultaneously at the

expense of other minerals.

Isobaric partial melting experiments in the

spinel lherzolite stability field show [e.g.,

Kinzler & Grove, 1992; Walter et al., 1995] :

a Cpx + b Opx + c Sp = 1.0 Melt + d Ol

where a, b, c and d are mass fractions of

the respective mineral phases, all < 1.0.

This reaction says that in order to produce

one mass unit of melt, a mass unit of Cpx,

b mass unit of Opx and c mass unit of Sp

must melt whereas d mass unit of Ol must

be produced.

In this isobaric experiments a > b, I.e., Cpx

melts faster than Opx, however, in

decompression melting case - resembles to

the reality, b > a. That is, Opx melts faster

than Cpx during decompression melting

[Niu, 1997, 1999].

Isobaric partial melting experiments in the

Garnet lherzolite stability field show [e.g.,

Herzburg, 1992] :

a Cpx + b Ol + c Gt = 1.0 Melt + d Opx

where a, b, c and d are mass fractions of

the respective mineral phases, all < 1.0.

This reaction says that in order to produce

one mass unit of melt, a mass unit of Cpx,

b mass unit of Ol and c mass unit of Gt

must melt whereas d mass unit of Opx

must be produced.

15

10

5

0

0.0 0.2 0.4 0.6 0.8

Wt.% TiO2

Dunite

Harzburgite

Lherzolite

Tholeiitic basalt

Residuum

Lherzolite is probably fertile unaltered mantle

Dunite and harzburgite are refractory residuum after basalt has been extracted by partial melting

Figure 10-1 Brown and Mussett,

A. E. (1993), The Inaccessible

Earth: An Integrated View of Its

Structure and Composition.

Chapman & Hall/Kluwer.

Wrong!

Peridotite • plagioclase (low P)


• garnet (high P)

• amphiboles

• phlogopite

• baddeleyite

Ol

Opx Cpx


Dunite

Harzburgite

Websterite

Olivine

Orthopyroxenite

Olivine

Clinopyroxenite

Wehrlite

Olivine

Websterite

Perid

oti

te

Lherzolite

(Pyrolite)Not magmatic Rock

Mechanisms of melt generation:

1. Decompression (-DP, e.g., MOR, hotspots/plumes)

2. Heating (DT, e.g., crustal melting for granite/granitoid due

to basaltic magma heating or possibly internal heating due

to K-U-Th heat accumulation)

3. Addition of H2O (and alkalis) (DPH2O, e.g., Arcs/subduction

zones)

4. Compression (DP, rare, but perhaps some carbonatite, post-

collisional granitoids etc.)

Granite and granitic (granitoid) magmas!!!

46

47

48

49

50

51

44.1

44.4

44.7

45.0

45.3

45.6

14

16

18

20

22

24

0.0

1.0

2.0

3.0

4.0

5.0

7.52

7.60

7.68

7.76

7.84

7.92

6.0

6.5

7.0

7.5

8.0

8.5

SiO2 SiO2

Al2O3

Al2O3

FeOt FeOt

Po = 25 kb

Po = 20 kb

Po = 15 kb

0 5 10 15 20 25 30 0 5 10 15 20 25 30

Increasing Extent of Melting (wt. %) With Decompression

Partial melts Melting Residues

8.0

11.0

12.5

14.0

15.5

9.5

37.5

39.5

41.5

43.5

45.5

47.5

4

6

8

10

12

14

0 5 10 15 20 25 30 0 5 10 15 20 25 300.0

0.8

2.4

3.2

4.0

1.6

MgO

MgO

CaO CaO

Increasing Extent of Melting (wt. %) With Decompression

Partial melts Melting Residues

Major element composition of Melt and Residue

by decompression melting [Niu, 1997, 1999]

Two basic processes of magmatic rocks:

1. Magma generation: Solid Melt

2. Magma evolution: Melt Solid

Liquid Lines of Descent - LLDs

How melt composition change during cooling

… … ?

Norman L. Bowen (1887-1956) - “Father of Modern Igneous Petrology”

<<The Evolution of the Igneous Rocks>>, Princeton

University Press, 334pp, 1928 - basic principles remain

valid.

“Fractional crystallization was possible because a

reaction, rather than a eutectic, relation held for many

experimentally investigated, rock-forming mineral

system.” - the well-known Bowen Reaction Series.

“Fractional crystallization could be affected by (1) crystal

settling of dense minerals formed during the early stages

of crystallization; (2) zonation of solid solutions; and (3)

straining of magma through a crystalline mesh during the

concluding stage s of crystallization. In each way, magma

compositions could be altered by separation of the

crystals from further contact with liquid.”

“Slow cooling promotes crystal growth and settling; too

slow cooling results an approach of equilibrium

crystallization and thereby minimize the possibility of

zoning; and too rapid cooling leads to the formation of

glass.”

“Crystalline rocks, particularly the monomineralogical

rocks such as anorthosite, dunite, and pyroxenite are

gravitationally accumulated crystals in magma

chambers.”

“Liquid lines of descent” - LLDs ?

From <<The Evolution of the Igneous Rocks>> by N.L. Bowen, 1928

0

2

4

6

8

10

12

Mg

O (

wt.

%)

T liquidus

(°C) =

1026e[0.01894M

gO(wt.%

)]

1050 1100 1150 1200 1250

Basalt Liquidus Temperatures (°C)

0.00

0.20

0.40

0.60

0.80

1.00

1050 1100 1150 1200 1250

Basalt Liquidus Temperatures (°C)

Mg

# =

Mg

/[M

g +

Fe2

+]

Basaltic liq

uids

Liguidus olivine

Tliquidus(°C) = 1066+12.067Mg#+312.3(Mg#)2

Mg# (melt) = 1/([1/Fo-1]/Kd +1)

(Kd = 0.30±0.03)

Niu, Y., T. Gilmore, S. Mackie, A. Greig, and W.

Bach, Mineral chemistry, whole-rock compositions

and petrogenesis of ODP Leg 176 gabbros: Data

and discussion, Proc. Ocean Drill. Prog. Sci. Results,

176, 1–60, 2002.

Liquidus temperatures or eruption temperatures

of basaltic magmas can be reliably calculated

(±10°C) if (1) phenocrystal olivine composition is

known; or (2) MgO (or Mg#) of basaltic melt is

known.

Caution: whole-rock compositions are NOT

compositions of basaltic melts unless the rocks

are (1) glass/aphyric and (2) entirely fresh.

50

55

60

65

13

14

15

16

17

10

12

14

16

5.0

7.5

10.0

0.1

0.2

0.3

0.4

SiO2

FeO

CaO

P2O5

Weig

ht P

ercen

t

Al2O3

0.3 0.4 0.5 0.6 0.7

Mg#= Mg/[Mg + Fe]

Remaining liquid

Olivine

Plagioclae

Clinopyroxene

Total crystallized

Apatite

Ti-F

e oxid

e

0.2

0.4

0.6

0.8

0.01

0.02

0.03

0.000.3 0.4 0.5 0.6 0.7

Mg#= Mg/[Mg + Fe]

Mass F

ractions

Dun

ite (Ol +

Ch

mt)

Troctolite

(Ol + Plag)

Gabbro

(Pl + Cpx + Ol)

Mg# ~ 0.72, ~ 1340°C, OL crystallized along with chromite (not

shown here) forming dunite (with or without Cr-deposit).

Mg# ~ 0.69, ~ 1225°C, Pl joins Ol to form Pl + Ol rock, called

troctolite;

Mg# ~ 0.58, ~ 1180°C, Cpx joins Pl & Ol to form Pl+Cpx+Ol

rock, called gabbros.

Mg# = ~ 0.37 in, ~ 1110°C, Ti-Fe oxides appear (± Opx & Fe-

rich Ol) forming Fe-Ti gabbros, gabbronorite etc. Note that

apatite, even zircon will crystallize at this late stage..

Importantly, magmatic V-Ti-Fe ore deposits are the

consequences of this late stage basaltic magma evolution.

1106 1135 1167 1206 1251

Liquidus T (C)

铬铁矿毫无例外地总与纯橄岩有关（如，罗布莎）

V-Ti-Fe矿与紫苏辉长岩有关（如，攀枝花）

Gaetani, G.A., T.L. Grove & W.B.

Bryan, Nature, 365, 332-334, 1993.

Troctolite (dry) or wehrlite

(wet): an important field guide for

tectonic setting diagnosis.

Plutons are NOT always intrusive equivalent of the volcanic rocks. In particular, gabbros

are NOT melt, not intrusive equivalent of basalts, but cumulate!

1

10

100

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Ch

on

dri

te-n

orm

ali

zed

ODP Leg 176 Gabbros

Gabbros are NOT melt, not intrusive equivalent of basalts, but cumulate, whose

compositions are controlled largely by plagioclase and clinopyroxene!

0.01

0.1

1

10

100

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

Pri

mit

ive

Ma

ntl

e-N

orm

ali

zed

ODP Leg 176 Gabbros

Depending on relative abundances of Ti-Fe oxides, gabbros can have “+” or “-” Nb-Ta-Ti

anomalies, and thus give MORB or IAB signatures etc. That is, gabbros are NOT melt

and their trace element compositions cannot be used to finger print tectonic settings

Rock type Identification History Pearce and Cann (1973) demonstrated the significance of the Zr/Ti

and Nb/Y ratios. Winchester and Floyd (1977) produced the first TAS

proxy diagram with Zr/Ti as the fractionation index and Nb/Y as the

alkalinity index

Finger-printing – tectonic Settings of rock

formation Based on melt – volcanic glass or aphyric samples

Caution:

Dunites, troctolites, Wehrlite, gabbros etc. are NOT melts, but

cumulate rocks.

Terminologies such as dunite magmas, gabbro magmas etc. are

WRONG in principle and DO NOT exist in practice.

The statement "gabbros" are intrusive equivalent to basalts in

many textbooks is WRONG. They are NOT equivalent.

Gabbros are cumulates, but basalts, in particular, the aphyric

ones are cooled, evolved, erupted, and then solidified basaltic

liquids.




1. Basic concept of magma generation and evolution

有关岩浆成因和演化的一些基本概念

2. Some petrologic and geochemical perspectives of mantle plumes,

ocean ridges, plume-ridge interactions and mantle convection

岩石学和地球化学观: 地幔柱、洋中脊、地幔柱-洋中脊相互作用、地幔对流动等

用岩浆岩岩石学和地球化学为手段 – 理解全球构造及地球动力学问题

如何运用？

用岩浆岩岩石学和地球化学为手段 – 理解全球构造及地球动力学问题

岩石地球化学参数

地质、地球物理参数

[相关关系]

[矿物含量，成分，岩石结构，主、微量元素，同位素等]

时间，空间，岩石圈厚度，洋脊扩张速率，水深，地震资料等]

[相关关系] 可能有成因联系

我们继续吧？！

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