Extraterrestrial Microspherules from Bajada del Diablo, Chubut, Argentina

MARÍA JULIA ORGEIRA; CASTRO, LILIANA; GOLDMANN, GASTÓN; PREZZI, CLAUDIA BEATRIZ; ELSA SILEO; D. VEGA; FRANZOSI, CORINA; ACEVEDO, ROGELIO; MARTÍNEZ, OSCAR; RABASSA, JORGE; PONCE, FEDERICO; RITA TÓFALO

Geoscience Frontiers

ELSEVIER SCIENCE BV

Año: 2017 vol. 8 p. 137 - 149

1674-9871

The main goal of this contribution is to analyze the stratigraphy of the infilling of a circular structure assigned by previous contributions to a crater strewn field located in Bajada del Diablo Chubut Province, Argentina. This contribution reported the finding of circa 65 microspherules collected in a trench excavated in the center of the crater structure. Surficial elemental chemical composition of microspherules was determined using energy dispersed spectrometry EDS. The mean grain size of the samples is 137 µm. The spherules are mainly composed of Fe and O wüstite. According to this composition, the spherules were classified as I-type. An accumulation rate of 47 spherulites per m2/yr was established for the studied microspherules. This value is two orders of magnitude higher than the reference flux for cosmic dust presented for the last 1 Ma in the Transantarctic Mountains. Following, the microspherules could be generated as a byproduct of an asteroid entry in the atmosphere. There is a concurrence of significative facts at Bajada del Diablo in which geomorphological, geophysical and the present findings suggest that at least a part of the study area could have undergone multiple impacts of extraterrestrial impactors.