In 1997, an ancient iron production site, Barun-Khal 2, was discovered in the Barun-Khal valley (Olkhon region, near the west shore of Lake Baikal). This discovery initiated studies of the archaeometallurgical potential of the valley. They included magnetometry, resistivity, self-potential (SP) and radiometric surveys, archaeological excavation, analysis of chemical composition and magnetism of slag and other residuals, and radiocarbon dating of charcoal samples. As expected, the most efficient was the magnetometric survey. Despite challenging field conditions such as geology-related magnetic anomalies of large amplitude and contrast, the magnetometer survey in the Barun-Khal valley resulted in the discovery of another iron production site, Barun-Khal 3. Using the magnetometry, the general structure of the sites was studied and the places of excavation were determined. The resistivity, SP and radiometric techniques, as well as magnetic survey were useful in studying near-surface geology and recent geological history. Excavations have found well-preserved slag-tapping bloomery furnaces built into the sides of a large pit (Barun-Khal 2) or a trench (Barun-Khal 3). According to radiocarbon dating, iron production began here within the second and third centuries BC and lasted until the seventh to the eleventh centuries AD. The significance of the works in the Barun-Khal valley is determined by the fact that there exist significant gaps in the coverage of Russia (including Siberia) with archaeometallurgical studies. Most available papers on the archaeometallurgical activity in Siberia were not published in English until now. For the first time, the study of ancient iron production sites in the Olkhon region was considered as an independent scientific task and carried out using both geophysical and archaeological methods.
Introduction. Determinations of (234 U/ 238 U) in groundwater samples are used for monitoring current deformations in active faults (parentheses denote activity ratio units). The cyclic equilibrium of activity ratio 234 U/ 238 U≈ ≈(234 U/ 238 U)≈γ≈1 corresponds to the atomic ratio ≈5.47×10-5. This parameter may vary due to higher contents of 234 U nuclide in groundwater as a result of rock deformation. This effect discovered by P.I.
The Kultuk volcano erupted at the axial South Baikal basin of the Baikal rift zone (BRZ). Now it exhibits facies of subvolcanic bodies, landlava eruptions and subaqueous pillow lavas and hyaloclastites. The volcano was controlled by the Obruchev fault that is currently a border of the basin which amplitude of vertical movements is rapidly decreasing in the westward direction. It is found that the Kultuk volcano was active at the beginning and end of the volcanic activity period of the Kamar, Stanovaya, and Bystrinskaya volcanic zones, which took place 18-12 Ma ago. In previous papers, it was assumed that dominant structures in the area under study were major Cenozoic shear displacements along the Main Sayan fault and/or along the Tunka rift valley; however, at the current stage of our study, linear configurations of the volcanic zones do not re veal any of such displacements. Based on analyses of distribution of volcanic rocks in the relief at the western coast of Lake Baikal, distinct vertical crustal movements are revealed; such movements started in the Early Miocene and continue to the present time. It is concluded that volcanism was controlled by the transtensional system of volcanic zones. Sources are iden tified for the shallow lithospheric mantle melt with the substantial admixture of the lowcrust component and deeper astheno spheric mantle melts in the Kamar and Stanovaya volcanic zones; for the Bystrinskaya volcanic zone, only components from the deeper source are revealed. The local shallow mantle magmatism occurred only within the lithosphere extension zone beneath the South Baikal basin. The lithosphere thinning is reflected in the change of activity from the sublithospheric to lithospheric sources under the Kamar zone. Rifting of the axial structure is recorded at the root of the Slyudyanka lithospheric block that was subjected to the collisionrelated Early Paleozoic metamorphism. Geochemical characteristics of the collision type components were inherited by the Miocene basaltic melts.
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