Composition and evolution of the lithospheric mantle in central Spain: inferences from peridotite xenoliths from the Cenozoic Calatrava volcanic field c. VILLASECN*, E. ANCOCHEN, D. OREJANA' & T. E. JEFFRIES2 I
Departamento de Petrologia y Geoquimica, UCM-CSIC, Facultad de Geologia, c/Jose Antonio Novais, 2, 28040 Madrid, Spain 2
Department of Mineralogy, Natural History Museum, London SW7 SBD, UK *Corresponding author (e-mail:
[email protected])
Abstract:
Spinel lherzolite xenoliths from the Cenozoic Calatrava volcanic field provide a
sampling of the lithospheric mantle of central Spaill. The xenoliths are estimated to originate
from depths of
35-50 km.
Trace element content of clinopyroxene and Cr-lllunber in spinel indi
cate low degrees of partial melting
(:::5%)
of the xenoliths. Although a major element whole-rock
model suggests wider degrees of melting, the Calatrava peridotite chemistry indicates a moderately fertile mantle beneath central Spain. Calatrava peridotite xenoliths bear evidence for interaction
with two different metasomatic agents. The emichment in LREE Oight rare earth element),
U and Pb,
Th,
and the negative anomalies in Nb-Ta in clinopyroxene and amphibole from xenoliths
of El Aprisco, indicate that the metasomatic agent was probably a subduction-related melt, whereas
the emichment in l\1REE in clinopyroxene from xenoliths of the Cerro Pelado centre suggests an alkaline melt similar to the host lUldersaturated magmas. These metasomatic agents are also con
sistent v..ith the chemistry of interstitial glasses fOlUld in xenoliths of the two volcanic centres.
Differences in metasomatism but also in mantle composition is supported by Sr-Nd whole-rock data, which show a more radiogenic nature for Sr isotopes of samples from the
(87Sr/86Sr ratios of
0.7035-0.7044
instead of
0.7032-0.7037
El Aprisco centre
for samples from Cerro Pelado).
The timing of the subduction-related metasomatic stage is unconstrained, although the Calatrava intraplate volcanism intrudes an old Variscan lithospheric section reworked during the converging
plate system affecting SE Iberia in the Tertiary. The presence o f w ehrlite types within the Calatrava
peridotite xenoliths is here interpreted as a reaction of host lherzolites with silica-lUldersaturated
silicate melts that could be related to the Calatrava alkalin e m agmatism. The Sr-Nd isotopic com position of Calatrava peridotites plot within the European asthenospheric reselVorr
(EAR)
mantle,
these values represent more emiched signatures than those fOlUld in the other Spanish Cenozoic alkaline province of Olot.
Studies of ultramafic xenoliths exhumed by Ceno zoic volcanic activity have provided substantial information regarding the nature of the subcontinen tal lithospheric mantle (e.g. Nixon 1987; Downes 2001). In the Iberian peninsula three main Cenozoic volcanic fields have provided significant mantle derived xenolith suites since studies from the last century: SE Spain (Ossan 1889), Olot (San Miguel de la Camara 1936) and Calatrava (Ancochea & Nixon 1987) (Fig. 1). Scarce ultramafic xenoliths have also been described in the Cofrentes volcanic area (Ancochea & Nixon 1987; Seghedi et al. 2002), and mantle-derived xenoliths have been found in Upper Permian subvolcanic dykes of the Spanish Central System, although they represent mafic-ultramafic cumulates instead of real mantle peridotitic fragments (Orejana et al. 2006; Villaseca et al. 2007; Orejana & Villaseca 2008).
In this work we study the chemical composition of the Calatrava sample suite, including major and trace elements for the constituent minerals, and major, trace elements and Nd and Sr isotopes for whole rocks. As for many spinel lherzolite xenolith suites, our data indicate the decoupling of chemical features caused by melt extraction during partial melting and subsequent metasomatism. This study, together with that of Bianchini et al. (2010), are the first attempts to characterize the subcontinental mantle beneath central Spain. Geological setting The Calatrava volcanic field comprises more than 200 volcanic centres in an area of around 5500 km' (Ancochea 1982). The volcanic field is exclusively formed by monogenetic edifices,
(.) ... Neogene-Quatemary volcanics
D
SE ,'o/Clmic
Post-Alpine sedimentary basins
13 .... __ ..
lamIIlIll
R"1:ion
g Alpine foldbelts
C/Jlo/rIJ,'1l
Eiiil Hercynian Massif
hI.f*
Ib atIU
(Ctntroi
*lIII
"ok,m;c Rc/:;on) £"sIun
lb'
,'oIClm;" R 130 /-Lm-thick polished sections using laser ablation (LA-ICP-MS) at the Natural History Museum of London using an Agilent 7500CS ICP-MS coupled to a New Wave UP213 laser source (213 nm frequency-quadrupled Nd-YAG laser). The counting time for one analysis was typically 90 s (40 s measuring gas blank to establish the background and 50 s for the remainder of the analysis). The diameter of the laser beam was around 50 1J.lll . The NIST 612 glass standard was used to calibrate relative element sensitivities for the analyses of the silicate minerals. Each analysis was normalized to Ca or Si (AI for spinel) using con centrations determined by electron microprobe. Detection limits for each element were in the range of 0.01-0.06 ppm, except for Sc and Cr (0.11 and 0.73 ppm, respectively). Eleven spinel peridotite xenoliths from two vol canic centres (El Aprisco and Cerro Pelado) were used in this investigation. The whole-rock major and trace element composition was analysed at ACTLABS. The samples were melted using LiB02 and dissolved with HN03. The solutions were analysed by inductively coupled plasma atomic emission spectrometry (ICP-AES) for major elements, whereas trace elements were deter mined by ICP mass spectrometry (ICP-MS). Uncer tainties in major elements are bracketed between 1 and 3%, except for :Mu0 (5-10%) and P20S (> 10%). The precision of ICP-MS analyses at low concentration levels was evaluated from repeated analyses of the international standards BR, DR-N, UB-N, AN-G and GH. The precision for Rb, Sr, Zr, Y, V, Hf and most of the REE were in the range 1-5%, whereas they range from 5 to 10% for the rest of trace elements, including Tm. Some samples had concentrations of certain elements below detection limits (K20 0.01%; Rb 1; Zr 1; Nb 0.2; Tb 0.01; Ho 0.01; Tm 0.005; Lu 0.002; Hf 0.1; Ta 0.01; Th 0.05; U 0.01). More infor mation on the procedure, precision and accuracy of ACTLABS ICP-MS analyses is available at www.actlabs.com. Sr-Nd isotopic analyses were carried out at the CA! de Geocronologfa y Geoquimica Isotopica of the Complutense University of Madrid, using an automated VG Sector 54 multicollector thermal ionization mass spectrometer with data acquired in multidynamic mode. Isotopic ratios of Sr and Nd were measured on a subset of whole-rock powders. The analytical procedures used in this laboratory have been described elsewhere (Reyes et al. 1997). Repeated analysis of NBS 987 gave 87Srj86Sr 0.710249 ± 30 (2,,-, n 15) and �
�
for
the
JM
Nd
standard
0.511809 ± 20 (2v-,
n =
the
143
Nd;
t44
Nd
01
=
13). The 2v- error on the
e(Nd) calculation is ± 0.4.
Petrography and mineral chemistry The studied Ca1atrava mantle xenoliths are rounded medium-size samples (from 5 to 45 cm in diameter) that show no evidence of alteration or host basalt infiltration. Xenoliths equilibrated in the spinel peri dotite stability field and display a wide modal vari
OIivine Webst&tite
ation from1herzolite to minor wehrlite types. Modal composition was detennined by mass-balance cal culations from the main minerals and the major element compositions of the whole rocks, using the least-squares inversion method of A1barede ( 1995). Within the 11 analysed rock samples, 10 are 1herzolites and only one is a wehrlite (sample 72674) (Fig. 2). Mantle xenoliths from the El Aprisco centre tend to have orthopyroxene more abundant than clinopyroxene, whereas those from Cerro Pe1ado are more clinopyroxene-rich, even
Opx
Cpx
Fig. 2. Modal proportions of the studied Calatrava mantle xenoliths calculated using the mass-balance method of Albarede (1995). The modal compositional field from mantle xenoliths from NE Spain (Olot) is taken from Bianchini et aL (2007) and Galan et al. (2008).
wehrlitic in composition (Fig. 2). The 1herzolitic harzburgitic mantle xenoliths from 010t (Bianchini
inequigranu1ar
et al. 2fXJ7; Gal:in et al. 2008) have been plotted
olivine or orthopyroxene are commonly the porphy
varieties
also
appear, in which
for comparison, and are similar in modal compo sition to those from SE Spain (Tallante: Becca1uva
roclasts. Grain boundaries are usually curvilinear defining mosaic or triple-junction textures. No
et al. 2004) (not shown). Ca1atrava lherzolites are
phase layering, foliation or lamination have been
richer in clinopyroxene and poorer in olivine than
found.
other Spanish mantle xenolith suites (Fig. 2).
Olivine crystals may have different sizes even
Scarce phlogopite-rich clinopyroxenites (glimmer
in a single sample. Some fine-grained interstitial
ite varieties) have been found at Cerro Pe1ado (Ancochea & Nixon 1987) but they have not been
crystals, spatially related to spine1 microaggregates or spine1 coronas as described below, have been considered to be of second generation. Both ortho
sampled for this study. Although in acassory amounts, the studied
pyroxene and clinopyroxene show mutual lamellae,
interstitial
and commonly a second superimposed spinellamel-
volatile-rich phases indicative of modal metasoma
1ae. Spine1 occurs as discrete, dispersed interstitial
tism: amphibo1e in samples from the El Aprisco
grains that usually show some fine-grained po1y
peridotite
xenoliths
usually
have
centre, and ph1ogopite from those of the Cerro Pelado maar. Only one xenolith is an anhydrous
crystalline coronas of amphibo1e (only in the El Aprisco outcrop) (Fig. 3b-d). Some scarce
wehrlite 72674 shows trace amounts of phlogopite
also observed, but the clearly hydrous character of
included in clinopyroxene. Although peridotite
the corona rejects the possibility of a reaction
xenoliths from Cerro Pelado 'With both hydrous
between pre-existing garnet and matrix olivine, as
minerals, amphibo1e and phlogopite, have been described previously (Ancochea & Nixon 1987)
suggested in other spinel symp1ectitic 1herzolite xenoliths (Ackennan et al. 2007) (Fig. 3c). Some
1herzolite (sample 72690 from El Aprisco). The
we did not find this type. Most peridotite xenoliths have a coarse-grained
spine1-pyroxene-amphibo1e symp1ectite has been
spine1 grains have sieve textures defined by a partial corona of a new fine-grained spinel-2 associ
texture of protogranu1ar aspect, defined by a grain
ated
size greater than 2 mm and commonly equigranular
olivine (Fig. 3f). These textural features have been
to
vesicular
glass and
second-generation
(Fig. 3a). Some porphyroc1astic textures or more
interpreted as re-equilibrations or reactions with a
Fig.3. Photomicrographsof representative Calatravamantlexenoliths. Lherzolite 72691 (El Aprisco): (a) equigranular texture; (b) interstitial amphibole around major per:idotite minerals (spinel, clinopyroxene, orthopyroxene) (BSE image); and (c) symplectitic intergrowths of spinel-2, amphibole, clinopyroxene-2 (an amph-cpx intergrowth is shown on the left) within orthopyroxene (BSE image). Lherzolite 72689 (El Aprisco) showing: (d) amphibole aurooles around spinel; and (e) a complex reaction zone shomng the breakdown of spinel to clinopyroxene-2, olivine-2 and vesicular
Fig.3. (Continu.ed) glass (BSE image). U,erzolite 65290 (Cerro Pelado): (f) reaction zones around primary spinel (Sp-l) composed of cellular spinel-2, microgranularolivine-2 and vesicular glass (BSE image). Wehrlite 72674 (Cerro Pelado): (g) highly vesicular interstitial glass (BSE image); and (h) vesicular glass vein with associated cpx-2 crystals (BSE image). 01, olivine; Opx, orthopyroxene; Cpx, clinopyroxene; Sp, spinel; Amph, amphibole; v, vesicle.
percolating intergranular melt (Shaw & Dingwell 2008). In sample 65290 it is possible to see a complex corona of symplectitic spinel-2 and interstitial glass rimming primary spinel (Fig. 3f). Acicular pentlandite, interstitial to olivine, is very scarce in some lherzolites. Accessory amounts of hydrous minerals (amphi bole or phlogopite) are present in most of the Cala trava lherzolite xenoliths (except in anhydrous lherzolite 72690). They are mostly intergranular phases forming small anhedral crystals. Amphibole in most lherzolites forms coronas around spinel grains or intergrowths with clinopyroxene around spinel symplectites (Fig. 3b-d), in textures similar to those described in other peridotite xenolith suites (e.g. Coltorti et a!. 2004, 2007b). Some xenoliths also show interstitial brown glass with small vesicle or bubble-like structures (Fig. 3e-h). Moreover, some interstitial glasses appear as part of a complex reaction zone that involves many of the primary lherzolite minerals, but especially spinel, which is surrounded either by symplectitic intergrowths of new spinel-2 and olivine-2 with interstitial glass (Fig. 3f) or by a microaggregate of newly formed cpx-ol-glass (Fig. 3e). The wehrlite 72674 is porphyroclastic in texture and the two pyroxenes do not show lamellar exsolu tion, as is typical in the lherzolite types. Wehrlite clinopyroxene shows a marked poikilitic texture with multiple glass, apatite, phlogopite and fiuid rich inclusions. Olivine grains show locally deformation twins and most crystals have smooth curvilinear boundaries. Only trace amounts of spinel (as microinclusions in olivine and clino pyroxene) appear in this sample. The wehrlite also shows interstitial vesicular glass, which is mainly concentrated in the fine-grained section of the inequigranular texture, defining some intercon nected veining (Fig. 3g, h). Major element mineral composition
The Calatrava hydrous mantle xenoliths consist of variable proportions of magnesian olivine, ortho pyroxene and clinopyroxene, aluminous spinel, and accessory amounts of calcic amphibole or phlo gopite, the compositions of which are summarized in Table 1. All minerals are unzoned and homo geneous within a single crystal. The Mg-number for olivine mostly ranges from 89.2 to 91.5, although neoformed varieties (oliv-2) and olivine from wehrlite 72674 show lower Mg-numbers (88.4 and 84.5-86.0, respectively). Olivine-2 in lherzolites also show slightly higher CaO and lower NiO content than Mg-rich olivine (Table 1), features typical of metasomatism (e.g. Coltorti et a!. 1999; Ionov et a!. 2005). Olivine in
the wehrlite shows the highest Ti02 content (up to 0.09 wt%), and high CaO and low NiO content (Table I). Orthopyroxene has a similar range of Mg numbers than olivine, mostly from 88.7 to 92.3 (Table 1), but it shows a wider range in content of Cr203 (0.13-0.52), AI203 (3.00-5.74) and CaO (0.12-1.09), always in a common range for abyssal peridotites (Bonatti & :Michael 1989). Cor relatively to olivine, orthopyroxene of wehrlite 72674 shows lower Mg-numbers (85.0-86.6), and higher content of Ti02 (0.22-0.41), CaO (0.943.86) and Na20 (0.12-0.25), than orthopyroxene from associated lherzolites (Fig. 4a). Lherzolite 72691 with the lowest averaged Al content of orthopyroxene (and the highest Mg-Cr values) could be the most depleted peridotite of the xenolith suite (Fig. 4a). Clinopyroxene also shows a wide range of Mg-numbers (87.6-92.7) with cpx-2 (neocrystals related to intergranular reaction zones) having low values (88.2-90.0) but variable AI-Ti-Cr content. For example, the cpx-2 analysis 71 in lher zolite 72689 (related to a spinel reaction zone with glass) shows the highest AI-Cr-Ti content of the whole analysed clinopyroxene population (Fig. 4b). Clinopyroxene from wehrlite 72674 is also Fe Ti-enriched, as are the other minerals of this xeno lith (Fig. 4b, c) (Table I). Lherzolite 72691 shows the lowest Al clinopyroxene, reinforcing the idea of being the most depleted peridotite xenolith. Primary spinel has low Cr-numbers (from 8.3 to 10.8) and a narrow Mg-number range (0.75-0.78) (Table 1). Ti02 content is generally low, ranging from 0.01 to 0.16 wt%. Spinel from the most depleted lherzolites (samples 72691 and 55570) shows a wider range of composition, with relatively higher Cr values and lower Al content than spinel from associated lherzolites (Fig. 5). In lherzolite 55570 cores of large spinel crystals show the highest Al and Mg content (and the lowest Cr values) compared with rims or interstitial rods, which are associated with intergranular amphibole. In fact, the smallest interstitial spinel crystals in lherzolite 55570 and the symplectitic spinel from lherzolite 72691 show the highest Cr-numbers (13.0-17.7) and the lowest Al203 contents (5155 wt%) ofthe Calatrava lherzolites. These contents are similar to those of the sieved sp-2 of lherzolites 65290 and 65298, which also show high Ti02 content (up to 0.44 wt%), suggestive of a reaction with a Ti-rich metasomatic agent (perinelli et a!. 2008b) (Fig. 5). Residual spinel micrograins pre served as inclusions in major minerals of wehrlite 72674 show the highest Ti and Cr (Ti02 up to 3.0 wt% and Cr-numbers in the range of 52.454.1), and the lowest AI-Mg content, of the studied peridotite xenoliths (Table 1). Owing to
Table 1. Major element composition of representative minerals from the Calatrava mantle xenoliths Representative olivines El Aprisco Sample
Si02 Ti02 Al203 FeO MnO MgO CaO Na20 K,O NiO Cr203 Total XMg
Cerro Pelado
55569 A39
55570 AI8
72688 AI42
72689 A82
72690 A38
72691 AI20
65290 A23
65298 A2
65298 21 (oliv-2)
72674 A95
41.33 bdl bdl 9.63 0.05 49.60 0.03 bdl 0.01 0.41 bdl
40.56 bdl bdl 9.18 0.18 49.54 0.04 0.02 bdl 0.47 0.08
41.05 bdl 0.02 9.88 0.20 49.61 0.09 0.01 bdl 0.22 0.01
39.97 bdl bdl 9.53 0.18 49.85 0.04 bdl bdl 0.42 0.07
41.20 0.01 bdl 9.31 0.06 49.74 0.02 0.02 bdl 0.33 0.02
40.63 bdl bdl 8.66 0.13 50.68 0.05 0.01 bdl 0.42 0.03
40.58 0.02 0.03 10.40 0.16 49.01 0.06 bdl bdl 0.21 0.07
40.67 0.01 bdl 9.29 0.07 50.43 0.09 0.01 bdl 0.36 0.03
40.69 0.01 bdl 11.36 0.13 48.71 0.13 bdl bdl 0.12 0.04
40.03 0.03 bdl 14.85 0.12 45.53 0.09 bdl bdl 0.20 bdl
101.06 90.19
99.98 90.59
101.09 89.97
99.99 90.31
100.71 90.50
100.58 91.25
100.49 89.36
100.92 90.62
101.15 88.44
100.91 84.47
Representative orthopyroxenes El Aprisco Sample
Si02 Ti02 Al203 FeO MnO MgO CaO Na20 K,O NiO Cr203 Total XMg
Cerro Pelado
55569 A36
55570 A32
72688 A59
72689 A76
72690 A41
72691 A65
65290 A27
65298 A23
65298 A3
72674 Al l 0
55.08 0.15 4.72 6.26 0.14 32.80 0.99 0.11 bdl 0.08 0.33
54.47 0.12 5.00 5.77 0.14 32.56 1.10 0.11 bdl 0.14 0.53
55.38 0.03 3.49 6.54 0.15 33.39 0.54 0.02 0.02 bdl 0.18
54.97 0.06 3.35 6.41 0.15 33.94 0.43 0.03 bdl 0.08 0.23
54.73 0.04 5.42 5.80 0.12 32.34 1.37 0.13 bdl 0.08 0.34
54.71 0.04 4.08 5.45 0.13 33.66 0.62 0.06 bdl 0.15 0.38
54.19 0.18 5.74 6.30 0.14 31.53 1.04 0.15 bdl 0.04 0.40
54.24 0.07 5.49 6.11 0.15 32.96 0.88 0.12 bdl 0.18 0.35
53.88 0.08 5.39 6.24 0.13 32.81 0.80 0.15 bdl 0.14 0.33
53.64 0.37 3.94 8.46 0.15 28.54 3.86 0.25 bdl bdl 0.44
100.68 90.31
99.93 90.94
99.74 90.11
99.66 90.38
100.38 88.94
99.29 91.66
99.70 89.92
100.55 90.59
99.95 90.35
99.64 85.78
(Continued)
Table 1. Continued Representative clinopyroxenes El Aprisco Sample
55569 A30
55570 A30
72688 A57
52.29 0.46
51.75 0.23
51.89 0.42
Ah03 FeO MnO
6.90 2.60 0.05
5.72 2.87 0.06
MgO CaO Na20 K,O NiO Cr203
14.94 19.69 1.62 bdl 0.04 0.79
Total XMg XCf
99.36 91.10
Si02 Ti02
om
72689 71 (Cpx-2)
Cerro Pelado 72689 A75
72690 A42
72691 A66
65290 A31
49.86 0.80
51.05 0.41
52.37 0.33
52.57 0.01
51.19 0.54
53.03 0.51
51.36 0.52
53.97 0.62
49.49 1.39
4.87 2.86 0.14
8.11 3.08 0.02
6.07 2.73 0.10
7.61 2.46 bdl
4.44 2.33 0.05
7.37 3.46 0.09
4.43 4.21 0.17
7.11 3.31 0.06
3.12 6.11 0.16
6.70 4.80 bdl
15.81 21.15 1.35 bdl 0.08 0.83
15.66 22.26 0.87 bdl 0.03 0.54
15.65 18.80 1.19 bdl 0.01 1.50
15.35 21.58 0.98 bdl 0.03 0.70
14.44 20.55 1.64 0.01
16.64 21.29 0.89 bdl 0.05 0.61
15.72 18.90 1.60 0.01 bdl 0.74
17.72 18.17 1.21 bdl bdl 0.97
15.66 19.09 1.61 bdl 0.01 0.66
17.90 16.57 1.04 0.03 0.01 0.63
14.39 20.95 1.04 bdl 0.01 0.59
99.85 90.79 0.09
99.55 90.72 0.06
99.03 90.06 0.08
98.99 90.98
100.42 91.56
om
om
98.88 92.65 0.10
99.63 88.98 0.09
100.41 88.20 0.13
99.39 89.33 0.06
100.14 83.94 0.12
99.34 84.20 0.09
65298 Al
72674 A13
om 0.94
65298 22 (Cpx-2)
65298 A4
72674 101 (Cpx-2)
72674 A96
Representative spinels El Aprisco Sample
Si02 Ti02 Ah03 Cr203 FeO MnO NiO MgO CaO Na20 K,O Total XCf XMg
55569 A40
55570 AI6
72688 AI44
72689 A90
om
0.02 0.10 52.23 15.73 12.09 0.10 0.33 19.65 0.03 0.01 bdl
0.13 0.10 55.96 9.61 13.23 0.15 0.29 19.81 0.09 0.04 bdl
om
0.13 56.51 10.17 11.97 0.04 0.34 20.41 0.03 0.04 bdl
0.06 57.78 8.84 12.00 0.11 0.48 20.49 0.01 0.01 bdl
100.00 10.78 0.75
100.28 16.81 0.74
99.74 10.33 0.73
100.12 9.30 0.75
Cerro Pelado 72690 A55 0.06 0.10 58.40 10.15 10.57 0.041 0.39 21.12 bdl 0.01 bdl 100.84 10.43 0.78
72691 121 sympl.
72691 56 symp!.
65290 A29
65290 A30 (Sp-2)
65298 A5 (Sp-2)
0.05 0.01 53.85 13.10 10.90 0.10 0.40 20.82 0.03 bdl bdl
0.04 bdl 51.03 16.32 11.73 0.07 0.25 19.90 0.06 bdl bdl
0.08 0.19 56.97 10.17 12.55 0.02 0.32 20.23 0.01 bdl 0.01
0.11 0.41 53.15 13.11 11.99 0.11 0.34 20.62 0.02 bdl bdl
0.11 0.38 51.64 14.46 11.10 0.13 0.28 20.93 0.03 bdl bdl
0.08 0.14 56.83 9.31 11.15 0.10 0.34 21.56 0.02 0.01 0.02
0.11 2.49 20.76 35.80 26.37 0.19 0.11 13.23 0.18 bdl bdl
99.54 14.05 0.77
99.65 17.66 0.75
100.78 10.71 0.74
100.13 14.21 0.76
99.36 15.83 0.77
99.93 9.90 0.78
99.22 53.64 0.48
Representative amphiboles and phlogopites Phlogopite
Amphibole Sample
55569 A27
55570 A35
72689 A85
72691 A55
72688 A51
72688 A68
65298 A13
65298 A19
72674 A116
Si02 Ti02 Ah03 FeO MnO MgO CaO Na20 K,O NiO Cr203
43.83 1.48 14.25 3.72 0.04 17.22 11.48 3.51 0.02 0.25 0.57
42.65 0.58 15.43 3.82 0.14 17.86 10.74 3.75 0.20 0.10 1.39
42.79 0.73 15.05 4.04 0.05 18.09 11.17 3.59 bdl 0.19 0.72
43.63 0.42 14.97 3.72 0.09 18.64 10.83 3.62 0.11 0.08 1.34
42.19 1.33 15.18 4.40 0.12 17.67 11.76 3.50 0.06
42.59 1.33 15.09 4.16 0.04 17.54 11.69 3.41
37.64 3.10 17.90 4.17 0.05 21.35 0.02 0.79 9.15
38.13 3.12 18.18 3.88 20.54 0.05 0.76 9.37
35.98 6.76 15.70 8.08 0.09 17.66 0.10 0.81 8.91
om
0.04 0.77
bdl
bdl
bdl
0.73
0.78
0.81
0.16
Total XMg XCf
95.54 89.18 2.64
95.17 89.29 5.71
95.50 88.87 3.10
96.02 89.93 5.66
96.20 87.75 3.14
95.92 88.27 3.30
94.93 90.14 2.85
94.83 90.43 2.90
94.25 79.58 0.69
om
bdl
Interstitial glasses El Aprisco Sample
Cerro Pelado
72689
72689
65290
65290
72674
72674
72674
72674
A22
A24
A34
A37
A7
Al
A5
AI09
Si02
57.73
56.79
55.66
54.60
53.29
53.68
58.17
59.74
Ti02 Ah03 FeO MnO MgO CaO Na20 K,O P205 Cr203
0.84 22.22 2.01 bdl 3.09 6.70 5.54 0.06 0.11 0.06
0.80 21.87 2.25 0.03 3.48 7.07 5.02 0.03 0.08 0.12
1.02 21.51 2.35 0.03 3.37 4.77 4.36 4.33 0.23 0.37
1.08 21.63 1.86 0.03 2.74 4.81 5.07 4.87 0.20 0.37
1.92 18.87 5.17 0.08 2.25 4.19 6.26 5.27 0.35
1.49 16.52 3.75 0.02 1.87 2.37 5.19 5.44 0.24 0.03
1.78 16.69 3.43
om
2.36 18.99 4.63 0.12 1.89 3.90 6.06 5.18 0.29 0.04
Total XMg
98.42 0.73
97.34 0.73
98.00 0.72
97.24 0.72
97.77 0.44
97.18 0.42
95.10 0.47
94.56 0.49
Abbreviation: bdl, below detection limits.
om 1.82 2.30 3.34 5.17 0.20 0.03
I J;,I Aprisco
I') lOO
055569 .55570 v 72688 .72689 072690 .72691
., . -J
80
Reaction "'ilh Ti-rich metasomatic agent
..
Cerro Pefado a. 65290
l!O U
OpX
·65298 + 72674
0. 1 ..
wchrk 72674 4
6
,
1
....
,. 0"
Ib)
Cpx Wchrlitc • • •
. � ..
,%
.
+ ... "
3
�
''''
O���JPD
80,
S..,
,,.
•
Cp:
