late cretaceous supra-subduction magmatism in north kozara ... · n kozara s kozara b u l k e a r t...
TRANSCRIPT
0 200 km100
Ad
r i at i c
Se
a
N Kozara:U-Pb Zr
S Kozara:Sm-Nd isochron
Borja: Sm-Ndpooled isochron
Lugovic et al. unpubl.
Konjuh: K-Ar Parg
Lanphere et al. 1975Zlatibor: Sm-Nd isochron
Bazylev et al. 2006
Zlatibor: K-Ar Parg, Amph
Lanphere et al. 1975
Brezovica: K-Ar Ms, Hbl161 - 169
Okrusch et al. 1978
Razbojna: K-Ar Amph182 - 187
Karamata & Popevic unpubl.
c. 84 - 70
Ophiolites, suture zones, oceanic accretionary prisms
Europe-derived unitsDinariccontinental marginTisza unit
East Vardar -TransylvanianSava ZoneDinaric ophiolite belt
age obtained from: age in Ma:mafics
metamorphic sole biostratigraphy
157
81.39
literaturethis studyultramafics
0.51294
0.51298
0.51302
0.51306
0.51310
0.51314
0.51318
0.51322
0.06 0.10 0.14 0.18 0.22 0.26 0.30
147Sm/144Nd
143 N
d/14
4 Nd
Age = 157,9 ± 7.6 MaInitial 143Nd/144Nd =0,512871 ± 8.6e-060
K135 Pl WR CPx
CPx
WR
Pl
S KozaraOl-gabbrosample K135
81.6
81.4
81.2
81.0
0.01264
0.01266
0.01268
0.01270
0.01272
0.01274
0.01276
0.0830 0.0832 0.0834 0.0836 0.0838 0.0840 0.0842
207Pb/235U
206P
b/23
8U
Concordia Age = 81.39 ±0.11 Ma(2 , decay-const. errs ignored)MSWD (of concordance) = 1.6,
Probability (of concordance) = 0.20
data-point error ellipses are 2
N Kozarazircons fromdoleritessample K149
Fig. 6a: U-Pb-concordia diagram of zircons from a dolerite from N Kozara. See Fig. 4 for sample locality.
Fig. 6b: Sm-Nd-isochron plot of an olivine cumulate gabbro from S Kozara. (MSWD 0.0109). The initial 143Nd/144Nd value is 0,512871 ± 9. See Fig. 4 for sample locality.
a. North Kozara
0
2
4
6
8
10
12
14
40 45 50 55 60 65 70
b. South Kozara
Na
O +
KO
[wt.%
]2
2
SiO [wt.%]2
gabbropegmatite gabbro
dolerite felsic dike felsic intrusive
Andesite Dacite
Trachyte
TrachydaciteBenmoreite
Mugearite
Hawaiite
Tephrite
Basalt Bas
altic
and
esite
Bas
anite
Picr
obas
alt
a lkal ine
subalkal ine/ tholei i t ic
subalkal ine/ tholei i t ic
0
2
4
6
8
10
12
14
40 45 50 55 60 65 70 75 80 85
Basalt
massive felsitefelsic dike
pillow basaltmassive basalts
composite dike
doleritegabbro
a iiH wa teMugearite
Benmoreite
Trachyte
Trachydacite
Rhyolite
Dacite
Andesite
Bas
altic
and
esite
Picr
obas
alt
Tephrite
Bas
anite
Phono-tephrite
Tephri-phonolite
Na
O +
KO
[wt.%
]2
2
SiO [wt.%]2
alkal ine
subalkal ine / tholei i t ic
subalkal ine / tholei i t ic
1
10
100
1000
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er TmYb Lu
gabbropegmatite gabbro
dolerite dike felsic dike syenite
rock
/ ch
ondr
ite
c. South Kozara
10
100
La Ce Pr Nd Sm Eu Gd Tb DyHo Er TmYb Lu
dolerite gabbro
pillow basalt massive basalt
rock
/ ch
ondr
ite
a. North Kozara - mafic rocks
1
10
100
1000
La Ce Pr Nd Sm Eu Gd Tb DyHo Er TmYb Lu
dolerite, comp. dike granophyre, comp. dike
felsic dike massive felsites
b. North Kozara - felsic rocks
rock
/ ch
ondr
ite
MORB
Sunda arc
lesserAntilles
Japan
Marianas, Alëutes,South Sandwich
New Zealand
0.5121
0.5122
0.5123
0.5124
0.5125
0.5126
0.5127
0.5128
0.5129
0.5130
0.5131
0.5132
0.5133
0.702 0.703 0.704 0.705 0.706 0.707 0.708 0.709 0.710 0.711
87Sr/86Sr
143 N
d/14
4 Nd
N KozaraS Kozara
B u l k E a r t hdepletedquadrant
enrichedquadrant
Late Cretaceous supra-subduction magmatism in North Kozara (northern Bosnia and Hercegovina): Implications for the Cretaceous to Paleogene collision between
Europe and the Dinaric margin of the Adriatic plateK. Ustaszewski (1), S.M. Schmid (1), B. Lugović (2), R. Schuster (3), U. Schaltegger (4), B. Fügenschuh (5), A. Kounov (1), D. Bernoulli (1), L. Hottinger (1)
& S. Schefer (1)
contact: [email protected]
IntroductionOphiolites are a distinctive feature of the internal Dinarides (Fig. 1). Formed in the Neotethys, they were incorporated into Jurassic mélange (Meliata) or obducted onto the passive margin of the Adriatic plate during the Late Jurassic (Vardar). These ophiolites occupy a structurally high position within the SW-verging nappe stack of the Dinarides. The Dinarides formed in Late Cretaceous to Paleogene times in response to closure of a remnant ocean between Adriatic plate and Europe-derived units. The very first evidence for Late Cretaceous intra-oceanic magmatism in the Dinarides was reported by Karamata et al. (2000).
ResultsThis study provides additional evidence for Late Cretaceous igneous activity between the internal Dinarides and Europe-derived units. In the N Kozara Mountains (Figs. 2, 3), a bimodal igneous succession is thrusted onto the Dinaric ophiolite succession of S Kozara, obducted in the Late Jurassic (Figs. 2, 4, 5). Pelagic limestones, intercalated with pillow lavas, contain Campanian globotruncanids (Fig. 3). This is in agreement with U-Pb ages of zircons from dolerites (Fig. 6). REE concentrations suggest an intra-oceanic island-arc origin of the N Kozara mafic rocks (Fig. 7). The initial isotopic values for 80 Ma are 4.4 to 6.3 for εNd and 0.70346 to 0.70507 for 87Sr/86Sr, respectively. With respect to MORB these values indicate only a very low degree of crustal contamination, again suggesting an intra-oceanic origin (Fig. 8).
ConclusionsOur results document the existence of a Campanian island-arc between the Adriatic plate and Europe-derived units (Fig. 10). Subsequent closure of this oceanic domain occurred during the Maastrichtian to earliest Paleogene (Figs. 3, 5). This Late Cretaceous oceanic domain may represent a remnant of either the Vardar ocean (i.e. Neotethys), or alternatively, of the Alpine Tethys.
GeochemistryGeochronology
Geology
Fig. 4: Geologic-tectonic map of the inselberg of Kozara (MGI Balkan 6 coordinates).
Fig. 1: Major tectonic units of the Alps, Carpathians and Dinarides (after Schmid et al., submit-ted). Arrows depict general structural vergences (compiled from various sources).
Fig. 5: Geological cross-section across Kozara and Prosara.
Fig. 2: Simplified geologic-tectonic map of the study area. Only Paleogene and older contacts are shown, disregarding faults related to Neo-gene Pannonian Basin extension.DOB = Dinaric ophiol-ite belt.E = East-Bosnian-Durmitor unit.
Fig. 3: Interpretative correlation of stratigraphic col-umns in the North Bosnian inselbergs (see Fig. 2) after restoring thrust repetitions. Correlated strati-graphic intervals are marked by black lines. The (Late Oligocene) Motajica granitoid of Fig. 2 is not shown in the corresponding stratigraphic column.
Conclusions
Fig. 11: Compilation of radio-metric ages across the Dinaric ophiolites. Mineral abbrevia-tions: Amph=amphibole, Hbl=hornblende, Ms=muscovite, Parg=pargasite, Zr=zircon.
Fig. 7: REE concentrations normalised over chondrite composition. Chondrite values from Boynton (1984).
Fig. 8: Nd- and Sr-isotopy of selected N and S Kozara mafic rock samples.
Fig. 9: IUGS classification of N and S Kozara igneous rocks. Filled symbols from Lugović et al. 1991.
valle
y of P
rijedo
r
S KozaraSSW NNEN Kozara
Gola P
lanina
876m Ta
tica V
is
383m
Sava r
iver
93m
Prosara198° 018°
Serbulo
vac
499m
+3
+2
+1
0
km abovesea level
-1
-2
-3
-4
-5 -5
+3
+2
+1
0
km abovesea level
-1
-2
-3
-4
0 5 km
Maastrichtian suture
projected dip
gabbros
ultramafics (?)
Ca
mp
an
Mid- to Upper Jurassicophiolitic mélangeDurmitor nappe
radiolarites (Bathon to Tithon)
Upper Paleocenelimestones
Eocene turbiditicsandstones & shales
conglomerates, sandstones(?Maastricht - Upper Paleocene)
lherzolites, serpentinites
Miocene to Quaternary
gabbrosdolerites, sheeteddikes & pillow lavas
rhyolites
pelagic limestones & breccias(Campan - ?Maastricht)
pelagic limestones("scaglia")
Prekarst unit
greenschist faciesmetamorphics
"Senonian
Flysch"
thrust ages
Late Jurassic
J CP J P P
P
C
J
P PaleogeneLate Cretaceous
TurjakTurjak
PrijedorPrijedor
Selbulovac 499mSelbulovac 499m
GornjiPodgradci
GornjiPodgradci
Mrakovica 804mMrakovica 804m
Lisina 978mLisina 978m
Gola Planina 876mGola Planina 876m
6400000 6405000
6405000
6410000
6410000
6415000
6415000
6420000
6420000
6425000
6425000
6430000
6430000
4975
000
4980
000
4985
000
4985
000
4990
000
4990
000
4995
000
4995
000
6400000
4975
000
4980
000
0 1 2 3 4 5 kmGabbros
Ca
mp
an
Mid- to Upper Jurassicophiolitic mélange
radiolarites(Bathon to Tithon)
Triassic olistolitheswithin mélange
Upper Paleocene bioclastic limestones
Eocene turbiditicsandstones
conglomerates, sandstones(Maastr. - Upper Paleocene)
ultramafics, serpentinites
Miocene to Quaternary
Gabbros
Dolerites, basaltspillow lavas
Rhyolites
shallow water limestones(Maastricht)
Upper Paleocenebioclastic limestones
pelagic limestones & breccias(Campan- ?Maastricht)
Pelagic limestones("scaglia")
S N
thrust, presumed
thrust, mappedunconformity
beddingfoliation
compiled
own databeddingbedding,overturned
cros
s se
ctio
n(F
ig. 5
)
radiometr ic ages in Ma81.4
80158
U-Pb zirconK-Ar WR
Sm-Nd isochron
80
81.4
158
sheeted dike chilledmargins
bedding: 6 dataslip lineations: 2 data
4 data
mountain peak
town / village
creek
300m
~150
0-20
00m
~150
0-20
00m
? 60
0 - 7
00m
150-
200m
150m
150m
>600
m
~250
m15
0m75
0m
500m
400m
560m
500m
0
S KozaraN Kozara &S Prosara
Motajica
N Prosara
S N
rudistsgraded bedding
unconformitythrust
planktonic foraminiferalarger foraminiferaalgae
Cam
pan
Jura
ssic
Maa
stric
ht -
Low
er P
aleo
cene
Upp
er P
aleo
cene
Up
pe
r P
ale
oce
ne
Eo
ce
ne
Eo
ce
ne
?
Ca
mp
an
?
Ma
as
tr
ic
ht
-
P
al
eo
ce
ne
? C
am
pa
n?
S
an
to
n
an
d
ol
de
r?
M
aa
st
ri
ch
t
-
Pa
le
oc
en
e
Alveolina primaevaDistichoplax biserialis
Orbitoides sp.Lepidorbitoides sp.
Discocyclina seunesi
granitoid, rhyolite, felsic dikemarly limestone
marlsandy limestone
limestone
pelite, shale sandstone, arcose
ophiolitic mélange
prasinite
doleritic sheeted dikes
mica schist
amphibolite
phyllite
marble
gabbro
pillow lavas
conglomerates
metasandstone /-conglomerate
metarhyolite
Globigerins
Campan
Distichoplax biserialis
Contusotruncanapatelliformis
GlobotruncanidsOrbitoides media
Globotruncanids
?
Not metamorphosed
Greenschist toamphibolite facies
Gabbros, dolerites, basaltsN-Kozara
Upper Jurassicophiolitic mélange(Permo)-Triassicto Late Jurassic
Upp
er C
reta
ceou
sto
Pal
eoce
ne
Paleogene granitoids
Upper Paleocene toMid Eocene
(Permo)-Triassic toJurassic cover
Maastrichtian to Paleocenepost-tectonic cover
Anchi- to epizonalmetamorphosed
Mafic and ultramafic rocksS-Kozara
Upper Cretaceousbimodal volcanics
Miocene to Quaternary
Cretaceous S-type granitoids
Cretaceous HT metamorphics
Cretaceous-age migmatite
Paleozoic undifferentiated(metamorphics and cover) P
apuk
-P
sunj
Ko
za
ra
Mos
lava
cka
gora
Pro
sara
, Mot
ajic
a&
Poz
eska
gor
a
boreholes thrust, known thrust, presumed
0 10 205 kmD O BD O BP r e -K a r s tP r e -K a r s t
Prosara
Kozara
Prosara
Kozara
Fig. 4
cross section trace(Fig. 5)
P a p u k
T i s z a
S a v aZ o n eS a v aZ o n e
Pozeskagora
Moslavackagora
Moslavackagora
Motajica
PsunjPsunj
Sava
Una
Dráva
Vrba
s
EEN KozaraS Kozara
Munich
Verona
Kraków
Beograd
Bucharest
Sofia
Sarajevo
Zagreb
Vienna
16°
Ophiolites, suture zones, oceanic accretionary prisms
Europe-derived units
Adria derived far-travelled nappes:Alps & West Carpathians
Dinaric continental margin,including Bükk Mts. (B)
undeformedAdriatic plate
important faults
general structural vergenceundeformedEuropean foreland
external foredeep
Miocene thrust belt
"Tisza" unit with mixedEuropean and Adriatic affinities
B
Adr
ia d
eriv
edth
rust
she
ets
Southern Alps
EVSava
DOB
EV ... East Vardar
DOB ... Dinaric ophiolite belt
Fig. 2Fig. 2
BlackSea
(3) Geologische BundesanstaltNeulinggasse 38A-1030 Wien
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(5) Institute for Geology and PaleontologyInnsbruck UniversityInnrain 52fA-6020 Innsbruck
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