Sediments of Lake Bolshoy Kisegach: seismoacoustic characteristics, chronology, and magnetic properties
Lina KOSAREVA , Nuriia NOURGALIEVA , Hong-Chun LI , Pavel KRYLOV , Dilyara KUZINA , Olga CHERNOVA , Danis NURGALIEV
Seismoacoustic profiling and rock-magnetic analyses provide a coherent basis for reconstructing the depositional history of Lake Bolshoy Kisegach (Southern Urals, Russia). We combined seismoacoustic sections with Accelerator Mass Spectrometry (AMS) 14C dating of bulk organic carbon from five core sites (258 to 540 cm) and measurements of magnetic susceptibility, natural remanent magnetization, coercivity spectra, differential thermomagnetic curves, and scanning electron microscopy (SEM) observations. The basin has heterogeneous bottom morphology that controls sediment distribution; sediment thickness reaches 7.5 m in the lake’s center. Two units are distinguished: Late Pleistocene strata (~3 m) overlain by Holocene sapropels (4.5 m). Calibrated radiocarbon ages indicate continuous accumulation since at least 12600 cal. yr BP and suggest lake initiation ~23000 cal. yr BP. Sedimentation rates vary from 0.2 to 1.24 mm·yr−1. Initial magnetic susceptibility (χ) ranges from 0.01 to 3.99 × 10−6 m3·kg−1, and natural remanent magnetization (NRM) ranges from 4.3 × 10−8 to 8.5 × 10−5 A/m. The magnetic fraction comprises mixtures of single-domain, multidomain, and superparamagnetic grains. Variations in magnetic parameters track recognized Late-Glacial and Holocene climate phases: the Younger Dryas marks the coldest interval, whereas the Subatlantic (~2000 cal. yr BP to recent) is the most humid. Lake regressions occurred during the Allerød interstadial, the Younger Dryas and the Boreal. These results demonstrate the value of integrating seismoacoustic guidance for coring with magnetic proxies to resolve lake-basin development.
14C radiocarbon dating / depositional environment / lake sediments / rock-magnetic properties / seismoacoustic profiling
| [1] |
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| [2] |
|
| [3] |
|
| [4] |
|
| [5] |
|
| [6] |
|
| [7] |
|
| [8] |
|
| [9] |
|
| [10] |
|
| [11] |
|
| [12] |
|
| [13] |
|
| [14] |
|
| [15] |
|
| [16] |
|
| [17] |
|
| [18] |
|
| [19] |
|
| [20] |
|
| [21] |
|
| [22] |
|
| [23] |
|
| [24] |
|
| [25] |
|
| [26] |
|
| [27] |
|
| [28] |
|
| [29] |
|
| [30] |
|
| [31] |
|
| [32] |
|
| [33] |
|
| [34] |
|
| [35] |
|
| [36] |
|
| [37] |
|
| [38] |
|
| [39] |
|
| [40] |
|
| [41] |
|
| [42] |
|
| [43] |
|
| [44] |
|
| [45] |
|
| [46] |
|
| [47] |
|
| [48] |
|
| [49] |
|
| [50] |
|
| [51] |
|
| [52] |
|
| [53] |
|
| [54] |
|
| [55] |
|
| [56] |
|
| [57] |
|
| [58] |
|
| [59] |
|
| [60] |
|
| [61] |
|
| [62] |
|
| [63] |
|
| [64] |
|
| [65] |
|
| [66] |
|
| [67] |
|
| [68] |
|
| [69] |
|
| [70] |
|
| [71] |
|
| [72] |
|
| [73] |
|
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