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Timescales of hydrothermal scavenging in the South Pacific Ocean from 234Th, 230Th, and 228Th EI Scopus SCIE
期刊论文 | 2019 , 506 , 146-156 | Earth and Planetary Science Letters
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© 2018 Elsevier B.V. Hydrothermal activity in the deep ocean generates plumes of metal-rich particles capable of removing certain trace elements from seawater by adsorption and sedimentation. This removal process, known as scavenging, can be probed using the insoluble radiogenic isotopes of thorium (Th), which are produced at a known rate in the water column via the decay of soluble uranium (234Th, 230Th) and radium (228Th) isotopes. We present dissolved and particulate measurements of these three thorium isotopes in a hydrothermal plume observed in the southeast Pacific Ocean on the GEOTRACES GP16 section. Since their half-lives vary from days (234Th) to years (228Th) to tens of thousands of years (230Th), the combination of their signals can be used to understand scavenging processes occurring on a wide range of timescales. Scavenging is a multi-step process involving adsorption and desorption onto particles, followed by particle aggregation, sinking, and eventual sedimentation. We use thorium isotopes to study how hydrothermal activity affects these steps. The rate constants for net adsorption of 234Th determined here are comparable to previous estimates from hydrothermal plumes in the Atlantic and North Pacific Oceans. The partitioning of 234Th and 230Th between large and small particles is more similar in the hydrothermal plume than above it, indicating faster aggregation of particles within the hydrothermal plume at stations nearby the East Pacific Rise than in waters outside the plume. In addition to rapid scavenging and aggregation near the ridge axis, we also infer continuous off-axis scavenging from observations and modeling of 228Th/228Ra activity ratios. The degree of depletion of the three thorium isotopes increases in order of half-life, with total 234Th activity close to that of its parent 238U, but 230Th showing nearly 70% depletion compared to expected values from reversible scavenging. By modeling the variations in depletion for the different isotopes, we show that much of the 230Th removal is inherited from scavenging events happening long before the most recent hydrothermal inputs.

Keyword :

East Pacific Rise GEOTRACES hydrothermal activity scavenging thorium

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GB/T 7714 Pavia, Frank J. , Anderson, Robert F. , Black, Erin E. et al. Timescales of hydrothermal scavenging in the South Pacific Ocean from 234Th, 230Th, and 228Th [J]. | Earth and Planetary Science Letters , 2019 , 506 : 146-156 .
MLA Pavia, Frank J. et al. "Timescales of hydrothermal scavenging in the South Pacific Ocean from 234Th, 230Th, and 228Th" . | Earth and Planetary Science Letters 506 (2019) : 146-156 .
APA Pavia, Frank J. , Anderson, Robert F. , Black, Erin E. , Kipp, Lauren E. , Vivancos, Sebastian M. , Fleisher, Martin Q. et al. Timescales of hydrothermal scavenging in the South Pacific Ocean from 234Th, 230Th, and 228Th . | Earth and Planetary Science Letters , 2019 , 506 , 146-156 .
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Investigating the 8.2 ka event in northwestern Madagascar: Insight from data?model comparisons EI SCIE
期刊论文 | 2019 , 204 , 172-186 | Quaternary Science Reviews
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The 8.2 ka event is a well-known cooling event in the Northern Hemisphere, but is poorly understood in Madagascar. Here, we compare paleoclimate data and outputs from paleoclimate simulations to better understand it. Records from Madagascar suggest two distinct sub-events (8.3 ka and 8.2 ka), that seem to correlate with records from northern high latitude. This could indicate causal relationships via changes in the Atlantic Meridional Overturning Circulation (AMOC) with changes in moisture source's δ18O, and changes in the mean position of the Inter-Tropical Convergence Zone (ITCZ), as climate modelling suggests. These two sub-events are also apparent in other terrestrial records, but the climatic signals are different. The prominent 8.2 ka sub-event records a clear antiphase relationship between the northern and southern hemisphere monsoons, whereas such relationship is less evident during the first 8.3 ka sub-event. Data–model comparison have also shown a mismatch between the paleoclimate data and the model outputs, the causes of which are more or less understood and may lie in the proxies, in the model, or in both data and model. Knowing that paleoclimate proxies and climate models produce different sets of variables, further research is needed to improve the data–model comparison approach, so that both paleoclimate data and paleoclimate models will better predict the likely climate status of a region during a specified time in the past with minimal uncertainties. © 2018 Elsevier Ltd

Keyword :

8.2 ka event AMOC Holocenes Madagascar Model comparison Paleoclimates Speleothems Stable isotopes

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GB/T 7714 Voarintsoa, Ny Riavo G. , Matero, Ilkka S.O. , Railsback, L. Bruce et al. Investigating the 8.2 ka event in northwestern Madagascar: Insight from data?model comparisons [J]. | Quaternary Science Reviews , 2019 , 204 : 172-186 .
MLA Voarintsoa, Ny Riavo G. et al. "Investigating the 8.2 ka event in northwestern Madagascar: Insight from data?model comparisons" . | Quaternary Science Reviews 204 (2019) : 172-186 .
APA Voarintsoa, Ny Riavo G. , Matero, Ilkka S.O. , Railsback, L. Bruce , Gregoire, Lauren J. , Tindall, Julia , Sime, Louise et al. Investigating the 8.2 ka event in northwestern Madagascar: Insight from data?model comparisons . | Quaternary Science Reviews , 2019 , 204 , 172-186 .
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Anatomy of a late Quaternary carbonate island: Constraints on timing and magnitude of sea-level fluctuations, West Caicos, Turks and Caicos Islands, BWI EI SCIE
期刊论文 | 2019 , 205 , 193-223 | Quaternary Science Reviews
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The data set of the island of West Caicos consists of a combination of high-resolution lidar and digital imagery, radiometric data, and amino acid racemization (AAR) D/L values as well as extraordinary preservation of sedimentary and bio-constructed deposits on the island. Together with a well-established regional stratigraphic framework from the neighboring Bahamian island chain and detailed field mapping, the West Caicos data set provides an opportunity to advance our understanding of the link between carbonate stratigraphy and the controlling parameters of sea level, sediment supply, tectonics, and climate. The exceptionally well-preserved stratigraphic record of the mid–late Pleistocene from West Caicos allows recognition of marine isotope stages (MIS) 9/11, 5e, and Holocene. The west coast of the island provides a continuous 8.4 km exposure of the MIS 5e record that enhances our understanding of the intra-MIS 5e bipartite succession in this region and supports a sea-level lowering that occurred during the last interglacial (LIG). West Caicos accreted as a series of eolian, foreshore–shoreface, barrier-reef, and fringing-reef facies. Shoreline positions for all but the MIS 7 and MIS 5a/c deposits are now captured in the sub-meter geodetic-quality topobathy lidar survey. The Star Town unit of MIS 9/11 age forms the southern margin of the island as well as the central karst-modified spine, with uranium–thorium (U–Th) coral ages of between 368 and 365 thousand years ago (ka) and a D/L Glu average of >0.60. Early MIS 5e strata include the Railroad Ridge unit in the center of the island, which was previously identified as one of the older units. The Railroad Ridge unit is a north–south linear dune ridge that has a D/L Glu average of 0.52 and indicates the onset of sediment sources from the east associated with a flooded central Caicos Platform. Approximately synchronously, the early MIS 5e South Reef unit (+3.75–4 m sea-level elevation) nucleated on the western coast of West Caicos, attached to the middle Pleistocene Star Town unit. The South Reef corals yield an average coral U–Th age of 126.5 ka, with an average D/L Glu from skeletal matrix of 0.46. This transitional barrier/fringing reef is unconformably overlain by the late MIS 5e Boat Cove unit. Corals in the basal transgressive phase of this upper MIS 5e Boat Cove unit yield an average 120.6 ka U–Th and average D/L Glu of 0.45. Shallow-marine, foreshore, and eolian facies of the late MIS 5e rest on a wave-cut terrace that cuts the early MIS 5e South Reef unit by as much as 3 m down to a +0.5 m above present sea-level elevation. The upper MIS 5e Boat Cove unit displays a maximum of +4.5 m elevation above present-day sea level, measured from the middle of the foreshore. This estimate may be a minimum value as the exposures on the west coast are part of a forced regressive foreshore sequence. Last stages of the upper MIS 5e deposition are seen in a series of regressive dune-beach ridge deposits referred to as the Northeast Ridges unit, with sea-level positions ranging from +4.5 m early in the central part of West Caicos, to +0.5 m on the far northeast coast, eventually building down below present-day sea level. This sea-level history fits well with previously documented records in the Bahamas and globally, and the extensive erosion supports a short-lived (between 126 and 120 ka) intra-MIS 5e relative-sea-level fall. Holocene deposition on West Caicos is restricted to northern and eastern margins of the island as a combination of strandplain and dune ridge mixed skeletal–oolitic units. Using the high-resolution digital elevation model (DEM) and linked digital geologic map makes it possible to compare areas of the different Pleistocene and Holocene units quantitatively and to constrain volumetric assessments and accumulation rates on the island for different units. The peak sediment volume production/accumulation rate—between 6.5 and 8 × 106 m3 or between 2.2 and 2.7 × 106 m3 per ka—is observed in the upper MIS 5e unit. This rate is 5 times greater than the 0.5 × 106 m3 per ka estimated for the Holocene ooid dune-ridge/strandplain complex, suggesting that the combination of higher sea level, greater wave and wind energy, and warmer ocean temperatures may have fostered the higher rate of chemically precipitated sediment supply. © 2018 Elsevier Ltd

Keyword :

Amino acid racemizations Carbonate stratigraphies Controlling parameters Digital elevation model Marine isotope stages Sea-level fluctuations Stratigraphic framework Stratigraphic records

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GB/T 7714 Kerans, Charles , Zahm, Chris , Bachtel, Steven L. et al. Anatomy of a late Quaternary carbonate island: Constraints on timing and magnitude of sea-level fluctuations, West Caicos, Turks and Caicos Islands, BWI [J]. | Quaternary Science Reviews , 2019 , 205 : 193-223 .
MLA Kerans, Charles et al. "Anatomy of a late Quaternary carbonate island: Constraints on timing and magnitude of sea-level fluctuations, West Caicos, Turks and Caicos Islands, BWI" . | Quaternary Science Reviews 205 (2019) : 193-223 .
APA Kerans, Charles , Zahm, Chris , Bachtel, Steven L. , Hearty, Paul , Cheng, Hai . Anatomy of a late Quaternary carbonate island: Constraints on timing and magnitude of sea-level fluctuations, West Caicos, Turks and Caicos Islands, BWI . | Quaternary Science Reviews , 2019 , 205 , 193-223 .
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Millennial and orbital scale variability of the South American Monsoon during the penultimate glacial period. PubMed SCIE
期刊论文 | 2019 , 9 , 1234 | Scientific reports
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The presence of large, rapid climate oscillations is the most prominent feature of the Earth's last glacial period. These oscillations are observed throughout the Northern Hemisphere and into the Southern Hemisphere tropics. Whether similar oscillations are typical of prior glacial periods, however, has not been well established. Here, we present results of a study of the South American Summer Monsoon system that covers nearly the entire penultimate glacial period, from 195 to 135 ky BP. We use a well-dated, high-resolution (~50 y) time series of oxygen isotopes to show that the precession of the earth's orbit is the primary control on monsoon intensity. After removing the precession signal we observe millennial oscillations that are very similar in amplitude and structure to the Dansgaard/Oeschger cycles of the last interglacial and that match well a synthetic reconstruction of millennial variability. Time series analyses shows that the most prominent of the observed cycles occur at considerably longer frequency (~3500 y) that the Dansgaard/Oeschger cycles from Marine Isotope Stages 2-4.

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GB/T 7714 Burns Stephen J , Welsh Lisa Kanner , Scroxton Nick et al. Millennial and orbital scale variability of the South American Monsoon during the penultimate glacial period. [J]. | Scientific reports , 2019 , 9 : 1234 .
MLA Burns Stephen J et al. "Millennial and orbital scale variability of the South American Monsoon during the penultimate glacial period." . | Scientific reports 9 (2019) : 1234 .
APA Burns Stephen J , Welsh Lisa Kanner , Scroxton Nick , Cheng Hai , Edwards R Lawrence . Millennial and orbital scale variability of the South American Monsoon during the penultimate glacial period. . | Scientific reports , 2019 , 9 , 1234 .
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Geochemical and isotopic (U, Th) variations in lake waters in the Qinghai Lake Basin, Northeast Qinghai-Tibet Plateau, China: origin and paleoenvironmental implications SCIE
期刊论文 | 2019 , 12 (3) | ARABIAN JOURNAL OF GEOSCIENCES
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A uranium (U) geochemical study of lake water samples from Qinghai Lake, Northeast Qinghai-Tibet Plateau, China, was undertaken to assess the primary controls on lake water chemistry. The U-234/U-238 activity ratios of lake water exhibited limited spatial and vertical variations and were relatively high compared to the values measured in rivers worldwide ((U-234/U-238)=1.171), lower than in the four river discharge inside the Lake Qinghai catchment. The U concentrations also varied minimally within three vertical sampling profiles and exhibited spatial patterns in surface waters that correlated with the distribution of total dissolved solid (TDS) values and salinity concentrations. These data suggest that the variability in U, TDS, and salinity are partially controlled by evaporation or a different secondary concentration pathway. Moreover, the U concentration and U-234/U-238 activity ratio indicates that the length of this procedure, which is controlled by the duration of water-rock interaction, is probably an important factor to consider when accounting for the variable salinities of lakes located in similar geographical areas. The Th-230(XS) content is primarily derived from the decay of dissolved U-234. The various (230)Thxs concentrations observed in the water column are interpreted to reflect various scavenging residence times in Qinghai Lake, ranging from 0.7 to 4years. The lower water mass age, such as at site 123, suggests a more rapid scavenging rate. Dissolved Th-232 is placed into the lake via the incomplete dissolution of lithogenic substances, such as dust aerosol, or other lithogenic sources (e.g., lake bed sediment or suspended riverine sediment). Water column Th-232 concentration data suggest that the Th concentrations of the lake water are controlled by three processes: (1) the dissolution of aerosol dust, (2) the dissolution of riverine and lake bed sediment, and (3) the scavenging of Th from the water.

Keyword :

Northeast Qinghai-Tibet Plateau Lake water chemistry China Qinghai Lake Basin U and Th isotopes Paleoenvironments

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GB/T 7714 Zhang, Pu , Cheng, Hai , Liu, Weiguo et al. Geochemical and isotopic (U, Th) variations in lake waters in the Qinghai Lake Basin, Northeast Qinghai-Tibet Plateau, China: origin and paleoenvironmental implications [J]. | ARABIAN JOURNAL OF GEOSCIENCES , 2019 , 12 (3) .
MLA Zhang, Pu et al. "Geochemical and isotopic (U, Th) variations in lake waters in the Qinghai Lake Basin, Northeast Qinghai-Tibet Plateau, China: origin and paleoenvironmental implications" . | ARABIAN JOURNAL OF GEOSCIENCES 12 . 3 (2019) .
APA Zhang, Pu , Cheng, Hai , Liu, Weiguo , Mo, Lingtong , Li, Xiangzhong , Ning, Youfeng et al. Geochemical and isotopic (U, Th) variations in lake waters in the Qinghai Lake Basin, Northeast Qinghai-Tibet Plateau, China: origin and paleoenvironmental implications . | ARABIAN JOURNAL OF GEOSCIENCES , 2019 , 12 (3) .
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An Abrupt Shift in the Indian Monsoon 4000 Years Ago CPCI-S CPCI-SSH Scopus
会议论文 | 2019 , 198 , 75-87 | American-Geophysical-Union (AGU) Chapman Conference on Climates, Past Landscapes, and Civilizations
WoS CC Cited Count: 75 SCOPUS Cited Count: 84
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The emergence of high-resolution proxy records from the Asian monsoon region suggests that the monsoon system is bistable and can abruptly transition between a suppressed and active state. This observation is critical in considering how the monsoon system may have influenced the development of societies across South and East Asia during the Holocene. Using a new high-resolution (similar to 5 years/sample) speleothem stable isotope record from northeast India that spans the early and mid-Holocene, a number of abrupt changes in the oxygen isotopic composition of precipitation (delta O-18(p)) are documented. The most dramatic of these events occurred similar to 4000 years ago when, over the course of approximately a decade, isotopic values abruptly rose above any seen during the early to mid-Holocene and remained at this anomalous state for almost two centuries. This event occurs nearly synchronously with climatic changes documented in a number of proxy records across North Africa, the Middle East, the Tibetan Plateau, southern Europe, and North America. We hypothesize that the excursion could represent a shift toward an earlier Indian Summer Monsoon withdrawal or a general decline in the total amount of monsoon precipitation. The new record provides a very significant advance with respect to age control and sample resolution of terrestrial climate change over South Asia during this period when a number of major societal changes occurred. While evidence of a causal relationship between climate and the reorganization of the Indus Valley and Old Kingdom Nile civilizations is beyond the scope of this study, the tight age constraints of the record show with a high degree of certainty that much of the documented deurbanization of the Indus Valley at 3.9 kyr B. P. occurred after multiple decades of a shift in the monsoon's character but before the monsoon returned to its previous mid-Holocene state.

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GB/T 7714 Berkelhammer, M. , Sinha, A. , Stott, L. et al. An Abrupt Shift in the Indian Monsoon 4000 Years Ago [C] . 2019 : 75-87 .
MLA Berkelhammer, M. et al. "An Abrupt Shift in the Indian Monsoon 4000 Years Ago" . (2019) : 75-87 .
APA Berkelhammer, M. , Sinha, A. , Stott, L. , Cheng, H. , Pausata, F. S. R. , Yoshimura, K. . An Abrupt Shift in the Indian Monsoon 4000 Years Ago . (2019) : 75-87 .
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Three-phased Heinrich Stadial 4 recorded in NE Brazil stalagmites SCIE
期刊论文 | 2019 , 510 , 94-102 | EARTH AND PLANETARY SCIENCE LETTERS
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The growth intervals of stalagmites from Northeast (NE) Brazil provide precise information on the timing of pluvial periods associated with the southward shift of the Intertropical Convergence Zone (ITCZ) during Heinrich Stadials (HS). Using Th-230 dating and annual band counting, we constrained the timing of the pluvial period associated with HS4 to occur between 40.06 +/- 0.11 and 38.38 +/- 0.10 thousand years before present (kyr B.P.), coinciding with the interval between the end of Greenland Interstadial (GIS)/Chinese Interstadial (CIS) 9 and GIS/CIS 8. Oxygen isotope analysis shows a close anti-correlation between NE Brazil wet periods and East Asian monsoon intensity recorded in Hulu Cave, supporting the hypothesis of a southerly migration of the global ITCZ during HS4. The pluvial anomaly can be divided into three phases, starting with a precursor, less intense pluvial interval (phase 1) between 40.06 +/- 0.11 and 39.59 +/- 0.10 kyr B.P., likely correlative to the cool phase of the North Atlantic immediately before the partial collapse of the Laurentide Ice Sheet (LIS). This phase ends abruptly (<30 yr) and is followed by an intense pluvial phase (phase 2) that spans approximately 5 centuries. Luminescent couplets are identified in all samples between 39.50 +/- 0.10 and 39.41 +/- 0.10 kyr B.P., and are interpreted as a period of two rainy seasons per year during which the southernmost extent of the inland West Atlantic ITCZ reached south of our study site (10 degrees S). Following the end of phase 2 at 39.07 +/- 0.32 kyr B.P., intermittent speleothem growth suggests intermittent rainfall over NE Brazil (phase 3) until the abrupt onset of GIS/CIS 8 at 38.38 +/- 0.10 kyr B.P. The phases identified in NE Brazilian stalagmites agree with the three-phased variation in low-latitude proxies registered in Northern Greenland, and are consistent with changes in methane concentrations recorded in the West Antarctic Ice Sheet (WAIS) Divide. The synchronicity of these distant records suggests a multi-phased response of tropical atmospheric circulation during HS4. The timescales surrounding the LIS collapse, as inferred from our precisely dated stalagmites, are on the same order as recent predictions for the impending collapse of the WAIS and may therefore serve as a past analogue. (C) 2018 Elsevier B.V. All rights reserved.

Keyword :

speleothem NE Brazil luminescent couplet ITCZ Heinrich Stadial pluvial phase

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GB/T 7714 Wendt, Kathleen A. , Hauselmann, Anamaria D. , Fleitmann, Dominik et al. Three-phased Heinrich Stadial 4 recorded in NE Brazil stalagmites [J]. | EARTH AND PLANETARY SCIENCE LETTERS , 2019 , 510 : 94-102 .
MLA Wendt, Kathleen A. et al. "Three-phased Heinrich Stadial 4 recorded in NE Brazil stalagmites" . | EARTH AND PLANETARY SCIENCE LETTERS 510 (2019) : 94-102 .
APA Wendt, Kathleen A. , Hauselmann, Anamaria D. , Fleitmann, Dominik , Berry, Akemi E. , Wang, Xianfeng , Auler, Augusto S. et al. Three-phased Heinrich Stadial 4 recorded in NE Brazil stalagmites . | EARTH AND PLANETARY SCIENCE LETTERS , 2019 , 510 , 94-102 .
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Intense hydrothermal scavenging of Th-230 and Pa-231 Pacific in the deep Southeast CPCI-S SCIE Scopus
会议论文 | 2018 , 201 , 212-228 | Conference on US Geotraces Eastern Tropical Pacific Transect (GP)
WoS CC Cited Count: 9 SCOPUS Cited Count: 12
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Hydrothermal circulation and subsequent eruption of seawater at mid-ocean ridges and back-arc basins has great potential to modulate deep ocean biogeochemistry, acting as both a source and a sink for many trace elements and their isotopes. The influence of hydrothermal vents as a source of iron and manganese has been demonstrated in all ocean basins. However, the long-range impact of scavenging by hydrothermal particles has yet to be documented in detail. We use dissolved and particulate measurements of long-lived radiogenic (Th-230, Pa-231) and primordial (Th-232) radionuclides to investigate the nature and geographic scale of scavenging processes occurring within a hydrothermal plume in the Southeast Pacific Ocean sampled during the GEOTRACES GP16 section. Due to their radioactive disequilibrium with respect to production by their parent uranium isotopes, Th-230 and Pa-231 provide unique insights into the rates of scavenging. We find strong deficits in Th-230 and Pa-231 coincident with elevated particulate Mn and Fe(OH)(3), indicating that trace metal scavenging is widespread and likely the result of the strong affinity of trace metals for nanoparticulate metal surface sites. The chemical composition of the particulate material is closely linked to the scavenging intensity of Th-230 and Pa-231, expressed as distribution coefficients between solid and solution. A comparison of Th-230 and Pa-231 inventories with mantle derived He-3 as well as a mass balance of Th-230 and Pa-231 suggests continuous scavenging removal over the course of the entire 4000 km transect. Unlike the two radiogenic isotopes, Th-232 is enriched above what would be expected from assuming identical scavenging behavior to Th-230, indicating a hydrothermal source of colloidal, unreactive Th-232.

Keyword :

Hydrothermal Thorium Scavenging East Pacific Rise Protactinium GEOTRACES

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GB/T 7714 Pavia, Frank , Anderson, Robert , Vivancos, Sebastian et al. Intense hydrothermal scavenging of Th-230 and Pa-231 Pacific in the deep Southeast [C] . 2018 : 212-228 .
MLA Pavia, Frank et al. "Intense hydrothermal scavenging of Th-230 and Pa-231 Pacific in the deep Southeast" . (2018) : 212-228 .
APA Pavia, Frank , Anderson, Robert , Vivancos, Sebastian , Fleisher, Martin , Lam, Phoebe , Lu, Yanbin et al. Intense hydrothermal scavenging of Th-230 and Pa-231 Pacific in the deep Southeast . (2018) : 212-228 .
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Contrasting Patterns in Abrupt Asian Summer Monsoon Changes in the Last Glacial Period and the Holocene SCIE Scopus
期刊论文 | 2018 , 33 (2) , 214-226 | PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
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Detailed Asian summer monsoon (ASM) variability across Heinrich stadials (HSs) 5 to 2 was reconstructed from four stalagmite oxygen isotopic (delta O-18) records in central and southern China. For the last glacial period, these speleothem records, combined with previous cave records, reveal a rapid ASM decline at the onset of each HS. During this time, ASM intensity decreases immediately to the weakest level within approximately 50years, which is followed by a gradual intensification in the mid-HS. Typically, this process of ASM weakening is synchronous with peak ice-rafted debris deposition and large freshwater outbursts into the North Atlantic, implying a tight link between the two. During the Holocene, however, a relatively gradual ASM decrease occurred at the start of the Bond events. Comparatively, the ASM decrease during the Bond events is generally accomplished within 110years, and the weakest ASM occurs near the end. This difference implicates a further southward displacement of the Intertropical Convergence Zone and a stronger impact from the Atlantic meridional overturning circulation on the ASM in the early HS. Moreover, contrasting expressions of the ASM during HSs and Bond events suggest that a fixed phase relationship during bipolar climate changes cannot be expected. Plain Language Summary The anatomy of internal structures in abrupt climate events under different climate boundaries is important for understanding the physical mechanisms. The delta O-18 records from Chinese cave deposits can be used as an indicator for Asian summer monsoon (ASM) variability, which is closely related to changes of North Atlantic climates and shifts of the Intertropical Convergence Zone. In this study, a comparison of delta O-18 records from different caves in China revealed that the ASM declined rapidly at the onset of the Heinrich events in the last glacial period but gradually at the onset of Bond events in the Holocene. This indicates that the volume of freshwater inputs into the North Atlantic during the Heinrich events was large, and the southerly movement of the Intertropical Convergence Zone was exceptionally significant. As an atmospheric bridge linking bipolar climate changes, different expressions in ASM variations in the last glacial and the Holocene should be considered when correlating northern and southern hemispheric climate changes.

Keyword :

Bond event Asian summer monsoon changes contrasting patterns of abrupt climate events Heinrich stadial Chinese speleothem records

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GB/T 7714 Liu, Dianbing , Wang, Yongjin , Cheng, Hai et al. Contrasting Patterns in Abrupt Asian Summer Monsoon Changes in the Last Glacial Period and the Holocene [J]. | PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY , 2018 , 33 (2) : 214-226 .
MLA Liu, Dianbing et al. "Contrasting Patterns in Abrupt Asian Summer Monsoon Changes in the Last Glacial Period and the Holocene" . | PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY 33 . 2 (2018) : 214-226 .
APA Liu, Dianbing , Wang, Yongjin , Cheng, Hai , Edwards, R. L. , Kong, Xinggong , Chen, Shitao et al. Contrasting Patterns in Abrupt Asian Summer Monsoon Changes in the Last Glacial Period and the Holocene . | PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY , 2018 , 33 (2) , 214-226 .
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Abrupt monsoonal shifts over the precessional cycles documented in Yongxing Cave in China during the antepenultimate glacial period EI SCIE Scopus
期刊论文 | 2018 , 77 (6) | ENVIRONMENTAL EARTH SCIENCES
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Precession is the major orbital control of monsoon intensity, but the monsoonal response to the transition between precessional cycles has yet to be explored. Here, we present an Asian Summer Monsoon history that spans 327.7-280.5 ka BP based on a Th-230-dated and centennially resolved multi-proxy speleothem record from Yongxing Cave, central China. The delta O-18 profile, a proxy of monsoon intensity, follows the summer insolation changes, with three abrupt shifts occurring at precessional transitions. These shifts are supported by the stalagmite delta C-13, grey-level and petrography analysis, indicating a coherent link between the karst processes and monsoon changes. Evidence from the coeval rapid changes in atmospheric CH4 and forest evolution records within dating errors suggests a wider regional signal of monsoon changes. The weak monsoon intervals are temporally consistent with the ice-rafted debris layers in the North Atlantic, indicating a strong coupling of the high-and low-latitude climate systems. We speculate that the abrupt monsoonal shifts are initiated by the south-north shifts of the Intertropical Convergence Zone associated with the Atlantic Meridional Overturning Circulation and further amplified by land cover. In addition, the rates and magnitudes of insolation changes modify monsoon shifts, thus indicating the abrupt monsoonal shift as a result of an interaction of orbital and millennial forcing.

Keyword :

Chinese stalagmite Asian Monsoon Interaction Abrupt shifts Precession cycle

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GB/T 7714 Liang, Yijia , Chen, Shitao , Zhang, Zhenqiu et al. Abrupt monsoonal shifts over the precessional cycles documented in Yongxing Cave in China during the antepenultimate glacial period [J]. | ENVIRONMENTAL EARTH SCIENCES , 2018 , 77 (6) .
MLA Liang, Yijia et al. "Abrupt monsoonal shifts over the precessional cycles documented in Yongxing Cave in China during the antepenultimate glacial period" . | ENVIRONMENTAL EARTH SCIENCES 77 . 6 (2018) .
APA Liang, Yijia , Chen, Shitao , Zhang, Zhenqiu , Yang, Shaohua , Li, Mingxia , Cheng, Hai et al. Abrupt monsoonal shifts over the precessional cycles documented in Yongxing Cave in China during the antepenultimate glacial period . | ENVIRONMENTAL EARTH SCIENCES , 2018 , 77 (6) .
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