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Electric discharge evidence found in a new class of material in the Chicxulub ejecta.

ABSTRACT: Chicxulub impact (66?Ma) event resulted in deposition of spheroids and melt glass, followed by deposition of diamectite and carbonate ejecta represented by large polished striated rounded pebbles and cobbles, henceforth, called Albion Formation1 Pook's Pebbles, name given from the first site identified in central Belize, Cayo District. Here we report that magnetic analysis of the Pook's Pebbles samples revealed unique electric discharge signatures. Sectioning of Pook's Pebbles from the Chicxulub ejecta from the Albion Formation at Belize showed that different parts of Pook's Pebbles had not only contrasting magnetization directions, but also sharply different level of magnetizations. Such behavior is indicative of electric discharge taking place sometimes during the formation of the Chicxulub ejecta blanket. In addition, some of the Pook's Pebbles' surface had recrystallized down to 0.2?mm depth. This is evidence of localized extreme pressures and temperatures during the fluidized ejecta formation which was imprinted in the outer layer of Pook's Pebbles. Recrystallization caused formation of nanophase iron along the surface, which was revealed by mapping of both natural remanent magnetization and of saturation remanence magnetization signatures. While the spheroids' magnetization orientation is consistent with reversed magnetic field at the time of impact, the study of the Pook's Pebbles provided, in addition, new evidence of electric charging during the vapor plume cloud processes.

SUBMITTER: Kletetschka G

PROVIDER: S-EPMC7271149 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Electric discharge evidence found in a new class of material in the Chicxulub ejecta.

Kletetschka Gunther G Ocampo Uria Adriana A Zila Vojtech V Elbra Tiiu T

Scientific reports 20200603 1

Chicxulub impact (66 Ma) event resulted in deposition of spheroids and melt glass, followed by deposition of diamectite and carbonate ejecta represented by large polished striated rounded pebbles and cobbles, henceforth, called Albion Formation<sup>1</sup> Pook's Pebbles, name given from the first site identified in central Belize, Cayo District. Here we report that magnetic analysis of the Pook's Pebbles samples revealed unique electric discharge signatures. Sectioning of Pook's Pebbles from th ...[more]

PMID: 32493963

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Project description:We describe two new, closely related species of toothed Brachyhypopomus (Hypopomidae: Gymnotiformes: Teleostei) from the central Amazon basin and create a new subgenus for them. Odontohypopomus, new subgenus of Brachyhypopomus, is diagnosed by (1) small teeth present on premaxillae; (2) medialmost two branchiostegal rays thin with blades oriented more vertically than remaining three rays; (3) background color in life (and to lesser extent in preservation) distinctly yellowish with head and sides peppered with small, widely spaced, very dark brown stellate chromatophores that greatly contrast with light background coloration; (4) a dark blotch or bar of subcutaneous pigment below the eye; (5) electric organ discharge waveform of very long duration (head-positive phase approx. 2 milliseconds or longer, head-negative phase shorter or absent) and slow pulse repetition rate (3-16 Hz). The type species of the new subgenus, Brachyhypopomus (Odontohypopomus) walteri sp. n., is diagnosed by the following additional character states: (1) subcutaneous dark pigment at base of orbit particularly prominent, (2) body semi-translucent and nearly bright yellow background coloration in life, (3) a biphasic electric organ discharge (EOD) waveform of very long duration (between 3.5 and 4 milliseconds at 25° C) with head-positive first phase significantly longer than second head-negative phase in both sexes. Brachyhypopomus (Odontohypopomus) bennetti sp. n. is diagnosed by two character states in addition to those used to diagnose the subgenus Odontohypopomus: (1) a deep electric organ, visible as large semi-transparent area, occupying approximately 14-17% body depth directly posterior to the abdominal cavity in combination with a short, but deep, caudal filament, and (2) a monophasic, head-positive EOD waveform, approximately 2.1 milliseconds in duration in both sexes. These are the only described rhamphichthyoid gymnotiforms with oral teeth, and Brachyhypopomus bennetti is the first Brachyhypopomus reported to have a monophasic (head-positive) EOD waveform. Unlike biphasic species, the waveform of its EOD is largely unaffected by tail damage from predators. Such injuries are common among specimens in our collections. This species' preference for floating meadow habitat along the major channels of the Amazon River basin may put it at particularly high risk of predation and "tail grazing."

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Electric discharge evidence found in a new class of material in the Chicxulub ejecta.

Publications

Electric discharge evidence found in a new class of material in the Chicxulub ejecta.

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