Using speleothems to constrain late Cenozoic uplift rates in karst terranes

Abstract

The utility of speleothems as environmental and geological archives has greatly expanded with recent advances in geochronology. Here we reevaluate their ability to constrain late Cenozoic uplift in karst terranes. Using combined U-Th and U-Pb speleothem chronologies for the Buchan karst along the passive margin of southeastern Australia, we calculate a maximum uplift rate of 76 ± 7 m m.y.–1 maintained over the past 3.5 m.y. The timing and extent of this process is consistent with independent constraints on Neogene uplift in Australia, possibly in response to increased plate-boundary strain with New Zealand. Speleothem chronologies provide highly precise age control on individual events and the potential for near-continuous records across long periods of geological time, complementing and expanding upon existing uplift proxies.

Geodynamically corrected Pliocene shoreline elevations in Australia consistent with midrange projections of Antarctic ice loss

“…Most of our simulated relative elevation changes also show good agreement with paleo-sea level observations (>50% yield a Pearson's correlation coefficient, r, between 0.73 and 0.97), further strengthening our confidence that these dynamic topography simulations can be used to correct postdepositional warping of paleoshorelines on a continental scale. Last, although sea level observations are only available at five sites, the agreement of our predictions with indirect constraints on uplift and subsidence from seismic stratigraphy, river profile analysis, speleothem records, and the location of Neogene magmatism across Australia provides additional verification of our dynamic topography reconstructions (29)(30)(31)(32)(33)47). An important corollary of this evidence for rapid (∼0.1 km Ma −1 ) vertical motion is that it is essential to consider the impact of evolving dynamic topography on marker elevations in studies of former sea level (13,(48)(49)(50).…”

“…Invoking an important role for dynamic topography in controlling Neogene vertical motions across Australia is not without precedent. Geological observations, including the uplift and subsidence of paleoshorelines in the Eucla and Murray basins, the width of continental shelves, stratigraphic geometries offshore, rapid subsidence of carbonate reefs on the Northwest Shelf, and volcanism and uplift of the Eastern Highlands as recorded by the fluvial geomorphological record have all previously been attributed to the spatiotemporal evolution of mantle flow beneath the continent (28)(29)(30)(31)(32)(33). Nevertheless, before we can simulate the spatiotemporal evolution of Australian dynamic topography, we must first obtain models of the present-day mantle structure that are consistent with available geodynamic, seismic, and geodetic constraints.…”

Observations and models of dynamic topography: Current status and future directions.

“…Jones & Veevers, 1982;Bishop, 1988;Holdgate et al, 2008). Nevertheless, multiple different datasets including uplifted marine rocks, speleothem records, palynology, river profile modelling, sedimentary flux into fringing basins, and the age and morphology of basaltic volcanism indicate significant Cenozoic uplift of the margin that likely continued into Neogene times (Wellman, 1987;Fernandes & Roberts, 2021;Holdgate et al, 2008;Czarnota et al, 2014;Engel et al, 2020;Ball et al, 2021).…”

Geodynamically corrected Pliocene shoreline elevations in Australia consistent with mid-range projections of Antarctic ice loss

“…Most of these relative elevation change predictions are in strong agreement with palaeo sea-level observations (>50% yield a Pearson's correlation coefficient, r, between 0.73 and 0.97), lending confidence to our use of these dynamic topography simulations to correct post-depositional warping of palaeoshorelines on a continental scale. This inference is further strengthened by agreement of predicted vertical motions with indirect constraints on uplift and subsidence from seismic stratigraphy, river profile analysis, speleothem records, and the location of Neogene magmatism across the continent 46,34,29,35,36,37 . An important corollary is that it is essential to consider the impact of evolving dynamic topography on marker elevations in studies of former sea level 47,13,48 .…”

“…Invoking a significant role for dynamic topography in controlling Neogene vertical motions across Australia is not without precedent. Geological observations including the uplift and subsidence of paleoshorelines in the Eucla and Murray Basins, the width of continental shelves, stratigraphic geometries offshore, rapid subsidence of carbonate reefs on the Northwest Shelf, and volcanism and uplift of the Eastern Highlands as recorded by the fluvial geomorphological record, have all previously been attributed to the spatiotemporal evolution of mantle flow beneath the continent 34,29,28,35,36,37 . Nevertheless, before we can simulate the spatio-temporal evolution of Australian dynamic topography, we must first obtain models of the present-day mantle structure that are consistent with available geodynamic, seismic, and geodetic constraints.…”