Ziegler Martin

No Thumbnail Available
Last Name
Ziegler
First Name
Martin
ORCID

Filters

2015 - 2020 4
3 1
4
Reset filters

Settings

Search Results

Now showing 1 - 4 of 4
  • Article
    Intercomparison of XRF core scanning results from seven labs and approaches to practical calibration
    (American Geophysical Union, 2020-09-09) Dunlea, Ann G. ; Murray, Richard W. ; Tada, Ryuji ; Alvarez-Zarikian, Carlos A. ; Anderson, Chloe H. ; Gilli, Adrian ; Giosan, Liviu ; Gorgas, Thomas ; Hennekam, Rick ; Irino, Tomohisa ; Murayama, Masafumi ; Peterson, Larry C. ; Reichart, Gert-Jan ; Seki, Arisa ; Zheng, Hongbo ; Ziegler, Martin
    X‐ray fluorescence (XRF) scanning of marine sediment has the potential to yield near‐continuous and high‐resolution records of elemental abundances, which are often interpreted as proxies for paleoceanographic processes over different time scales. However, many other variables also affect scanning XRF measurements and convolute the quantitative calibrations of element abundances and comparisons of data from different labs. Extensive interlab comparisons of XRF scanning results and calibrations are essential to resolve ambiguities and to understand the best way to interpret the data produced. For this study, we sent a set of seven marine sediment sections (1.5 m each) to be scanned by seven XRF facilities around the world to compare the outcomes amidst a myriad of factors influencing the results. Results of raw element counts per second (cps) were different between labs, but element ratios were more comparable. Four of the labs also scanned a set of homogenized sediment pellets with compositions determined by inductively coupled plasma‐optical emission spectrometry (ICP‐OES) and ICP‐mass spectrometry (MS) to convert the raw XRF element cps to concentrations in two ways: a linear calibration and a log‐ratio calibration. Although both calibration curves are well fit, the results show that the log‐ratio calibrated data are significantly more comparable between labs than the linearly calibrated data. Smaller‐scale (higher‐resolution) features are often not reproducible between the different scans and should be interpreted with caution. Along with guidance on practical calibrations, our study recommends best practices to increase the quality of information that can be derived from scanning XRF to benefit the field of paleoceanography.
  • Preprint
    A warm and poorly ventilated deep Arctic Mediterranean during the last glacial period
    ( 2015-07) Thornalley, David J. R. ; Bauch, H. A. ; Gebbie, Geoffrey A. ; Guo, Weifu ; Ziegler, Martin ; Bernasconi, Stefano M. ; Barker, Stephen ; Skinner, Luke C. ; Yu, Jimin
    Changes in the formation of dense water in the Arctic Ocean and Nordic Seas (the ‘Arctic Mediterranean’, AM) likely contributed to the altered climate of the last glacial period. We examine past changes in AM circulation by reconstructing 14C ventilation ages of the deep Nordic Seas over the last 30,000 years. Our results show that the deep glacial AM was extremely poorly ventilated (ventilation ages of up to 10,000 years). Subsequent episodic overflow of aged water into the mid-depth North Atlantic occurred during deglaciation. Proxy data also suggest the deep glacial AM was ~2-3°C warmer than modern; deglacial mixing of the deep AM with the upper ocean thus potentially contributed to melting sea-ice and icebergs, as well as proximal terminal ice-sheet margins.
  • Article
    Consistently dated Atlantic sediment cores over the last 40 thousand years
    (Nature Research, 2019-09-02) Waelbroeck, Claire ; Lougheed, Bryan C. ; Vazquez Riveiros, Natalia ; Missiaen, Lise ; Pedro, Joel ; Dokken, Trond ; Hajdas, Irka ; Wacker, Lukas ; Abbott, Peter ; Dumoulin, Jean-Pascal ; Thil, Francois ; Eynaud, Frederique ; Rossignol, Linda ; Fersi, Wiem ; Albuquerque, Ana Luiza ; Arz, Helge W. ; Austin, William E. N. ; Came, Rosemarie E. ; Carlson, Anders E. ; Collins, James A. ; Dennielou, Bernard ; Desprat, Stéphanie ; Dickson, Alex ; Elliot, Mary ; Farmer, Christa ; Giraudeau, Jacques ; Gottschalk, Julia ; Henderiks, Jorijntje ; Hughen, Konrad A. ; Jung, Simon ; Knutz, Paul ; Lebreiro, Susana ; Lund, David C. ; Lynch-Stieglitz, Jean ; Malaizé, Bruno ; Marchitto, Thomas M. ; Martínez-Méndez, Gema ; Mollenhauer, Gesine ; Naughton, Filipa ; Nave, Silvia ; Nürnberg, Dirk ; Oppo, Delia W. ; Peck, Vicky L. ; Peeters, Frank J. C. ; Penaud, Aurélie ; Portilho-Ramos, Rodrigo da Costa ; Repschläger, Janne ; Roberts, Jenny ; Ruhlemann, Carsten ; Salgueiro, Emilia ; Sanchez Goni, Maria Fernanda ; Schönfeld, Joachim ; Scussolini, Paolo ; Skinner, Luke C. ; Skonieczny, Charlotte ; Thornalley, David J. R. ; Toucanne, Samuel ; Van Rooij, David ; Vidal, Laurence ; Voelker, Antje H. L. ; Wary, Mélanie ; Weldeab, Syee ; Ziegler, Martin
    Rapid changes in ocean circulation and climate have been observed in marine-sediment and ice cores over the last glacial period and deglaciation, highlighting the non-linear character of the climate system and underlining the possibility of rapid climate shifts in response to anthropogenic greenhouse gas forcing. To date, these rapid changes in climate and ocean circulation are still not fully explained. One obstacle hindering progress in our understanding of the interactions between past ocean circulation and climate changes is the difficulty of accurately dating marine cores. Here, we present a set of 92 marine sediment cores from the Atlantic Ocean for which we have established age-depth models that are consistent with the Greenland GICC05 ice core chronology, and computed the associated dating uncertainties, using a new deposition modeling technique. This is the first set of consistently dated marine sediment cores enabling paleoclimate scientists to evaluate leads/lags between circulation and climate changes over vast regions of the Atlantic Ocean. Moreover, this data set is of direct use in paleoclimate modeling studies.
  • Article
    High-resolution and high-precision correlation of dark and light layers in the Quaternary hemipelagic sediments of the Japan Sea recovered during IODP Expedition 346
    (Springer, 2018-03-26) Tada, Ryuji ; Irino, Tomohisa ; Ikehara, Ken ; Karasuda, Akinori ; Sugisaki, Saiko ; Xuan, Chuang ; Sagawa, Takuya ; Itaki, Takuya ; Kubota, Yoshimi ; Lu, Song ; Seki, Arisa ; Murray, Richard W. ; Alvarez-Zarikian, Carlos A. ; Anderson, William T. ; Bassetti, Maria-Angela ; Brace, Bobbi J. ; Clemens, Steven C. ; da Costa Gurgel, Marcio H. ; Dickens, Gerald R. ; Dunlea, Ann G. ; Gallagher, Stephen J. ; Giosan, Liviu ; Henderson, Andrew C. G. ; Holbourn, Ann E. ; Kinsley, Christopher W. ; Lee, Gwang Soo ; Lee, Kyung Eun ; Lofi, Johanna ; Lopes, Christina I. C. D. ; Saavedra-Pellitero, Mariem ; Peterson, Larry C. ; Singh, Raj K. ; Toucanne, Samuel ; Wan, Shiming ; Zheng, Hongbo ; Ziegler, Martin
    The Quaternary hemipelagic sediments of the Japan Sea are characterized by centimeter- to decimeter-scale alternation of dark and light clay to silty clay, which are bio-siliceous and/or bio-calcareous to a various degree. Each of the dark and light layers are considered as deposited synchronously throughout the deeper (> 500 m) part of the sea. However, attempts for correlation and age estimation of individual layers are limited to the upper few tens of meters. In addition, the exact timing of the depositional onset of these dark and light layers and its synchronicity throughout the deeper part of the sea have not been explored previously, although the onset timing was roughly estimated as ~ 1.5 Ma based on the result of Ocean Drilling Program legs 127/128. Consequently, it is not certain exactly when their deposition started, whether deposition of dark and light layers was synchronous and whether they are correlatable also in the earlier part of their depositional history. The Quaternary hemipelagic sediments of the Japan Sea were drilled at seven sites during Integrated Ocean Drilling Program Expedition 346 in 2013. Alternation of dark and light layers was recovered at six sites whose water depths are > ~ 900 m, and continuous composite columns were constructed at each site. Here, we report our effort to correlate individual dark layers and estimate their ages based on a newly constructed age model at Site U1424 using the best available paleomagnetic datum and marker tephras. The age model is further tuned to LR04 δ18O curve using gamma ray attenuation density (GRA) since it reflects diatom contents that are higher during interglacial high-stands. The constructed age model for Site U1424 is projected to other sites using correlation of dark layers to form a high-resolution and high-precision paleo-observatory network that allows to reconstruct changes in material fluxes with high spatio-temporal resolutions.