Table 2-2 Average Chemical and Mineral Compositions of Selected Plutonic Rocks Chemical composition Granite Syenite Granodiorite Quartz Die rite Diorite Gabbro Olivine Diabase Diabase Dunite Lherzolite (Peridotite) Si02 70.18 60.19 65.01 61.59 56.77 48.24 48.54 50.48 40.49 43.95 Ti02 0.39 0.67 0.57 0.66 0.84 0.97 1.31 1.45 rj.02 0.10 14.47 16.28 15.94 16.21 16.67 17.88 15.24 15,34 0.86 4.82 Fe203 1.57 2.74 1.74 2.54 3.2Ó 3.1ft 3.06 3.84 2.84 2.20 FeO 1.78 3.28 2.65 3.77 4.40 5.95 8.88 7.78 5,54 6.34 MnO 0.12 0.14 0.07 0.10 0.13 0.13 0.21 0.20 0.16 0.19 MgO 0.88 2.49 1.91 2.80 4.17 7.51 8.08 5.79 46.32 36.81 CaO 1.99 4.30 4.42 5.38 6.74 10,99 9.38 8.94 0.70 3.57 Na,0 3.48 3.98 3.70 3.37 3.39 2.55 2.69 3.07 Ü.10 6.63 K,0 4.11 4.49 2.75 2.10 2.12 0.89 0.98 0.97 0.04 0.21 H20 0.84 1.16 1.04 1.22 1.36 1.45 1.35 1.89 2.88 1.08 PA 0.19 0.28 0.2Ü 0.26 0.25 0.23 0.28 0.25 0.05 0.10 Density 2.667 2.757 2.716 2.806 2.839 2.976 2.970 2.965 3.289 3.330 Mineral composition Quartz 25 — 21 20 2 _ _ J_, K Feldspar 40 72 15 é ?■ — — _ _. __ Oligoclase 26 12 ..— — - — _ _ _ _ Andesine -- — 46 56 64 ._ _. _ _ Labradorite — í— — — — 65 63 62 _- Biotite 5 2 3 4 5 i 1 Amphibole 1 7 13 8 12 3 — 1 _ ;__ Orrhopyroxene — — 1 3 6 -r- — 2 15 Clinopyroxene — 4 — 3 8 14 21 29 ,_. 10 Olivine — — — — 7 12 3 95 71 Magnetite 2 2 1 2 2 2 2 2 2 1 Itmenite 1 1 — — i—; 2 2 2 Apatite t] tr tr tr tr — — _ _ Sphene tr tr 1 tr tr — _ _ ._ _ Spinel — — — — — — 1 3 Source: After Daly and Larsen, Gcol. Sac. Am. Special Pafier 36, 1942 with modifications and reduced to 100%. !<) KiH.lii and classification ol posiiively ch-u^d iutis <>l major (hold tctrtiis) and truce elements. Radii based on eightfold courdina-don in uppet pun of diagram and on sixfold in lower part. Hare iartiitl«iieiits (REEs) in tenter ol'diflgrnm ate plotted an an expanded scale mi upper ripht. On the basis of ionic potential (charge/radius), most elements can be subdivided into IWo tillc- gories surrounded by polypous, namely, (l) Low held strength (LFS) elements, more commonly called Iarju-iun tiijmpjiilv '111' clemcnm, in upper left; (£) hiph-Jield-strengih (MPS) elements in riplil center. The liihophile designation arises from iin illfiriily lor silicate rocks, as contrasted with elements having ;in affinity fur metallic phases (sidemphile) containing Fe. Co, Ni, nnd so on, as in the tore of the Earth, or for sulfide phases (chal-eophi.lt) containing S, (,u, Zn, and so cm, lotlie potential also serves ns a VOUfth index of I he mobility of curious of the elements, thai' is. their solubility in aqueous solutions; elements with low (<■ i) and by i ( >I2)potej1tial tend lobe more soluble and mobile than eK'Uli'lltN in iiiidriiii).',e IX d'„ pliiiinum prtwp elements (Ru, Hh, Pd, Os. Ir, Pi), (Data from Shannon, 1976.) E E Figure S-1 As the basalt jc magma tn the lava fake of Kil^uea Iki so.'idified. the concentrations of the vanous components changed in response to progressive crystallization. The plot above shows the variations of several of these components in liquids [quenched to glass] in samples recovered by drilling into the crystaJli2Jng basalt. No:e that sc:T,e components are depleted from the liquid while others are enriched. The rates of enrichment or depJetion depend on the compositions and proportions of crystalJrzing minerals. Jf the differentiated liquids were removed and allowed to crystallize elsewhere, they woufcf form a series of rocks of different conv positions- Without this second step of segregation, fhe process of differentiation is incomplete. [Data from W. C Luthr Sanda Corporation, personal communication.! Com[>QsiTion attd Clarification of Magmatic Rocks 23 Table 2.3 Generally Compatible Trace Elements and the Minerals in Which They Occur MAiuRMi.M-.kAi. Olivine Onhopynwtene ClJnopyrosfcne } EDrnblende Muscovite PJajfio? Use K-fxdclspar iV i VJiSOKY MlNITRALV1 M:L^nc[IEC llrniTiice Sulfides Apatite Alknitc Xtitot me Monazilc Titaniic- I spherep StMI'l.t fchlmula (Me, K-)&Ot [Mfr Fe)SiO, (Ca. Mg, FttjJSi, A]|aOb (Cp.Na);.,(Mj!.Fe,A]l, {Si. AVJ^OH. F>j Kj(Mg. Ft, A], TiV < ,0$ FflJQ, ZrSiQ, CijiF^Tt, AlMO. [Mil YPO« Rh.Ra Sr.Eu Bl Srh Eu V,Sc Cu, Au, A*. NLPGE?* Hi, U, Th, h«vy REEs U, middle REEs Light RF,Esh V, U, Th F Iwvy REEs Y, light REEs U, Th, Nh, T*, middle REE* *A«eSSOry minerals connlituic nnly ji small fraction of rods hul their very htflh panitiori coefficient* create a dispnjnoniorute mfluciiceon built ilbiributiun efficients. T . .mm umu|i elements: Kli. Ilh. Pd. Os, Jr. Pt, Table 2.4 Trace Elements Substituting for Major Elements of Similar Ionic Size and Charge (see Figure 2.20) Majok Element Substituting Trace Element (s) Si Ge,P Ti Al V . ^ i Pc Ga Cr, Co, Ni is 'Gi, Co, Ni Ca Sr, Eüt REEs Na Eu ■■K Rbt Baf Sr, Eu TiWe 23 Parmno Cocftibenij. ľcr So=e Tracr ELemcrní V E E = 5* V lj4 Q Zs Ti v CiL BASALT MAGM.fi üjjt U7 . U C'3-l aw CLL n ch í a-KS ■met axK CLU a* DJQCG C-j í - 1JJ :- 3J-U Údl-E ClS4 D-15 cue a cs D* 10 ■5 Otm OjJl O.iXC 0X114 Mill r r-: tear CLOOT Caw Dulľ OJE Dl* ■o ** IM ia u •j 7J j- > Gand DjJU uu oxaz I1J i tXfl j-H aai org au (u : bhyoute yjuv.K L OJ: O.l OJL M n.Cřř ■: li l: oje DJ oní - Ut ■:■>- ľ - 007 D.W :. -- ŮJEJ - - OJMÍ 0/122 oxrrľ ota» D 015 0.cü« aur *J C-.5H asľ *3 DX* u* -1 5.1-t : i - - MO sít 16 n r? wj j- - - ■ i-"- ."■i 5L ::: 5» (J J Ľfci En» RoAoem. Ifl?. I) - C I O I 0. "T-r COMPATIBLE La Ce Nd T-i-1-r Rbyolite rnelt^ INCOMPATIBLE j_t-1-l J Sm Eu Gd Dv Er Yb Lu 2.21 Partition coefficients for REEs between amphibole find indicated mete. REE» are more compatible in more silicic and lowers melts. (Redrawn from Rollinson. 1993.) 42 igMttjUS Pi'trulogy Table 2,6 Trace Element Characteristics Usefi]l in Evaluating Petrogenesis of Hocks F.iyjM'a r Ch.\ h.v i i ktsTtii avij IkI kkiwi-rrATiow Ni, Co, Cr Typically highly compatible elements. I ligh concerirratinris (eg-. Ni = 25n->0Q ppm, Cr = 500-600 ppm) of these demaiB indicate derivation of parental magmas train n pcridotitc miunli- source. I liniiij: concentniiartt of Ni and to a Jester-extent CIo in ;i rock scries surest olivine fractionation. Decrease in CIr suggests spinel or clinopyroxcnc fracikwaiiun. PC tli, Cu. Strongly partitioned into immiscible sulfide melts. A series of malic magmas that lack sulfides may show increase* if) uSeSt Au. Ajj elements. In mnt utlier magma series, these are compatible elements thai tie-dine with increasing silica. V, Ti Typically compatible elements in ilmemieand tiianomagnelile. ,ilt hough Ti tan Womt enriched in some mafic magnustha luck rhese oxide minerals. Mb Incompatible element in most magmas. However, because il substitutes somewhat (or Ti. residual tttanates isuch a> mlilrJ may cause depletions of Nb in subduction-zone magma sources. Mb has a lower solubility in aqueou* fluids than whtt equally incompatible elements. Zr, Hi Characteristically incompatible in mafic magmas and not readily substituting, in mantle phases, in irircon-saiuiated Isdlicifl magmas both may behave as compatible elements. I3 Ghsractnisiictilly intompaiiblt: in mafic magmas but btenmes a cumpittiblc clement in inTcrntcdimc mid silirit tntgm where apatite is a stable phase. Bd Subslilutes tor K in micas. K leldspar. and to a lesser exlenL amphibole. A change bom incompatible m cnmpauhEc bcht*- ior in 4» magma series may ituiicure ,m iin.rc;isinL: role IW uncol dioe phases Rb Incompatible element in most magma, but it substitutes for K in mica* and K-feldspar in silicic magmas, though rax a strongly as Ba. Si, Hu Substitute readily for Ca in plagiotlase and K in K-leldspar. Declining Sr concentrations indicates felibp.n i. ■ r: i ■: i ■.. ■ 11 run: series ol related magmas. Sr is more incompatible under mantle conditions because of the absence of feldspar. REEs Generally, the tmvltnl rare earth elements are incompatible in basaltic magmas. Garnet more readily accommodates hemy REE* than light RliEs and 4i steep REE patrefn may mdioti- tumci remained in ;i mantle residue. Tltanite prefers the raddle RLdls. Apatite, monazite, and allaniic have wry high partition coefficients for Light REEi; consequently, light REEa ire commonly compaii hie clement1? in rhyotirjc magmas that have these minerals, Zircon and xeiiotime prefer heavy KHJfsba their abundance in namral magmas rarely sulhcicnt to make the heavy REEs behave as compatible elements. Y Generally behaves incompatibly, as do middle to heavy RELs. It has a high partiiion coefficient in garnci and 101 letfCf tern in amphibole. lis behavior is strongly atdected by REE-rich accessory minerals such as iipSTtte and especially X Dam from Green (19891. 2A Igtiettus Petrology 3 J Plotting Compositional data tin variation digrams, A mm pit miliums ¥. 17 m.% FeO, J.2J wt.% NftjO, and 54.10 wt.% SiOj. In lJk Cartesian diagram (a), FeO and Na,0tie plotted against Jii02 (all in vn.%>, To ptot SiOj. Na2Q. and |-'cO on the iruutjtLLlar'dugram lb), {bey mutt be makuLtcd to total IU0.00. First, they are summed, 54.50 + 9.17 4 Hi = 6,7 + 4.8 » 100,0 These recalculated value* can then he plotted H> dut each ape* represents 100 wt.% of a constituent and the leg of the triangle opposite the apex is the locus of points reprcsOaai Owt.% of thai constituent. A line parallel to the leg of the triangle opposite the FeO apex and 1 of the way toward thai apes is the locus of points representing 15.7 wi.% l-'eO. Similarly, the line labeled 4.S % is fk \ti i.. Hi of thwc tm lines is a point that represents the relative SKJj, FeO, and Ns»0 wt.% in the sample. Noie thai it is only mxe>-sary to draw Unci for any [Woof the three constituents represented in the diagram heeJUM- the third variable is the difference from 100% ol the other two. ( in:ij!iiMi:n:i and Classification of Magma t k Hocks 25 00 Upper limit or analyses 41 ne 330 462 Tou! analyses 5.449 S XI Tata! 41.102 Antilyws as OS 46.73 3a.o: 13. ľ! 2.00 100.00 Chemical analyses of uver 41.000 igneous rocks from around the world of all aprs. Each symbolized pitted point represent* a particular number of analyses falling iftlliii rht; indicated ranfje (0-41.42-116. eltl. Nearly half 146,7% I of iill igneous rocks .hl- widely scattered over the diugram dUwh aymlvol >. whereas, sliphtJy more than half 153.3%) ate rightly cluttered in a central band. Note the still higher concentration of analyses near 2.5 (Na^O + KjOl and 5» ut.":. Sit)... cwn-spondinn roujihl) to basalt, the dominám ma^manc rock rypc on Harth. (Compiled by und furnished courtesy oť R. VP. Le Maitre, Unutrsiiy of Melbourne, Australia.* SLO^ fwi. ft) Ab Albite 1lm llmenite An Anorthite Kfü K-feldspar Bi Biotiie Let Leuciie Fa Fayalilc Mag Magnetite Fo FonUerile Ne Nephrine Hhl Hornblende Phi PnJogopite Qtz Quaru 23 End-member compositions of major raagmatic rok-forming minerals compared with the field of worldwide magmark rocks (shaded) from Figure 2 A. Triangular field of feldspar solid solution is outlined by the K feldspar albite snort Elite eod members. Trspesohedrd Gdd js hornblende solid solutions. 36 Igneous Pcrroiogy I l 12 10 i a 3 Ei-. i iic^- a* * i ■ j Ei.lVllllL- | n iintlcshe i Andcsite I [>ucile \ \ I 41 45 49 53 57 61 -i-L 05 73 11 2.16 lots J illkaJiB-Hil.Lj di^um showing „elds an*! examples of subalkatine *nd alkaline n«k *Uilea. Irregular solid line wp.nlCrt the fold o\ iH'pncliK-nomwiv* rocfa from rocks having no normative nepKclinc in iht 15,164 sample database of Lr Bus et n| (1992) Lighl da^-d Iin« delineate ,hc IUGS volcanic rock ivpc classification from Figure 2.12 Note thai 0 single rock type, such «hjHih can be other jjkahne (Ke-nnrmaiJve) or sobalkaline (ty-norm,tiW,, The alkaline vokan ic suite of basanitc, phonotcph rite, tephriphnnnliie a*J phonolno Uilled tirdi-O i.s from Irtsfwi lni' 1000 htmnii Jtst-riiiiiiuirion diagrinn iw ßrariilic rocks hast-nä «nKont rations oJ Rh versus Y ■+ NIí. Symbols show niotlťm r