MINERALOGICAL MAGAZINE Supra-subduction zone ophiolites of Central Anatolia

14 Pages·2006·0.86 MB·English

MINERALOGICAL MAGAZINE
VOLUME 60 NUMBER 402 OCTOBER 1996
Supra-subduction zone ophiolites of Central
Anatolia: geochemical evidence from the
Sarikaraman Ophiolite, Aksaray, Turkey
M. K. ZINILAY
Dept. of Geological Engineering, Middle East Technical University, Ankara, Turkey
P. A. DYOLF
Department of Earth Sciences, University of Keele, Staffordshire, ST5 5BG, U.K.
AND
M. C. UL~02~CNOG
Department of Geological Engineering, Middle East Technical University, Ankara, Turkey
Abstract
The Central Anatolian Crystalline Complex (CACC), situated between the northern and southern oceanic
strands of Neotethys, contain a number of little-studied ophiolitic bodies of late Cretaceous age that have a
bearing on the Mesozoic development of this region. The pillow lavas and sheeted dykes of the Safikaraman
Ophiolite were originally a comagmatic differentiated series of vesicular, aphyric and olivine-poor,
plagioclase-clinopyroxene phyric tholeiites, but now exhibit gmenschist facies assemblages. A set of late
dolerite dykes cross-cutting the whole volcanic sequence are more chemically evolved and were probably
derived from a different source. Relative to N-MORB the lavas and dykes are enriched in some LIL elements
(K, Rb, Cs, U, Th and St) and depleted in HFS elements (Nb, Ta, Hf, Zr, Ti and Y) and light REE. In terms of
immobile elements the ophiolitic basalts have the broad chemical characteristics of island arc tholeiites that
were formed in a supra-subduction zone setting, whereas the late dykes are more akin to N-MORB. In this
respect the Sarikaraman Ophiolite is similar to other ophiolites found in the eastern Mediterranean region and
emphasizes the preservation of this particular environment in the CACC. If all the Central Anatolian
Ophiolites (of which the Sarikaraman Ophiolite is one example) were derived via southward thrusting from
the Vardar-Izmir-Ankara-Erzincan Ocean branch to the north, age relationships suggest that this segment of
ocean crust was relatively short-lived before obduction onto the CACC.
:SDROWYEK ophiolites, supra-subduction zone, geochemical evidence, Central Anatolia, Turkey.
Introduction play an important role in plate tectonic reconstruc-
tions (Coleman, 1977; Moores and Vine, 1971).
OPHIOLITES~ as remnants of obducted ancient ocean Those of Mesozoic age are ubiquitous in Turkey and
crust, mark the presence of former suture zones and the Middle East region generally (e.g. Vourinos,
Mineralogical Magazine, October 1996, Vol. 60, pp. 69~7i0
(cid:14)9 Copyright the Mineralogical rCeicoS
698 .M .K YALINIZ ET AL.
Othris, Argolis, Troodos, Baer-Bassit, Semail), and accretional prism (Koqyi~it et al., 1988; Ko~yi~it,
represent the variably disrupted fragments of 1991). The Central Anatolian Ophiolites (CAO) are
branches of the Neotethyan ocean that was situated represented by two main groups: (a)high-grade
between Eurasia and Gondwanaland (Juteau, 1980; ophiolites, deformed and metamorphosed at the same
Seng/Sr and Yilmaz, 1981; Robertson and Dixon, time as the Central Anatolian metamorphic base-
.)5891 ment, and (b) essentially non-metamorphic or low-
The most outstanding feature that differentiates the grade ophiolites tectonically overlying the basement
Mesozoic suture zones in Turkey (and Greece) from ul~oi~cnOG( and T~ireli, 1993b).
the rest of the Alpine-Himalayan belt, is the The state of knowledge concerning these two
significance attributed to the areal distribution of groups is relatively poor, both in terms of the
ophiolite-related bodies, and hence the number and pseudostratigraphic relationships of the magmatic
location of their root-zones or sources. Interpretative units, their chemical designation, and inferred
models range from all ophiolitic bodies being derived tectonic setting relative to the other ophiolitic belts.
from a single ocean (e.g. Ricou, 1971; Ricou et al., In particular, do they display the chemical features
1984) to multiple source models, where separate that appear to be characteristic of Tethyan ophiolites
ophiolite alignments are considered to have origi- from the Eastern Mediterranean? For example,
nated from different ocean basins (e.g. Sengrr, 1985; ophiolites from the southern Turkish belt (and
with ten Tethyan sutures recorded). Greece) exhibit a chemical composition more akin
At the present state of knowledge, a more realistic to arc-related tectonic settings than ocean spreading
tectonic approach suggests that the Turkish ridges (e.g. Pearce, 1979; Capedri et al., 1980;
Neotethyan ophiolites are represented by only three Alabaster et aL, 1982) and have been referred to as
main broadly east-west trending zones, each one supra-subduction zone (SSZ) ophiolites (Pearce et
characterizing allochthonous ophiolite-related units al., 1984). Whether the Central Anatolian Ophiolites
derived from separate ocean basins (Fig. 1 inset): (a) represent fragments of a major ocean basin or were
a northern belt representing remnants of the Intra- produced in a supra-subduction environment is not
Pontide Ocean, (b) a median belt representing two known, but clearly has important implications for the
groups of aUochthonous units derived from the regional tectonic interpretation of this unique area.
Vardar-lzmir-Ankara-Erzincan Ocean, (although Furthermore, if the Central Anatolian Ophiolites
Gtirtir et al. (1984) consider a separate derivation were initially derived from the Vardar-Izmir-Ankara-
for the Inner Tauride Belt), and (c) a southern belt, Erzincan Ocean (as suggested by Gt~ncao~lu, 1982)
variably called the Peri-Arabic Belt (Ricou, 1971) or they represent a better example of largely unfrag-
Southern Neotethyan Ocean (Sengtir and Yilmaz, mented ocean crust than their equivalents in the
1981). The ophiolites of the northern belt and the Ankara ophiolitic mrlange.
Vardar-Izmir-Ankara-Erzincan suture have not yet The object of this paper is to present chemical data
been studied in detail, whereas those from the on the volcanic component of one of the most
southern belt and Inner Tauride Belt have undergone complete and best exposed of the second group of
considerable investigation (e.g. references in CAO bodies -- the Sarikaraman Ophiolite -- as a
Robertson and Dixon, 1985). Despite these more or basis for tectonic environment evaluation. We aim to
less well-defined belts, numerous, little known and compare the geochemical characteristics with other
isolated ophiolitic bodies are exposed in the Central Eastern Mediterranean ophiolites and discuss the
Anatolian Crystalline Complex (CACC), just to the implications for current regional geodynamic models
south of the Vardar-Izmir-Ankara-Erzincan suture (Sengtir and Yilmaz, 1981; Gtirflr et al., 1984;
(Fig. 1 inset). Robertson and Dixon, 1985). The Sarikaraman
The CACC is a triangular wedge of high-grade Ophiolite is situated in the southern part of the
(amphibolite facies) metamorphic basement CACC, between Aksaray (to the south) and Kirsehir
(GOnctio~lu et al., 1991, 1992a) which is considered (to the north) (Fig.l).
to represent the northern passive margin of the
Mesozoic Tauride-Anatolide Platform, facing the
Field relationships and features
Vardar-Izmir-Ankara-Erzincan Ocean (Ozgtil,
1976). Isolated outcrops of late Cretaceous ophiolitic The Sarikaraman Ophiolite is representative of a
rocks, termed the Central Anatolian Ophiolites somewhat dismembered ophiolite body retaining a
(GSnc~ioglu and Ttireli, 1993a) are found as recognizable magmatic pseudostratigraphy (Fig.l).
allochthonous bodies in the CACC. Their structural Voluminous ultramafics are not exposed in direct
setting differs from the remnants of the Vardar-lzmir- contact with the rest of the ophiolitic slab, the lowest
Ankara-Erzincan Ocean that are now represented by section being composed of isotropic gabbros, which
an ophiolitic mrlange ((~apan and Floyd, 1985; are faulted against a sheeted dyke complex that
Floyd, 1993) largely generated in a fore-arc merges up section into basalt lavas and breccias. The
SUPRA-SUBDUCTION ZONE OPHIOLITES 699
F-
.11 x x x x x x x
NAMARAKIRIA$ ~ (cid:141) . i~x x x x x
~\ x x x x x x
x x ~ x X )< x x x x
x x "~,,,~ x x (cid:141) x x x X x
1 | x x x x
x (cid:141) x
(cid:141) x x
NAENARRETIDEM }
.GIF .1 Geological map of the Sarikaraman ophiolite, Central Anatolia: 1-- Isotropic gabbro, 2-- Plagiogranite
(trondhjemite), 3-- Dolerite dyke complex, 4-- Basalt pillow lava, 5-- Basalt pillow breccia, 6-- Lower Turonian-
Campanian sediments, 7-- Campanian limestone unit, 8-- Felsic volcanic block unit, 9 Maastrichtian-Lower
Palaeocene(?) Terlemez monzogranite, 10-- Palaeocene(?) volcaniclastic unit, 11-- Fault, 21 Neogene cover
units. Inset shows the ophiolitic belts of Turkey (Juteau, 1980) and the location of the Sarikaraman ophiolite (SO)
within the Central Anatolian Crystalline Complex (CACC): a-- Intra-Pontide Suture, b-- Vardar-Izmir-Ankara-
Erzincan Suture, c-- Inner Tauride Belt, d-- Peri-Arabic Belt.
gabbros are cut by intrusive trondhjemitic plagio- All units are cut by a late set of isolated dolerite
granites which appear to be genetically related to dykes. The ophiolite is overlain by a sequence of
various high-level rhyolitic dykes and sills that Lower Turonian-Campanian pelagic sediments
traverse the upper volcanic section of the ophiolite. (including pink fossiliferous limestones), together
700 M. K. YALINIZ ET AL.
e~
e'~
0 ~ o ~ ~ ~
r~
r'q 0
~o
.,-,
g
M d M ~ d ~ d M d d d ~
d d M d d d ~ d d ~ d
d d ~ d ~ d M d d s d
&
cL~
. . . ~ . . . . . . .
~.~
d
f~. oooooo oo:
o
SUPRA-SUBDUCTION ZONE OPHIOLITES 701
C
. . ~ . . . . . . . . .
4..~ 0 0 0 o 0 0 ~ 0 o o ~
0
v
o00
e'3
N~
~ r~ ~'4
~, ,~.
,"-4 o ~,'q
o ~.
~N
~ 0 0 0 ~ o 0 ~ 0 ~ 0
m
~1 I '~
~g
m
,n Lt~
m
..g
,m
E r'q r ir-~
o,m .,
c,~ ,N <
<
z
a-
,..o
(cid:14)9
m
~
702 M.K. YALINIZ ET .LA
with minor olistrostromes containing felsic blocks apparently replacing original glass. Epidote, as fan-
derived from the plagiogranites. Both the ophiolite shaped aggregates (up to 2-3 cm in diameter),
and cover sediments are intruded by a late generally occurs in vesicles along with quartz and
Cretaceous/Lower Palaeocene monzogranite. These minor chlorite. Late quartz may also replace the
granites have their counterpart in other areas of the matrix. Actinolite is much less abundant than other
CACC and are not related to the ophiolites, being the alteration phases, but is present as scattered fibres
post-collisional products of the melting of thickened throughout the matrix or occasionally replacing relict
crust (Gtinctio~lu and T~ireli, 1994). Finally, the pyroxene rims.
ophiolite and late granites are unconformably over- The dominant secondary assemblages indicate that
lain by Palaeocene volcaniclastites. The field the greenschist facies of metamorphism was reached,
relationships and faunal age of the ophiolite-related although late circulation of low-temperature fluids is
sediments indicates that the Sarikaraman Ophiolite is indicated by the development of quartz and carbonate
broadly late Cretaceous (Turonian-Santonian) in age. that replace earlier alteration phases and occur as
The volcanic unit of the Sarikaraman Ophiolite is veinlets.
mainly composed of basaltic pillow lavas with
subordinate interbedded massive lavas, and associate yrtsimehcoeG
pillow breccia (Fig.l). The pillowed and massive
lava flows are predominantly coloured grey-green to Sampling and analytical methods. Representative
light green and reflect the proportion of secondary basaltic rocks (42 samples) were collected from the
minerals, whereas rare reddish-brown flows are the Sarikaraman Ophiolite and analysed for major and
result of subsequent oxidization. Individual flows selected trace elements, with a subset of 5 samples
reach 5-6 m in thickness and may exhibit columnar being determined for rare earth elements (REE) and
jointing. The pillow lavas form a pile of draped Hf, Ta, Th and U. All samples were analysed on an
elongate tubes, some of which may attain a ARL 8420 X-Ray Fluorescence spectrometer (De-
maximum diameter of 2 m. Pillow margins were partment of Earth Sciences, University of Keele)
originally glassy, but are now mostly replaced by calibrated against both international and internal
secondary chlorite, whereas interiors are holocrystal- Keele standards of appropriate composition, whereas
line and often vesicular. Vesicles (up to 1 cm in the REE etc. were determined by Instrumental
diameter) are usually filled with chlorite, epidote, Neutron Activation Analysis (Activation Labora-
quartz and late replacive carbonate. The sheeted dyke tories Ltd., Canada). Details of methods, accuracy
complex comprises 80-100% sub-vertical dykes of and precision are given in Floyd and Castillo (1992).
dolerite and basalt, generally between 0.5-2.5 m in Analysed samples were confined to three groups:
width. The late set of isolated dolerite dykes that cut (a) pillowed and massive lavas, (b) dolerite dykes
the full magmatostratigraphy are more irregular with lu the sheeted dyke complex, and (c) late, cross-
variable width and sharp margins. cutting dolerite dykes; these groups are distinguished
in all chemical diagrams. Representative analyses are
yhpargorteP shown in Table .1
Chemical alteration features. The basaltic samples
In many of the basalts and dolerites of the all show some degree of low-grade secondary
Sarikaraman Ophiolite primary minerals and textures alteration and as such can be expected to have
are strongly overprinted by secondary assemblages suffered selected element mobility, especially invol-
produced during initial ocean-floor hydrothermal ving the large-ion-lithophile (LIL) elements (e.g.
alteration. However, inference from relict features Hart et al., 1974; Humphris and Thompson, 1978;
suggest that recognizable primary textures relate to Thompson, 1991). The wide variation in loss-on-
cooling history with variolitic textures at the margins ignition (LOI) values (Table )1 is a crude measure of
of flows and intersertal to subophitic textures in the the degree of alteration and reflects the contribution
coarser grained interiors. The basalts are aphyric to by secondary hydrated and carbonate phases. LIL
weakly porphyritic with plagioclase and subordinate element (e.g. K, Na, Rb, Ba) abundances are often
clinopyroxene as phenocryst phases. Dolerites are highly variable, together with most major elements
either poorly plagioclase phyric or aphyric. and ratios (e.g. FeO*/MgO), and thus are unreliable
The effects of alteration may be so intense that as indicators of petrogenetic relationships. Character-
only secondary phases are present, with assemblages istic and systematic interelement relationships often
comprising admixtures of albite, epidote, chlorite, shown by unaltered basic suites are only shown by
quartz, iron oxide, and minor actinolite, being those elements that are considered relatively im-
common. Throughout all the basalts and dolerites, mobile during alteration, such as high field strength
albite replaces both phenocrysts and matrix laths, (HFS) elements and the rare earth elements (REE)
whereas chlorite commonly occurs in the matrix, (e.g. Pearce and Cann, 1973; Smith and Smith, 1976;
SUPRA-SUBDUCTION ZONE OPHIOLITES 703
MgO
1000
--
~i~itw
Ba
0
ppm +
1 0O oC~ o
01
0(cid:12)9 (cid:12)9 (cid:12)9 O0ooo 0
01 (cid:12)9 o
~ ~ ~6e ,~-
5 #r "4,
(cid:12)9
g
OlOO
1 / I I I I O I
0
0 50 100 150 OO2 0 50 100 150 200
Zr ppm Zr ppm
-I-Late etirelod sekyd /
0 Basalt lavas (cid:12)9 Dolerite sheeted dykes
J
3 75
Ti02 Y
wt.% ppm
-I-.O
2 50
u
25
!
I I
0 I I I 0
0 50 100 150 200 0 O5 100 150 200
Zr ppm Zr ppm
.GIF 2. Variations of mobile (Ba, Mg) and immobile (Ti, Y) elements relative to Zr (corrresponding to a stable
fractionation index) in Sarikaraman Ophiolite basaltic rocks.
Floyd and Winchester, 1978). As seen in Fig. 2, Under some circumstances, such as extensive
components that are mobile during alteration (Ba, carbonation of the tavas, the REE and HFS elements
MgO) exhibit scattered non-magmatic distributions, can be mobilized and/or abundances diluted (e.g.
whereas generally immobile elements (Ti, Y) have Hynes, 1980; Humphris, 1984; Rice-Birchall and
characteristic linear relationships, relative to Zr. In a Floyd, 1988), although in this study such carbonate-
similar manner, normalized REE data develop rich rocks were avoided.
smooth patterns of variation (see later) that are Volcanic sequences of ophiolites are invariably
considered typical of their original composition. altered mineralogically and chemically by submarine
704 M. K. YALINIZ ET AL.
hydrothermal processes within the zeolite to greens- be interpreted as follows. The broad overlap in stable
chist facies of metamorphism (e.g. Gass and incompatible element abundances (Fig.2) and simi-
Sinewing, 1973; Pearce and Cann, 1973; Spooner larity of normalized REE patterns (Fig.3) for the
and Fyfe, 1973; Smewing and Potts, 1976; Venturelli basalt lavas and dolerites of the sheeted dyke
et al., 1981 ), a feature also typical of the Sarikaraman complex indicate a possible comagmatic
Ophiolite basalts. Thus, the following chemical relationship.That is, in the chemical sense some
assessment and discrimination rely mainly on the feeder dykes can be matched with their extrusive
distribution of the relatively stable HFS and REE products. However, some of the dykes are more
elements in the mineralogically least-altered samples. chemically evolved than the bulk of the lavas and
Chemical relationships and tectonic discrimina- suggests that the full range of pillow lavas has not
tion. On the basis of relatively immobile trace been sampled or they are now missing from the initial
elements the basalts and dolerites show the following volcanic pile. A significant difference is also
broad characteristics (Figs. 2 and 3): (a) generally exhibited by the later cross-cutting dolerite dykes.
low (depleted) abundances of incompatible elements Relative to the lavas and sheeted dykes, they are
with a limited range (e.g. 26-124 ppm Zr, I-5 ppm generally more evolved and exhibit normalized tlat
Nb), but positive interelement covariance, (b) low (undifferentiated) REE patterns possibly indicative of
Nb/Y ratios (0.04-0.20) characteristic of sub-alka- a different source.
line (tholeiitic) basalts (Winchester and Floyd, 1977), Chemical discrimination of the eruptive environ-
(c) a wide range of Cr and Ni contents (together with ment for basic rocks, using such diagrams as
variable FeO*/MgO ratios), and (d) a range of displayed in Fig. 4, suggests that the majority of
chondrite-normalized, light REE depleted patterns the Sarikaraman Ophiolite basalt lavas have affinities
to fiat patterns (La/YbN 0.6-1.0). Overall the with island arc-related tholeiites (IAT) rather than
preliminary data indicates that the volcanic samples typical mid-ocean ridge basalts (MORB). Both the
represent a moderately differentiated (involving dolerites of the sheeted dykes and late dykes spread
mafic and oxide phases) comagmatic, tholeiitic suite across into the MORB fields. The main trace element
featuring depleted characteristics. characteristics of IAT relative to MORB include (a)
However, when the three separate basaltic groups high LIL/HFS element ratios, and (b) overall low
are considered their respective chemical features can HFS values (<1) when normalized to N-MORB (e.g.
100=
m
m
.o 50--
,i.
~
I,..,.
r-" . . . . o 4
O 10-
c-
m
O m
5
o tlasaB aval (P- 11 )
..O
E (cid:12)9 Basalt lava (M-82)
D Dolerite sheeted dyke 1( 57-D)
30
(cid:12)9 Late dolerite dyke (M-66)
(cid:12)9 Late d01erite dyke (M-74)
I I I I I I I I I I I I I I
La Ce Pr Nd Sm uE Gd Tb Dy Ho Er Tm Yb uL
Fro. 3. Chondrite-normalized, light REE depleted patterns characteristic of Sarikaraman Ophiotite basalts and fiat
patterns typical of the late dolerite dykes.
SUPRA-SUBDUCTION ZONE OPHIOLITES 705
/ / 1000
600 Arc basalts Cr
V
C/Ooy ppm
100
PP o0
o O~oo
O Basalt lavas
200
(cid:12)9
Dolerite sheeted dykes Arc (cid:12)9
-~- Late dolerite dykes basalts
O
0 I 1 I ,
'ill
' '
0 1 2 3 1 10 100
Ti02 wt.% Y ppm
FI6.4. Chemical discrimination of the least altered basalts and dolerites from the Sarikaraman ophiolite indicates a
predominantly subduction-related eruptive environment rather than a major ocean. IAT = Island arc tholeiite field;
MORB = Mid-ocean ridge basalt field. V-TiO2 diagram from Shervais (1982) and Cr-Y diagram from Pearce
(1982).
Saunders et al., 1979; Pearce, 1983; Saunders and considered to be another feature of SSZ ophiolites
Tarney, 1984), both features of which are exhibited (e.g. Alabaster et al., 1982).
by the Sarikaraman basaks. For samples where
reliable data (by INAA) are available, Th/Yb ratios
nosirapmoC with Tethyan ophiolites
(0.1-0.4) are higher than MORB (0.03) for the same
degree of chemical evolution. An N-MORB normal- The Sarikaraman Ophiolite is just one member of a
ized plot (Fig. 5) exhibits the depletion of the HFS long linear zone of Tethyan ophiolites that extend
elements (and light REE) coupled with the strong from the western Mediterranean to the Persian Gulf
enrichment of selected stable LIL elements and and beyond. Several groups of workers (e.g. Nicholas
broadly confirms the subduction-related character of and Jackson, 1972; Rocci et al., 1975; Abbate et al.,
the Sarikaraman basalts. Note, however, that the late 1976) have divided the ophiolites of this region into
dolerite dykes are distinct and show a pattern parallel two groups on the basis of degree of tectonic
to N-MORB, with little Th enrichment. Within the deformation and age: (a) fragmented Jurassic
LIL element group, Th is a relatively stable and ophiolites in the western and central area (Alps,
reliable indicator, whose enrichment relative to other Apennines, Carpathians, Dinarides, Hellenides), and
incompatible elements is taken to represent the (b) mid- to late-Cretaceous ophiolites displaying a
subduction zone component (e.g. Wood et al., pseudostratigraphy, at the eastern end (Troodos,
1979; Pearce, 1983). That is, the source region for Semail, Baer-Bassit, Hatay). There is also a
arc melts has been modified by the addition of LIL difference in chemical characterization (Pearce,
element-bearing aqueous fluids derived from the 1979; Robertson and Dixon, 1985) with the first
underlying subduction zone (e.g. Best, 1975; Pearce, group displaying MORB-like features, whereas the
1982, 1983; Hawkesworth et a/.,1977; McCulloch second group exhibit SSZ features often comparable
and Gamble, 1991). The chemical features displayed with younger back-arc basins worldwide (Pearce et
by the lavas and dykes imply that the Sarikaraman al., 1984). This distinction is clearly shown in Fig. 6
Ophiolite was formed in a subduction-related with the separation of Cretaceous ophiolites (area 1
environment rather than at a large ocean spreading plotting in IAT field) and Jurassic ophiolites (area 2
centre and is thus another SSZ-type ophiolite (Pearce plotting in MORB field). The Sarikaraman data plots
et al., 1984). The later dykes appear to be more with the SSZ ophiolites of the eastern region and
MORB-like and less depleted in character, and covers the full range of Th enrichment displayed:
reflect a change in source with time which is Like the majority of the Troodos basalts, the
706 M.K. YALINIZ ET AL.
100--
o Basalt lava (P-11 )
(cid:12)9 Basalt lava (M-82)
0 Dolerite sheeted dyke (157-D)
o~
(cid:12)9 Late dolerite dyke (M-66)
m (cid:12)9 Late dolerite dyke (M-74)
10-=
EE
0 m
Z
_o 1
E
03
1.0
I I I I I I I I I I I I I I I I I I I I I
CsRbBaYh U K NbTa LaCeSr P NdSmZr HfEu Ti Gd Y Yb
Fie. .5 N-MORB-normalized multi-element diagram for Sarikaraman Ophiolite basalts showing relative HFS
element +light REE depletion with Th enrichment, and the MORB-like pattern for late dolerite dykes. Normalization
factors from Sun and McDonongh (1989).
Sarikaraman basalts have low and restricted Zr/Y
ratios of between 2.2-5.0 and similar depleted light Hf/3
REE patterns. However, what is rarely seen are the A = N-MORB
more evolved tholeiitic compositions (basaltic B = E-MORB & within-plate TB (cid:12)9 Basalts & dolerites
C = Within-plate AB
andesites and andesites) with high incompatible D = Island arc basalts
element abundances described from the lower-series
Troodos lavas (Thy et al., 1985). This could be a
reflection of limited sampling at the Sarikaraman
complex where only higher stratigraphic levels are
exposed for study.
Application to regional tectonic environment
The designation of the Sarikaraman Ophiolite as an
SSZ-type is in keeping with the recognition that most Th 'Ta
Eastern Mediterranean ophiolites of Cretaceous age
were formed in this eruptive setting. This feature may
also be typical of the other, little known, Central
Anatolian Ophiolites (CAO) of the CACC. If this is .GIF 6. Comparison of Sarikaraman Ophiolite basalts and
the case, the SSZ setting may help to explain the dolerites with SSZ-type eastern Mediterranean ophio-
short time-span between ophiolite generation in the lites (area )1 and MORB-type western Mediterranean
Vardar-lzmir-Ankara-Erzincan Ocean (to the north) ophiolites (area 2). Comparison data selected from the
and its initial emplacement onto the southern passive Tethyan ophiolite literature. Discrimination fields after
margin (the CACC). Wood (1980).