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ISSN 1028-334X, Doklady Earth Sciences, 2009, Vol. 425, No. 2, pp. 223–225. © Pleiades Publishing, Ltd., 2009.Original Russian Text © V.U. Matsapulin, A.R. Yusupov, V.I. Cherkashin, 2009, published in Doklady Akademii Nauk, 2009, Vol. 424, No. 6, pp. 792–795.

There are no magmatic formations in the EasternCaucasus that could be sources of primary ore or placeroccurrences of gold and platinum. That is why geolog-ical works for these metals are practically absent. Goldand silver were determined as a by-product during geo-logical exploration works at the pyritic and quartz–sul-fide vein ores as well as during geological surveying(Sevkavgeologiya). Occurrences of the enriched con-centrations of Au, Pt, and Pd in the Miocene sandy-argillaceous sediments located in the amagmatic terri-tory at the conjugation between the northern slope ofthe Eastern Caucasus orogene and Tersk–Kaspian fore-deep were not predicted.

Single finds of panned gold from the alluvial sandsin loose sediments of the river valleys from the north-eastern slope of the Eastern Caucasus occurred at thefollowing areas: Kubachi (basin of the Ullu–ChaiRiver), Vachi, and Kuli (basin of the KazikumukhskoyeKoysu River) in the downstream tributaries of the SulakRiver. Silver was detected by spectral analyses duringthe bottom sampling of the streams belonging to thenorthern slope of the Eastern Caucasus where vast aure-oles with silver content varying from 10 to 100 ppm werefound. In the Upper Jurassic and Lower Cretaceoussandy rocks, silver contents varying from 10 to 20 ppmalso occurred. The researchers apparently wished toconnect these terrigenic occurrences of noble metalswith indigenous sources. But such sources were notfound, and that is why works connected with terrigenicgold and silver were stayed without continuation.

Beginning from the 1990s, the Institute of Geologyof the Dagestan Scientific Center of the Russian Acad-emy of Sciences conducted mineralogical investiga-tions of heavy fractions based on the selective slimesampling of loose stream sediments, Caspian Sea coast,and recently of the primary Meso-Cenozoic rocks,

mainly, weakly cemented quartz sandstones of theChokrak and Karagan ages [1–5].

During the slime sampling of these sediments on thetitanium–zirconium raw material, single gold and plat-inum signs within the fraction less than 0.2 mm wereestablished at the areas Buglen, Shura-Ozen’, Cherkez-Ozen’, and Khuchni. It should be noted that the sam-pling was conducted according to the method used forthe titanium–zirconium placers prospecting with thesample weight accounting for less than 0.2 kg. But thesample weight for the slime sampling for gold pros-pecting should be two orders of magnitude heavier thanthat mentioned. For this reason it can be imagined thatthe gold content in the rocks (especially finely dis-persed gold) may be much higher than it was fixed afterwashing. It is also necessary to assume that water wash-ing was conducted manually in pans, and gold was pre-sented by the fraction of less than 0.2 mm. Under suchconditions, up to 90–95% of free gold could not bedetermined [6].

In 2007, we used bromoform during the panningsamples processing for obtaining heavy fractions. Inthis case, in every sample (weight 50 g), we began tofind specks of gold, and in some samples we found sev-eral specks of gold (up to seven) at a time. Along withgold, we found platinum, a soft and ductile light graycolored metal. Some grains of platinum have magneticfeatures that are an indication of its ferruginosity. Fromthe volume of gold and platinum grains, their contentsin the rock have been calculated approximately. Resultsof the slime sampling are shown in Table 1.

During the microscopic investigation of pannedgold and platinum, their dimensions and morphologi-cally peculiar features were established. The maximumdimensions of specks of gold are 0.13 mm. Wire-shaped,isometric, and elongated gold specks were found. One ofthe samples contained gold in a “cover” of dark browncolor. In separate cases weak roundness of gold specksoccurred. Platinum has maximum dimensions up to0.2 mm. Isometric and elongated lamellar platinumgrains in intergrowths with a greenish colored mineral

First Occurrences of Terrigenic Gold and Platinum in the Miocene Sediments of the Eastern Caucasus, Dagestan

V. U. Matsapulin, A. R. Yusupov, and V. I. Cherkashin

Presented by Academician D.V. Rundqvist March 20, 2008

Received March 27, 2008

DOI:

10.1134/S1028334X0902010X

Institute of Geology, Dagestan Scientific Center, Russian Academy of Sciences, Makhachkala, ul. M. Yaragskogo 75, 367030 Dagestan Republic, Russia

GEOLOGY

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MATSAPULIN

et al.

are observed. Weak roundness of platinum grains rarelyoccurs (Fig. 1).

In order to establish the true content of gold andplatinum in the analyzed rocks, we conducted their bulk

sampling with the help of the atomic-absorptionmethod (Table 2). The obtained results showed a vastdevelopment of industrial concentrations of these met-als in the Chokrak–Karagan sandstones. Furthermore,there are separate samples containing Au and Pt in theterrigenic–carbonate Upper Jurassic–Lower Cretaciousrocks. Gold and platinum also occur in the blackargillaceous shales alternating with the Chokrak–Karagan sandstones. Five samples of these rocks con-tain (in ppm; average content is in brackets) gold 1.0–2.9 (1.72), platinum 2.2–7.2 (3.46), palladium 1.3–3.2(1.96), and silver 0.06–0.2 (0.13).

We assign titanium–zirconium minerals as well asgold and platinoids to the terrigenic formations. Eitherremote objects (Voronezh crystalline rock mass) orcloser formations such as volcanogenes of the northernslope of the Tersk–Caspian foredeep may serve as asource of washdown.

The discussed territory of washdown has repeatedlyundergone epochs of continental development with theformation of surfaces of alignment and crusts of chem-ical weathering. According to the data of Dagneft’(K.A. Sabanayev), beginning from the Permian–Trias-sic up to the Holocene, there were about twelve suchepochs within the region. It was very favorable forextraction of useful components from the primary rocksand formation of placers.

Analogous thin forms of gold and platinoids arewidespread in placers of the different regions: Azov–Black Sea, connected with the Voronezh massif, Urals,Siberian, and Far East [7, 8]. Simultaneous occurrenceof these metals is an indication of polytypical characterof their sources of washdown. Accumulations of noblemetals do not correlate with increased concentrationsof titanium–zirconium minerals, which is probablycaused by their different densities.

Table 1.

Concentration of gold and platinum according to the results of the slime sampling of the Chokrak–Karagan quartzsandstones, ppm

Numbers by order

Number of sample Age of rock Heavy fraction

yield, %Au Pt

specks ppm specks ppm

1 100/06 Chokrak 0.6 1 – – –2 107/06 Karagan 1.0 1 – 2 –3 120/06 – 0.3 – – 2 –4 130/06 – 0.7 1 – 1 –5 101/06 Chokrak 0.7 7 2 5 36 131/06 – 0.3 3 0.5 2 27 116/06 – 1.0 2 0.2 1 0.58 103/06 Karagan 0.6 3 1 5 79 104/06 – 2.5 2 1 3 20

10 105/06 – 0.5 4 1.5 5 211 115/06 – 0.7 1 0.2 2 0.712 102/06 – 0.3 4 1.5 2 0.3

Note: Heavy liquids were used for separation of heavy fractions in samples no. 5–12.

63

µ

m

(a) (b)

(c)

(d)

Fig. 1.

Panning gold (a, b) and platinum (c, d) from theMiocene quartz weakly cemented small-grained and middle-grained sandstones of Dagestan. (a) Buglen village (Chokrak);(b) Kapchugay (Chokrak); (c) Kumtorkala village (Karagan);(d) Buglen village (Chokrak).

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The conducted investigations allow to make the fol-lowing conclusions: (1) widely distributed (with a hugevolume of billions m

3

), weakly cemented quartz sand-stones of the Miocene Chokrak–Karagan age may beconsidered as a polycomponent raw material for gold,plationoids, titanium, zircon, and quartz; (2) the regionmay be estimated as highly promising for occurrencesof industrial accumulations of noble metals, zirconium,and titanium; (3) it may be recommended to conductwide geochemical investigations and survey-forecastworks on the Chokrak–Karagan sediments for gold, sil-ver, and platinum group metals.

REFERENCES

1. Matsapulin, V. U. and Gasanov, O. M., in Mat. Sem.

“Melkiye tsennye mineraly magmaticheskikh, metamor-phicheskikh i osadochnykh porod”

(“Small-grainedValuable Minerals of Magmatic, Metamorphic, and Sed-imentary Rocks”), Abstr., Perm’, 1991, pp. 8–9.

2. Matsapulin, V. U. and Yusupov, A. R., Doklady Akad.Nauk., 1994, vol. 337, no. 6, pp. 790–793.

3. Matsapulin, V. U., Magomedov, A. M.-Kh., and Yusu-pov, A. R., Trudy Inst. Geol. DNTs RAN, Makhackala,1995, pp. 17–21.

4. Cherkashin, V. I., Matsapulin, V. U., and Yusupov, A. R.,in Mat. Soveshch.

“Titano-zirkonievye mestorozhdeniyaRossii i perspectivy ikh osvoyeniya”

(“Titanium–zirco-nium Deposits of the Russia and Their Exploration Per-spectives”), Moscow: IGEM RAN, 2006, pp. 81–83.

5. Cherkashin, V. I., Matsapulin, V. U., and Yusupov, A. R.,

Trudy Inst. Geol. DVNTs RAN,

Makhackala, 2006,vol.

45, pp. 73–85.

6. Shilo, N. A.,

Ucheniye o rossypyakh

(Sience of Placers),Vladivostok: Dal’nauka, 2002.

7. Volkov, V. A., Yushin, A. A., and Shashorin, Yu. N., inAbstr. XIII Int. Meet. Geol. Placers and Depos. Weather.Crusts, Perm,’ 2005, pp. 29–30.

8. Matveeva, K. V., Filippov, V. P., Osaulenko, R. N. andProkof’eva, N. I., in Mat. Soveshch.

“Titano-zirkonievyemestorozhdeniya Rossii i perspectivy ikh osvoyeniya”

(“Titanium–zirconium Deposits of Russia and TheirExploration Perspectives”), Moscow: IGEM RAN,2006, pp. 36–39.

Table 2.

Concentration of gold, silver, and platinoids in the Miocene sandstones and argillaceous rocks, ppm

Numberby order Site of sampling Amount of

samples Age of strata Au Pt Pd AgTotal amount

of Au, Pt,and Pd

1 Buglen village 4 Chokrak – 5.72

2 Kul’zeb village 2 Sarmat – 1.8

3 Khuchni village 2 Karagan – 19.2

4 Shura-Ozen’ river 26 Chokrak – 6.26

5 Buynaksky mountain pass 2 Karagan – 7.9

6 Ekibulak gully 2 Sarmat – 10.72

7 Downstream of the Sulak River 2 Sarmat – 5.8

15 Karagan 2.65

8 Kul’zeb village 1 Sarmat 0.3 1.2 0.3 – 1.8

9 Uchkent village 4 Karagan 1.14

10 Khadzhal–Makhi 2 Upper Jurassic 2.2 5.05

11 Tsudakhar 1 Lower Creta-ceous 2.3 2.2 1.2 – 5.7

Note: Ag concentrations are shown only for the samples where it was determined. Numbers over the line show the concentration interval;numbers under the line show average concentrations.

0.2–0.83.05

------------------ 1.8–4.72.4

------------------ 0.1–0.30.27

------------------

0.3–1.81.05

------------------ 0–1.20.6

------------- 0–0.30.15

-------------

2.0–6.84.4

------------------ 3.2–25.514.35

--------------------- 0–0.70.35

-------------

0.10–1.882.17

------------------------ 0–24.73.74

---------------- 0–1.00.35

-------------

0.5–1.00.75

------------------ 4.7–7.25.95

------------------ 0.7–1.71.2

------------------

1.4–2.21.82

------------------ 3.0–9.46.2

------------------ 2.2–3.22.7

------------------

1.3–2.21.75

------------------ 1.7–2.21.95

------------------ 1.7–2.52.1

------------------

Tr.–2.30.8

------------------ 0.2–2.60.92

------------------ 0.1–3.00.9

------------------ 0.02–0.060.03

------------------------

0.2–0.60.36

------------------ 0.2–1.00.48

------------------ 0.2–0.40.3

------------------ 0.02–0.060.036

------------------------

1.25–1.501.37

------------------------ 1.3–1.41.35

------------------ 0.06–0.20.13

---------------------