Xianghui Kong

Bio: Xianghui Kong is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Loess & Materials science. The author has an hindex of 6, co-authored 17 publications receiving 250 citations. Previous affiliations of Xianghui Kong include Xi'an Jiaotong University & University of Arizona.

A 550,000-year record of East Asian monsoon rainfall from 10Be in loess

Abstract: Cosmogenic 10 Be flux from the atmosphere is a proxy for rainfall. Using this proxy, we derived a 550,000-year-long record of East Asian summer monsoon (EASM) rainfall from Chinese loess. This record is forced at orbital precession frequencies, with higher rainfall observed during Northern Hemisphere summer insolation maxima, although this response is damped during cold interstadials. The 10 Be monsoon rainfall proxy is also highly correlated with global ice-volume variations, which differs from Chinese cave δ 18 O, which is only weakly correlated. We argue that both EASM intensity and Chinese cave δ 18 O are not governed by high-northern-latitude insolation, as suggested by others, but rather by low-latitude interhemispheric insolation gradients, which may also strongly influence global ice volume via monsoon dynamics.

Postglacial changes in the Asian summer monsoon system: a pollen record from the eastern margin of the Tibetan Plateau

Abstract: Zhou, W., Yu, S.-Y., Burr, G. S., Kukla, G. J., Jull, A. J. T., Xian, F., Xiao, J., Colman, S. M., Yu, H., Liu, Z. & Kong, X. 2010: Postglacial changes in the Asian summer monsoon system: a pollen record from the eastern margin of the Tibetan Plateau. Boreas, Vol. 39, pp. 528–539. 10.1111/j.1502-3885.2010.00150.x. ISSN 0300-9483. A new pollen record constrained by 32 AMS radiocarbon dates from the Hongyuan peatland in the Zoige Basin reveals the long-term dynamics of an alpine wetland ecosystem on the eastern margin of the Tibetan Plateau over the last 13 500 years. Changes in pollen assemblages and influxes suggest that local vegetation has experienced three distinct stages, from alpine coniferous forest–meadow (13 500–11 500 cal. a BP), through alpine coniferous forest (11 500–3000 cal. a BP), back to alpine coniferous forest–meadow (3000 cal. a BP–present). This record reflects an ecosystem response along a transition zone where the South Asian and East Asian monsoon systems may have had different palaeoclimatic influences. A comparison of this record with other pollen records across the Tibetan Plateau shows common features with regard to large-scale Holocene climatic changes, but highlights a pattern of regional temporal and spatial variability that depends on the topography and position relative to the South Asian and East Asian monsoon fronts.

The last 130 ka precipitation reconstruction from Chinese loess 10Be

Abstract: Cosmogenic 10Be is a promising precipitation index, because its fallout flux in sediments is mainly controlled by wet precipitation after its production in the atmosphere. Here we report on a new study for reconstructing precipitation during the last 130 ka using 10Be measurements from Chinese loess, with multivariable linear regression to remove the geomagnetic field modulation and dust flux dilution effects from the loess 10Be record. The broad similarity between our result and speleothem δ18O indicates that the new precipitation record is robust. It also records an interesting increase in precipitation that occurred during Marine Isotope Stage 3 (MIS 3), exhibiting a similar rainfall amount with that of MIS 5, suggesting that MIS 3 is a special period with strengthened summer Monsoon intensity. By comparison with a stacked marine isotope record and a summer insolation record, our precipitation data clearly show a close correspondence with Northern Hemisphere summer (June, July, and August) solar insolation changes on orbital timescales. During MIS 3, our record follows the insolation differential between 30°N and 30°S, suggesting that rising rainfall changes during MIS 3 are a response to the interhemispheric summer insolation differential forcing.

Timing of the Brunhes-Matuyama magnetic polarity reversal in Chinese loess using 10Be

Abstract: In Chinese loess, the Brunhes-Matuyama (B-M) geomagnetic reversal occurs ∼25 k.y. prior to the age found in marine sediments. This offset has been attributed by some to post-depositional magnetic overprinting of loess, while others have argued it is due to errors in the loess time scale. Here we solve this long-standing debate by exploiting a new method to extract reproducible records of geomagnetic field intensity from loess with 10 Be—a proxy for global average geomagnetic field intensity—and using it to show that a pronounced minimum in field intensity (a requirement for dipole field reversal) is recorded in two separate loess records at ca. 780 ± 3 kyr B.P. This timing is synchronous with the B-M reversal timing seen in marine records, verifying the standard loess time scale as correct, but it is ∼25 k.y. younger than the age (depth) of the magnetic polarity reversal recorded in these same Chinese loess sediments, demonstrating that loess magnetic overprinting has occurred.

Reconstruction of 130-kyr Relative Geomagnetic Intensities from 10Be in Two Chinese Loess Sections

Abstract: Efforts to extract weak geomagnetic excursion signals from Chinese loess-paleosol 10Be have generally been unsuccessful due to the complexities of its accumulation, because the geomagnetic and climate (precipitation and dust) signals contained in loess-paleosol sequence are tightly overprinted. Here, we present a reconstruction of geomagnetic relative paleointensities for the past 130 kyr from 10Be records in 2 Chinese loess-paleosol sections using a correction based on the correlation of 10Be with magnetic susceptibility (SUS) to remove the climatic contamination. Both these records reveal the Laschamp and Blake events, which lie in the loess and paleosol (L1SS1 and S1SS3) horizons corresponding to mid-MIS 3 and 5e, respectively. The good agreement between our results and other geomagnetic intensities reconstructions from Atlantic and Pacific sediments indicates that our method is robust. Our study suggests the potential application of loess-paleosol 10Be for reconstructing geomagnetic intensity variations spanning the whole Quaternary.

A late Middle Pleistocene Denisovan mandible from the Tibetan Plateau

Abstract: Denisovans are members of a hominin group who are currently only known directly from fragmentary fossils, the genomes of which have been studied from a single site, Denisova Cave1–3 in Siberia. They are also known indirectly from their genetic legacy through gene flow into several low-altitude East Asian populations4,5 and high-altitude modern Tibetans6. The lack of morphologically informative Denisovan fossils hinders our ability to connect geographically and temporally dispersed fossil hominins from Asia and to understand in a coherent manner their relation to recent Asian populations. This includes understanding the genetic adaptation of humans to the high-altitude Tibetan Plateau7,8, which was inherited from the Denisovans. Here we report a Denisovan mandible, identified by ancient protein analysis9,10, found on the Tibetan Plateau in Baishiya Karst Cave, Xiahe, Gansu, China. We determine the mandible to be at least 160 thousand years old through U-series dating of an adhering carbonate matrix. The Xiahe specimen provides direct evidence of the Denisovans outside the Altai Mountains and its analysis unique insights into Denisovan mandibular and dental morphology. Our results indicate that archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene epoch and successfully adapted to high-altitude hypoxic environments long before the regional arrival of modern Homo sapiens. Fossil evidence indicates that Denisovans occupied the Tibetan Plateau in the Middle Pleistocene epoch and successfully adapted to this high-altitude hypoxic environments long before the regional arrival of modern Homo sapiens.