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Triassic and the formation of an island arc in the Late Triassic-Jurassic. According to
Kravchenko (1979) flysch, andesites, gabbro and plagiogranite intrusions represent the
island arc, whereas molasse deposits and granite intrusions associated with weak
folding document major activity during the Late Jurassic and Early Cretaceous.
In the eastern Central Pamirs Precambrian basement rocks are exposed in the E-W
striking Muzkol- and Sares antiforms. The intensity and age of the tectonothermal
history and associated granite intrusions of the basement remain unclear.
From the above it becomes clear that there is a strong need for a better defined age
zonation and geochemical classification of magmatic belts in the Pamirs. In a N-S
profile across the Pamirs only the Shyok suture is better constrained by geochemical
and geochronological studies (e.g. Fraser et al. 2001, Rolland et al. 2000).
3.3 Petrology and geochemistry
The following part deals with the typology of the studied plutons, particularly with
regards to their geochemical and petrological aspects. New own data help to
characterise the magmatic belts and to constrain their first-order setting. Published
data from the Tien Shan, Afghanistan and Tibet will be included into the interpretations
of the geotectonic setting. The sample locations (Fig. 3.3) are summarised in
Appendix A, Tab. A1.
3.3.1 Petrology
Southernmost Tien Shan
Six samples collected at four localities (Fig. 3.2 and 3.3) comprise plutonic or
subvolcanic rocks of granitic and dioritic compositions (Appendix A, Tab. A2). The
samples intruded into Lower to Middle Carboniferous host rocks. Samples TS12a,
TS12b, TS18a, and TS20a contain amphiboles, which are in the latter two samples
intergrown with biotites and/or clinopyroxenes. Some biotites show chloritisation and
feldspar is partly sericitized. Accessory minerals are apatite, zircon and opaque
phases. Calcite is abundant in some samples as a secondary mineral. Widespread
fault- and thrust tectonics caused cataclastic to weakly ductile deformation and
mineral alteration in samples TS1, TS12b and TS20a.
North Pamirs (NP)
Two sections in the Northern Pamirs have been examined: (1) a N-S transect along
the Altyndara valley in the external part of the Pamirs and (2) around the Karakul lake
in the north-eastern part of the North Pamirs (Fig. 3.3 and 3.4).
Altyndara valley
The stratigraphically lowermost rocks of Carboniferous age are distributed in the
southern part of the Altyndara section. Massive metavolcanic successions predominate.
These subalkaline series range from basaltic to rhyolitic in composition
(Appendix A, Tab. A2). The Carboniferous rocks are progressively deformed towards
the north. The volcanic rocks are metamorphosed under greenschist facies conditions
and intercalated with clastic sedimentary layers. The middle part of the section is
dominated by Mesozoic clastic and carbonate rocks with a major mylonitic zone, where
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