Electron backscatter diffraction (EBSD) as a tool for detection of coral diagenesis

Cusack, Maggie; England, Jennifer; Dalbeck, Paul; Tudhope, Alexander W.; Fallick, Anthony E.; Allison, Nicola

doi:10.1007/s00338-008-0414-3

Cited by 44 publications

(33 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, the white polyp appears to either have crystals too small for visualisation, or a high organic content (e.g. Cusack et al13). While individual crystal orientation may change depending upon the cross-section location, the lack of crystallographic organisation in the white polyp compared to the orange polyp (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…3 was set in EpoHeat epoxy (Buehler) and cross-sectioned using a slow-speed saw. The sample was polished using progressive grits (320, 1200, 2500, 4000), micropolished using alpha aluminium oxide at 1 and 0.3 μm, and then fine-polished with 0.06 μm amorphous colloidal silica (Buehler) on a short nap to remove any residual damaged surface layers13. Back scatter electron micrographs of the entire cross section, and likely points of fusion were then taken using an FEI Quanta 200F field emission scanning electron microscope (SEM) equipped with a TSL EBSD system and OIM version 6 at the University of Glasgow.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Self-recognition in corals facilitates deep-sea habitat engineering

Hennige¹,

Morrison

Form

et al. 2014

Sci Rep

View full text Add to dashboard Cite

The ability of coral reefs to engineer complex three-dimensional habitats is central to their success and the rich biodiversity they support. In tropical reefs, encrusting coralline algae bind together substrates and dead coral framework to make continuous reef structures, but beyond the photic zone, the cold-water coral Lophelia pertusa also forms large biogenic reefs, facilitated by skeletal fusion. Skeletal fusion in tropical corals can occur in closely related or juvenile individuals as a result of non-aggressive skeletal overgrowth or allogeneic tissue fusion, but contact reactions in many species result in mortality if there is no ‘self-recognition’ on a broad species level. This study reveals areas of ‘flawless’ skeletal fusion in Lophelia pertusa, potentially facilitated by allogeneic tissue fusion, are identified as having small aragonitic crystals or low levels of crystal organisation, and strong molecular bonding. Regardless of the mechanism, the recognition of ‘self’ between adjacent L. pertusa colonies leads to no observable mortality, facilitates ecosystem engineering and reduces aggression-related energetic expenditure in an environment where energy conservation is crucial. The potential for self-recognition at a species level, and subsequent skeletal fusion in framework-forming cold-water corals is an important first step in understanding their significance as ecological engineers in deep-seas worldwide.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Self-recognition in corals facilitates deep-sea habitat engineering

Hennige¹,

Morrison

Form

et al. 2014

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Care was taken to sample only pristine-looking micritic carbonate (DeCelles et al, 2007b), but micro-scale solution-precipitation of calcite does not necessarily result in a loss of micritic texture and thus cannot be ruled out on this basis. In future studies, electron backscatter diffraction could be used to identify micro-scale recrystallization (e.g., Cusack et al, 2008;Pérez-Huerta et al, 2014). If recrystallization in a rock-buffered environment did occur, under warmer burial conditions the carbonate O-isotopic composition should remain approximately constant while the water O-isotopic values become enriched in 18 O and T(Δ 47 ) increases (e.g., Henkes et al, 2014).…”

Section: Preservation Of Isotopic Signals During Burial Reheating In mentioning

confidence: 98%

High late Miocene–Pliocene elevation of the Zhada Basin, southwestern Tibetan Plateau, from carbonate clumped isotope thermometry

Huntington

Saylor

Quade

et al. 2014

Geological Society of America Bulletin

View full text Add to dashboard Cite

The timing and pattern of Tibetan Plateau rise provide a critical test of possible mechanisms for the development and support of high topography, yet views range widely on the history of surface uplift to modern elevations of ~4.5 km. To address this issue we present clumped isotope thermometry data from two well-studied basins in central and southwestern Tibet, for which previous carbonate δ 18 O data have been used to reconstruct high paleoelevations from late Oligocene to Pliocene time. Clumped isotope thermometry uses measurements of the 13 C-18 O bond ordering in carbonates to constrain the temperature [T(Δ 47 )] and δ 18 O value of the water from which the carbonate grew. These data can be used to infer paleoelevation by exploiting the systematic decrease of surface temperature and the δ 18 O value of meteoric water with elevation, provided samples record original depositional conditions and appropriate context exists for interpreting T(Δ 47 ) and δ 18 O values. Previous calcite δ 18 O and δ 13 C values for Oligocene-age marls from the Nima Basin in central Tibet are thought to refl ect original depositional conditions; however, T(Δ 47 ) values exceed Earth-surface temperatures, indicating that the samples have been diagenetically altered. Maximum burial temperatures were not high enough to cause solid-state C-O bond reordering. Instead, the elevated T(Δ 47 ) and water δ 18 O values are consistent with recrystallization of the samples in a rock-buffered system.Miocene-Pliocene aragonitic gastropod shells from the Zhada Basin in southwestern Tibet record primary environmental temperatures, which we interpret in the context of modern shell and tufa T(Δ 47 ) values and lake water temperatures. Modern shell and tufa T(Δ 47 ) values are similar to warmseason water temperatures. The ca. 9-4 Ma shell temperatures are signifi cantly colder, suggesting a 9 ± 3 °C (2σ) average increase in warm-season lake water temperatures since the late Miocene. If the temperature increase is due entirely to elevation change and the modern June-July-August (JJA) surface water lapse rate of 6.1 °C/km applies, it implies >1 km of elevation loss since the late Miocene-Pliocene-corresponding to an average basin fl oor paleoelevation of 5.4 ± 0.5 km (2σ). A warmer mid-Pliocene climate would make this a minimum estimate. Our fi nding of cold paleotemperatures contrasts with previous conclusions based on Pliocene snail shell T(Δ 47 ) data interpreted in the absence of modern shell and water temperature data, but is consistent with δ 18 O-based paleoaltimetry and with paleontological and isotopic data indicating the presence of coldadapted mammals living in a cold, high-elevation climate. We suggest that late Neogene elevation loss across the Zhada Basin catchment probably related to local expression of east-west extension across much of the southern Tibetan Plateau at this time.

show abstract

“…In times of environmental stress, however, corals may retract the polyp exposing the exterior of the corallite to corrosive waters and therefore to erosion and dissolution (Lazier et al, 1999), resulting in anomalous minor element ratios caused by differential leaching (Hendy et al, 2007). Endolithic borings could also be filled with aragonitic or calcitic cements (Nothdurft et al, 2007;Cusack et al, 2008). Post-mortem, dissolution, boring, and infilling may continue, and early marine aragonite cement may precipitate on the skeletal surface, altering the values of important geochemical proxies.…”

Section: Ablation Of Thick Sections Versus Exterior Of Septamentioning

confidence: 99%

Seawater nutrient and carbonate ion concentrations recorded as P/Ca, Ba/Ca, and U/Ca in the deep-sea coral Desmophyllum dianthus

Anagnostou

Sherrell

Gagnon

et al. 2011

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

As paleoceanographic archives, deep sea coral skeletons offer the potential for high temporal resolution and precise absolute dating, but have not been fully investigated for geochemical reconstructions of past ocean conditions. Here we assess the utility of skeletal P/Ca, Ba/Ca and U/Ca in the deep sea coral D. dianthus as proxies of dissolved phosphate (remineralized at shallow depths), dissolved barium (trace element with silicate-type distribution) and carbonate ion concentrations, respectively. Measurements of these proxies in globally distributed D. dianthus specimens show clear dependence on corresponding seawater properties. Linear regression fits of mean coral Element/Ca ratios against seawater properties yield the equations: P/Ca coral (lmol/ mol) = (0.6 ± 0.1) P/Ca sw (lmol/mol) -(23 ± 18), R 2 = 0.6, n = 16 and Ba/Ca coral (lmol/mol) = (1.4 ± 0.3) Ba/Ca sw (lmol/ mol) + (0 ± 2), R 2 = 0.6, n = 17; no significant relationship is observed between the residuals of each regression and seawater temperature, salinity, pressure, pH or carbonate ion concentrations, suggesting that these variables were not significant secondary dependencies of these proxies. Four D. dianthus specimens growing at locations with O arag 6 0.6 displayed markedly depleted P/Ca compared to the regression based on the remaining samples, a behavior attributed to an undersaturation effect. These corals were excluded from the calibration. Coral U/Ca correlates with seawater carbonate ion: U/Ca coral (lmol/ mol) = (À0.016 ± 0.003) ½CO 2À 3 (lmol/kg) + (3.2 ± 0.3), R 2 = 0.6, n = 17. The residuals of the U/Ca calibration are not significantly related to temperature, salinity, or pressure. Scatter about the linear calibration lines is attributed to imperfect spatialtemporal matches between the selected globally distributed specimens and available water column chemical data, and potentially to unresolved additional effects. The uncertainties of these initial proxy calibration regressions predict that dissolved phosphate could be reconstructed to ±0.4 lmol/kg (for 1.3-1.9 lmol/kg phosphate), and dissolved Ba to ±19 nmol/kg (for 41-82 nmol/ kg Ba sw ). Carbonate ion concentration derived from U/Ca has an uncertainty of ±31lmol/kg (for 60-120 lmol=kg CO 2À 3 ). The effect of microskeletal variability on P/Ca, Ba/Ca, and U/Ca was also assessed, with emphasis on centers of calcification, Fe-Mn phases, and external contaminants. Overall, the results show strong potential for reconstructing aspects of water mass mixing and biogeochemical processes in intermediate and deep waters using fossil deep-sea corals.

show abstract

Electron backscatter diffraction (EBSD) as a tool for detection of coral diagenesis

Cited by 44 publications

References 66 publications

Self-recognition in corals facilitates deep-sea habitat engineering

Self-recognition in corals facilitates deep-sea habitat engineering

High late Miocene–Pliocene elevation of the Zhada Basin, southwestern Tibetan Plateau, from carbonate clumped isotope thermometry

Seawater nutrient and carbonate ion concentrations recorded as P/Ca, Ba/Ca, and U/Ca in the deep-sea coral Desmophyllum dianthus

Contact Info

Product

Resources

About