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PETROCHEMICAL
AND GEOCHEMICAL CHARACTERISTICS OF VARIOUS GEODYNAMIC SETTING
BAIKALIDES, EARLY CALEDONIAN AND CALEDONIAN GRANITOIDS
(ON
EXAMPLE OF THE SIBERIAN PLATFORM SOUTH-WESTERN MARGIN STRUCTURES)
Datsenko V.M.
Krasnoyarsk
Scientific Research Institute of the Geology and Mineral Resources,
Krasnoyarsk, Russia datsenko@kniigims.ru
Granitoids
as an indicator of the geodynamic settings of the past plate tectonic
model are
adopted now
and then as a single criterion for the establishment of this or that
geodynamic setting. The geodinamic standarting was carried out on the
basis of the complex of geological and structure-formation signs,
including the data received by the author on the petrochemical and
geochemical studies of the granitoids and the classification and
discrimination in diagrams, taking into account the latest
isotopic-geochronological data of the complex. Reviving the of idea
E. Suess about the centrifugas spread of the continents now
developed by I.V. Gordienko (2006 et al.), one may say that beginning
with the Neoproterozoic the Siberian craton (in modern coordinates)
in his SW segment developed at the expense of the ocean surrounding
area it. The fold belt Baikalides (the Yenisei Ridge, the
Protero-Sayan), the Late Caledonides (the Cambrian-Sayan, the
Kuznetsk Alatau), real Caledonides (the West Sayan) and the
Hercynides (the Mountainjus and the Mongolian Altai) consecutively
joined them. The figurative expression I.V. Gordienko (1987, p. 3),
the area understudy is the “unique natural laboratory”
for the study of granitoids, formed under various geodynamic
conditions. The indicator role of magmatites for the geodynamic
reconstructions of the Altai-Sayan area and the Enisei Ridge was
shown inthe papers by L.P. Zonenshain, M.I. Kuzmin, I.V.
Gordienko,A.N. Distanova, A.E. & V.A. Vernikovsky, the author and
etc. Our research includes the region of the Krasnoyarsk territory
from the Podkamennaya Tunguska river in the north up to Tuva in the
south and the time period from the Early Proterozoic to Devonian
including (Datsenko et al., 1994; Datsenko, 1998, 2000 and etc).
The granite
formation processes related to the plate tectonics, in the structures
margining the Siberian craton are confidently fixed from
Neo-Proterozoic. Till this time, the episodes of the within plate
subduction and continental collision (unmagnetite S-granites
Taraka complex of the Yenisei Ridge, 2-1, 85 Ga) are very notable on
the continent. The Baikalides themselves displayed mainly on the
Yenisei Ridge, the Neo-Proterozoic deposits, being accumulated on the
crust of the continental type under the condition of the pericraton
lowering the Siberian craton border. As a result of the destruction,
this area was divided into several terranes, the stacking of which
brought to the successive display of the collision processes, taking
more than 200 Ma. We suppose that the collisional granites of the
Central terrane of the Yenisei Ridge, that were previously united
into the Tatarka-Ayakhta complex of the unmagnetite granites, must be
considered as the temporary series of the collisional Kalami (about
870 Ma), Ayakhta (760 Ma) and Tatarka (630 Ma) complexes (all the
data obtained with use of the of U-Pb zircon method by Vernikovsky
and Vernikovsaya). Granites belong to the IS-type.
The consideration of this paradox reasons is beyond the scope of the
short paper.
It
is necessary to say
that the late collisional leucogranites of the Glushikha and Garevka
complexes were widely developed in the west in autonomous formed
Angaro-Tissk terrane (720-750 Ma, according to A.E. and V.A.
Vernikovsky). They are the typical crust S-type
granites,
specialized in the rare metals.
We can see
another situation in the Altai-Sayan accretion-collision area
that
formed in the place of the Paleo-Asian ocean. Its geological
structure is mosaic-block. It includes several terranes of the
ancient platform, the ocean structure relicts, island-arc complexes,
collision belts, late-collision grabens, etc. Their collision with
the Siberian continent and the surrounding terranes (the Derbina
type) brought to the creation of the subduction zone and formation of
the typical magmatic and ore formation above them. The ore magmatic
zonation associated with the PZ1
island-arc and margin-continental complex evolution was clearly
observed in the «ocean-continent» joint zone. During the
Early Caledonian (Salair period), the plagiogranites of the tholeitic
(Hercynides, according to L.V.Tauson) geochemical series (the Maina
M-type granites complex with copper ore, 550-532 Ma) had been formed
in the frontal volcano-plutonic arcs. In the active continental
margin, the formation of andesitic geochemical type granitoids was
taking place: the auriferous Olkhovka (544-515 Ma), Zun Kholba and
other I-type granite complexes. In back-arc basin situation, near the
continental Derbina terrane, the latite geochemical type granitoids -
Buedzhul A-type granite complex with molybdenum-porphyry
mineralization (533-521 Ma) were developed.
During the
Ordovic, in the same area, the crust torsion had been transforming
into collision and the collisional granite belts were formed: the
Bellyk (465 Ma), the Kuturchin (474±8 Ma) crust granite
complexes with larger mantle component.
In the
back-arc basin zones, the compression effects in the collision belts
were compensated by the stretching processes and those of the late
collisional graben formation (Oslo-type), with the volcano-plutonic
formations having been widely developed. In the Agul graben, the late
collisional molybdenum-containing granites and leucogranites of the
Ognit complex were represented by the peraluminous A-type granites
(440-450 Ma).
The
Caledonian granitoid magmatism had been well demonstrated in the West
Sayan, where the granites and leucogranites of the Dzhoj complex
formed the extended granite belt (more than 200 km). The granitoids
belong to A-type (415-393 Ma).
The results
obtained allow to more reasonably solve the problems of about the
correlation between the granitoid mineral composition and the
tectonic development regime. This should be taken into consideration
when mapping and evaluating the ore content granite potential.
References
Datsenko V.M. (1998) Geochemical
criteria of diagnosing the granite formation geodynamic conditions //
Magmatism and
geodynamics. Ekaterinburg. UGG of Urals Branch RAS. P.22-32. (in
Russian)
Datsenko V.M. (2000) Petrogeochemical
typization of the Siberian Platform south-western rim granitoids //
Petrography at the
boundary of XXI century: results and perspectives. (Materials of the
2nd
All-Union Petrographic Meeting.Vol.III. Syktyvkar. Institute of
Geology, Komi Research Centre, Urals Branch RAS. P.270-274. (in
Russian)
Datsenko V.M., Aleksandrovsky Yu.S.,
Kosorukov A.P. et al. (1994) The most significant epochs and
geodynamic settings of granitoid magmatism and endogenic ore
formation in structures of the Siberian Platform south-western rim //
Russian Geology. N10. p.27-39. (in
Russian)
Gordienko I.V. (1987) Paleozoic
magmatism and geodynamics of Central Asian Fold Belt. M. Nauka,
238p. (in Russian)
Gordienko I.V. (2006) Geodynamic
evolution of southern Siberian Platform fold rim late baikalids and
paleozoids. // Geology and Geophysics. V.47. N1. p.53-70. (in
Russian)
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