Jingjing Guo, Martin Ziegler, Louise Fuchs, Youbin Sun, Francien Peterse
{"title":"Quantitative reconstruction of past monsoon precipitation based on tetraether membrane lipids in Chinese loess","authors":"Jingjing Guo, Martin Ziegler, Louise Fuchs, Youbin Sun, Francien Peterse","doi":"10.5194/egusphere-2024-1648","DOIUrl":null,"url":null,"abstract":"<strong>Abstract.</strong> Variations in the oxygen isotope composition (δ<sup>18</sup>O) of cave speleothems and numerous proxy records from loess-paleosol sequences have revealed past variations in East Asian monsoon (EAM) intensity. However, challenges persist in reconstructing precipitation changes quantitatively. Here, we use the positive relationship between the degree of cyclization (DC) of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in modern surface soils from the Chinese loess Plateau (CLP) and mean annual precipitation (MAP) to quantify past monsoon precipitation changes on the CLP. We present a new ~130,000-year long DC-based MAP record for the Yuanbao section on the western edge of CLP, which closely tracks the orbital- and millennial-scale variations in both the speleothem δ<sup>18</sup>O record and the hydrogen isotope composition of plant waxes (δ<sup>2</sup>H<sub>wax</sub>) from the same section. Combing our new data with existing brGDGT records from other CLP sites reveals a spatial gradient in MAP that is most pronounced during glacials, when the western CLP experiences more arid conditions and receives up to ~250 mm less precipitation than in the southeast, whereas MAP is ~850 mm across the CLP during the Holocene optimum. Furthermore, the DC records show that precipitation amount on the CLP varies at the precession as well as obliquity scale, as opposed to the primarily precession scale variations in speleothem δ<sup>18</sup>O and δ<sup>2</sup>H<sub>wax</sub> at Yuanbao, and the 100-kyr cycle in other loess proxies such as magnetic susceptibility, which rather indicates the relative intensity of the EAM. At the precession scale, the DC record is in phase with δ<sup>2</sup>H<sub>wax</sub> from same section as well as the speleothem δ<sup>18</sup>O record, which supports the hypothesis that monsoon precipitation is driven by northern hemisphere summer insolation.","PeriodicalId":10332,"journal":{"name":"Climate of The Past","volume":"27 1","pages":""},"PeriodicalIF":3.8000,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Climate of The Past","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5194/egusphere-2024-1648","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Abstract. Variations in the oxygen isotope composition (δ18O) of cave speleothems and numerous proxy records from loess-paleosol sequences have revealed past variations in East Asian monsoon (EAM) intensity. However, challenges persist in reconstructing precipitation changes quantitatively. Here, we use the positive relationship between the degree of cyclization (DC) of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in modern surface soils from the Chinese loess Plateau (CLP) and mean annual precipitation (MAP) to quantify past monsoon precipitation changes on the CLP. We present a new ~130,000-year long DC-based MAP record for the Yuanbao section on the western edge of CLP, which closely tracks the orbital- and millennial-scale variations in both the speleothem δ18O record and the hydrogen isotope composition of plant waxes (δ2Hwax) from the same section. Combing our new data with existing brGDGT records from other CLP sites reveals a spatial gradient in MAP that is most pronounced during glacials, when the western CLP experiences more arid conditions and receives up to ~250 mm less precipitation than in the southeast, whereas MAP is ~850 mm across the CLP during the Holocene optimum. Furthermore, the DC records show that precipitation amount on the CLP varies at the precession as well as obliquity scale, as opposed to the primarily precession scale variations in speleothem δ18O and δ2Hwax at Yuanbao, and the 100-kyr cycle in other loess proxies such as magnetic susceptibility, which rather indicates the relative intensity of the EAM. At the precession scale, the DC record is in phase with δ2Hwax from same section as well as the speleothem δ18O record, which supports the hypothesis that monsoon precipitation is driven by northern hemisphere summer insolation.
期刊介绍:
Climate of the Past (CP) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on the climate history of the Earth. CP covers all temporal scales of climate change and variability, from geological time through to multidecadal studies of the last century. Studies focusing mainly on present and future climate are not within scope.
The main subject areas are the following:
reconstructions of past climate based on instrumental and historical data as well as proxy data from marine and terrestrial (including ice) archives;
development and validation of new proxies, improvements of the precision and accuracy of proxy data;
theoretical and empirical studies of processes in and feedback mechanisms between all climate system components in relation to past climate change on all space scales and timescales;
simulation of past climate and model-based interpretation of palaeoclimate data for a better understanding of present and future climate variability and climate change.