The magnitude, rate, and extent of past and future East Asian monsoon (EAM) rainfall fluctuations remain unresolved. Here, late Pleistocene–Holocene EAM rainfall intensity is reconstructed using a ...well-dated northeastern China closed-basin lake area record located at the modern northwestern fringe of the EAM. The EAM intensity and northern extent alternated rapidly between wet and dry periods on time scales of centuries. Lake levels were 60 m higher than present during the early andmiddle Holocene, requiring a twofold increase in annual rainfall, which, based on modern rainfall distribution, requires a ∼400 km northward expansion/migration of the EAM. The lake record is highly correlated with both northern and southern Chinese cave deposit isotope records, supporting rainfall “intensity based” interpretations of these deposits as opposed to an alternative “water vapor sourcing” interpretation. These results indicate that EAM intensity and the northward extent covary on orbital and millennial timescales. The termination of wet conditions at 5.5 ka BP (∼35 m lake drop) triggered a large cultural collapse of Early Neolithic cultures in north China, and possibly promoted the emergence of complex societies of the Late Neolithic.
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Extreme hydrologic events such as storms and floods have the potential to severely impact modern human society. However, the frequency of storms and their underlying mechanisms are limited by a ...paucity of suitable proxies, especially in inland areas. Here we present a record of speleothem magnetic minerals to reconstruct paleoprecipitation, including storms, in the eastern Asian monsoon area over the last 8.6 ky. The geophysical parameter IRMsoft-flux represents the flux of soil-derived magnetic minerals preserved in stalagmite HS4, which we correlate with rainfall amount and intensity. IRMsoft-flux exhibits relatively higher values before 6.7 ky and after 3.4 ky and lower values in the intervening period, consistent with regional hydrological changes observed in independent records. Abrupt enhancements in the flux of pedogenic magnetite in the stalagmite agree well with the timing of known regional paleofloods and with equatorial El Niño–Southern Oscillation (ENSO) patterns, documenting the occurrence of ENSO-related storms in the Holocene. Spectral power analyses reveal that the storms occur on a significant 500-y cycle, coincident with periodic solar activity and ENSO variance, showing that reinforced (subdued) storms in central China correspond to reduced (increased) solar activity and amplified (damped) ENSO. Thus, the magnetic minerals in speleothem HS4 preserve a record of the cyclic storms controlled by the coupled atmosphere–oceanic circulation driven by solar activity.
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Homo floresiensis, a primitive hominin species discovered in Late Pleistocene sediments at Liang Bua (Flores, Indonesia), has generated wide interest and scientific debate. A major reason this taxon ...is controversial is because the H. floresiensis-bearing deposits, which include associated stone artefacts and remains of other extinct endemic fauna, were dated to between about 95 and 12 thousand calendar years (kyr) ago. These ages suggested that H. floresiensis survived until long after modern humans reached Australia by ~50 kyr ago. Here we report new stratigraphic and chronological evidence from Liang Bua that does not support the ages inferred previously for the H. floresiensis holotype (LB1), ~18 thousand calibrated radiocarbon years before present (kyr cal. BP), or the time of last appearance of this species (about 17 or 13-11 kyr cal. BP). Instead, the skeletal remains of H. floresiensis and the deposits containing them are dated to between about 100 and 60 kyr ago, whereas stone artefacts attributable to this species range from about 190 to 50 kyr in age. Whether H. floresiensis survived after 50 kyr ago--potentially encountering modern humans on Flores or other hominins dispersing through southeast Asia, such as Denisovans--is an open question.
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Very little is known about Neanderthal cultures, particularly early ones. Other than lithic implements and exceptional bone tools, very few artefacts have been preserved. While those that do remain ...include red and black pigments and burial sites, these indications of modernity are extremely sparse and few have been precisely dated, thus greatly limiting our knowledge of these predecessors of modern humans. Here we report the dating of annular constructions made of broken stalagmites found deep in Bruniquel Cave in southwest France. The regular geometry of the stalagmite circles, the arrangement of broken stalagmites and several traces of fire demonstrate the anthropogenic origin of these constructions. Uranium-series dating of stalagmite regrowths on the structures and on burnt bone, combined with the dating of stalagmite tips in the structures, give a reliable and replicated age of 176.5 thousand years (±2.1 thousand years), making these edifices among the oldest known well-dated constructions made by humans. Their presence at 336 metres from the entrance of the cave indicates that humans from this period had already mastered the underground environment, which can be considered a major step in human modernity.
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Caves are special environments that harbour an incredible diversity of life, including fungal species. Brazilian caves have been demonstrated to be biodiversity hotspots for known and unknown fungal ...species. We investigated the richness of culturable fungi in a tropical cave in Brazil
by isolating these microorganisms from the sediment and air. The fungal abundance of colony-forming units (CFUs) was 3 178 in sediment and 526 in air. We used morphological features and phylogenetic analyses of actin (actA), calmodulin (cmdA), internal transcribed spacer regions
and intervening 5.8S rRNA (ITS), large subunit (LSU) rDNA, RNA polymerase II second largest subunit (rpb2), translation elongation factor 1-alpha (tef1), and β-tubulin (tub2) genes to identify these isolates. Forty-one species belonging to 17 genera of Ascomycota
and two of Basidiomycota were identified, and the genus Aspergillus was most commonly observed in the cave (13 taxa). Twenty-four species were found in sediment (16 exclusives) and 25 species were found in air (17 exclusives). In this study, we introduced a new genus (Pseudolecanicillium
gen. nov.) in the family Cordycipitaceae and six new species (14 % of the total taxa identified) of fungal isolates obtained from sediment and air: Aspergillus lebretii sp. nov., Malbranchea cavernosa sp. nov., Pseudohumicola cecavii sp. nov., Pseudolecanicillium
caatingaense sp. nov., Talaromyces cavernicola sp. nov., and Tritirachium brasiliense sp. nov. In addition, we built a checklist of the fungal taxa reported from Brazilian caves. Our results highlight the contribution of Brazilian caves to the estimation of national and global
fungal diversity.
Variations in speleothem oxygen-isotope values (
δ
18O) result from a complicated interplay of environmental controls and processes in the ocean, atmosphere, soil zone, epikarst, and cave system. As ...such, the controls on speleothem
δ
18O values are extremely complex. An understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem
δ
18O as paleoclimate and paleoenvironmental proxies, and is best complemented by study of site-specific cave processes such as infiltration, flow routing, drip seasonality and saturation state, and cave microclimate, among others. This review is a process-based summary of the multiple controls on
δ
18O in the atmosphere, soil, epikarst, and speleothem calcite, illustrated with case studies. Primary controls of
δ
18O in the atmosphere include temperature and relative humidity through their role in the multiple isotope “effects”. Variability and modifications of water
δ
18O values in the soil and epikarst zones are dominated by evaporation, mixing, and infiltration of source waters. The isotopically effective recharge into a cave system consists of those waters that participate in precipitation of CaCO
3, resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state. Recent modeling, experimental, and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid CaCO
3, and have implications for the ‘Hendy’ test. To assist interpretation of speleothem
δ
18O time series, quantitative and semi-quantitative
δ
18O-climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records. Finally, several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of
δ
18O to reconstruct past climate changes in regions that have been typically poorly represented in paleoclimate records, such as tropical and subtropical terrestrial locations. The new approach to speleothem paleoclimatology emphasizes climate teleconnections between regions and attribution of forcing mechanisms. Such investigations allow paleoclimatologists to infer regional to global-scale climate dynamics.
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Caves are special environments that harbour an incredible diversity of life, including fungal species. Brazilian caves have been demonstrated to be biodiversity hotspots for known and unknown fungal ...species. We investigated the richness of culturable fungi in a tropical cave in Brazil by isolating these microorganisms from the sediment and air. The fungal abundance of colony-forming units (CFUs) was 3 178 in sediment and 526 in air. We used morphological features and phylogenetic analyses of actin ( actA ), calmodulin ( cmdA ), internal transcribed spacer regions and intervening 5.8S rRNA (ITS), large subunit (LSU) rDNA, RNA polymerase II second largest subunit ( rpb2 ), translation elongation factor 1-alpha ( tef1 ), and β-tubulin ( tub2 ) genes to identify these isolates. Forty-one species belonging to 17 genera of Ascomycota and two of Basidiomycota were identified, and the genus Aspergillus was most commonly observed in the cave (13 taxa). Twenty-four species were found in sediment (16 exclusives) and 25 species were found in air (17 exclusives). In this study, we introduced a new genus ( Pseudolecanicillium gen. nov. ) in the family Cordycipitaceae and six new species (14 % of the total taxa identified) of fungal isolates obtained from sediment and air: Aspergillus lebretii sp. nov. , Malbranchea cavernosa sp. nov. , Pseudohumicola cecavii sp. nov. , Pseudolecanicillium caatingaense sp. nov. , Talaromyces cavernicola sp. nov. , and Tritirachium brasiliense sp. nov. In addition, we built a checklist of the fungal taxa reported from Brazilian caves. Our results highlight the contribution of Brazilian caves to the estimation of national and global fungal diversity.
Recent archaeological discoveries have revealed that pigment use, beads, engravings, and sophisticated stone and bone tools were already present in southern Africa 75,000 y ago. Many of these ...artifacts disappeared by 60,000 y ago, suggesting that modern behavior appeared in the past and was subsequently lost before becoming firmly established. Most archaeologists think that San hunter–gatherer cultural adaptation emerged 20,000 y ago. However, reanalysis of organic artifacts from Border Cave, South Africa, shows that the Early Later Stone Age inhabitants of this cave used notched bones for notational purposes, wooden digging sticks, bone awls, and bone points similar to those used by San as arrowheads. A point is decorated with a spiral groove filled with red ochre, which closely parallels similar marks that San make to identify their arrowheads when hunting. A mixture of beeswax, Euphorbia resin, and possibly egg, wrapped in vegetal fibers, dated to ∼40,000 BP, may have been used for hafting. Ornaments include marine shell beads and ostrich eggshell beads, directly dated to ∼42,000 BP. A digging stick, dated to ∼39,000 BP, is made of Flueggea virosa . A wooden poison applicator, dated to ∼24,000 BP, retains residues with ricinoleic acid, derived from poisonous castor beans. Reappraisal of radiocarbon age estimates through Bayesian modeling, and the identification of key elements of San material culture at Border Cave, places the emergence of modern hunter–gatherer adaptation, as we know it, to ∼44,000 y ago.
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There is little fossil evidence for cave arthropods. Small size, disfunctional wings, extremely long antenna, dense minute setation, palidity and reduced eyes are typical adaptations to life in caves ...shown by the cockroach Mulleriblattina bowangi gen. et sp. n., found together with epigeic Crenocticola svadba sp. n., both from Myanmar amber and belonging to the cavernicolous cockroach family Nocticolidae. These lineages of earliest still living cavernicoles suggest large, numerous caverns, lava tubes or caves within the source area. They provide the first unequivocal evidence for the Mesozoic origin of any living troglomorphic organism, and explain the “long branches” in DNA analyses. Phylogenetic trees show little hierarchical structure and place Latindiinae and Myrmecoblatta within the explosively radiating Nocticolidae. Biogeography indicates a common cosmopolitan Early Cretaceous ancestor except for 8 (of 49) species of true Nocticolidae, which diverged during the Late Cretaceous breakup of Gondwana. A review of all troglofauna documents no other unequivocal pre-Cenozoic cave biotas (including vertebrates). Stable environments and small populations result in a short-time (˂3 Ma) origination of bizarre forms and long term extinctions (˃30 Ma).
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•All cave organisms including vertebrates reveal Cenozoic origin.•Why all cave fauna of the Mesozoic went extinct becomes now a big enigma.•Exceptions are herein described cockroaches from Myanmar amber.
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Local collapse of the surrounding rock often occurs during tunnel construction in a karst area, particularly when the rock pillar between the tunnel and the karst cave is very thin. The collapse of ...the surrounding rock in tunnel construction is sudden and may lead to great economic loss or even loss of life. To predict the collapse of rock mass where a tunnel is excavated above a karst cave, an analytical expression of the collapse surface is derived from variational calculation in the framework of the upper bound theorem. Based on the analytical solution, the shape of the collapse surface is plotted to investigate the effects of rock parameters on the collapse surface of the rock mass where a karst cave exists beneath a tunnel. According to the changing law of the collapse surface varying with the distance between tunnel and cave, the computational formula of the minimum safety thickness for preventing the collapse of rock pillar is derived. To evaluate the validity of the proposed method in this paper, we compared the analytical solution with numerical solution. The comparison result indicates the analytical solution matches up with the numerical solution very well, which suggests that the analytical approach proposed in this paper is valid.
•Equation of collapse surface for rock with a karst cave beneath a tunnel is derived.•The definition of minimum safety thickness for the rock pillar is given.•Range of collapse surface for rock with a karst cave beneath a tunnel is determined.
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