Papers by Dr. Diederik Liebrand
Abrupt change in North African hydroclimate and landscape evolution 3.2 million years ago
Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocen... more Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocene due to deep-sea dysoxia and enhanced carbon burial at times of intensified North African run-off during ‘Green’ Sahara Periods (GSPs). The existence of orbital precession-dominated Saharan aridity/humidity cycles is well known, but lack of long-term, high-resolution records hinders understanding of their precise relationships with environmental and hominin evolution. Here we present continuous, high-resolution geochemical and environmental magnetic records for the Eastern Mediterranean that span the past 5.2 million years, which reveal that organic burial in sapropels intensified 3.2 Myr ago. We deduce that fluvial terrigenous sediment inputs during GSPs doubled abruptly at this time, whereas monsoon run-off intensity remained relatively constant. We attribute the increase in sediment mobilisation to an abrupt non-linear North African landscape response associated with a major increase...
Optimal PCA analyses of paleomagnetic of IODP Site 342-U1406
(Table S12) Tuning tie points for ODP Site 208-1264
Oligocene-Miocene Transition in the North Atlantic Interrupted by Warming: New Records from the Newfoundland Margin, IODP Expedition 342
(Table S11) ODP Site 208-1266 to Site 208-1264 tie points
(Table S13) Paleomagnetic stratigraphy of ODP Site 208-1265
(Table 09b) Splice data of ln(Ca/K) from different holes of IODP Site 342-U1406
Oligocene stable isotope record and calcareous nannofossils of IODP Site 208-1264
Abrupt change in North African hydroclimate and landscape evolution 3.2 million years ago
Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocen... more Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocene due to deep-sea dysoxia and enhanced carbon burial at times of intensified North African run-off during ‘Green’ Sahara Periods (GSPs). The existence of orbital precession-dominated Saharan aridity/humidity cycles is well known, but lack of long-term, high-resolution records hinders understanding of their precise relationships with environmental and hominin evolution. Here we present continuous, high-resolution geochemical and environmental magnetic records for the Eastern Mediterranean that span the past 5.2 million years, which reveal that organic burial in sapropels intensified 3.2 Myr ago. We deduce that fluvial terrigenous sediment inputs during GSPs doubled abruptly at this time, whereas monsoon run-off intensity remained relatively constant. We attribute the increase in sediment mobilisation to an abrupt non-linear North African landscape response associated with a major increase...
(Table 03) Revised splice interval from different holes of IODP Site 342-U1406
(Table S7) Composite depth scale of ODP Site 208-1266
Astronomical climate forcing during the Oligo-Miocene
In this thesis newly generated high-resolution Oligo-Miocene climate proxy records from Walvis Ri... more In this thesis newly generated high-resolution Oligo-Miocene climate proxy records from Walvis Ridge ODP Site 1264 (south-eastern Atlantic Ocean) are presented (Chapters 2 and 3). The records are tuned to an eccentricity solution (Chapter 3) and they are compared to published Atlantic and Pacific palaeoclimate chronologies (Chapters 2 and 4). The main research objectives are 1) to identify astronomical pacemakers of global significance and test earlier pacing theories, 2) to describe global climate and oceanographic change on astronomical and tectonic time scales and 3) to test the strong hysteresis in ice sheet models that suggest a very stable Antarctic ice sheet once formed. Chapter 1 gives a general introduction on the “mid”-to-late Oligocene climatic, oceanographic, geographic and cryospheric settings. Climate evolution and dynamics, together with the major underlying processes are introduced. In Chapter 2, high-resolution early Miocene stable oxygen and carbon isotope chronolo...
(Table S10) ODP Site 208-1265 to Site 208-1264 tie points
Intensities of IODP Site 342-U1406
Oxygen and Carbon stable isotope ratios for Site U1334
(Table 08b) Splice data of reflectance spectrophotometer (RSC) from different holes of IODP Site 342-U1406
(Table S15) CaCO3 estimates of ODP Site 208-1264
(Table 06b) Splice data of Gamma ray attenuation (GRA) from different holes of IODP Site 342-U1406
(Table S18) Calcareous nannofossil biostratigraphy of ODP Site 208-1264
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Papers by Dr. Diederik Liebrand