Browsing by Author "Lindhorst, Sebastian"
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- Correction to: A two million year record of low-latitude aridity linked to continental weathering from the MaldivesPublication . Kunkelova, Tereza; Jung, Simon J. A.; de Leau, Erica S.; Odling, Nick; Thomas, Alex L.; Betzler, Christian; Eberli, Gregor P.; Alvarez-Zarikian, Carlos A.; Alonso-Garcia, Montserrat; Bialik, Or M.; Blättler, Clara L.; Guo, Junhua A.; Haffen, Sébastien; Horozal, Senay; Mee, Anna L. H.; Inoue, Mayuri; Jovane, Luigi; Lanci, Luca; Laya, Juan C.; Lüdmann, Thomas; Bejugam, Nagender N.; Nakakuni, Masatoshi; Niino, Kaoru; Petruny, Loren M.; Pratiwi, Santi D.; Reijmer, John J. G.; Reolid, Jesús; Slagle, Angela L.; Sloss, Craig R.; Su, Xiang; Swart, Peter K.; Wright, James D.; Yao, Zhengquan; Young, Jeremy R.; Lindhorst, Sebastian; Stainbank, Stephanie; Rueggeberg, Andres; Spezzaferri, Silvia; Carrasqueira, Igor; Yu, Siyao; Kroon, DickIn the original version of this article (Kunkelova et al. 2018), published on 18 December 2018, there was 1 error in the author name of Dr. Yu.
- Ostracod response to monsoon and OMZ variability over the past 1.2 MyrPublication . Alvarez Zarikian, Carlos A.; Nadiri, Chimnaz; Alonso-Garcia, Montserrat; Rodrigues, Teresa; Huang, Huai-Hsuan M.; Lindhorst, Sebastian; Kunkelova, Tereza; Kroon, Dick; Betzler, Christian; Yasuhara, MoriakiWe present the first continuous middle through late Pleistocene record of fossil ostracods from the Maldives in the northern Indian Ocean, derived from sediment cores taken at Site U1467 by Expedition 359 of the International Ocean Discovery Program (IODP). Site U1467 lies at 487 m water depth in the Inner Sea of the Maldives archipelago, an ideal place for studying the effects of the South Asian Monsoon (SAM) system on primary productivity, intermediate depth ocean circulation, and the regional oxygen minimum zone (OMZ). The Inner Sea acts as a natural sediment trap that has undergone continuous sedimentation for millions of years with minor terrestrial influence. Our record spans from Marine Isotope Stage (MIS) 35 to the present, covering the mid Pleistocene transition (1.2-0.6 Ma) and the Mid-Brunhes Event (MBE, at similar to 480 ka) the time when ice age cycles transitioned from occurring every 40,000 years to 100,000 years. The ostracod data is interpreted alongside the existing datasets from the same site of sedimentological (grain-size) and XRF-elemental analyses, and new organic biomarker data also from Site U1467. These datasets support the paleoenvironmental interpretation of the ostracod assemblages. Ostracods are abundant and diverse, displaying a prominent change in faunal composition at the MBE related to the increase in the amplitude of glacial-interglacial cycles, which deeply affected the monsoon system and thereby the past oceanographic conditions of the Maldives Inner Sea. Furthermore, ostracods exhibit distinctly different assemblages across glacial-interglacial cycles, particularly after the MBE, and these changes convincingly correspond to variability of the OMZ. Glacial periods are characterized by ostracod indicators of well-oxygenated bottom water due to the intensification of the winter monsoon and the contraction of the OMZ. Abundant psychrospheric ostracods during glacials suggests that a southern sourced water mass, such as Antarctic Intermediate Water (AAIW) and/or Subantarctic Mode water, bathed the Maldives Inner Sea during glacial periods. In contrast, interglacial stages are characterized by ostracod species and biomarker data that indicate low-oxygen conditions and sluggish bottom water circulation pointing to an expansion of the regional OMZ due to the strengthening of the summer monsoon. Our results highlight the sensitivity of ostracods to oceanographic and climate variability.
- A two million year record of low-latitude aridity linked to continental weathering from the MaldivesPublication . Kunkelova, Tereza; Jung, Simon J. A.; de Leau, Erica S.; Odling, Nick; Thomas, Alex L.; Betzler, Christian; Eberli, Gregor P.; Alvarez-Zarikian, Carlos A.; Alonso-Garcia, Montserrat; Bialik, Or M.; Blättler, Clara L.; Guo, Junhua A.; Haffen, Sébastien; Horozal, Senay; Mee, Anna L. H.; Inoue, Mayuri; Jovane, Luigi; Lanci, Luca; Laya, Juan C.; Lüdmann, Thomas; Bejugam, Nagender N.; Nakakuni, Masatoshi; Niino, Kaoru; Petruny, Loren M.; Pratiwi, Santi D.; Reijmer, John J. G.; Reolid, Jesús; Slagle, Angela L.; Sloss, Craig R.; Su, Xiang; Swart, Peter K.; Wright, James D.; Yao, Zhengquan; Young, Jeremy R.; Lindhorst, Sebastian; Stainbank, Stephanie; Rueggeberg, Andres; Spezzaferri, Silvia; Carrasqueira, Igor; Hu, Siyao; Kroon, DickIndian-Asian monsoon has oscillated between warm/wet interglacial periods and cool/dry glacial periods with periodicities closely linked to variations in Earth’s orbital parameters. However, processes that control wet versus dry, i.e. aridity cyclical periods on the orbital time-scale in the low latitudes of the Indian-Asian continent remain poorly understood because records over millions of years are scarce. The sedimentary record from International Ocean Discovery Program (IODP) Expedition 359 provides a well-preserved, high-resolution, continuous archive of lithogenic input from the Maldives reflecting on low-latitude aridity cycles. Variability within the lithogenic component of sedimentary deposits of the Maldives results from changes in monsoon-controlled sedimentary sources. Here, we present X-ray fluorescence (XRF) core-scanning results from IODP Site U1467 for the past two million years, allowing full investigation of orbital periodicities. We specifically use the Fe/K as a terrestrial climate proxy reflecting on wet versus dry conditions in the source areas of the Indian-Asian landmass, or from further afield. The Fe/K record shows orbitally forced cycles reflecting on changes in the relative importance of aeolian (stronger winter monsoon) during glacial periods versus fluvial supply (stronger summer monsoon) during interglacial periods. For our chronology, we tuned the Fe/K cycles to precessional insolation changes, linking Fe/K maxima/minima to insolation minima/maxima with zero phase lag. Wavelet and spectral analyses of the Fe/K record show increased dominance of the 100 kyr cycles after the Mid Pleistocene Transition (MPT) at 1.25 Ma in tandem with the global ice volume benthic δ18O data (LR04 record). In contrast to the LR04 record, the Fe/K profile resolves 100-kyr-like cycles around the 130 kyr frequency band in the interval from 1.25 to 2 million years. These 100-kyr-like cycles likely form by bundling of two or three obliquity cycles, indicating that low-latitude Indian-Asian climate variability reflects on increased tilt sensitivity to regional eccentricity insolation changes (pacing tilt cycles) prior to the MPT. The implication of appearance of the 100 kyr cycles in the LR04 and the Fe/K records since the MPT suggests strengthening of a climate link between the low and high latitudes during this period of climate transition.