Weihe Basin Drilling Project (WBDP): Cenozoic tectonic-monsoon interactions

Author(s):  
Zhisheng An ◽  
Peter Molnar ◽  
Peizhen Zhang ◽  
Hendrik Vogel ◽  
Mark Level ◽  
...  

<p>Earth’s climate underwent dramatic cooling throughout much of the Cenozoic, which has been linked to continental drift, mountain building, and the formation and expansion of ice-sheets in Antarctica and the Arctic. In particular, the India-Asia collision and uplift of the Tibetan Plateau (TP) have been posited as critical events responsible for increasing the rates of physical and chemical weathering on land, thereby decreasing the CO2 concentration of the atmosphere. The uplift of the TP ultimately led to the onset of the complexly coupled monsoon-arid environmental system in East Asia. Global-scale studies of Cenozoic deep-sea sediments and Quaternary ice cores indicate that, superimposed to the long-term cooling trend, climate variability at orbital-to-centennial time-scales is primarily induced by changing solar insolation and irradiance, and strongly modulated by complex internal land-air-ocean interactions. From the continental perspective, however, both the dynamics and impacts of long-term climate evolution and short-term climate variability remain poorly constrained due to the paucity of continuous terrestrial sequences spanning the entire Cenozoic.<br>The Weihe Basin is located in the monsoon-sensitive region to the north of the Qinling Mountains, a landform that constitutes the geographic and climatic boundary between northern and southern China. In the depocentre of this basin, a predominantly lacustrine sedimentary sequence with a thickness of >7 km, provides an unprecedented opportunity for: (1) reconstructing tectonic-to-millennial-scale climate changes from the Eocene to the present; (2) elucidating basin-mountain coupling processes; (3) assessing the effects of Cenozoic tectonic-climate interactions on the onset and evolution of the Asian paleomonsoon; and (4) investigating climatic/environmental impacts on the evolution of microbial communities. Importantly also, (5) sedimentary filling of the Weihe Basin can potentially yield unique high-resolution records of continental climate variability during high atmospheric CO2 periods of the Eocene, mid-Miocene, and Late Pliocene, and thus serve an analog for Earth’s near future climate.<br>The Weihe Basin Drilling Project (WBDP) proposes a two-phase drilling strategy to recover a complete as possible Cenozoic terrestrial sedimentary record from the eastern Weihe Basin depocenter. In the first phase (applied for here) we aim at producing a 3-km-long pilot sedimentary record (WBDP-1) to test the best suitable analytical approach and to reconstruct orbital-to-millennial-scale climate variability since the Late Miocene. In the second phase our aim is to produce a 7.5-km-long sedimentary record (WBDP-2) spanning the entire Cenozoic sedimentary infill of the Weihe Basin. The regional geological framework is well characterized through numerous exploration boreholes and detailed multichannel seismic reflection surveys. Scientific drilling operations will be accompanied by downhole logging, as well as on- and off-site analyses of the retrieved cores. The WBDP-1 borehole is expected to yield a world-class paleoclimate record for the last ~10 Ma and lead to fundamental advances in our understanding of multi-timescale climate variability and tectonic-climate monsoon linkages. The project will also enhance public awareness of human adaptation to Earth’s changing environment.</p>

2020 ◽  
Vol 28 ◽  
pp. 63-73
Author(s):  
Zhisheng An ◽  
Peizhen Zhang ◽  
Hendrik Vogel ◽  
Yougui Song ◽  
John Dodson ◽  
...  

Abstract. The Weihe Basin, enclosed by the Chinese Loess Plateau to the north and the Qinling Mountains to the south, is an outstanding, world-class continental site for obtaining high-resolution multi-proxy records that reflect environmental changes spanning most of the Cenozoic. Previous geophysical and sedimentary studies indicate that the basin hosts 6000–8000 m thick fluvial–lacustrine sedimentary successions spanning the Eocene to Holocene. This sedimentary record provides an excellent and unique archive to decipher long-term tectonic–climate interactions related to the uplift of the Tibetan Plateau, the onset/evolution of the Asian monsoon, and the development of the biogeography of East Asia. Owing to its location at the interface of the opposing westerly and Asian monsoon circulation systems, the Weihe Basin also holds enormous promise for providing a record of changes in these circulation systems in response to very different boundary conditions since the Eocene. To develop an international scientific drilling programme in the Weihe Basin, the Institute of Earth Environment, Chinese Academy of Sciences, organized a dedicated workshop with 55 participants from eight countries. The workshop was held in Xi'an, China, from 15 to 18 October 2019. Workshop participants conceived the key scientific objectives of the envisaged Weihe Basin Drilling Project (WBDP) and discussed technical and logistical aspects as well as the scope of the scientific collaboration in preparation for a full drilling proposal for submission to the International Continental Scientific Drilling Program (ICDP). Workshop participants mutually agreed to design a two-phase scientific drilling programme that will in a first phase target the upper 3000 m and in a second phase the entire up to 7500 m thick sedimentary infill of the basin. For the purpose of the 7500 m deep borehole, the world's only drill rig for ultra-deep scientific drilling on land, Crust 1, which previously recovered the entire continental Cretaceous sediments in the Songliao Basin, will be deployed in the WBDP.


2021 ◽  
Author(s):  
Maria Hoerhold ◽  
Thomas Münch ◽  
Stefanie Weißbach ◽  
Sepp Kipfstuhl ◽  
Bo Vinther ◽  
...  

<p>Climate variability of the Arctic region has been investigated by means of temperature reconstructions based on proxies from various climate archives around the Arctic, compiled over the last 2000a in the so called Arctic2k record. However, the representativeness of the Arctic2k reconstruction for central Greenland remains unclear, since only a few ice cores have been included in the reconstruction, and observations from the Greenland Ice Sheet (GIC) report ambiguous warming trends for the end of the 20th and the beginning of the 21st century which are not displayed by Arctic2k. Today, the GIC experiences periods with temperatures close to or above the freezing point at high elevations, area-wide melting and mass loss. In order to assess the recent warming as signature of global climate change, records of past climate changes with appropriate temporal and spatial coverage can serve as a benchmark for naturally driven climate variability. Instrumental records for Greenland are short and geographically sparse, and existing temperature reconstructions from single ice cores are noisy, leading to an inconclusive assessment of the recent warming for Greenland.</p><p>Here, we provide a Greenland firn-core stack covering the time span of the last millennium until the first decade of the 21<sup>st </sup>century in unprecedented quality by re-drilling as well as analyzing 16 existing firn core sites. We find a strong decadal to bi-decadal natural variability in the record, and, while the record exhibits several warming events with trends that show a similar amplitude as the recent one, we find that the recent absolute values of stable oxygen isotope composition are unprecedented for the last 1000 years.</p><p> </p><p>Comparing our Greenland record with the Arctic 2k temperature reconstruction shows that the correlation between the two records changes throughout the last millennium. While in the periods of 1200-1300 and 1400-1650 CE the records correlate positively, between 1300 and 1400 and 1650-1700 CE shorter periods with negative correlation are found. Since then the correlation is characterized by alternation between positive and zero correlation, with a drop towards negative values at the end of the 20<sup>th</sup> century. Including re-analysis data, we hypothesize that the climate on top of the GIC was decoupled from the surrounding Arctic for the last decades, leading to the observed mismatch in observations of warming trends.</p><p>We suggest that the recently observed Greenland temperatures are a superposition of a strong natural variability with an anthropogenic long-term trend. Our findings illustrate that global warming has reached the interior of the Greenland ice sheet, which will have implications for its surface mass balance and Greenland’s future contribution to sea level rise.</p><p>Our record complements the Arctic 2k record to a profound view on the Arctic climate variability, where regional compilations may not be representative for specific areas.</p>


2013 ◽  
Vol 9 (2) ◽  
pp. 679-686 ◽  
Author(s):  
L. Cunningham ◽  
H. Vogel ◽  
V. Wennrich ◽  
O. Juschus ◽  
N. Nowaczyk ◽  
...  

Abstract. To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El'gygytgyn in northeast Arctic Russia. Sediments from this lake contain a paleoclimate record of glacial-interglacial cycles during the last three million years. Low-resolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical parameters are used to infer past climatic conditions thus providing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Following this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.


The Holocene ◽  
2007 ◽  
Vol 17 (7) ◽  
pp. 939-953 ◽  
Author(s):  
Filipa Naughton ◽  
Jean-François Bourillet ◽  
Maria Fernanda Sánchez Goñi ◽  
Jean-Louis Turon ◽  
Jean-Marie Jouanneau

2004 ◽  
Vol 39 ◽  
pp. 585-594 ◽  
Author(s):  
Susan Kaspari ◽  
Paul A. Mayewski ◽  
Daniel A. Dixon ◽  
Vandy Blue Spikes ◽  
Sharon B. Sneed ◽  
...  

AbstractThirteen annually resolved accumulation-rate records covering the last ~200 years from the Pine Island–Thwaites and Ross drainage systems and the South Pole are used to examine climate variability over West Antarctica. Accumulation is controlled spatially by the topography of the ice sheet, and temporally by changes in moisture transport and cyclonic activity. A comparison of mean accumulation since 1970 at each site to the long-term mean indicates an increase in accumulation for sites located in the western sector of the Pine Island–Thwaites drainage system. Accumulation is negatively associated with the Southern Oscillation Index (SOI) for sites near the ice divide, and periods of sustained negative SOI (1940–42, 1991–95) correspond to above-mean accumulation at most sites. Correlations of the accumulation-rate records with sea-level pressure (SLP) and the SOI suggest that accumulation near the ice divide and in the Ross drainage system may be associated with the mid-latitudes. The post-1970 increase in accumulation coupled with strong SLP–accumulation-rate correlations near the coast suggests recent intensification of cyclonic activity in the Pine Island– Thwaites drainage system.


2018 ◽  
Author(s):  
Dimitri Osmont ◽  
Isabel A. Wendl ◽  
Loïc Schmidely ◽  
Michael Sigl ◽  
Carmen P. Vega ◽  
...  

Abstract. Produced by the incomplete combustion of fossil fuel and biomass, black carbon (BC) contributes to Arctic warming by reducing snow albedo and thus triggering a snow-albedo feedback leading to increased snow melting. Therefore, it is of high importance to assess past BC emissions to better understand and constrain their role. However, only few long-term BC records are available from the Arctic, mainly originating from Greenland ice cores. Here, we present the first long-term and high-resolution refractory black carbon (rBC) record from Svalbard, derived from the analysis of two ice cores drilled at the Lomonosovfonna ice field in 2009 (LF-09) and 2011 (LF-11) and covering 800 years of atmospheric emissions. Our results show that rBC concentrations strongly increased from 1860 on due to anthropogenic emissions and reached two maxima, at the end of the 19th century and in the middle of the 20th century. No increase in rBC concentrations during the last decades was observed, which is corroborated by atmospheric measurements elsewhere in the Arctic but contradicts a previous study from another ice core from Svalbard. While melting may affect BC concentrations during periods of high temperatures, rBC concentrations remain well-preserved prior to the 20th century due to lower temperatures inducing little melt. Therefore, the preindustrial rBC record (before 1800), along with ammonium (NH4+), formate (HCOO−) and specific organic markers (vanillic acid (VA) and p-hydroxybenzoic acid (p-HBA)), was used as a proxy for biomass burning. Despite numerous single events, no long-term trend was observed over the time period 1222–1800 for rBC and NH4+. In contrast, formate, VA and p-HBA experience multi-decadal peaks reflecting periods of enhanced biomass burning. Most of the background variations and single peak events are corroborated by other ice-core records from Greenland and Siberia. We suggest that the paleofire record from the LF ice core primarily reflects biomass burning episodes from Northern Eurasia, induced by decadal-scale climatic variations.


Radiocarbon ◽  
2007 ◽  
Vol 49 (2) ◽  
pp. 837-854 ◽  
Author(s):  
V A Dergachev ◽  
O M Raspopov ◽  
F Damblon ◽  
H Jungner ◽  
G I Zaitseva

High-precision radiocarbon age calibration for different terrestrial samples allows us to establish accurate boundaries for many climatic time series. At the same time, the fluctuations of 14C content reflect solar variability. A bispectrum analysis of long-term series of the 14C content deduced from decadal measurements in tree rings demonstrates the existence of amplitude modulation, with a period of main modulation of ∼2400 yr. In 14C time series for the last 11 kyr, major oscillations are distinguished at 8.5–7.8, 5.4–4.7, 2.6–2.2, and 1.1–0.4 cal kyr BP with ∼2400-yr periodicity. High amplitudes in cosmogenic isotope content with a periodicity of about 2400 yr appear synchronous to cooling events documented in Greenland ice cores, to the timing of worldwide Holocene glacier expansion, and to the periods of lake-level changes. This paper focuses on revealing solar forcing on the Earth's climate and about the nature, significance, and impact of sharp Holocene climate variability on human societies and civilizations.


2015 ◽  
Vol 2 (4) ◽  
pp. 489-492 ◽  
Author(s):  
Jane Qiu

Abstract The Tibetan Plateau and surrounding mountain regions covers 5 million square kilometres—nearly half the China's landmass—with an average elevation of over 4000 metres. It's often regarded as the Third Pole because it has the largest stock of ice outside the Arctic and the Antarctic. Tibetan Plateau research is one of China's Strategic Pioneering Programmes that was launched in 2012 with a budget of 300 million yuan (US $47 million) over 5 years and is led by Chinese Academy of Sciences (CAS)’ Institute of Tibetan Plateau Research (ITP) in Beijing. In January 2014, CAS set up the Centre for Excellence in Tibetan Plateau Earth Sciences, headquartered in ITP, aiming at providing long-term support for this area of research and raising academic standards. NSR recently talked to glaciologist Tandong Yao and geologist Weiming Fan—ITP's director and deputy director, respectively—about why Tibetan Plateau research is important, what it is like to work there, how the region is faring in face of climate change and why international collaboration is important.


2020 ◽  
pp. 1-13
Author(s):  
Joanna Charton ◽  
Vincent Jomelli ◽  
Irene Schimmelpfennig ◽  
Deborah Verfaillie ◽  
Vincent Favier ◽  
...  

Abstract Debris-covered glaciers constitute a large part of the world's cryosphere. However, little is known about their long-term response to multi-millennial climate variability, in particular in the Southern Hemisphere. Here, we provide first insights into the response of a debris-covered glacier to multi-millennial climate variability in the sub-Antarctic Kerguelen Archipelago, which can be compared to that of recently investigated debris-free glaciers. We focus on the Gentil Glacier and present 13 new 36Cl cosmic-ray exposure ages from moraine boulders. The Gentil Glacier experienced at least two glacial advances: the first one during the Late Glacial (19.0–11.6 ka) at ~14.3 ka and the second one during the Late Holocene at ~2.6 ka. Both debris-covered and debris-free glaciers advanced broadly synchronously during the Late Glacial, most probably during the Antarctic Cold Reversal event (14.5–12.9 ka). This suggests that both glacier types at Kerguelen were sensitive to abrupt temperature changes recorded in Antarctic ice cores, associated with increased moisture. However, during the Late Holocene, the advance at ~2.6 ka was not observed in other glaciers and seems to be an original feature of the debris-covered Gentil Glacier, related to either distinct dynamics or to distinct sensitivity to precipitation changes.


2012 ◽  
Vol 8 (6) ◽  
pp. 5341-5358 ◽  
Author(s):  
L. Cunningham ◽  
H. Vogel ◽  
V. Wennrich ◽  
O. Juschus ◽  
N. Nowaczyk ◽  
...  

Abstract. To date, terrestrial archives of long-term climatic change within the arctic region have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El'gygytgyn in Northeast Arctic Russia. Sediments from this lake contain a paleoclimate record of glacial-interglacial cycles during the last three million years. Low resolution studies at this lake have suggested that changes observed during Transition IV are of greater amplitude than any observed since. In this study, geochemical parameters are used to infer past climatic conditions thus providing the first high resolution analyses of Transition IV from a terrestrial arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica production. Following this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and biogenic silica (BSi) records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.


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