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Research about Lake Baikal

Source-linked reports with geographic coverage including Lake Baikal.

13 recordsLinked to original sources
USGS2022

Rift flank segmentation, basin initiation and propagation: a neotectonic example from Lake Baikal

New surficial data (field, Landsat TM and topography) define morpho-tectonic domains and rift flank segmentation in the Ol'khon region of the Central Baikal rift. Deformation, drainage and depositional patterns indicate a change in the locus of active extension that may relate to a recent (<l Ma) change in the kinematics of the Siberian plate boundary. The westwards migration of the border fault location has broadened the rift with concomitant shifts in depocentres. Within the hanging wall of the new western border fault, distinct segments control the location of drainage paths and syn-rift deposits. Morphology, sediment thicknesses and fault scarp amplitude indicate that a segmented rift flank graben has propagated southwards along the rift flank and is still actively fragmenting. These surficial data are used to constrain a model for the time-dependent topographic variations during progressive subsidence along a rift flank, involving the transfer of footwall units to hanging-wall domains. Rapid changes in border fault footwall relief in this model are associated with change in the active border fault location with widespread mass-wasting. The model shows that time-dependent histories need to be integrated with flexural uplift models for active normal faults. The active, syn-rift depositional systems of the Ol'khon region provide a valuable analogue for the early evolution of continental margins and the structural controls on syn-rift hydrocarbon sources and reservoirs.

Siberia↗
USGS2017

Evidence from Lake Baikal for Siberian glaciation during oxygen-isotope substage 5d

The paleoclimatic record from bottom sediments of Lake Baikal (eastern Siberia) reveals new evidence for an abrupt and intense glaciation during the initial part of the last interglacial period (isotope substage 5d). This glaciation lasted about 12 000 yr from 117 000 to 105 000 yr BP according to correlation with the SPEC-MAP isotope chronology. Lithological and biogeochemical evidence of glaciation from Lake Baikal agrees with evidence for the advance of ice sheet in northwestern Siberia during this time period and also with cryogenic features within the strata of Kazantzevo soils in Southern Siberia. The severe 5d glaciation in Siberia was caused by dramatic cooling due to the decrease in solar insolation (as predicted by the model of insulation changes for northern Asia according to Milankovich theory) coupled with western atmospheric transport of moisture from the opea areas of Northern Atlantic and Arctic seas (which became ice-free due to the intense warming during preceeding isotope substage 5e). Other marine and continental records show evidence for cooling during 5d, but not for intense glaciation. Late Pleistocene glaciations in the Northern Hemisphere may have begun in northwestern Siberia.

Lake Baikal↗
USGS2003

Quaternary sedimentation and subsidence history of Lake Baikal, Siberia, based on seismic stratigraphy and coring

The long, continuous, high-latitude, stratigraphic record of Lake Baikal was deposited in three broad sedimentary environments, defined by high-resolution seismic-reflection and coring methods: (1) turbidite depositional systems, by far the most widespread, characterizing most of the margins and floors of the main basins of the lake, (2) large deltas of major drainages, and (3) tectonically or topographically isolated ridges and banks. Holocene sedimentation rates based on radiocarbon ages vary by more than an order of magnitude among these environments, from less than about 0.03 mm/yr on ridges and banks to more than about 0.3 mm/yr on basin floors. Extrapolating these rates, with a correction for compaction, yields tentative estimates of about 25 and 11 Ma for the inception of rifting in the Central and North basins, respectively, and less than 6 Ma for the 200-m sediment depth on Academician Ridge. The Selenga Delta has the distinctive form of a classic prograding Gilbert-type delta, but its history appears to represent a complex combination of tectonism and sedimentation. The central part of the delta is underlain by prograding, shallow-water sequences, now several hundred meters below the lake surface. These deposits and much of the delta slope are mantled by fine-grained, deep-water, hemipelagic deposits whose base is estimated to be about 650,000 years old. Modern coarse-grained sediment bypasses the delta slope through fault-controlled canyons that feed large, subaqueous fans at the ends of the South and Central basins. These relations, along with abundant other evidence of recent faulting and the great depths of the Central and South basins, suggest that these two rift basins have experienced a period of unusually rapid subsidence over the last 650,000 years, during at least part of which sedimentation has failed to keep pace.

Lake Baikal↗
USGS2002

Crustal structure of central Lake Baikal: Insights into intracontinental rifting

The Cenozoic rift system of Baikal, located in the interior of the largest continental mass on Earth, is thought to represent a potential analog of the early stage of breakup of supercontinents. We present a detailed P wave velocity structure of the crust and sediments beneath the Central Basin, the deepest basin in the Baikal rift system. The structure is characterized by a Moho depth of 39–42.5 km; an 8-km-thick, laterally continuous high-velocity (7.05–7.4 km/s) lower crust, normal upper mantle velocity (8 km/s), a sedimentary section reaching maximum depths of 9 km, and a gradual increase of sediment velocity with depth. We interpret the high-velocity lower crust to be part of the Siberian Platform that was not thinned or altered significantly during rifting. In comparison to published results from the Siberian Platform, Moho under the basin is elevated by <3 km. On the basis of these results we propose that the basin was formed by upper crustal extension, possibly reactivating structures in an ancient fold-and-thrust belt. The extent and location of upper mantle extension are not revealed by our data, and it may be offset from the rift. We believe that the Baikal rift structure is similar in many respects to the Mesozoic Atlantic rift system, the precursor to the formation of the North Atlantic Ocean. We also propose that the Central Baikal rift evolved by episodic fault propagation and basin enlargement, rather than by two-stage rift evolution as is commonly assumed.

Lake Baikal↗
USGS1997

Preliminary results of the first scientific Drilling on Lake Baikal, Buguldeika site, southeastern Siberia

The Baikal Drilling Project (BDP) is a multinational effort to investigate the paleoclimatic history and tectonic evolution of the Baikal sedimentary basin during the Late Neogene. In March 1993 the Baikal drilling system was successfuly deployed from a barge frozen into position over a topographic high, termed the Buguldeika saddle, in the southern basin of Lake Baikal. The BDP-93 scientific team, made up of Russian, American and Japanese scientists, successfully recovered the first long (>100 m) hydraulic piston cores from two holes in 354 m of water. High quality cores of 98 m (Hole 1) and 102 m (Hole 2), representing sedimentation over the last 500,000 years, were collected in 78 mm diameter plastic liners with an average recovery of 72% and 90%, respectively. Magnetic susceptibility logging reveals an excellent hole-to-hole correlation. In this report the scientific team describes the preliminary analytical results from BDP-93 hole 1 cores. Radiocarbon dating by accelerator mass spectrometry provides an accurate chronology for the upper portion of Hole 1. Detailed lithologic characteristics, rock magnetic properties and inorganic element distributions show a significant change to the depositional environment occuring at 50 m subbottom depth, approximately 250,000 BP. This change may be due to uplift and rotation of the horst block in the Buguldeika saddle. The sedimentary section above 50 m is pelitic with varve-like laminae, whereas the section below 50 m contains a high proportion of sand and gravel horizons often organized into turbidite sequences. Accordingly, high resolution seismic records reveal a change in sonic velocity at this depth. It is inferred that sedimentation prior to 250 ka BP was from the west via the Buguldeika river system. After 250 ka BP the Buguldeika saddle reflects an increase in hemipelagic sediments admixed with fine-grained material from the Selenga River drainage basin, east of Lake Baikal. Variations in the spore-pollen assemblage, diatoms, biogenic silica content, rock magnetic properties, clay mineralogy and organic carbon in the upper 50 m of BDP-93-1 reveal a detailed record of climate change over approximately the last 250,000 years. These variables alternate in a pattern characteristic of glacial/interglacial climatic fluctuations. The present age model suggests that the climate signal recorded in Lake Baikal sediments is similar to Late Quaternary signals recorded in Chinese loess sections and in marine sediments.

Siberia↗
USGS1997

Lignin phenols in sediments of Lake Baikal, Siberia: Application to paleoenvironmental studies

Sediments from three cores obtained from distinct depositional environments in Lake Baikal, Siberia were analyzed for organic carbon, total nitrogen and lignin phenol concentration and composition. Results were used to examine changes in paleoenvironmental conditions during climatic cycles of the late Quaternary (< 125 ka). Average organic carbon, and total nitrogen concentrations, atomic C/N ratios and organic carbon accumulation rates were significantly higher in the Holocene compared with the late Pleistocene, reflecting overall warmer temperatures and increased runoff during the Holocene. A Holocene maximum in organic carbon was observed at about 6 ka, and may represent the warmest wettest period of the Holocene. At one site (Academician Ridge) pronounced late Pleistocene maxima in organic carbon and biogenic silica were observed at about 80-85 ka, probably indicative of an interstadial period with enhanced aquatic productivity. Total sedimentary lignin phenol contents were generally lower in the late Pleistocene compared to the Holocene, but with several peaks in concentration during the late Pleistocene. These late Pleistocene peaks in total sedimentary lignin content (dated at about 80, 50 and 30 ka) directly precede or occur during peaks in sedimentary biogenic silica contents. These periods likely represent relatively warm interstadial times, with increased precipitation producing the observed increase in terrestrial runoff and aquatic productivity. Lignin phenol ratios (S/V, C/V and P/V) were used to examine changes in terrestrial vegetation type resulting from changes in paleoenvironmental conditions during the late Pleistocene. A degree of caution must be used in the interpretation of these ratios with regard to vegetation sources and paleoenvironmental conditions, because of potential compositional changes in lignin resulting from biodegradation. Nevertheless, results show that long glacial periods were characterized by terrestrial vegetation composed of a mix of non-woody angiosperm vegetation and minor gymnosperm forest. Shorter interstadial periods are defined by a change to dominant gymnosperm forest and were observed at about 80, 75, 63, 50 and 30 ka, ranging from about 2-6 kyr in duration. These interstadial periods of the late Pleistocene defined by lignin phenol ratios generally occur during longer periods of enhanced sedimentary biogenic silica content (about 10-15 ka in duration), providing corroborative evidence of these warm interstadial periods.Sediments obtained in Lake Baikal were analyzed for organic carbon, total nitrogen and lignin phenol composition and used to study changes in paleoenvironmental conditions during climatic cycles of the late Quaternary. The organic carbon, total nitrogen concentrations, atomic C/N ratios and organic carbon accumulation rates were higher in the Holocene showing overall warmer temperatures and increased runoff. Total lignin phenol contents were lower in the Pleistocene representing relatively warm interstadial times with increased precipitation, runoff and aquatic productivity. Lignin phenol was used to examine vegetation changes due to paleoenvironmental conditions and showed that long glacial periods were characterized by terrestrial vegetation.

Siberia↗
USGS1994

A synthesis of post-glacial diatom records from Lake Baikal

The biostratigraphy of fossil diatoms contributes important chronologic, paleolimnologic, and paleoclimatic information from Lake Baikal in southeastern Siberia. Diatoms are the dominant and best preserved microfossils in the sediments, and distinctive assemblages and species provide inter-core correlations throughout the basin at millennial to centennial scales, in both high and low sedimentation-rate environments. Distributions of unique species, once dated by radiocarbon, allow diatoms to be used as dating tools for the Holocene history of the lake. Diatom, pollen, and organic geochemical records from site 305, at the foot of the Selenga Delta, provide a history of paleolimnologic and paleoclimatic changes from the late glacial (15 ka) through the Holocene. Before 14 ka diatoms were very rare, probably because excessive turbidity from glacial meltwater entering the lake impeded productivity. Between 14 and 12 ka, lake productivity increased, perhaps as strong winds promoted deep mixing and nutrient regeneration. Pollen evidence suggests a cold shrub — steppe landscape dominated the central Baikal depression at this time. As summer insolation increased, conifers replaced steppe taxa, but diatom productivity declined between 11 and 9 ka perhaps as a result of increased summer turbidity resulting from violent storm runoff entering the lake via short, steep drainages. After 8 ka, drier, but more continental climates prevailed, and the modern diatom flora of Lake Baikal came to prominence. On Academician Ridge, a site of slow sedimentation rates, Holocene diatom assemblages at the top of 10-m cores reappear at deeper levels suggesting that such cores record at least two previous interglacial (or interstadial?) periods. Nevertheless, distinctive species that developed prior to the last glacial period indicate that the dynamics of nutrient cycling in Baikal and the responsible regional climatic environments were not entirely analogous to Holocene conditions. During glacial periods, the deep basin sediments of Lake Baikal are dominated by rapidly deposited clastics entering from large rivers with possibly glaciated headwaters. On the sublacustrine Academician Ridge (depth = 300 m), however, detailed analysis of the diatom biostratigraphy indicates that diastems (hiatuses of minor duration) and (or) highly variable rates of accumulation complicate paleolimnologic and paleoclimatic reconstructions from these records.

Lake Baikal↗
USGS1994

A rock-magnetic record from Lake Baikal, Siberia: Evidence for Late Quaternary climate change

Rock-magnetic measurements of sediment cores from the Academician Ridge region of Lake Baikal, Siberia show variations related to Late Quaternary climate change. Based upon the well-dated last glacial-interglacial transition, variations in magnetic concentration and mineralogy are related to glacial-interglacial cycles using a conceptual model. Interglacial intervals are characterized by low magnetic concentrations and a composition that is dominated by low coercivity minerals. Glacial intervals are characterized by high magnetic concentrations and increased amounts of high coercivity minerals. The variation in magnetic concentration is consistent with dilution by diatom opal during the more productive interglacial periods. We also infer an increased contribution of eolian sediment during the colder, windier, and more arid glacial conditions when extensive loess deposits were formed throughout Europe and Asia. Eolian transport is inferred to deliver increased amounts of high coercivity minerals as staining on eolian grains during the glacial intervals. Variations in magnetic concentration and mineralogy of Lake Baikal sediment correlate to the SPECMAP marine oxygen-isotope record. The high degree of correlation between Baikal magnetic concentration/mineralogy and the SPECMAP oxygen-isotope record indicates that Lake Baikal sediment preserves a history of climate change in central Asia for the last 250 ka. This correlation provides a method of estimating the age of sediment beyond the range of the radiocarbon method. Future work must include providing better age control and additional climate proxy data, thereby strengthening the correlation of continental and marine climate records. ?? 1994.

Lake Baikal↗
USGS1994

Biogenic silica in Lake Baikal sediments: results from 1990-1992 American cores

The Lake Baikal Paleoclimate Project is a joint Russian-American program established to study the paleoclimate of Central Asia. During three summer field seasons, duplicate Russian and American cores were taken at a number of sites in different sedimentary environments in the lake. Eight cores returned to the U.S. were quantitatively analyzed for biogenic silica using a single-step 5-hour alkaline leach, followed by dissolved silicon analysis by inductively-coupled-plasma atomic-emission spectroscopy. Sediments of Holocene age in these cores have biogenic silica maxima that range from about 15 to 80 percent. An underlying zone in each core with low biogenic-silica concentrations (0 to 5 percent) dates from the last glacial maximum. The transition from the last glaciation to the present interglaciation, recorded by biogenic silica, began about 13,000 years ago. Biogenic silica profiles from these cores appear to be a good measure of past diatom productivity and a useful basis for paleoclimatic interpretations.

Lake Baikal↗
USGS1992

Depositional and tectonic framework of the rift basins of Lake Baikal from multichannel seismic data

Recent multichannel seismic reflection data from Lake Baikal, located in a large, active, continental rift in central Asia, image three major stratigraphic units totalling 3.5 to 7.5 km thick in four subbasins. A major change in rift deposition and faulting between the oldest and middle-rift units probably corresponds to the change from slow to fast rifting. A brief comparison of the basins of Lake Baikal with those of the East African rift system highlights differences in structural style that can be explained by differences in age and evolution of the surrounding basement rocks. -from Authors

Lake Baikal↗