An invited contribution concerning the activities of the European Association of Geochemistry'... more An invited contribution concerning the activities of the European Association of Geochemistry's Diversity, Equity, and Inclusion Committee
IODP 353-U1446 trace element (Mg/Ca, Mn/Ca, Nd/Ca and U/Ca) and isotope (δ18O and δ13C) of plankt... more IODP 353-U1446 trace element (Mg/Ca, Mn/Ca, Nd/Ca and U/Ca) and isotope (δ18O and δ13C) of planktic foraminifera Neogloboquadrina dutertrei across ~70-140 thousand years ago. The data have corresponding core depth (m) and assigned age (ka)
When Caribbean long-spined sea urchins, Diadema antillarum, are stable at high population densiti... more When Caribbean long-spined sea urchins, Diadema antillarum, are stable at high population densities, their grazing facilitates scleractinian coral dominance. Today, populations remain suppressed after a mass mortality in 1983–1984 caused a loss of their ecosystem functions, and led to widespread declines in ecosystem health. This study provides three lines of evidence to support the assertion that a lack of habitat complexity on Caribbean coral reefs contributes to their recovery failure. Firstly, we extracted fractal dimension (D) measurements, used as a proxy for habitat complexity, from 3D models to demonstrate that urchins preferentially inhabit areas of above average complexity at ecologically relevant spatial scales. Secondly, controlled behaviour experiments showed that an energetically expensive predator avoidance behaviour is reduced by 52% in complex habitats, potentially enabling increased resource allocation to reproduction. Thirdly, we deployed a network of simple and c...
The geological history of the South Asian monsoon (SAM) before the Pleistocene is not well‐constr... more The geological history of the South Asian monsoon (SAM) before the Pleistocene is not well‐constrained, primarily due to a lack of available continuous sediment archives. Previous studies have noted an intensification of SAM precipitation and atmospheric circulation during the middle Miocene (∼14 Ma), but no records are available to test how the monsoon changed prior to this. In order to improve our understanding of monsoonal evolution, geochemical and sedimentological data were generated for the Oligocene‐early Miocene (30–20 Ma) from Indian National Gas Hydrate Expedition 01 Site NGHP‐01‐01A in the eastern Arabian Sea, at 2,674 m water depth. We find the initial glaciation phase (23.7–23.0 Ma) of the Oligocene‐Miocene transition (OMT) to be associated with an increase in water column ventilation and water mass mixing, suggesting an increase in winter monsoon type atmospheric circulation, possibly driven by a relative southward shift of the intertropical convergence zone. During th...
Proceedings of the International Ocean Discovery Program, 2016
Background and objectives 2 Operations 5 Lithostratigraphy 13 Biostratigraphy 19 Geochemistry 22 ... more Background and objectives 2 Operations 5 Lithostratigraphy 13 Biostratigraphy 19 Geochemistry 22 Paleomagnetism 29 Physical properties 33 Downhole logging 38 Stratigraphic correlation 39 References Hole U1445A Hole U1445A was spudded at 1900 h on 1 January. The seafloor was estimated at 2502 mbsl. Cores 353-U1445A-1H through 24H (0-225.1 m DSF) were retrieved using the APC system. Temperature measurements were taken on Cores 4H, 7H, 10H, and 13H. Core orientation data were obtained from Cores 3H through 24H using the Icefield MI-5 tool. The XCB system was deployed for Cores 25X through 77X (225.1-672.6 m DSF). Coring advances of 8 m were utilized for Cores 33X, 34X, and 38X through 66X to allow for core expansion within the core liner. After completion of coring operations in Hole U1445A, the hole was swept with 50 bbl of high-viscosity mud and then displaced with heavy weight (10.6 lb/gal) mud in preparation for downhole logging operations. The hole was then logged using the triple combo tool string, including the magnetic susceptibility sonde (MSS), and the Formation MicroScanner (FMS)-sonic tool string. Each tool string was run twice from 85 to 444 m DSF. Neither tool string was able to pass below a bridge at 444 m DSF. Downhole logging operations were completed at 0630 h on 7 January. The drill string was pulled from the hole with the bit clearing the seafloor at 0711 h, ending Hole U1445A. A total of 24 APC cores were taken over a 225.1 m interval with a total core recovery of 234.31 m (104% core recovery). The XCB system was used for 53 cores over a cored interval of 447.5 m with 432.09 m recovered (97%). Total core recovery for Hole U1445A was 99%. Hole U1445B The vessel was offset 20 m south, and Hole U1445B was spudded at 1010 h on 7 January. Hole U1445B was dedicated for highresolution pore water sampling. Cores 353-U1445B-1H through 4H were retrieved with 101% recovery. The bit cleared the seafloor at 1320 h, ending Hole U1445B. Four APC cores were taken over a 33.0 m interval with a total core recovery of 33.36 m (101% core recovery). Hole U1445C The vessel was offset 20 m west, and Hole U1445C was spudded at 1415 h on 7 January. Cores 353-U1445C-1H through 24H were retrieved using the APC system. Temperature measurements were taken with the advanced piston corer temperature tool (APCT-3) on Cores 20H and 22H. Cores 3H through 24H were oriented using the Icefield MI-5 tool. The XCB system was deployed for Cores 25X through 36X (218.2-305.2 m DSF). Cores 26X through 36X used 8 m advances to allow for core expansion within the core liner. A total of 24 APC cores were taken over a 218.2 m interval with a total core recovery of 219.67 m (101% core recovery). The XCB system was used for 12 cores over a cored interval of 87.0 m with 85.93 m recovered (99%). Total core recovery for Hole U1445C was 100%.
X-ray fluorescence (XRF) core scanning of marine and lake sediments has been extensively used to ... more X-ray fluorescence (XRF) core scanning of marine and lake sediments has been extensively used to study changes in past environmental and climatic processes over a range of timescales. The interpretation of XRF-derived element ratios in paleoclimatic and paleoceanographic studies primarily considers differences in the relative abundances of particular elements. Here we present new XRF core scanning data from two long sediment cores in the Andaman Sea in the northern Indian Ocean and show that sea level related processes influence terrigenous inputs based proxies such as Ti/Ca, Fe/Ca, and elemental concentrations of the transition metals (e.g. Mn). Zr/Rb ratios are mainly a function of changes in median grain size of lithogenic particles and often covary with changes in Ca concentrations that reflect changes in biogenic calcium carbonate production. This suggests that a common process (i.e. sea level) influences both records. The interpretation of lighter element data (e.g. Si and Al) based on low XRF counts is complicated as variations in mean grain size and water content result in systematic artifacts and signal intensities not related to the Al or Si content of the sediments. This highlights the need for calibration of XRF core scanning data based on discrete sample analyses and careful examination of sediment properties such as porosity/water content for reliably disentangling environmental signals from other physical properties. In the case of the Andaman Sea, reliable extraction of a monsoon signal will require accounting for the sea level influence on the XRF data.
Asian Monsoon rainfall supports the livelihood of billions of people, yet the relative importance... more Asian Monsoon rainfall supports the livelihood of billions of people, yet the relative importance of different drivers remains an issue of great debate. Here, we present 30 million-year model-based reconstructions of Indian summer monsoon and South East Asian monsoon rainfall at millennial resolution. We show that precession is the dominant direct driver of orbital variability, although variability on obliquity timescales is driven through the ice sheets. Orographic development dominated the evolution of the South East Asian monsoon, but Indian summer monsoon evolution involved a complex mix of contributions from orography (39%), precession (25%), atmospheric CO2 (21%), ice-sheet state (5%) and ocean gateways (5%). Prior to 15 Ma, the Indian summer monsoon was broadly stable, albeit with substantial orbital variability. From 15 Ma to 5 Ma, strengthening was driven by a combination of orography and glaciation, while closure of the Panama gateway provided the prerequisite for the mode...
As oceans are rising in temperature and becoming more acidic but changing our diet could be a way... more As oceans are rising in temperature and becoming more acidic but changing our diet could be a way to help deal with it.
An invited contribution concerning the activities of the European Association of Geochemistry'... more An invited contribution concerning the activities of the European Association of Geochemistry's Diversity, Equity, and Inclusion Committee
IODP 353-U1446 trace element (Mg/Ca, Mn/Ca, Nd/Ca and U/Ca) and isotope (δ18O and δ13C) of plankt... more IODP 353-U1446 trace element (Mg/Ca, Mn/Ca, Nd/Ca and U/Ca) and isotope (δ18O and δ13C) of planktic foraminifera Neogloboquadrina dutertrei across ~70-140 thousand years ago. The data have corresponding core depth (m) and assigned age (ka)
When Caribbean long-spined sea urchins, Diadema antillarum, are stable at high population densiti... more When Caribbean long-spined sea urchins, Diadema antillarum, are stable at high population densities, their grazing facilitates scleractinian coral dominance. Today, populations remain suppressed after a mass mortality in 1983–1984 caused a loss of their ecosystem functions, and led to widespread declines in ecosystem health. This study provides three lines of evidence to support the assertion that a lack of habitat complexity on Caribbean coral reefs contributes to their recovery failure. Firstly, we extracted fractal dimension (D) measurements, used as a proxy for habitat complexity, from 3D models to demonstrate that urchins preferentially inhabit areas of above average complexity at ecologically relevant spatial scales. Secondly, controlled behaviour experiments showed that an energetically expensive predator avoidance behaviour is reduced by 52% in complex habitats, potentially enabling increased resource allocation to reproduction. Thirdly, we deployed a network of simple and c...
The geological history of the South Asian monsoon (SAM) before the Pleistocene is not well‐constr... more The geological history of the South Asian monsoon (SAM) before the Pleistocene is not well‐constrained, primarily due to a lack of available continuous sediment archives. Previous studies have noted an intensification of SAM precipitation and atmospheric circulation during the middle Miocene (∼14 Ma), but no records are available to test how the monsoon changed prior to this. In order to improve our understanding of monsoonal evolution, geochemical and sedimentological data were generated for the Oligocene‐early Miocene (30–20 Ma) from Indian National Gas Hydrate Expedition 01 Site NGHP‐01‐01A in the eastern Arabian Sea, at 2,674 m water depth. We find the initial glaciation phase (23.7–23.0 Ma) of the Oligocene‐Miocene transition (OMT) to be associated with an increase in water column ventilation and water mass mixing, suggesting an increase in winter monsoon type atmospheric circulation, possibly driven by a relative southward shift of the intertropical convergence zone. During th...
Proceedings of the International Ocean Discovery Program, 2016
Background and objectives 2 Operations 5 Lithostratigraphy 13 Biostratigraphy 19 Geochemistry 22 ... more Background and objectives 2 Operations 5 Lithostratigraphy 13 Biostratigraphy 19 Geochemistry 22 Paleomagnetism 29 Physical properties 33 Downhole logging 38 Stratigraphic correlation 39 References Hole U1445A Hole U1445A was spudded at 1900 h on 1 January. The seafloor was estimated at 2502 mbsl. Cores 353-U1445A-1H through 24H (0-225.1 m DSF) were retrieved using the APC system. Temperature measurements were taken on Cores 4H, 7H, 10H, and 13H. Core orientation data were obtained from Cores 3H through 24H using the Icefield MI-5 tool. The XCB system was deployed for Cores 25X through 77X (225.1-672.6 m DSF). Coring advances of 8 m were utilized for Cores 33X, 34X, and 38X through 66X to allow for core expansion within the core liner. After completion of coring operations in Hole U1445A, the hole was swept with 50 bbl of high-viscosity mud and then displaced with heavy weight (10.6 lb/gal) mud in preparation for downhole logging operations. The hole was then logged using the triple combo tool string, including the magnetic susceptibility sonde (MSS), and the Formation MicroScanner (FMS)-sonic tool string. Each tool string was run twice from 85 to 444 m DSF. Neither tool string was able to pass below a bridge at 444 m DSF. Downhole logging operations were completed at 0630 h on 7 January. The drill string was pulled from the hole with the bit clearing the seafloor at 0711 h, ending Hole U1445A. A total of 24 APC cores were taken over a 225.1 m interval with a total core recovery of 234.31 m (104% core recovery). The XCB system was used for 53 cores over a cored interval of 447.5 m with 432.09 m recovered (97%). Total core recovery for Hole U1445A was 99%. Hole U1445B The vessel was offset 20 m south, and Hole U1445B was spudded at 1010 h on 7 January. Hole U1445B was dedicated for highresolution pore water sampling. Cores 353-U1445B-1H through 4H were retrieved with 101% recovery. The bit cleared the seafloor at 1320 h, ending Hole U1445B. Four APC cores were taken over a 33.0 m interval with a total core recovery of 33.36 m (101% core recovery). Hole U1445C The vessel was offset 20 m west, and Hole U1445C was spudded at 1415 h on 7 January. Cores 353-U1445C-1H through 24H were retrieved using the APC system. Temperature measurements were taken with the advanced piston corer temperature tool (APCT-3) on Cores 20H and 22H. Cores 3H through 24H were oriented using the Icefield MI-5 tool. The XCB system was deployed for Cores 25X through 36X (218.2-305.2 m DSF). Cores 26X through 36X used 8 m advances to allow for core expansion within the core liner. A total of 24 APC cores were taken over a 218.2 m interval with a total core recovery of 219.67 m (101% core recovery). The XCB system was used for 12 cores over a cored interval of 87.0 m with 85.93 m recovered (99%). Total core recovery for Hole U1445C was 100%.
X-ray fluorescence (XRF) core scanning of marine and lake sediments has been extensively used to ... more X-ray fluorescence (XRF) core scanning of marine and lake sediments has been extensively used to study changes in past environmental and climatic processes over a range of timescales. The interpretation of XRF-derived element ratios in paleoclimatic and paleoceanographic studies primarily considers differences in the relative abundances of particular elements. Here we present new XRF core scanning data from two long sediment cores in the Andaman Sea in the northern Indian Ocean and show that sea level related processes influence terrigenous inputs based proxies such as Ti/Ca, Fe/Ca, and elemental concentrations of the transition metals (e.g. Mn). Zr/Rb ratios are mainly a function of changes in median grain size of lithogenic particles and often covary with changes in Ca concentrations that reflect changes in biogenic calcium carbonate production. This suggests that a common process (i.e. sea level) influences both records. The interpretation of lighter element data (e.g. Si and Al) based on low XRF counts is complicated as variations in mean grain size and water content result in systematic artifacts and signal intensities not related to the Al or Si content of the sediments. This highlights the need for calibration of XRF core scanning data based on discrete sample analyses and careful examination of sediment properties such as porosity/water content for reliably disentangling environmental signals from other physical properties. In the case of the Andaman Sea, reliable extraction of a monsoon signal will require accounting for the sea level influence on the XRF data.
Asian Monsoon rainfall supports the livelihood of billions of people, yet the relative importance... more Asian Monsoon rainfall supports the livelihood of billions of people, yet the relative importance of different drivers remains an issue of great debate. Here, we present 30 million-year model-based reconstructions of Indian summer monsoon and South East Asian monsoon rainfall at millennial resolution. We show that precession is the dominant direct driver of orbital variability, although variability on obliquity timescales is driven through the ice sheets. Orographic development dominated the evolution of the South East Asian monsoon, but Indian summer monsoon evolution involved a complex mix of contributions from orography (39%), precession (25%), atmospheric CO2 (21%), ice-sheet state (5%) and ocean gateways (5%). Prior to 15 Ma, the Indian summer monsoon was broadly stable, albeit with substantial orbital variability. From 15 Ma to 5 Ma, strengthening was driven by a combination of orography and glaciation, while closure of the Panama gateway provided the prerequisite for the mode...
As oceans are rising in temperature and becoming more acidic but changing our diet could be a way... more As oceans are rising in temperature and becoming more acidic but changing our diet could be a way to help deal with it.
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Papers by Pallavi Anand