Site M0077: Post-Impact Sedimentary Rocks

Gulick, S. P. S.; Morgan, Joanna; MMellett, Claire L.; Green, S. L.; Kring, D. A.

doi:10.14379/iodp.proc.364.105.2017

Cited by 15 publications

(23 citation statements)

References 12 publications

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“…This may indicate a less intense thermal alteration of shocked quartz during emplacement. The size of spherulitic calcite spheroids in subunit 4 is in a similar range to calcareous dinoflagellates, the latter of which are common at Cretaceous-Paleogene ejecta sites (e.g., Wendler and Willems, 2002) and are also observed at the base of the postimpact sedimentary section of IODP-ICDP Hole M0077A (Gulick et al, 2017b). The microstructure of the spherulitic calcite spheroids, however, is different from calcareous dinoflagellates and resembles the larger 250 µm carbonate melt spheroids in subunit 3 and the spheroidal calcite aggregates in accretionary lapilli.…”

Section: Subunitmentioning

confidence: 89%

Petrographic and chemical studies of the Cretaceous-Paleogene boundary sequence at El Guayal, Tabasco, Mexico: Implications for ejecta plume evolution from the Chicxulub impact crater

Salge

Tagle

Schmitt

et al. 2021

Large Meteorite Impacts and Planetary Evolution VI

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A combined petrographic and chemical study of ejecta particles from the Cretaceous-Paleogene boundary sequence of El Guayal, Tabasco, Mexico (520 km SW of Chicxulub crater), was carried out to assess their formation conditions and genetic relation during the impact process. The reaction of silicate ejecta particles with hot volatiles during atmospheric transport may have induced alteration processes, e.g., silicification and cementation, observed in the ejecta deposits. The various microstructures of calcite ejecta particles are interpreted to reflect different thermal histories at postshock conditions. Spherulitic calcite particles may represent carbonate melts that were quenched during ejection. A recrystallized microstructure may indicate short, intense thermal stress. Various aggregates document particle-particle interactions and intermixing of components from lower silicate and upper sedimentary target lithologies. Aggregates of recrystallized calcite with silicate melt indicate the consolidation of a hot suevitic component with sediments at ≳750 °C. Accretionary lapilli formed in a turbulent, steam-condensing environment at ~100 °C by aggregation of solid, ash-sized particles. Concentric zones with smaller grain sizes of accreted particles indicate a recurring exchange with a hotter environment. Our results suggest that during partial ejecta plume collapse, hot silicate compo nents were mixed with the fine fraction of local surface-derived sediments, the latter of which were displaced by the preceding ejecta curtain. These processes sustained a hot, gas-driven, lateral basal transport that was accompanied by a turbulent plume at a higher level. The exothermic back-reaction of CaO from decomposed carbonates and sulfates with CO2 to form CaCO3 may have been responsible for a prolonged release of thermal energy at a late stage of plume evolution.

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Section: Subunitmentioning

confidence: 89%

Petrographic and chemical studies of the Cretaceous-Paleogene boundary sequence at El Guayal, Tabasco, Mexico: Implications for ejecta plume evolution from the Chicxulub impact crater

Salge

Tagle

Schmitt

et al. 2021

Large Meteorite Impacts and Planetary Evolution VI

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“…Ages were then estimated for each sample assuming constant sedimentation rates within each biozone. Age estimates were not calculated for the top seven samples (609.74– 607.61 m below seafloor [mbsf]) due to uncertainty in the placement of the P3 biozone and the presence of a series of stacked unconformities at the top of the Paleocene (Gulick et al 2017).…”

Section: Methodsmentioning

confidence: 99%

Size and shape variation in the calcareous nannoplankton genusBraarudosphaerafollowing the Cretaceous/Paleogene (K/Pg) mass extinction: clues as to its evolutionary success

2021

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Calcareous nannoplankton have been one of the dominant primary producers in the surface oceans since the late Triassic. The bolide impact at the Cretaceous/Paleogene (K/Pg) boundary ~66.0 Ma, led to the elimination of >90% of nannoplankton species: the largest extinction event in their evolutionary history. One of the few nannoplankton genera to survive the K/Pg mass extinction and even thrive in its aftermath was Braarudosphaera, which precipitates pentagonal calcite plates (pentaliths). The only Braarudosphaera species to span the K/Pg boundary (B. bigelowii) is extant and has formed geographically and temporally restricted “blooms” throughout geologic time. Four morphologically and genetically distinct cryptic species of B. bigelowii have been identified in the modern ocean. However, it is uncertain whether these cryptic species have disparate ecophysiological tolerances that have allowed them to adapt to varying environmental conditions. For the first time, we assess changes in the size and shape of Braarudosphaera pentaliths following the K/Pg mass extinction at three geographically and environmentally disparate sites that have early Paleocene Braarudosphaera blooms. Our results show that different Braarudosphaera morphotypes were dominant in the Gulf of Mexico compared with the Tethys Ocean, likely due to regional environmental differences. In addition, we provide evidence that the dominant Braarudosphaera morphotypes shifted in response to changes in upper water column stratification. This ability to rapidly adapt to unstable environments likely helped Braarudosphaera thrive in the aftermath of the K/Pg extinction and explains why this lineage has enjoyed such a long evolutionary history.

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“…The sample collected at 503.6 m DSF is middle Eocene in age and indicative of a normal marine setting with bathyal water depths (~500-700 m). Semiquantitative abundance counts for this sample are included in Biostratigraphy in the Site M0077: Post-Impact Sedimentary Rocks chapter (Gulick et al, 2017b).…”

Section: Biostratigraphymentioning

confidence: 99%