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Cretaceous

Jurassic

Triassic

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Carboniferous

Devonian

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Cambrian

Neoproterozoic

Main source = Baratov, R.B., et al. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Publishing House "Donish", Dushanbe, 269 pp. plus tables. Provided by Dr. Jovid Aminov, Nazarbayev University, Astana, Kazakhstan Translated to English by the GeoGPT group, Zhejiang Lab, Hangzhou, China--see About

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Khoreg Formation

Khoreg Fm

Period:

Archean

Age Interval:

Eoarchean (AR? hg), Sh1

Province:
SE Tajik (SW Pamir)

Type Locality and Naming

Includes in Shadarlan and Schugnan ranges.

Delineated by B. Ya. Khorova and K. T. Budanova (1965). Within the volumes accepted in this work, these suites were delineated in 1957-1970 by V. P. Bulin, K. T. Budanova, G. S. Volos, and A. G. Davydchenko during geological mapping. In somewhat different volumes, and sometimes under different names, these suites or those close to them were previously delineated by S. I. Klunnikov, V. A. Maslennikov, and M. I. Rabkin (Geol. USSR, vol. 24, 1959; Barhatov, 1963). This is the lowermost formation in Shakhdaryn Gr

Synonym: Khoreg suite, Khorig suite, Khoreghsky suite

Reference section:

Lithology and Thickness

It begins the section of the Shakhdaryn Gr and has the greatest consistency of composition compared to the rest of its suites. The Khoreg Fm is composed of greenish-black amphibolite and garnet-biotite-amphibolite gneisses and crystalline schists with lenses and layers of amphibolites with a total thickness of 500-1500 m. In subordinate quantities, there are layers of gneisses of metapelitic composition: biotite, sillimanite-biotite, and garnet-disthene-biotite. Here, metamorphosed hyperbasites are often encountered in sheet-like deposits from a few meters to 30-80 m in thickness. There are lenses of eclogite-like pyroxene-garnet-plagioclase rocks with secondary amphibole, transitioning along the periphery of the lenses into garnet amphibolites. Phenomena of ultrametamorphism led to the transformation on individual sections of the metabasites of the Khoreg Fm into various granitoids, among which parageneses of the charnockite series are encountered (association of rhombic and monoclinic pyroxenes with plagioclase and potassium feldspar).

Lithology Pattern:

Gneiss

Relationships and Distribution

Lower contact

The relationships of the Khoreg Fm with the underlying Goran Gr is conformable, such they have been considered by all researchers to date, except for B. Ya. Khorova (as mentioned above).

Upper contact

Conformably overlying with Darshay Fm, such they have been considered by all researchers to date, except for B. Ya. Khorova (as mentioned above).

Regional extent

It is widespread in the Southwest Pamir.

GeoJSON

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Fossils

Age

Eoarchean

Age Span:

Beginning stage:

Eoarchean

Fraction up in beginning stage:

0.5

Beginning date (Ma):

3,800.00

Ending stage:

Eoarchean

Fraction up in the ending stage:

1.0

Ending date (Ma):

3,600.00

Depositional setting

Depositional pattern:

Additional Information

V. I. Budanov and K. T. Budanova consider both contacts to be tectonic for the following reasons. Firstly, mylonites are universally developed at the base and top of the Khoreg Fm (sometimes recrystallized). Secondly, different thermodynamic conditions are established that existed during the metamorphism of the Khoreg Fm (P=8-10 kbar), on the one hand, and the metamorphism of the Goran series and the rest of the suites of the Shakhdaryn Gr (6-8 kbar, on the other hand, this allows us to assume that the association of rocks of the Khoreg Fm is deep, formed at the base of the continental-type crust. The presence of the Khoreg Fm between rocks with different mineral associations, according to these researchers, should be explained by tectonic displacement (extrusion) of the granulite-basite layer plate (Khoreg Fm) into the formations of the granite-gneiss layer (Goransk Gr and Shakhdaryn Gr). From this perspective, the apparent conformity of contacts of this suite with underlying and overlying strata was created by subsequent tectonic deformations and subsequent metamorphism in the amphibolite facies, to which the already formed complex thrust structure was subjected.

Compiler:

Extracted from Baratov, R. B. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Donish, Dushanbe, 276.