Zhang Wentong, Pang Jiangli, Lü Ye, et al. Chroma characteristics of the Mituosi profile in the upper Hanjiang River and their paleoenvironmental implications[J/OL]. Acta Scientiarum Naturalium Universitatis Sunyatseni, 2026, 1-8.
DOI:
Zhang Wentong, Pang Jiangli, Lü Ye, et al. Chroma characteristics of the Mituosi profile in the upper Hanjiang River and their paleoenvironmental implications[J/OL]. Acta Scientiarum Naturalium Universitatis Sunyatseni, 2026, 1-8. DOI: 10.11714/acta.snus.ZR20250268.
Chroma characteristics of the Mituosi profile in the upper Hanjiang River and their paleoenvironmental implications
相反,在古土壤层中为高值(平均值为0.39)。色度参数与磁化率、黏粒含量及Rb/Sr的相关性具有统计学意义,证实其可作为有效的古气候替代指标。揭示了研究区全新世早期(11.5~8.0 ka BP)气候冷干,成壤作用弱;中期(8.0~3.1 ka BP)气候暖湿,成壤作用强烈,但在约6.48 ka BP前后出现显著的冷干波动事件;晚期(3.1 ka BP以来)气候再次转向冷干。研究成果不仅为汉江上游古气候重建提供了新证据,也深化了对南北过渡带气候演变规律的理解。
Abstract
The upper reaches of the Hanjiang River are located in the north-south climatic transition zone of China, where sedimentary sequences are crucial for revealing the evolution history of the East Asian monsoon. This study examined the Mituosi profile in the upper Hanjiang River. Chromaticity parameters were systematically measured and integrated with magnetic susceptibility and grain size to assess their paleoclimatic significance and reconstruct the Holocene climate evolution. The results show that lightness
L
*
is negatively correlated with Fe
2
O
3
content (
R
=-0.83). Influenced by organic matter content,
L
*
values are lowest in the paleosol layer (average 48.41), reflecting strong pedogenesis. Redness
a
*
exhibits a significant positive correlation with Fe₂O₃ content (
R
=0.77), reaching peak value in the paleosol layer (average 4.99). This reflects the enrichment of iron oxides under warm and humid conditions. Yellowness
b
*
and hue angle
h
*
display maximum values in the cold-dry Malan loess unit and decline in the paleosol layer. Conversely, the
a
*
/
b
*
ratio shows an opposite trend to
h
*
, with a high value (average 0.39) in the paleosol layer. Significa
nt correlations among chromaticity parameters and magnetic susceptibility, clay content, and the Rb/Sr ratio confirming their utility as reliable paleoclimate proxies. The record reveals a cold, dry early Holocene (11.5~8.0 ka BP) characterized by weak pedogenesis. This was followed by warm, humid mid-Holocene (8.0~3.1 ka BP)with strong pedogenesis, albeit interrupted by a significant cold-dry event at ~6.48 ka BP. The late Holocene (since ~3.1 ka BP) saw a return to cold, dry climates. These findings not only provide new evidence for paleoclimate reconstruction in the upper Hanjiang River but also enhance our understanding of climate dynamics in the north-south transition zone.
Balsam W L , Deaton B C , Damuth J E , 1999 . Evaluating optical lightness as a proxy for carbonate content in marine sediment cores [J]. Mar Geol , 161 ( 2/3/4 ): 141 - 153 .
Bloemendal J , Demenocal P , 1989 . Evidence for a change in the periodicity of tropical climate cycles at 2.4 Myr from whole-core magnetic susceptibility measurements [J]. Nature , 342 ( 6252 ): 897 - 900 .
Pang H , Jia Y , 2025 . Sedimentary records of paleoflood events in the desert section of the upper Yellow River since the late quaternary [J]. Atmosphere , 16 ( 9 ): 1019 .
Sun Y , He L , Liang L , et al , 2011 . Changing color of Chinese loess: Geochemical constraint and paleoclimatic significance [J]. J Asian Earth Sci , 40 ( 6 ): 1131 - 1138 .
Wang Y , Song Y , Li Y , et al , 2025 . New interpretation of the Rb/Sr ratio of the Ili loess, northeastern Central Asia [J]. Quat Sci Rev , 368 : 109549 .
Zhou L P , Shackleton N J , 2001 . Photon-stimulated luminescence of quartz from loess and effects of sensitivity change on palaeodose determination [J]. Quat Sci Rev , 20( 5 / 6 /7/ 8 / 9 ): 853 - 857 .