Indian-Asian monsoon has oscillated between warm/wet interglacial periods and cool/dry glacial pe... more Indian-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 variabili [...]
... The boundary between the offshore and lithologically identical subglacial Melville Till and g... more ... The boundary between the offshore and lithologically identical subglacial Melville Till and glacimarine Melville Laminated Clay at 49.5°N at 135 m below sea-level probably marks the palaeo-grounding line [28]. The Melville ...
Abstract A qualitative scanning electron microscopy study of coccoliths of Emiliania huxleyi from... more Abstract A qualitative scanning electron microscopy study of coccoliths of Emiliania huxleyi from the Norwegian fjord mesocosm experiments has been undertaken. The types of variation observed are documented here together with preliminary results of a quantitative ...
Indian-Asian monsoon has oscillated between warm/wet interglacial periods and cool/dry glacial pe... more Indian-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 variabili [...]
... The boundary between the offshore and lithologically identical subglacial Melville Till and g... more ... The boundary between the offshore and lithologically identical subglacial Melville Till and glacimarine Melville Laminated Clay at 49.5°N at 135 m below sea-level probably marks the palaeo-grounding line [28]. The Melville ...
Abstract A qualitative scanning electron microscopy study of coccoliths of Emiliania huxleyi from... more Abstract A qualitative scanning electron microscopy study of coccoliths of Emiliania huxleyi from the Norwegian fjord mesocosm experiments has been undertaken. The types of variation observed are documented here together with preliminary results of a quantitative ...
An overview is given of the various techniques which can be used to obtain information on the str... more An overview is given of the various techniques which can be used to obtain information on the structure of coccolilhs by scanning electron microscopy and by light microscopy. Special attention is given to determination of calcite c-axis orienlation by light mlcroscopy and elucidation of concealed connections between elements by electron microscopy. Coccolithus pelagicus coccoliths are used to illustrate the various techniques and an amended description of their structure is given.
Page 1. GUIDELINES FOR COCCOLITH AND CALCAREOUS NANNOFOSSIL TERMINOLOGY by JEREMY R. YOUNG, JAMES... more Page 1. GUIDELINES FOR COCCOLITH AND CALCAREOUS NANNOFOSSIL TERMINOLOGY by JEREMY R. YOUNG, JAMES A. BERGEN, PAUL R. BOWN, JACKIE A. BURNETT, ANDREA FIORENTINO, RICHARD W. JORDAN ...
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Papers by Jeremy R Young