Combined noble gas and trace element measurements on individual stratospheric interplanetary dust particles

Abstract

Abstract-The trace element compositions and noble gas contents of 32 individual interplanetary dust particles (IDPs) collected in the Earth's stratosphere were measured. Trace element compositions are generally similar to CI meteorites, with occasional depletions in ZnRe with respect to CI. Noble gases were detected in all but one of the IDPs. Noble gas elemental compositions are consistent with the presence of fractionated solar wind. A rough correlation between surface-normalized He abundances and ZnIFe ratios is observed; Zn-poor particles generally have lower He contents than the other IDPs. This suggests that both elements were lost by frictional heating during atmospheric entry and confirms the view that Zn can serve as an entry-heating indicator in IDPs. INTRODUCTIONApproximately 30 000 metric tons of cosmic dust rains down on the Earth each year . Most of this material is melted or vaporized by frictional heating during atmospheric entry. Because entry heating scales with Earth-encounter velocity, size and density, small (less than -50 pm), low-speed (<20 kmh) particles can survive entry without significant melting. Dust grains in t h s size range, known as interplanetary dust particles (IDPs), subsequently settle through the stratosphere at rates of a few centimeters per second (Brownlee, 1985, and references therein). IDPs are now routinely collected using NASA ER-2 high altitude research aircraft (Zolensky et al., 1984). Collected particles are archved at the cosmic dust laboratory at NASA's Johnson Space Center (JSC) where they are made conveniently available for approved research.Most IDPs appear to be more primitive than CI chondrites. On theoretical grounds, it is expected that IDPs probably sample a wider range of ancient parent objects than do meteorites, including comets and distant asteroids (e.g., Kortenkamp et al., 2001). However deciphering the primitive record in these particles is complicated by the fact that all were heated to some degree during atmospheric entry. Alterations from entry heating are often subtle and may include the presence of a magnetite rim (e.g., Keller et al., l992), the inferred annealing of solarflare heavy ion tracks, thermal alteration of a particle's infrared spectrum (Sandford and Bradley, 1989) or solar-He release profile , apparent loss of volatile trace elements , andor partial or complete melting.It is important to be able to identify entry-heating alterations in IDPs so that they can be distinguished from primordial features. In addition, several researchers have pointed out that the connection between the degree of frictional heating and entry velocity may permit delineation of IDPs from high speed source objects such as comets (e.g., Flynn, 1989; Nier, 1994).Heating indicators based on the concentrations of volatile trace elements are particularly attractive because such elements can be measured non-destructively using x-ray fluorescence spectroscopy. Previous trace element analyses have revealed that -25% of all IDPs are depleted in the volatile element...

Noble gases in fossil micrometeorites and meteorites from 470 Myr old sediments from southern Sweden, and new evidence for the L‐chondrite parent body breakup event

“…As discussed below, the solar noble gases indicate that the SEC grains came to Earth as small particles. The element ratios 4 He/ 22 Ne lie between the atmospheric (3.1) and the solar (~9000) value, indicating partial loss of solar gases, as is also observed for recent interplanetary dust particles (IDPs) (Kehm et al 2002).…”

3He, 20,21,22Ne, 14C, 10Be, 26Al, and 36Cl in magnetic fractions of cosmic dust from Greenland and Antarctica

“…Detailed studies of individual cosmic dust particles began with the recovery of magnetic cosmic spherules from the ocean floor (Bradley and Brownlee 1982) and later of interplanetary dust particles (IDPs) by high-altitude aircraft (Brownlee 1985). Schlutter (1990, 1993), Kehm et al (1998Kehm et al ( , 2002Kehm et al ( , 2006, and Pepin et al (1999Pepin et al ( , 2000Pepin et al ( , 2001) have all reported on cosmogenic and solar gases in IDPs.…”

Single grain noble gas analysis of Antarctic micrometeorites by stepwise heating method with a newly constructed miniature furnace

“…Errors are 1σ . (Nier andSchlutter, 1990, 1993;Kehm et al, 2002) and ice-AMMs (Osawa and Nagao, 2002;Osawa et al, 2003a) are presented for comparison. The ratios for solar abundance (850: Anders and Grevesse, 1989) and SW (556: Heber et al, 2009) Ar ratio slightly higher than those of both SW and Q would be fractionated SW-Ar as in case of He and Ne in the snow-AMMs, although trapped Fig.…”

“…and reported He and Ne isotopic ratios attributed to implantation of solar energetic particles ("SEP") in individual IDPs and spherules from deep sea sediments, although this composition has now been shown to be implantation of mass discriminated solar wind "SW" (Grimberg et al, 2008). Laser heating methods have been used to extract noble gases from single IDPs; the measured He, Ne, and Ar were of solar origin (Kehm et al, 1998(Kehm et al, , 2002. Isotopic compositions of all noble gases for more than 100 individual iceAMMs have been measured using a Nd-YAG laser combined with a low blank and highly sensitive mass spectrometer (e.g.…”