Hannigan Robyn E.

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Hannigan
First Name
Robyn E.
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  • Article
    Evolving east Asian river systems reconstructed by trace element and Pb and Nd isotope variations in modern and ancient Red River-Song Hong sediments
    (American Geophysical Union, 2008-04-30) Clift, Peter D. ; Long, Hoang Van ; Hinton, Richard ; Ellam, Robert M. ; Hannigan, Robyn E. ; Tan, Mai Thanh ; Blusztajn, Jerzy S. ; Duc, Nguyen Anh
    Rivers in east Asia have been recognized as having unusual geometries, suggestive of drainage reorganization linked to Tibetan Plateau surface uplift. In this study we applied a series of major and trace element proxies, together with bulk Nd and single K-feldspar grain Pb isotope ion probe isotope analyses, to understand the sediment budget of the modern Red River. We also investigate how this may have evolved during the Cenozoic. We show that while most of the modern sediment is generated by physical erosion in the upper reaches in Yunnan there is significant additional flux from the Song Lo, draining Cathaysia and the SW Yangtze Block. Nd isotope data suggest that 40% of the modern delta sediment comes from the Song Lo. Carbonates in the Song Lo basin make this a major control on the Red River Sr budget. Erosion is not a simple function of monsoon precipitation. Active rock uplift is also required to drive strong erosion. Single grain Pb data show a connection in the Eocene between the middle Yangtze and the Red River, and probably with rivers draining the Songpan Garze terrane. However, the isotope data do not support a former connection with the upper Yangtze, Mekong, or Salween rivers. Drainage capture appears to have occurred throughout the Cenozoic, consistent with surface uplift propagating gradually to the southeast. The middle Yangtze was lost from the Red River prior to 24 Ma, while the connection to the Songpan Garze was cut prior to 12 Ma. The Song Lo joined the Red River after 9 Ma. Bulk sample Pb analyses have limited provenance use compared to single grain data, and detailed provenance is only possible with a matrix of different proxies.
  • Dataset
    Smallmouth grunt mortality data after exposure to experimental pH treatments
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-09-01) Holmberg, Robert J. ; Bourque, Bradford ; Gallagher, Eugene D. ; Hannigan, Robyn E. ; Rhyne, Andrew L. ; Tlusty, Michael F.
    This dataset reports mortality counts from Haemulon chrysargyreum (Smallmouth grunt) reared in an experimental trial in which subjects were raised under one of four pH treatments (8.10, 7.80, 7.60, 7.30). Survival counts were subtracted from the initial stocking density to calculate mortality counts. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/876987
  • Dataset
    Smallmouth grunt condition/otolith morphology data and SEM images
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-09-01) Holmberg, Robert J. ; Bourque, Bradford ; Gallagher, Eugene D. ; Hannigan, Robyn E. ; Rhyne, Andrew L. ; Tlusty, Michael F.
    This dataset includes condition and morphology measurements from Haemulon chrysargyreum (Smallmouth grunt) otoliths and scanning electron microscope (SEM) images after completion of an experimental trial in which subjects were raised under one of four pH treatments (8.10, 7.80, 7.60, 7.30). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/876937
  • Article
    Laurentian crustal recycling in the Ordovician Grampian Orogeny : Nd isotopic evidence from western Ireland
    (Cambridge University Press, 2004-04-21) Draut, Amy E. ; Clift, Peter D. ; Chew, David M. ; Cooper, Matthew J. ; Taylor, Rex N. ; Hannigan, Robyn E.
    Because magmatism associated with subduction is thought to be the principal source for continental crust generation, assessing the relative contribution of pre-existing (subducted and assimilated) continental material to arc magmatism in accreted arcs is important to understanding the origin of continental crust. We present a detailed Nd isotopic stratigraphy for volcanic and volcaniclastic formations from the South Mayo Trough, an accreted oceanic arc exposed in the western Irish Caledonides. These units span an arc–continent collision event, the Grampian (Taconic) Orogeny, in which an intra-oceanic island arc was accreted onto the passive continental margin of Laurentia starting at [similar] 475 Ma (Arenig). The stratigraphy corresponding to pre-, syn- and post-collisional volcanism reveals a progression of [varepsilon]Nd(t) from strongly positive values, consistent with melt derivation almost exclusively from oceanic mantle beneath the arc, to strongly negative values, indicating incorporation of continental material into the melt. Using [varepsilon]Nd(t) values of meta-sediments that represent the Laurentian passive margin and accretionary prism, we are able to quantify the relative proportions of continent-derived melt at various stages of arc formation and accretion. Mass balance calculations show that mantle-derived magmatism contributes substantially to melt production during all stages of arc–continent collision, never accounting for less than 21% of the total. This implies that a significant addition of new, rather than recycled, continental crust can accompany arc–continent collision and continental arc magmatism.
  • Article
    Holocene evolution in weathering and erosion patterns in the Pearl River delta
    (John Wiley & Sons, 2013-07-26) Hu, Dengke ; Clift, Peter D. ; Boning, Philipp ; Hannigan, Robyn E. ; Hillier, Stephen ; Blusztajn, Jerzy S. ; Wan, Shiming ; Fuller, Dorian Q.
    Sediments in the Pearl River delta have the potential to record the weathering response of this river basin to climate change since 9.5 ka, most notably weakening of the Asian monsoon since the Early Holocene (∼8 ka). Cores from the Pearl River delta show a clear temporal evolution of weathering intensity, as measured by K/Al, K/Rb, and clay mineralogy, that shows deposition of less weathered sediment at a time of weakening monsoon rainfall in the Early-Mid Holocene (6.0–2.5 ka). This may reflect an immediate response to a less humid climate, or more likely reduced reworking of older deposits from river terraces as the monsoon weakened. Human settlement of the Pearl River basin may have had a major impact on landscape and erosion as a result of the establishment of widespread agriculture. After around 2.5 ka weathering intensity sharply increased, despite limited change in the monsoon, but at a time when anthropogenic pollutants (e.g., Cu, Zn, and Pb) increased and when the flora of the basin changed. 87Sr/86Sr covaries with these other proxies but is also partly influenced by the presence of carbonate. The sediments in the modern Pearl River are even more weathered than the youngest material from the delta cores. We infer that the spread of farming into the Pearl River basin around 2.7 ka was followed by a widespread reworking of old, weathered soils after 2.5 ka, and large-scale disruption of the river system that was advanced by 2.0 ka.