Fission track age of Transantarctic Mountain microtektites

Nickel abundance in stony cosmic spherules: Constraining precursor material and formation mechanisms

“…It is, however, in contradiction with the conventional belief that most of the micrometeorites derive from carbonaceous CM2-like precursors (Kurat et al 1994;Brownlee et al 1997;Genge et al 1997;Engrand and Maurette 1998;Engrand et al 1999Engrand et al , 2005. The Transantarctic Mountain and the South Pole Water Well micrometeorite collections both contain abundant Ni-rich spherules, but sample the extraterrestrial influx at very different time scales (1 Ma and <3500 yr, respectively; Taylor et al 2000;Folco et al 2008Folco et al , 2011Suavet et al 2011). Thus, the influx of C-poor, metal-rich micrometeoroids has been significant over the last 1 Ma.…”

“…2008) during the 2006 Programma Nazionale di Ricerche in Antartide (PNRA) expedition. The Transantarctic Mountain collection contains thousands of cosmic spherules in the 200–1600 μm size range accumulated over the last 1 Ma (Folco et al. 2008, 2009, 2011; Suavet et al.…”

“…The Transantarctic Mountain and the South Pole Water Well micrometeorite collections both contain abundant Ni‐rich spherules, but sample the extraterrestrial influx at very different time scales (1 Ma and <3500 yr, respectively; Taylor et al. 2000; Folco et al. 2008, 2011; Suavet et al.…”

HED-like cosmic spherules from the Transantarctic Mountains, Antarctica: Major and trace element abundances and oxygen isotopic compositions

“…This suggests that the Transantarctic Mountain collection >200 lm in size is essentially unbiased by accumulation or weathering processes. The proportion of micrometeorites >200 lm in traps is, therefore, indicative of the flux of (large) micrometeoroids to Earth since the onset of the trapping mechanism $1 Ma ago (Folco et al, , 2011Suavet et al, 2011a). For the present study, we selected 362 stony cosmic spherules covering a range of color (colorless to black), size (220-850 lm in diameter), shape (spherical to oblate), external morphology (smooth to knobbly surface) and internal textures (six porphyritic, 57 barred-olivine, five cryptocrystalline and 294 glass spherules as defined by Genge et al (2008).…”

Ordinary chondrite-related giant (>800μm) cosmic spherules from the Transantarctic Mountains, Antarctica

“…The Transantarctic Mountain (TAM) micrometeorite collection has particles accumulated by direct infall into joints and weathering pits of glacially eroded granitic mountain tops. This collection is representative of the flux of extraterrestrial materials to the Earth in the 100-1600 lm size range (Suavet et al, 2009a) over the last $1 Myr Welten et al, 2008;Folco et al, 2009;van Ginneken et al, 2010;Folco et al, 2011;Suavet et al, 2011). Thanks to the large number of micrometeorites with masses >0.3 mg (size > ca.…”