1 **Experimental Determination of Zn Isotope Fractionation**

2 **During Evaporative Loss at Extreme Temperatures**

3 Josh Wimpenny¹*, Naomi Marks¹, Kim Knight¹, John M. Rolison¹, Lars Borg¹, Gary Eppich¹,

4 James Badro², Frederick J. Ryerson¹, Matt Sanborn³, Magdalena H. Huyskens³, Qing-zhu Yin³

5 *Corresponding author. Email: wimpenny1@llnl.gov

6 1 – Lawrence Livermore National Laboratory, Livermore, CA, 94550

7 2 – Institut de physique du globe de Paris, Paris, France

8 3 – University of California, Davis, CA, 95615

9

10 For submission to Geochimica Et Cosmochimica Acta

11

12

13 LLNL-JRNL-756623
14 Abstract

15 Zinc isotopes fractionate during evaporation, and thus can potentially be used to calculate the
16 proportion of volatile elemental loss from objects such as tektites, nuclear fallout melt glasses
17 formed from silicate soils, and rocks from the Moon. The utility of the Zn isotope system in
18 constraining the magnitude of volatile loss depends on accurate knowledge of its fractionation
19 behavior during evaporation, i.e., the Zn isotope fractionation factor. Here, we present new
20 results of Zn isotope analyses of experimentally heated soil samples, together with analyses of
21 environmentally derived fallout melt glasses, and australite tektites, to better constrain how
22 and to what extent Zn isotopes fractionate during thermally-driven evaporation.

23 Major and trace element analyses of melt glass derived from the experimental heating of
24 rhyolitic and arkosic soils demonstrates that elemental fractionation progressively becomes
25 more important with increasing temperature and time. Initial Zn isotope ratios in the rhyolitic
26 and arkosic soils are similar to upper continental crustal (UCC) values but become increasingly
27 isotopically heavy as more Zn is lost from the heated glass, with a maximum δ<sup>66</sup>Zn value of
28 +1.49 ± 0.05 ‰. The progressive loss of Zn from the rhyolitic soil is consistent with a
29 fractionation factor (α) of 0.99879 ± 13. After loss of a labile component from the arkosic soil
30 further evaporative loss of Zn from the silicate rich residue is also consistent with an α of
31 ~0.9988. This fractionation factor is not sensitive to either the heating temperature or duration.

32 The fallout melt glass, derived from near surface nuclear weapons tests, and natural tektite
33 samples are both relatively enriched in isotopically heavy Zn compared to the UCC. Although
34 the fallout melt glass is largely comprised of the same rhyolitic soil used in our experiments the
35 extent of Zn isotope fractionation is lower; consistent with an α of 0.9997. This is similar to
36 estimated values of α associated with loss of Zn from Trinitite and lunar rocks. It is more
37 difficult to constrain a value for α from australite tektites because the location of the impact
38 site is not well constrained. Based on our analyses, we estimate a range of α values between
39 0.9988-0.9997, which is broadly consistent with experimental data and analyses of fallout melt
40 glass.

41 In all cases the measured Zn isotope fractionation factors are much lower than would be
42 expected from evaporative loss of Zn in a high vacuum. We hypothesize that, for Zn, the value
43 of α is dependent on the localized gas pressure and composition, with the degree of isotopic
44 fractionation decreasing from high vacuum (< 1×10⁻⁹ bar) to atmospheric pressure. This would
45 have consequences for the interpretation of Zn systematics on the Moon. Recent studies
46 suggest that Zn loss from the Moon was dominantly caused by the Giant Impact and proceeded
47 with an α of ~0.9997. If correct, and taken together with our experimental data, this suggests
48 that evaporative loss of Zn from the Moon is unlikely to have occurred in high vacuum and is
49 more likely to have taken place at pressures similar to or higher than the current terrestrial

50 atmosphere.

51
52

# 1. Introduction:

53

54 Rudnick & Gao 2003), and has five stable isotopes; ⁶⁴Zn (48.63%), ⁶⁶Zn (27.90%), ⁶⁷Zn (4.10%),

55

56 the isotopic composition of Zn has become increasingly well studied due to its importance as a
57 micronutrient (e.g. Vance et al., 2016) and its moderate volatility (Tc ~ 726K, Lodders et al.

58 While the isotopic composition of Zn in crustal rocks is relatively uniform (e.g. Chen et al.

59 2013, Telus et al., 2012, Huang et al., 2018, Sossi et al., 2015), studies have shown that
60 significant isotopic fractionation of Zn can occur as a result of volatile loss (e.g. Cloquet et al.

61 2008, Moynier et al. 2009). During volatilization, isotopic fractionation of Zn occurs with a
62 preference for isotopically light Zn in the vapor phase, causing the residual solid/melt to be

63 relatively enriched in heavy Zn. This isotopic behavior can be utilized to quantify volatile
64 element loss, assuming the degree to which Zn isotopes fractionate during evaporation is

65

known (i.e. the isotopic fractionation factor).

66

67 impact melt rock from meteorite impact, or tektites (Moynier et al. 2009, Rodovska et al.,
68 2017), and melt glass derived from nuclear tests, or fallout (Day et al. 2017). These studies

69 confirm that during evaporative loss the light isotope of Zn is preferentially partitioned into the
70 vapor phase, leaving the solid phase enriched in isotopically heavy Zn. Although the

71 fractionation factor, α, associated with the evaporative loss of Zn is calculated to range from
72 0.999 to 0.9998 (Moynier et al., 2009, Day et al., 2017), it is not clear how robust these values

73 are, or how relevant they are in calculating Zn loss from volatile depleted bodies such as the
74 Moon. A major problem with using natural, or environmental samples to calculate Zn

75 fractionation factors is that α is inherently related to the proportional loss of Zn during
76 evaporation. This requires, i) knowledge of the starting Zn isotope ratio and Zn concentration, a

77 difficult parameter to estimate in the case of both tektites and nuclear fallout, and ii) the
78 assumption that the system is closed, which cannot be guaranteed if we consider that tektites

79 are mixtures of terrestrial material and impactor, and fallout is a variable mixture of bomb
80 materials mixed with the target lithology and anthropogenic carrier materials. Further

81 considerations include how potential variables such as temperature and mineralogy might
82 affect α. For these reasons, and due to the importance of new Zn isotope data in elucidating

83 information about how the Earth-Moon system formed (Herzog et al., 2009, Paniello et al.,
84 2012, Kato et al., 2015, Day et al., 2017), we re-investigate the behavior of Zn isotopes during
85 evaporative loss in an experimental system using controlled starting materials.

86 To this end, we present new Zn isotope data from a series of heating experiments designed to
87 melt silicate soils at a range of temperatures (1600-2200 °C) and heating durations (1-120 s)
relevant to the rapid-heating conditions experienced by tektites and fallout melt glass (e.g. Adams et al., 1960; Anderson 1961; Cassata et al., 2014). The experiments are performed on different mineral components and proportions, meaning the Zn isotope data can also be interpreted with respect to mineralogy. The arkosic soil sample was collected near the location of the Trinity test. The rhyolitic soil was collected near the site of fallout samples previously described in Eppich et al., (2014), Lewis et al., (2015) and Weisz et al., (2017). We additionally provide new Zn isotope data for the fallout melt glass samples. Entrained soil from the nuclear test sites is the volumetrically dominant contributor to glassy fallout in near surface tests, with the bomb vapor component adding only part-per-millions by weight (e.g. Eppich et al., 2014, Bonamici et al., 2017). Thus, collectively, these data in combination with recently published Zn isotope data from trinitite (Day et al., 2017) allow direct comparison of the behavior of Zn isotopes during evaporative loss in the laboratory with behavior during the formation of fallout melt glass. Differences in the behavior of Zn isotopes in experimental samples and fallout samples are less likely to be caused by differences in the Zn carrier materials but could be related to differences in physical parameters such as pressure, as has been observed for K isotopes (Yu et al., 2003, Wang & Jacobsen 2016).

Finally, we present new Zn isotope data for a series of 11 tektites from South-East Asia (australites). To date, only two studies have published Zn isotope ratios for tektites (Moynier et al., 2009, Rodovska et al., 2017). Both studies found that tektites are depleted in Zn relative to their potential source material, and have isotopically heavy $\delta^{66}$Zn values compared to typical crustal rocks. The data are inconsistent with simple kinetic isotope fractionation and the lack of a clear relationship between $\delta^{66}$Zn and Zn abundance suggests that heterogeneities in the Zn systematics of the precursor sediments could be important. In our case, the tektite samples originate from the same locality, minimizing potential heterogeneities in starting material mineralogy that could affect the Zn concentration of the precursor rock and potentially simplifying the interpretation. Thus, by potentially obtaining a more coherent set of Zn isotope data we can better constrain the isotopic effects of volatilization during tektite formation.

The comparison of fallout melt glass and tektite data with the results of experimental heating help ascertain whether Zn isotope fractionation due to volatilization is a constant or can be affected by chemical and physical constraints such as mineralogy, temperature and pressure. Ultimately, the results of this study provide new evidence constraining the behavior of Zn isotopes during volatilization. The results have implications for interpretation of Zn isotope data in volatile depleted and enriched samples, both in terrestrial environments and in planetary bodies such as the Moon.

## 2. Methods
## 2.1. Laser melting experiments

We undertook a series of high temperature melting experiments using a gas-mixing aerodynamic levitation laser furnace at the Institut de physique du globe de Paris (IPGP). The aerodynamic levitation laser apparatus is an instrument in which spherical samples are freely floated on top of a stream of gas while being heated with a CO₂ laser to maximum temperatures of 2200°C. Levitation spheres were created from two types of soil; an arkosic soil (feldspar rich sand) from the Trinity test site and rhyolitic soil from the site of a second nuclear test. Both soils were crushed and homogenized prior to heating using an agate pestle and mortar. The arkosic soil from the Trinity test site has been described previously (Ross 1948; Eby et al., 2015; Bonamici et al., 2017); it is composed of alkali feldspar, sodic plagioclase, quartz and limestone fragments. The calcite content ranges from 15-30%, and mafic mineralogy includes hydrated minerals such as chlorite and hornblende. The rhyolitic soil was previously characterized by Eppich et al., (2014), and consists of K-feldspar, quartz, plagioclase and glassy groundmass. It is more enriched in K and Na than the arkosic soil, and relatively depleted in Ca. The rhyolitic soil shows little evidence of weathering or alteration. For this project, 20 arkosic soil samples and 21 rhyolitic soils were subjected to aerodynamic levitation laser heating. Samples of each of the powders were pelletized using a Specac pellet die and hydraulic press, compressed to ~8 tons. Once the pellets were formed, the pellets were cracked and a small portion (~5-40 mg) of material was introduced into the laser heating apparatus.

Samples were first heated and melted above their melting (liquidus) temperature over a period of 20 to 60 seconds and then rapidly ramped up to target temperature (1600 - 2200°C) for a duration of between 1 and 120 seconds. Temperature of the spheres was monitored and recorded during heating using an external pyrometer. During the heating process, samples float freely on top of a stream of Ar gas. As a result of the heating and aerodynamic rotations during heating, the samples rapidly take on a spherical shape (Fig. 1) while degassing and convectively mixing. The samples from this set of experiments formed spheres that range from 0.8 to 3 mm in diameter with varying amounts of vesicularity. Samples heated to temperatures <1800 °C, commonly did not form spheres, but rather melted and formed non-aerodynamic forms.

## 2.2. Major and trace element analyses

Trace element analyses were performed at Lawrence Livermore National Laboratory (LLNL) using the Thermo Scientific Element XR inductively coupled plasma mass spectrometer (ICP-MS), and following techniques previously described in Eppich et al., (2014). All samples were digested using ultra-pure concentrated acids (HF-HNO₃-HCl). Aliquots of stock solutions were weighed, dried down in Teflon beakers, and diluted in 2% HNO₃ that was spiked with an
internal standard consisting of a 1 ppb mixture of <sup>115</sup>In, <sup>187</sup>Re, and <sup>209</sup>Bi. Signal intensities of the internal standard isotopes were used to correct for instrumental sensitivity changes throughout the analyses. Concentrations were calculated by normalizing background and drift corrected intensities to a calibration curve prepared on the day of the analytical run. This calibration curve was created using a set of serial dilutions of concentration standards obtained from Inorganic Ventures. To determine measurement accuracy and reproducibility, the USGS rock standard BCR-2 and water standard NIST 1640a were analyzed along with the sample batch. Based on the accuracy of these standards, typical uncertainties for trace element analyses are better than 5%.

168

2.3. Zn isotopic analyses

170
2.3.1. *Sample preparation and materials*

171 All sample processing and Zn purification was performed in a class-1000 clean laboratory at LLNL. All acids are Baseline® grade, purchased from Seastar Chemicals Inc™. Acids were diluted
172 using high resistivity water (18.2 MΩ) provided by Milli-Q water purification systems. Due to
173 the use of Zn in the mold release process for most clean laboratory gloves (e.g. Garcon et al.,
174 2016) a number of glove types were tested during the development of the Zn project. These
175 include white nitrile, polyvinyl, co-polymer and polyethylene gloves. Testing involved inverting
176 the gloves on a 15 mL centrifuge tube filled with 5 mL of 2% HNO₃ acid for one second. The
177 resulting solution was analyzed using a Thermo Element XR at LLNL and intensities were
178 quantified using variably diluted multi element solutions. Zinc concentrations liberated from
179 the glove testing ranged from below detection for the polyethylene gloves to over a microgram
180 for white nitrile gloves. Thus, polyethylene gloves were used for the duration of the Zn method
181 development and sample analyses.
182

183 For standard testing the USGS rock standards BCR-2, BHVO-2 and BIR-1a were dissolved using the standard HNO3-HF technique. Any fluoride formation was accounted for by fluxing and drying each sample with ~100 µL of concentrated perchloric acid. Zinc isotopes have previously been normalized to the JMC-Lyon standard (Marachel et al., 1999) but this standard material is not widely available and has now been mostly consumed (e.g. Archer et al., 2017).
184
185
186
187 Consequently, data in this manuscript have been normalized to the Zn isotope standard IRMM-3702 (Ponzevera et al., 2006).
188
189

190

191
2.3.2. Double spike development
192 Zinc has five stable isotopes so is well suited to isotopic analysis using a double spike. A range of 193 spike compositions have previously been used in the literature; the most common being a ⁶⁷Zn- 194 ⁶⁴Zn double spike (e.g. Bermin et al. 2006, Arnold et al. 2010, Little et al. 2014, Conway et al. 195 2013), but others used include ⁶⁷Zn-⁶⁸Zn (Samanta et al. 2016) and ⁶⁷Zn-⁷⁰Zn (Makishima & 196 Nakamura 2013). To design the double spike tracer for our Zn isotope measurements we used 197 data from Rudge et al. (2009), to calculate the optimal double spike combinations for Zn and 198 the optimal double spike-sample mixing ratios based on modelled uncertainties. As a result, we 199 chose a ⁶⁶Zn-⁶⁸Zn double spike that, when optimally spiked, results in uncertainty on the 200 calculated natural fractionation factor that is less than other isotopic combinations except for 201 double spikes employing ⁷⁰Zn (Rudge et al., 2009, Arnold et al., 2010).

202 The double spike was calibrated using the certified values for IRMM-3702 (Ponzevera et al. 2006). However, when analyzing an unspiked aliquot of IRMM-3702 in either wet or dry plasma 203 we observed that we could not achieve a constant mass fractionation factor (β) for different Zn 204 isotope ratios based on the difference between measured and certified isotope ratios. Here, we 205 define β as follows: 206

$$
207 \quad \beta = \frac{\ln\left[\frac{\left(\frac{x_{Zn}}{y_{Zn}}\right)_{\text{measured}}}{\left(\frac{x_{Zn}}{y_{Zn}}\right)_{\text{true}}}\right]}{\left[\frac{m^{x_{Zn}}}{m^{y_{Zn}}}\right]} \qquad \text{Equation 1}
$$

208 Where x and y denote specific isotopes of Zn, and m is the mass of each isotope. Assuming the 209 exponential mass fractionation law holds true, a value for β obtained from the difference 210 between the measured and true ⁶⁶Zn/⁶⁴Zn ratios should, in theory, enable us to calculate the 211 true ⁶⁷Zn/⁶⁴Zn and ⁶⁸Zn/⁶⁴Zn ratios. We observed, however, that based on the certified values of 212 IRMM-3702, the calculated value of beta varies as a function of mass difference between 213 isotopes (Fig. 2). This means that different β values are obtained for ⁶⁶Zn/⁶⁴Zn, ⁶⁷Zn/⁶⁴Zn and 214 ⁶⁸Zn/⁶⁴Zn, which is *not* consistent with the exponential fractionation law.

215 Examining the data reduction of Ponzevera et al. (2006) in more detail shows that they in fact 216 do not assume that mass discrimination is constant for different isotope pairs of the same 217 element. Instead, an expression in which the mass discrimination factor is dependent on the 218 average mass of the two isotopes involved was utilized. Thus, their calculated isotope ratios for 219 IRMM-3702 are not well reproduced by the exponential law and cannot be used in the 220 calibration of a double spike. To account for this we analyzed a pure solution of IRMM-3702 221 multiple times (n = 20), correcting the data using the exponential law based on the reported 222 ‘true’ ⁶⁶Zn/⁶⁴Zn ratio of IRMM-3702 being 0.56397 (Ponzevera et al. 2006). Based on this, we 223 obtained ⁶⁷Zn/⁶⁴Zn and ⁶⁸Zn/⁶⁴Zn ratios of 0.082017 ± 6 and 0.372984 ± 46 for the isotopic 224 composition of IRMM-3702. These values were used to calculate the composition of the double
spike and used in the final double spike reduction following the iterative reduction method of Siebert et al., (2001). In future studies we caution against the use of the IRMM 3702 standard in calibrating a double spike. Either this standard should be recalibrated and the values of Ponzevera et al., (2006) recalculated, or a new standard that is abundant and widely available should be characterized, such as the NIST standard SRM 683 (Chen et al., 2016; Yang et al., 2018).

A potential drawback with the use of a <sup>66</sup>Zn-<sup>68</sup>Zn double spike is that it is more sensitive to the exact mixing ratio between sample and spike, with uncertainties increasing if non-optimal sample-spike ratios are used (see Rudge et al., 2009). As a result, we tested several spike-sample ratios between 1 and 5, finding that uncertainties remained at around 0.02‰ regardless of the spike-sample ratio. Only when spike-sample ratios increased to above 10 did we notice significant shifts in the accuracy and precision of the double spike technique (Fig. 3). In application, this issue was easily avoided by pre-screening the samples prior to addition of the double spike to ensure the optimal spike amount was always added.

239

240

### 2.3.3. Ion-exchange chromatography

Zinc was purified from matrix elements following a method modified from Sossi et al. (2016) and similar principles to previous techniques designed to purify transition elements based on their different partition coefficients for anion resin in HCl (e.g. Marechal et al. 1999). In brief, samples were dried and dissolved in 0.25 mL of 0.1 M HCl, before loading into a column bed of 0.25 mL of Bio-Rad AG1-X8 anion resin (200-400 mesh). Further elution of 0.1 M HCl rinses most matrix elements, including Fe, away from the sample while Zn remains bound to the resin. Final solutions had Fe/Zn ratios of <0.02. With the addition of 3M HNO₃ the Zn is immediately eluted, with over 99% recovery in 0.75 mL. While the 0.1 M HCl is effective at removing most matrix elements, some residual tailing of Fe and other major elements can remain in the sample after a single pass. To ensure a high purity Zn cut, the column procedure was repeated. Total procedural blanks associated with Zn purification were measured to be between 0.1 and 1 ng of Zn. To ensure that the blank component remained <1% of the processed sample, we processed a minimum of 100 ng of Zn through column chemistry in these experiments.

254

255

### 2.3.4. Mass spectrometry

All experimental samples and tektites were analyzed using the Thermo *Neptune-Plus* MC-ICP-MS at UC Davis. Fallout melt glass samples were analyzed using the *Neptune-plus* at LLNL. The two instruments have identical front-end components. Samples were dissolved in 2% HNO₃ and
259 introduced to the plasma using an ESI Apex IR desolvating system. Typical sensitivity was 60V of
260 $^{64}$Zn per ppm using a high sensitivity 'Jet' sample cone and regular 'H' skimmer cone, together
261 with 10$^{11}$ ohm resistors. Samples were typically analysed at 50-100 ppb, with $^{64}$Zn intensities of
262 3-6V. Collectors were set to analyze $^{62}$Ni, $^{63}$Cu, $^{64}$Zn, $^{65}$Cu (axial collector), $^{66}$Zn, $^{67}$Zn and $^{68}$Zn.
263 We did not include $^{70}$Zn in the double spike reduction and so did not collect $^{70}$Zn data. All
264 sample and standard analyses consisted of 30 × 8s integrations. A typical analytical routine
265 involved multiple analyses of the IRMM-3702 standard throughout the session, followed by the
266 QC standards (BCR-2 and BHVO-2) and unknowns. To ensure that the final data were insensitive
to the sample-spike ratio, we also analyzed multiple IRMM-3702 samples with varying spike-
267 sample ratios (1-10) over several different analytical sessions.
268

269 Final data reduction followed the iterative technique developed for molybdenum isotopes in
270 Siebert et al. (2001) where only a spiked sample is necessary to calculate the mass dependent
271 fractionation. A drawback to this process is that only mass dependent fractionation can be
272 analyzed, rather than mass independent effects. Because the evaporative fractionation of zinc
273 is a mass dependent process, however, it is unnecessary to consider other effects. The method
274 could be further adapted to search for isotopic anomalies if required; in this case both a spiked
275 and unspiked sample aliquot would need to be processed.
276

276 To assess the accuracy and precision of the total procedure we measured a series of QC
277 standards throughout the different analytical sessions. All unknowns were normalized to the
278 IRMM-3702 standard which, in theory, should always have a $\delta^{66}$Zn value of 0‰. In practice we
279 noticed that the value of IRMM-3702 varied both between and within each analytical session,
280 from a minimum of -0.05 to a maximum of +0.05‰. To account for this small discrepancy all
281 unknowns were bracketed by a spiked sample of IRMM-3702 and normalized to the bracketing
282 standard values.
283

283 Final $\delta^{66}$Zn values are thus the $^{66}$Zn/$^{64}$Zn ratio of the unknown relative to the average $^{66}$Zn/$^{64}$Zn
284 ratio of the bracketing standards using the following equation:

$$285 \qquad \delta^{66}Zn = \left[ \left( \frac{\frac{66Zn}{64Zn_{Sample}}}{\frac{66Zn}{64Zn_{IRMM 3702}}} \right) - 1 \right] \times 1000 \qquad \text{Equation 2}$$

286 Zinc isotopic compositions were calculated relative to the IRMM-3702 standard. To make final
287 data consistent with previously published work these values were then converted to the JMC-
288 Lyon scale ($\delta^{66}$Zn$_{JMC-Lyon}$ = $\delta^{66}$Zn$_{IRMM 3702}$ + 0.3‰, Cloquet et al., 2008, Petit et al., 2008, Sossi et
289 al., 2015). Based on this method, our long-term precision can be assessed using a combination
290 of data for BCR-2 and BHVO-2. On average, BHVO-2 had a $\delta^{66}$Zn value of 0.26 ± 0.05‰ (n = 7,
291 2SD) and BCR-2 had a $\delta^{66}$Zn value of 0.25 ± 0.05‰ (n = 7, 2SD). These values are consistent with
292 previously published Zn isotope ratios for both standards (e.g., Bigalke et al., 2010, Chen et al., 2013, Sossi et al., 2015,). Generally, external reproducibility was ~2 times larger than the internal precision of the technique, with typical uncertainties for δ<sup>66</sup>Zn values on individual measurements of 0.01 to 0.03‰.

296

297 **3. Results**

298 Major and trace element concentrations, and Zn isotope data for the heating experiments are 299 presented in Table 1, and data for the fallout melt glass and tektites are presented in Table 2.

300

301 **3.1. Experimental samples**

302 The rhyolitic and arkosic soils have fundamental differences in their bulk geochemistry that are 303 consistent with differences in mineralogy (see Section 2.1). The rhyolitic soil is relatively 304 enriched in Na (3.1 wt%) and K (4.0 wt%) and relatively depleted in Ca (0.6 wt%) compared with 305 the calcite-rich arkosic soil (1.1 wt%, 2.9 wt% and 4.8 wt% for Na, K and Ca respectively). It also 306 contains significantly more Zn than the arkosic soil (~153 and 51 ppm respectively). 307 Consequently, the Zn concentrations in rhyolitic laser spheres are generally higher (10 – 172 308 ppm) than Zn concentrations in the arkosic laser spheres (8 – 35 ppm). Due to the low Zn 309 concentration in the arkosic spheres only a restricted data set could be analysed for Zn 310 isotopes.

311 In both the rhyolitic and arkosic experiments the major and trace element concentrations in the 312 melted soil evolved with increasing heating temperature and duration, due to the evaporative 313 loss of volatile components (e.g. Zn, Na, K) and the ensuing enrichment in refractory 314 components (e.g. Al, Ca), (Table 1). In general, the concentrations in the rhyolitic experiments 315 were less fractionated from the starting soil, with significant elemental fractionation only 316 occurring at higher temperatures (> 2000 °C) and longer heating times (10-120 s). In contrast, 317 significant changes in elemental abundance occurred in the arkosic soils after heating to 1600 318 °C for a few seconds. Elements that typically increased in concentration with heating 319 temperature and duration included Ca and Al (Fig. 4). For example, the rhyolitic soil has Al and 320 Ca concentrations of 6.72 and 0.65 wt % respectively. After heating at 2200°C for 90 s, the 321 respective concentrations of Al and Ca had increased to 26.2 and 1.92 wt %. Elements that 322 typically decreased in concentration with increasing heating temperature and duration include 323 K, Na, Pb, Tl, and Zn (Fig. 5). The rhyolitic soil has Na and K concentrations of 3.5 and 4.6 wt % 324 respectively. After heating at 2200°C for 90 s, the respective concentrations of Na and K had 325 decreased to 0.07 and 0.6 wt %. While similar decreases in concentration occur during heating 326
326 of the arkosic soil at temperatures between 2000-2200 °C, there are also significant decreases
327 in concentration of elements including Fe, Mn, Ti, and Zn that occur after heating to a
328 maximum of 1600 °C for 1 s. For example, the concentration of Zn in the arkosic soil is 52 ppm,
329 but after heating at 1600 °C for 1 s, the Zn concentration dropped to 19 ppm.

330 The δ⁶⁶Zn value of the starting rhyolitic and arksosic soil was 0.26 and 0.22 ‰ respectively,
331 consistent with Zn isotopic values measured in continental crustal materials (e.g., Chen et al.,
332 2013). Relative to these starting values, the laser spheres were either similar to, or variably
333 enriched in isotopically heavy Zn after heating (Fig. 6). The rhyolitic laser spheres range in δ⁶⁶Zn
334 from 0.26 to 1.49 ‰, while the arkosic laser spheres range from 0.33 to 1.42 ‰. In both
335 experiments the laser spheres with the heaviest δ⁶⁶Zn values were subjected to higher heating
336 temperatures and longer heating durations. The laser spheres with the heaviest δ⁶⁶Zn values
337 also have the lowest concentrations of Zn and other elements that are typically considered to
338 be volatile, including Pb and Tl.

339
340 3.2. Fallout melt-glass
341 Relative to their rhyolitic soil precursor, the fallout samples have similar chemical compositions,
342 but are depleted in Na, K, Zn, Tl, and Pb, and enriched in Ca. The concentration of Zn in these
343 fallout samples ranges from 45 to 89 ppm, compared to 149 ppm in the rhyolitic parent soil.
344 Measured δ66Zn values range from 0.33 to 0.67 ‰ (Fig. 6) and are thus relatively enriched in
345 isotopically heavy Zn compared to the rhyolitic soil, and similar to δ66Zn values in trinitite
346 reported by Day et al., (2017).

347
348 3.3. Australite tektites
349 Major and trace element data for the australite samples are given in Table 2. For context,
350 typical upper continental crust (UCC) values are also provided. Unfortunately, there is no
351 information relating to the chemical composition of the precursor local crustal material with
352 which these data can be compared. Zinc concentrations range from 10 to 28 ppm, which is
353 lower than the average Zn concentration in the UCC (67 ppm, Rudnick & Gao 2003). Zinc
354 isotope ratios range from δ66Zn values of 1.02 to 2.04 ‰ (Fig. 6). This is within range of
355 previously published δ66Zn values for australites (Moynier et al., 2009).

356
357 4. Discussion
358 4.1. Chemical fractionation during rapid extreme heating
The experimental heating of soil to form melted glass (here termed laser spheres) resulted in elemental abundances within the laser spheres being fractionated relative to the initial abundances of the precursor soil. Since the aerodynamic levitation laser furnace is a container-less instrument, one can assume that exchange with the gas (i.e. evaporation) is the dominant process. It follows that progressive heating of the laser spheres should result in progressive fractionation of the chemical composition relative to the composition of the initial soil. The observed decrease in the concentrations of more volatile elements (e.g., Na, K, Zn) in both soil types with increasing heating temperatures and durations is entirely consistent with this hypothesis (Fig. 5).

Because we cannot constrain the mass of soil used during each experiment we cannot quantitatively account for mass loss during heating. Thus, measured elemental concentrations cannot provide accurate information about element depletion or conservation during heating. Such information is critical for accurate determination of Zn depletion, which is used to calculate the Zn isotope fractionation factor. To address this problem we instead normalized elemental concentrations in the starting soils and laser spheres to the concentration of a refractory index element, which we assume is conserved during heating. Here, we have chosen Al as the index element, supported by the fact that it is highly abundant in early Solar System condensates, has a high 50% condensation temperature (1677 K, Lodders 2003), and has concentrations with apparent enrichments of up to 300% in the laser heating experiments. That being said, we cannot rule out that a small loss of Al also occurred during the heating experiments.

By normalizing the concentration of each element to the concentration of Al it is possible to calculate changes in elemental abundance (%) in the laser spheres relative to their average abundance in the soil. Thus, we can determine the degree to which elements such as Zn were volatilized during heating (Table 3 and plotted in Fig. 7 and 8). As is expected, there is a clear relationship between heating temperature and heating duration with elemental fractionation. This is easily observed in a plot of the % depletion of Tl and Pb for both sets of experiment, where the proportion of element loss is greatest in the higher temperature experiments (Fig. 8).

Although there are similarities in the behavior of the rhyolitic and arkosic soils there are also clear differences. In Fig. 8 we plot the enrichment factors for Mg and Ti in the two sets of experiments. In the rhyolitic experiments the concentrations of Mg and Ti were generally unaffected by heating. The only samples that were fractionated were those heated at the highest T-t conditions (2200 °C, 60-90 s). In contrast, significant amounts of Mg and Ti were lost from the arkosic soil after heating at a maximum temperature of 1600 °C for 1 s. Because the laser experiments involved a slow pre-melting period prior to attaining peak temperature it is
likely that volatilization from the arkosic spheres occurred during this warming up period, i.e. at temperatures between 0-1600 °C. As illustrated in Fig. 8, arkosic soil that was heated at temperatures between 1800-2200 °C did not experience further Mg and Ti loss. This suggests that the Mg and Ti were associated with an easily volatilized phase that was not present in the rhyolitic soil. Similar behaviour was observed for other elements that are not typically considered to be highly volatile such as Fe and Mn. In the case of Zn, significant loss (67-76%) also occurred during heating to 1600 °C, but this was followed by further mass loss as the temperatures and heating durations increased. For example, between 92-98% of the initial Zn was lost after heating the arkosic soil to 2200 °C. Other volatile elements such as Na, K, Tl, and Pb experienced little to no mass loss during this initial heating period, but lost up to 99% of their initial mass as peak heating temperatures increased to 2200 °C. These data demonstrate that the behaviour of major and trace elements in the arkosic soil is complicated; typical indices of volatility, such as the 50% condensation temperature, cannot predict which elements are volatilised and to what extent.

To explain these observations, we hypothesize that the arkosic soil contains two distinct phases that have different chemical compositions and different reactivities. One phase is more labile and easily volatilised at temperatures < 1600 °C, while the other is significantly more refractory. Based on the major and trace element data, the easily volatilised phase in the arkosic soil contains significant amounts of Mg, Ti, Fe, Mn and Zn, while the more refractory phase contains most of the Na, K, Tl and Pb. Although arkosic sand commonly comprises quartz and feldspar, arkosic sand from the Trinity test site also contains calcite and the hydrated mafic minerals amphibole, hornblende, and biotite (Ross 1948; Eby et al., 2015; Bonamici et al., 2017). Carbonate-rich, hydrated melts have lower liquidus temperatures (500-600 °C, Osinski & Spray 2001) than silicate melts, particularly the high Si-melts analysed here that have liquidus temperatures of ~1200 °C (e.g. Jones et al. 2013, McKenzie 1985). If melting and evaporation can be initiated at lower temperatures in the arkosic soil, and the more reactive phase contains elements that include Zn, Mg, Ti, Fe and Mn then this could explain how a mixture of relatively refractory and volatile elements can be evaporated at temperatures < 1600 °C.

In summary, there are clear differences between the rhyolitic and arkosic soils in terms of degrees of element depletion and temperatures at which element loss occurs. These results highlight the influence of both the physical conditions (i.e. temperature and time) and the chemical composition of the starting material on the magnitude of resulting element depletion. While these experiments are useful for generalized interpretation of elemental fractionation during rapid heating events at atmospheric pressures, the sensitivity of physical parameters on these results remains unclear. Previous studies have shown that the loss of volatiles from silicate melts is dependent on a wide range of parameters including the temperature, time, pO₂ and chemical composition of the silicate material (e.g. Tsuchiyama et al., 1981; Yu & Hewins,
1998; Grossman et al., 2000; Richter et al., 2002; Richter 2004). As such, additional constraints are needed to draw more robust connections between overall volatile loss and heating temperature and duration or other physical or chemical factors.

4.2. Zinc isotope fractionation

4.2.1. *Experimental samples*

We present the first experimental dataset to support the quantitative interpretation of the isotopic fractionation of Zn caused by evaporative loss. Consistent with previous studies that have observed isotopically heavy Zn in volatile depleted solids (e.g. Moynier et al. 2009, Paniello et al. 2012, Day et al. 2017), the isotopic composition of Zn in the laser spheres is consistently isotopically heavy relative to the starting soil. In general, laser spheres heated for longer, and at higher temperatures lost more Zn. Correspondingly, the magnitude of Zn isotope fractionation generally increases with temperature and duration of heating, with a maximum observed δ⁶⁶Zn value of +1.49‰ in RH-15. This is a similar magnitude to previously published values for tektites (Moynier et al. 2009) and lunar basalts (Paniello et al. 2012) but is more fractionated than values measured for fallout melt glass from the Trinity nuclear test (Day et al. 2017).

The isotopic fractionation factor (α) associated with evaporative loss of Zn can be calculated from Zn isotope data using the following relationship:

$$R = R_0 \times f^{\alpha-1} \qquad \text{Equation 3}$$

Where R is the Zn isotope ratio of a volatile depleted sample, R₀ is the initial Zn isotope ratio and f is the fraction of Zn that remains after evaporation. Based on reasoning outlined in Section 4.1 we calculated the % Zn loss for each laser sphere by normalizing the Zn/Al ratio in the sphere to the Zn/Al ratio in the starting soil, assuming that the Al has been conserved during heating. Calculated Zn loss in the rhyolitic soil experiments ranges from 0 to 57%, and Zn loss in the arkosic soil experiments ranges from 68 to 94%. Zinc systematics from the rhyolitic soil experiments constrain a well-defined fractionation factor of 0.99879 ± 13 (Fig. 9). In contrast, the laser spheres from the arkosic soils show a more complicated relationship between Zn loss and δ⁶⁶Zn, where initial loss of Zn is significant but not accompanied by isotopic fractionation (Fig. 10a). For example, in arkosic soil experiments 13 and 17 (performed at 1600 °C for 1-5 s) the laser spheres lost ~70% of initial Zn, with little to no accompanying isotopic fractionation (δ⁶⁶Zn sphere-soil of ~0.1‰). In comparison, the rhyolitic laser sphere with the greatest depletion is sample RH-15 (2200 °C, 60 s), with a 57% loss of Zn, but a δ⁶⁶Zn sphere-soil of ~1.2‰.
This discrepancy probably reflects the presence of carbonates and hydrated silicates in the arkosic soil, which depresses the liquidus and initiates melting at lower temperatures. If we assume that the $\delta^{66}\text{Zn}$ values of the various mineral constituents within the arkosic soil are similar, the quantitative loss of a more reactive Zn reservoir would not result in any isotopic fractionation. Of course, partial loss of this labile phase would be expected to impart an isotopic fractionation of Zn. However, even sample AR-17, which was heated to a peak temperature of 1600°C for 1s, has lost 70% of its initial Zn. This implies that total loss of the labile phase occurred during preheating and this Zn loss occurred without any corresponding isotopic fractionation. With more prolonged heating, and heating to higher peak temperatures we hypothesize that Zn then volatilizes from the remaining silicate material. This results in Zn isotope fractionation, with arkosic laser spheres becoming progressively more enriched in isotopically heavy Zn.

Because a significant proportion of the Zn in the arkosic soil was lost without imparting any isotopic fractionation (i.e., quantitative loss), it is not representative to calculate a fractionation factor from the resulting isotope data. A more meaningful fractionation factor can be calculated by replacing the starting soil with a sample in which the labile Zn has already been evaporated. In this case we have taken sample AR-17 (1600 °C, 1 s) as a proxy for the starting material with a $\delta^{66}\text{Zn}$ value of 0.30 ‰, a Zn concentration of 19 ppm, and Zn/Al ratio of 0.00029. The Zn isotope data for the arkosic soils can then be projected as a function of % Zn loss (Fig. 10b). Removing the effects of the inferred labile reservoir places Zn isotope data for the arkosic soil experiments on approximately the same evolution line as data from rhyolitic laser spheres, consistent with an alpha of 0.9987-0.9989. This fractionation factor is greater than has been previously calculated from tektites or nuclear fallout (Moynier et al., 2009, Day et al., 2017). The fact that the Zn data from both experiments lie on similar evolution lines could suggest that the residual high temperature assemblage in the arkosic soil is compositionally similar to the rhyolitic soil. Alternatively, it could suggest that in simple, silicate-dominated systems the isotopic fractionation factor associated with evaporative loss of Zn is insensitive to the silicate mineralogy and temperature of heating. The data from the arkosic soil experiments suggest that in more complicated systems with varying mineralogies and reactivities, the simple relationship between $\delta^{66}\text{Zn}$ and proportion of Zn loss, as described by equation 3, is no longer valid.

### 4.2.2. Zinc isotopes in fallout

In this study we present new Zn isotope data for aerodynamic fallout melt glass samples derived from the interaction of a nuclear weapons test with rhyolitic soils. This same rhyolitic soil was homogenized for use in the laser sphere experiments. Studies of major element
abundances in the fallout and soil show that the rhyolitic soil is the main environmental component of the fallout glass (Eppich et al., 2014, Lewis et al., 2015, Weisz et al., 2017), such that these soils constrain the chemical composition of the fallout glass prior to interaction with the fireball. Fallout melt glass additionally carries a chemical signal from the device and other man-made materials in the vicinity of the blast that could contribute Zn to the resulting fallout samples. Anthropogenic Zn can have isotope ratios that are fractionated from typical crustal values. For example, John et al., (2007) analyzed Zn isotopes in anthropogenically produced zinc products, finding $\delta^{66}\text{Zn}$ values in raw metal that range between -0.04 to 0.24‰, and galvanized and electroplated hardware such as screws and nails with $\delta^{66}\text{Zn}$ values ranging from -0.55 to 0.75‰. While the exact sources of anthropogenic Zn are not known for these samples, anthropogenic contributions to fallout are generally at the part-per-million level (e.g. Eppich et al., 2014) so any signal from anthropogenic material is likely overwhelmed by that of the soil.

If we assume that the initial rhyolitic soil component in the fallout was the same as the rhyolitic soil and had a Zn/Al ratio of 0.0023, these fallout samples lost between 34-68% of their initial Zn. Based on $\delta^{66}\text{Zn}$ values that range between 0.33 and 0.67‰ these values are consistent with an alpha value of 0.9997, forming an array distinct from those of the related rhyolitic experimental samples (Fig. 10). These data compare well with recently published work by Day et al., (2017) who analyzed Zn isotopes in trinitite.

520

521

### 4.2.3. Zn isotope ratios in tektites

To calculate the proportion of Zn loss during tektite formation requires an assumption about the chemical composition of the precursor material. The australite tektites are derived from continental sediments offshore from Southeast Asia (Chaussidon & Koeberl 1995). The average upper continental crust (UCC) has a Zn concentration of ~ 67 ppm (Rudnick & Gao 2003) and $\delta^{66}\text{Zn}$ value of 0.31 ‰ (Little et al., 2014). While a UCC composition would be a reasonable estimate for the Zn composition of the precursor material, it does not account for the Muong-Nong group of australites, which can have Zn concentrations as high as 90 ppm (Koeberl 1992). The general similarity between major element geochemistry, isotopic composition and age of Muong-Nong and main group australites suggests they are co-genetic. The Muong-Nong tektites are unusual in comparison to other australites, however, because they have a blocky appearance, contain numerous gas bubbles, and generally have very high volatile element concentrations (including halogens and sulphur). The inference from these observations is that they formed at lower temperatures than typical splash form tektites and possibly contain a volatile element budget that is more representative of the starting material (Koeberl 1992). Previous analyses of soils and loess from the vicinity of the Muong-Nong type tektites report Zn concentrations of up to 81 ppm (Koeberl 1992). Based on this value, together with a maximum
538 Zn concentration of 90 ppm in Muong-Nong tektites, we estimate the crustal component had a
539 Zn concentration of ~100 ppm. While this estimate doesn't consider the proportion of Zn that
540 originated from the impactor, studies of platinum group elements in tektites have
demonstrated that the proportion of meteoritic material that is incorporated into tektites is
541 very small (e.g., 0.6% in Ivory Coast tektites, Koeberl & Shirey 1993). If we assume that the
542 australite precursor had a Zn concentration of 100 ppm, our new Zn isotope data for australites
543 plot on a fractionation line with an alpha of 0.9992 (Fig. 11). Clearly this fractionation factor is
544 dependent on the assumption of the Zn concentration in the tektite precursor; Day et al.,
545 (2017) speculated that the australites formed from a precursor with a Zn concentration of >200
546 ppm. In this case the new australite data is consistent with an alpha of 0.9996, similar to the
547 fractionation factor calculated from analyses of fallout (0.9997). In contrast, if we assume a
548 precursor concentration that is similar to the average UCC (67 ppm Zn, Rudnick & Gao 2003),
549 the resulting array is more consistent with the experimentally determined alpha value of 0.9988
550 (Fig. 11). Thus, although we obtain a relatively coherent data array for Zn systematics in
551 australites, without good constraints over the precursor composition it is difficult to judge the
552 significance of the resulting fractionation factor value when compared to the better
553 constrained experimental systems and the suite of fallout samples. With our current knowledge
554 we can state that Zn loss from tektites is consistent with a range of α values between 0.9988-
555 0.9997.
556

557

558 4.3. Controls over Zn isotope fractionation during evaporation

559 Zinc isotope ratios in fallout melt glass, tektites and experimentally heated soil are fractionated
to a lower degree than is predicted by simple Rayleigh fractionation. In other words, the
560 fractionation factor associated with evaporative loss of Zn, α, is relatively suppressed. In the
561 following section we discuss in turn i) causes for suppression of α in these sample suites, and ii)
562 why Zn fractionates to different extents in the experimental and fallout melt glass samples.
563

564

565 4.3.1. Suppression of Zn isotope fractionation factor

566 The theoretical kinetic fractionation factor for the evaporation of elemental Zn is estimated
based on the following equation:
567

$$
568 \quad \alpha = \sqrt{\frac{m^{64}Zn}{m^{66}Zn}} \qquad \text{Equation 4}
$$
Where m is the mass of the isotope or evaporating species. This is the true kinetic fractionation factor where free evaporation is assumed to take place in a vacuum. The theoretical α for the evaporation of elemental Zn is 0.985 for the ⁶⁶Zn/⁶⁴Zn ratio. This α value will vary as a function of Zn speciation during evaporation. Zinc is well known to combine with S and Cl in igneous systems (Symonds et al., 1987; Toutain et al., 2008) so that the theoretical α would change depending on the masses of the isotopologues. Based on the most abundant isotopes of Cl and S (³⁵Cl = 75.76%, ³²S = 94.99%) the α values for kinetic evaporation of ZnCl₂ and ZnS would be 0.993 and 0.990 respectively. Thus, although α does depend on the speciation of evaporated Zn, in all cases the degree of Zn isotope fractionation related to free kinetic evaporation is far greater than we obtain experimentally or is measured in tektites and fallout melt glass (this study, Moynier et al., 2009; Rodovska et al., 2017; Day et al., 2017). This relative suppression of α is consistent with previous experimental studies investigating the kinetic fractionation of Mg, Si and O during evaporation of olivine and refractory inclusions in chondritic meteorites (e.g. Davis et al., 1990; Wang et al., 1999; Grossman et al., 2000, 2002; Richter et al., 2002, 2007, 2011; Knight et al., 2009; Mendybaev et al., 2017). The relationship between the ideal kinetic fractionation factor α in a vacuum and the effective fractionation factor α' at higher pressure can be approximated by the following equation from Richter et al., (2002):

$$ \alpha' - 1 \approx \alpha - 1 \left( 1 - \frac{P_i}{P_{i,sat}} \right) \qquad \text{Equation 5} $$

Where Pᵢ is the pressure of gas species i at the evaporating surface and Pᵢ,sat is the equilibrium vapor pressure of i (Richter et al., 2002, Young et al., 2019). At higher pressures the value of Pᵢ/Pᵢ,sat moves towards 1, which results in an effective fractionation factor (α') of 1 (i.e. no isotopic fractionation). As the ambient pressure rises recondensation of evaporated material back onto the sample surface becomes more important, resulting in lower isotopic fractionation until the system reaches equilibrium (Richter et al., 2002). This dependency of α on the ambient pressure and the identity of the gas phase (e.g. H₂, CO and He) has been verified experimentally (e.g. Grossman et al., 2000; Richter et al., 2011; Yu et al., 2003). Our Zn data are consistent with this relationship; the experimental samples, fallout and tektites were all evaporated at ambient pressures of 1 bar or greater and Zn loss proceeded with an α between 0.9988-0.9997, which is significantly lower than the α associated with free kinetic evaporation in a vacuum.

Another potentially important parameter is the diffusivity of Zn in the melt. The isotopic composition of Zn in an evaporative residue is also dependent on the relative difference between the rate of evaporative loss and the speed of Zn diffusion within the melt (e.g. Richter et al., 2002, 2007, 2011; Moynier et al., 2009). If evaporative loss proceeds faster than the rate at which diffusion can homogenise the δ⁶⁶Zn value of the residual melt, the net result is the formation of a diffusive boundary layer, and suppression of Zn isotope fractionation (see Fig. 5).
14, Richter et al., 2002). The formation of a diffusive boundary layer was hypothesized to explain suppression of α in tektites (Moynier et al., 2009), although these authors did not consider the effect of pressure in their discussion. The importance of diffusion can be estimated from calculation of the evaporation number E<sub>v</sub> as described in Richter et al., (2002, 2007):

$$E_v = \frac{\tau_D}{\tau_{evap}} \qquad \text{Equation 6}$$

Where τ<sub>D</sub> is the diffusivity timescale, and τ<sub>evap</sub> is the evaporation timescale. For high values of E<sub>v</sub> (>1) the diffusion rate is much slower than the evaporation rate and suppression of α results. If E<sub>v</sub> is low (<1) the diffusion rate is relatively fast within the melt and no diffusive boundary layer develops. Hence suppression of α is limited. We can calculate τ<sub>evap</sub> from our experimental data if we consider that τ<sub>evap</sub> = M/(Ja), where M is the moles of Zn in the solid phase, J is the evaporation rate in mol<sup>-1</sup>cm<sup>-2</sup>s<sup>-1</sup> and a is the surface area in cm<sup>-2</sup>. Based on the experimental data in Table 3, and assuming a constant surface area of 0.07 cm<sup>-2</sup>, we calculate Zn evaporation rates of 9.2 × 10<sup>-10</sup> and 1.1 × 10<sup>-8</sup> mol<sup>-1</sup>cm<sup>-2</sup>s<sup>-1</sup>, which correspond to τ<sub>evap</sub> values of 2400 and 320s at 1600 and 2000 °C respectively. To calculate τ<sub>D</sub> requires experimentally derived data for the rate of Zn diffusion in silicate melts. To date, the only published data for Zn diffusivity is from Baker & Watson (1988) and Koepke & Behrens (2001), who calculated Zn diffusion coefficients in rhyolitic and andesitic melts, at temperatures up to 1400 °C and pressures up to 1 GPa. Based on these data we would estimate Zn diffusivities of 3 × 10<sup>-6</sup> cm<sup>-2</sup>s<sup>-1</sup> at 1600 °C and 2 × 10<sup>-5</sup> cm<sup>-2</sup>s<sup>-1</sup> at 2000 °C. If τ<sub>D</sub> = L<sup>2</sup>/D, where L is the radius of the sphere and D is the diffusivity of Zn, we can use these data to calculate τ<sub>D</sub> values of 2000 s and 280 s at 1600 and 2000 °C respectively. Using these values for τ<sub>evap</sub> and τ<sub>D</sub> we calculate final Ev values of ~1, which would suggest that diffusion does not exert a significant control over Zn isotope fractionation in this system (e.g. Richter et al., 2002). However, the results of this calculation rely heavily on the Zn diffusion coefficients, which derive from experiments performed at relatively low temperatures (900-1400 °C), high pressures, and varying degrees of melt hydration. Thus the extrapolation of these data to our experimental system will impart unconstrained uncertainties to the final diffusivity estimates. Due to the inherent uncertainties associated with such a calculation we would recommend that more detailed studies be performed to confirm the role of Zn diffusion within silicate melts during evaporation. At the very least, better constraints over Zn diffusion coefficients at high temperatures are required.

Ultimately, our data suggest that the most likely cause for suppression of α in our various sample suites is the environment in which Zn evaporation takes place; the ambient partial pressure and presence of various gas species, including Zn, that may inhibit evaporative loss and/or suppress isotopic fractionation. The role of diffusion appears limited, although better constraints over Zn diffusivity would be required to confirm this. The importance of the ambient pressure is consistent with the results of experimental studies of stable isotope
fractionation at pressures between 10⁻⁹ bar and 1 bar (e.g. Grossman et al., 2000, 2002; Yu et al., 2003). More experiments are required at varying degrees of vacuum to test whether a robust relationship exists between the fractionation factor of Zn and pressure. Several studies have shown that stable isotope fractionation is sensitive to gas composition (e.g. Grossman et al., 2000; Yu et al., 2003; Richter et al., 2011). Therefore, any future experimental studies investigating Zn isotope fractionation should incorporate the role of gas phase composition effects

648

649

### 4.3.2. *Isotopic differences between experimental and fallout melt glass samples*

The laser heating experiments were performed on the same rhyolitic soil that served as the primary contributor to the fallout sample suite, meaning differences in α are unlikely to reflect differences in the chemical composition of the silicate melt. Temperature has been shown to be an important control over α for the experimental evaporation of Mg from a CAI like liquid (Richter et al., 2007). However, the fact that the rhyolitic soil experiments lie on a single fractionation line despite heating at a range of temperatures between 1600-2200 °C and times between 1-120 s demonstrate that both heating temperature and duration do not impose a dominant control over the Zn fractionation factor. The input of Zn with an isotopically light composition could, in theory, cause δ⁶⁶Zn values in fallout to be depressed, for example through the addition of a Zn-rich anthropogenic material (see Section 4.2.2). Such two-component mixing could be important in nuclear fallout samples, particularly for trace elements present in man-made metals (e.g. copper from wiring or pipes or steel structure). However, it is highly unlikely that the mixing of anthropogenic material could have an identical effect in two separate nuclear events (present data and data from Trinity (Day et al., 2017)) which had different precursor soils (arkosic and rhyolitic).

If we can rule out apparent differences in Zn isotope fractionation related to compositional effects or caused by two component mixing then we must consider the alternative; that the differences in α are real, and represent different degrees of isotopic fractionation during evaporation. Based on the discussion in Section 4.3.1 the physical environment in which Zn evaporation occurs (i.e. the ambient pressure and gas composition) plays a key role in controlling α. The experimental samples were heated at atmospheric pressure and levitated by a steady stream of argon, whereas the fallout melt glass is soil that was entrained within a fireball and, presumably, lost volatile elements rapidly within a physically and chemically evolving debris cloud. Though the conditions within that debris cloud are unconstrained, we can assume that the partial pressure of many species, including Zn and other metals are closer to their vapor pressures than they would be in air. Thus as Pᵢ/Pᵢ,sat is likely to be closer to 1 in the debris cloud the back reaction will be more important resulting in a greater effective
suppression of α. Recent in-situ analyses of fallout spheres have shown the presence of outer layers that are enriched in certain elements, including Ca and U, that could be supportive of this recondensation mechanism (Weisz et al., 2017). Unfortunately, Zn concentrations are low in these samples (< 50 ppm) meaning it would be challenging to confirm such redeposition by in situ imaging techniques.

It is difficult to assess the relative importance of Zn diffusivity in the two sample sets without good constraints over physical conditions within the fireball or a detailed in situ study of Zn abundance and isotopic composition within fallout melt glass or other silicate melts. Several recent studies have published in situ chemical analyses of elemental abundances and isotopic compositions within fallout melt glass samples (Lewis et al., 2015; Weisz et al., 2017, 2018). These data demonstrate that distinct chemical layers are present at the surface and, less commonly, in layers within some fallout samples (e.g. Weisz et al., 2017, 2018). However, these layers are thin (on a micron scale) and likely formed through depositional processes, such as condensation from a debris cloud, rather than reflecting a diffusive boundary layer resulting from evaporation (Weisz et al., 2018). This would suggest that diffusion is unlikely to be the cause of the lower α value calculated from the fallout samples.

Based on this discussion the difference in α between the experimental samples (α = 0.9988) and fallout (α = 0.9997) is most likely to reflect the higher partial pressure within the fireball, which promotes the recondensation of evaporated Zn that is relatively isotopically light. In addition, the flow of argon that levitates the laser spheres is likely to more rapidly transport Zn and other evaporated species away from the surface of the melt glass, further reducing the amount of evaporated material that can recondense on the experimental samples.

## 5. Implications for understanding Zn loss from the Moon

Although no lunar samples were analyzed in this study, it is worth comparing the Zn isotope data produced here with previously obtained Zn isotope data for rocks from the Moon (e.g. Moynier et al., 2006, Paniello et al., 2012, Kato et al., 2015, Day et al., 2017). Lunar rocks have highly heterogeneous δ⁶⁶Zn values in comparison to rocks from the Earth, ranging from -11.37‰ in a cataclastic anorthosite (65315) to +6.39‰ in a lunar regolith sample (15231) (Kato et al., 2015). Such isotopic heterogeneity was likely caused by impact sputtering and geological processing that occurred after the Moon accreted and is unimportant when considering the δ⁶⁶Zn value of the Bulk Silicate Moon (BSM). Instead, the relatively consistent δ⁶⁶Zn values in pristine mare basalts (+1.4 ± 0.5‰, Herzog et al., 2009; Paniello et al., 2012; Kato et al., 2015) have been used as evidence that the Moon had a homogenous initial δ⁶⁶Zn value upon its formation. The offset between the δ⁶⁶Zn value of lunar rocks and the terrestrial mantle is
712 interpreted as reflecting evaporative Zn loss from the Moon as a result of the Moon-forming event (Paniello et al., 2012). If the BSM is assumed to have a homogenous δ⁶⁶Zn value of ~1.4‰, and the relative enrichment of heavy Zn in these samples relative to the BSE is entirely caused by evaporative loss of Zn during accretion, then based on knowledge of Zn isotope fractionation factors the proportion of Zn loss from the Moon can be estimated. This has implications for mass loss from the Earth-Moon system as a result of the Giant Impact.

718 A simple Rayleigh fractionation model is used to calculate how the δ⁶⁶Zn value of the Bulk Silicate Moon (BSM) would change with the extent of evaporative Zn loss (Fig. 12a). A range of Zn fractionation factors were used in these calculations ranging from theoretical α values for evaporation into a vacuum (0.985-0.993) to empirically derived α values from evaporation experiments (0.9988; this study) to volatile depleted samples such as tektites and fallout (0.9997; this study, Day et al., 2017, Moynier et al., 2009). The δ⁶⁶Zn value of the pre-impact system is assumed to be similar to δ⁶⁶Zn values in the present-day BSE (0.16 ± 0.06‰, Sossi et al., 2018). The results indicate that, depending on the value of α, between 8-99% Zn loss by evaporation is required to shift the δ⁶⁶Zn value of the BSM to +1.4‰. We can place added constraints on this calculation if we consider that the Earth and Moon are likely to have shared a cogenetic origin as supported by similarities in stable isotope ratios such as O, Si, Ti and W (Wiechert et al., 2001, Touboul et al., 2007; Armytage et al., 2012; Zhang et al., 2012). Thus, it is reasonable to assume that the Moon evolved from material with a Zn concentration that is similar in magnitude to the Zn concentration in the terrestrial mantle (~50-55 ppm, Jagoutz et al., 1979, McDonough & Sun 1995). Because Zn concentrations in mare basalts, Mg-suite and pristine ferroan anorthosites are highly depleted in Zn (0.5-2 ppm, Kato et al., 2015; Paniello et al., 2012), we can conclude that only the evaporative loss of Zn with an α of ~0.9997 is consistent with measured lunar Zn-systematics (Fig. 12b). For the BSM to have evolved a δ⁶⁶Zn value of 1.4 ± 0.5‰ (Kato et al., 2015) requires the Moon to have lost 92-99% of its initial Zn. This is similar to estimates for Zn loss from the Moon based on Zn/Fe ratios (>99%, Albarede et al., 2015). Clearly this modeling relies on having accurate knowledge of Zn-systematics in the BSM and assumes that the mechanism(s) that can cause Zn isotope fractionation in lunar magmatic systems are fully understood.

741 Even accounting for the uncertainties involved with these calculations, a predicted α of ~0.9997 differs significantly from the expected fractionation factor for evaporation of elemental Zn or Zn-compounds such as ZnS and ZnCl₂ into a vacuum (α = 0.985-0.993). However, it is very similar to the α derived from analyses of fallout melt glass (this study, Day et al., 2017). In section 4.3 we discuss potential controls over the Zn isotopic fractionation factor and hypothesize that α is controlled by physical conditions of the evaporative environment such as the vapor pressure and gas composition. We stress that further experiments, performed in controlled pressure environments, would be required to confirm this. If true, this would be
consistent with the approximately linear relationship between α and pressure for K isotopes (Yu et al., 2003). Thus, the suppressed Zn fractionation factor calculated from mare basalt data could be controlled by the physical environment into which Zn evaporation occurs. Based on our experimental data, and data from tektites and fallout melt glass, we hypothesize that lunar Zn loss occurred at pressures similar to, or higher than, the current Earth's atmosphere (i.e., 1 bar). The broader implications of this depend on whether Zn isotope ratios in mare basalts record volatile loss during the Giant Impact or reflect more localized geological processes after accretion of the Moon. If the former, then the mare basalt Zn isotope data might support a model in which the Moon condensed from a silicate vapor disk with broadly BSE composition and pressures higher than 10 bar, as proposed from K isotope data (Wang & Jacobsen 2016) and consistent with recent models of Moon formation from a terrestrial synestia (Lock et al., 2018). In the latter scenario the data might suggest that localized degassing of Zn took place, either at depth or into an early rock vapor atmosphere that itself was derived from degassing of the lunar magma ocean (e.g. Stern 1999). In either case, our study highlights that an improved understanding of the factors that control Zn isotope fractionation during evaporation will help us to better interpret Zn systematics from volatile depleted bodies, such as the Moon.

765

## 6. Conclusions

We present the first experimentally derived Zn isotope data to constrain Zn isotope fractionation behavior during evaporation. These data provide important insights into the use of Zn isotopes to constrain the degree of evaporative loss from volatile depleted objects such as tektites, fallout melt glass, and rocks from the Moon. Our data confirm that the evaporative loss of Zn results in the preferential loss of isotopically light Zn, leaving the residual solid to be relatively isotopically heavy. This is fully consistent with previous analyses of volatile depleted samples. We calculate a well constrained fractionation factor for Zn loss from a rhyolitic soil at atmospheric pressure (α = 0.99879 ± 13) which is far smaller than the theoretical fractionation factor for evaporation of Zn in a high vacuum (α = 0.985-0.993). The fractionation factor is independent of temperature and heating time. Comparison between two experiments with different starting mineralogy generate different Zn isotope behavior, but we interpret this to be caused by initial volatilization of a labile phase in the arkosic soil, in which Zn loss is fully quantitative. Continued Zn loss from the residual silicate portion of the arkosic soil is consistent with a fractionation factor of ~ 0.9988.

Analyses of Zn isotopes in fallout glass and tektites are fully consistent with previously published work. Zinc loss from the fallout melt glass is consistent with an α of ~0.9997, which is similar to previous analyses of Zn isotopes in trinitite. Due to insufficient constraints over the identity and Zn concentration of the precursor material, we cannot calculate a precise
785 fractionation factor for Zn based on the tektite data but constrain a broad range of α values
786 between 0.9988-0.9997. The difference between the fractionation factor of Zn in experimental
787 samples and fallout melt glass cannot be ascribed to mineralogical differences as the starting
788 rhyolitic soil is common to both systems. Instead the differences in fractionation factor appear
789 to be related to differences in the pressure of the system. At higher pressures the back reaction
790 between the vapor phase and melting glass causes suppression of the Zn isotope fractionation,
791 because the vaporized Zn is relatively isotopically light. This is consistent with previous
792 experimental determination of K isotope ratios with varying pressure. Thus, varying pressure
793 should be considered when using Zn isotope ratios to calculate the degree of volatile loss from
794 volatile depleted samples in terrestrial samples and in planetary systems.

795

796 Acknowledgements

797 We thank Jian Huang and two anonymous reviewers for their detailed and constructive
798 comments that have served to greatly improve this manuscript. We also acknowledge the
799 efficient editorial handling of Stefan Weyer. We thank Dr Jutta Zipfel at the Senckenburg
800 Museum in Frankfurt for providing the australite samples.

801 This work was performed under the auspices of the U.S. Department of Energy by Lawrence
802 Livermore National Laboratory under Contract DE-AC52-07NA27344

803 This work was supported by the LLNL-LDRD Program under Project No. 18-ERD-003, and by the
804 Office of Defense Nuclear Nonproliferation Research and Development within the U.S.
805 Department of Energy's National Nuclear Security Administration. QZY acknowledges the NASA
806 grant NNX16AD34G for support. We also acknowledge support of the Institut de physique du
globe de Paris programs PARI (SESAME Grant no. 12015908) and UnivEarthS Labex (ANR-10-
807 LABX-0023 and ANR-11-IDEX-0005-02).
808

809 LLNL-JRNL-756623

810
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## Figure captions

**Fig. 1** - Typical vesicular spherical sample formed in the aerodynamic levitation laser furnace. Right: Non-aerodynamic sample formed at 1600°C after heating for 60 s. Note the bright rings in the center of the objects are an imaging artifact from the microscope ring light.

**Fig. 2** - Beta values for IRMM 3702 calculated from a comparison of the measured and certified ratios in Ponzevera et al., (2006). Beta is linearly proportional to the mass difference between isotopes, which is inconsistent with the exponential fractionation law.

**Fig. 3** - Isotopic composition of the IRMM 3702 standard analysed at LLNL using the ⁶⁸Zn-⁶⁶Zn double spike. Spike-sample ratios of <5 give results that are within uncertainty of 0. Spike-sample ratios of >5 result in δ⁶⁶Zn values that are too heavy and causes the uncertainty to increase.

**Fig. 4** - Concentrations of Ca and Al in the laser heating experiments using a) arkosic soil, and b) rhyolitic soil. Each data point represents a separate experiment. The starting soil composition is marked with a star. Uncertainties (2σ) are smaller than the data points.

**Fig. 5** - Concentrations of Na and K in the laser heating experiments using a) arkosic soil, and b) rhyolitic soil. Each data point represents a separate experiment. The starting soil composition is marked with a star. All uncertainties are 2σ.

**Fig. 6** - Zn isotope ratio and concentration in experimental samples, tektites and fallout melt glass analysed in this study. The estimated δ⁶⁶Zn value of the Upper Continental Crust (UCC) is +0.31 ± 0.11‰ (Little et al., 2014). All uncertainties on the δ⁶⁶Zn value are 2σ, and either taken from the external reproducibility of standards or internal uncertainty, whichever is greater.

**Fig. 7** - Tl and Pb enrichment factors in the laser spheres, relative to the starting soil. Data from the arkosic soils is given in a), and data from the rhyolitic soils is given in b). All uncertainties are 2σ, and reflect the error associated with each individual sample, together with the uncertainty of replicate analyses of the starting soil. In both figures the starting soil is represented by a star.

**Fig. 8** - Mg and Ti enrichment factors in the laser spheres, relative to the starting soil. Data from the arkosic soils is given in a), and data from the rhyolitic soils is given in b). All uncertainties are 2σ, and reflect the error associated with each individual sample, together with the uncertainty of replicate analyses of the starting soil. In both figures the starting soil is represented by a star.

**Fig. 9** - Zn isotopic data from the rhyolitic soil experiments (R/R₀) plotted against the fraction of Zn loss (-ln(f)). R is the ⁶⁶Zn/⁶⁴Zn ratio in the evaporated residue and R₀ is the initial ⁶⁶Zn/⁶⁴Zn ratio in the rhyolitic soil. The slope of the straight line represents 1000 × (1-α). The data have been regressed using a York fit, and uncertainties in x and y have been incorporated into the final calculation to obtain a valid 2σ uncertainty on α. Because the degree of isotopic fractionation is relatively small (<1.2‰) we can assume that the -ln(fZn) ≈ -ln(f⁶⁴Zn). The error bars associated with the fraction of Zn loss reflect the error associated with each individual sample, together with the uncertainty of replicate analyses of the starting soil.
**Fig. 10** – a) Zn isotope ratios plotted as a function of Zn enrichment factor from the laser heating experiments and fallout melt glass samples. In b) the arkosic soil experiments are plotted with recalculated Zn enrichment factors that take into account the initial quantitative loss of a labile phase that is rich in Zn, Fe, Mg, Ti and Mn. Here, the fractionation factor is close to the value from the rhyolitic soil experiments (~0.9988). The estimated δ<sup>66</sup>Zn value of the Upper Continental Crust (UCC) is +0.31 ± 0.11‰ (Little et al., 2014). All uncertainties are 2σ. The error bars associated with Zn enrichment factor reflect the error associated with each individual sample, together with the uncertainty of replicate analyses of the starting soil.

**Fig. 11** – Zn isotope ratios of australites plotted alongside data from Moynier et al., (2009). If we assume that the precursor soil had a starting Zn concentration of 100 ppm then they are consistent with a fractionation factor of ~0.9992. If we consider that the precursor soil could have had Zn concentrations between 50 – 200 ppm then these data are consistent with an α between 0.9988 – 0.9997.

**Fig. 12** – a) Modeling the evolution of δ<sup>66</sup>Zn values with increasing evaporative Zn loss. Five fractionation factors are considered; the theoretical α for evaporation of Zn into a vacuum as either elemental Zn (0.985), ZnS (0.990) or ZnCl<sub>2</sub> (0.993), together with empirically derived α from the heating experiments (0.9988) and analyses of fallout (0.9997). Depending on the value of α, an isotopic shift of ~1.1‰ between BSE and BSM can be caused by between 8-99% evaporative Zn loss. b) Assuming a starting Zn concentration of 50 ppm we can calculate the bulk Zn concentration of the Moon from the 5 different α values. Only an α of 0.9997 predicts a Zn concentration that is similar to those measured in lunar basalts and pristine crustal rocks (0.5-2 ppm). The estimated δ<sup>66</sup>Zn value of the BSM is taken from Kato et al., (2015), and the estimated δ<sup>66</sup>Zn value of the BSE is taken from Sossi et al., (2018).
<figure><img src="image_1.png" /></figure>

1 mm

<figure><img src="image_2.png" /></figure>

1 mm
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a) Arkosic heating experiments

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b) Rhyolitic heating experiments

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<figure><img src="image_7.png" /></figure>

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<figure><img src="image_10.png" /></figure>

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<figure><img src="image_12.png" /></figure>

<figure><img src="image_13.png" /></figure>

Arkosic spheres

Arkosic soil

Rhyolitic spheres

Rhyolitic soil

Tektites

Fallout

Zn (ppm)

UCC
<figure><img src="image_14.png" /></figure>

<figure><img src="image_15.png" /></figure>
<figure><img src="image_16.png" /></figure>

<figure><img src="image_17.png" /></figure>
<figure><img src="image_18.png" /></figure>

York Fit result (95% C.L.)

slope = 1.21 ± 0.13

MSWD = 2.35

α = 0.99879 ± 0.00013
<figure><img src="image_19.png" /></figure>

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<figure><img src="image_21.png" /></figure>
<figure><img src="image_22.png" /></figure>

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<table><caption>**Table 1** – Heating parameters, major and trace element concentrations and Zn isotope ratios in experimentally heated soil samples. All concentrations are ppm.</caption><thead><tr><th></th><th>diameter (mm)</th><th>Time (s)</th><th>Temp. (°C)</th><th>δ<sup>66</sup>Zn (‰)</th><th>2σ</th><th>Na</th><th>2σ</th><th>Mg</th><th>2σ</th><th>Al</th><th>2σ</th><th>K</th><th>2σ</th><th>Ca</th><th>2σ</th><th>Ti</th><th>2σ</th><th>Mn</th><th>2σ</th><th>Fe</th><th>2σ</th><th>Zn</th><th>2σ</th><th>Tl</th><th>2σ</th><th>Pb</th><th>2σ</th></tr></thead><tbody><tr><td>Arkose soil</td><td></td><td></td><td></td><td>0.22</td><td>0.02</td><td>10969</td><td>207</td><td>7318</td><td>145</td><td>55892</td><td>68</td><td>26568</td><td>3589</td><td>45495</td><td>1640</td><td>2223</td><td>80</td><td>415</td><td>14</td><td>16841</td><td>302</td><td>51.46</td><td>0.78</td><td>0.68</td><td>0.03</td><td>23.77</td><td>0.45</td></tr><tr><td>Arkose soil-17</td><td>1.76</td><td>1</td><td>1600</td><td>0.36</td><td>0.04</td><td>16609</td><td>254</td><td>2393</td><td>15</td><td>67013</td><td>1353</td><td>67113</td><td>2439</td><td>77745</td><td>712</td><td>370</td><td>3</td><td>196</td><td>2</td><td>4046</td><td>73</td><td>19.40</td><td>0.34</td><td>0.86</td><td>0.01</td><td>23.14</td><td>0.18</td></tr><tr><td>Arkose soil-13</td><td>1.93</td><td>5</td><td>1600</td><td>0.33</td><td>0.03</td><td>13845</td><td>201</td><td>2510</td><td>30</td><td>54579</td><td>366</td><td>50449</td><td>2083</td><td>62449</td><td>801</td><td>461</td><td>7</td><td>155</td><td>3</td><td>3464</td><td>47</td><td>12.08</td><td>0.23</td><td>0.64</td><td>0.01</td><td>18.29</td><td>0.17</td></tr><tr><td>Arkose soil-9</td><td>1.81</td><td>10</td><td>1600</td><td></td><td></td><td>17028</td><td>165</td><td>2764</td><td>62</td><td>67454</td><td>1175</td><td>57028</td><td>2435</td><td>92633</td><td>1954</td><td>396</td><td>8</td><td>337</td><td>4</td><td>4050</td><td>51</td><td>17.18</td><td>0.37</td><td>0.67</td><td>0.01</td><td>21.89</td><td>0.26</td></tr><tr><td>Arkose soil-5</td><td>1.91</td><td>60</td><td>1600</td><td>0.95</td><td>0.02</td><td>29252</td><td>347</td><td>4308</td><td>72</td><td>119701</td><td>1458</td><td>45841</td><td>3551</td><td>82680</td><td>2255</td><td>824</td><td>7</td><td>406</td><td>4</td><td>6570</td><td>93</td><td>17.88</td><td>0.39</td><td>0.52</td><td>0.01</td><td>21.62</td><td>0.24</td></tr><tr><td>Arkose soil-1</td><td>2.02</td><td>120</td><td>1600</td><td>1.20</td><td>0.02</td><td>19611</td><td>410</td><td>3569</td><td>31</td><td>94691</td><td>1320</td><td>46458</td><td>2673</td><td>96168</td><td>2789</td><td>780</td><td>17</td><td>339</td><td>9</td><td>6498</td><td>55</td><td>14.50</td><td>0.42</td><td>0.20</td><td>0.01</td><td>10.99</td><td>0.15</td></tr><tr><td>Arkose soil-18</td><td>1.49</td><td>1</td><td>1800</td><td>0.62</td><td>0.04</td><td>19343</td><td>215</td><td>2587</td><td>54</td><td>70171</td><td>1748</td><td>53629</td><td>3082</td><td>96451</td><td>1936</td><td>477</td><td>12</td><td>206</td><td>4</td><td>5963</td><td>113</td><td>15.86</td><td>0.40</td><td>0.58</td><td>0.01</td><td>17.65</td><td>0.28</td></tr><tr><td>Arkose soil-14</td><td>1.38</td><td>5</td><td>1800</td><td></td><td></td><td>465</td><td>4</td><td>3121</td><td>30</td><td>98272</td><td>1122</td><td>4059</td><td>250</td><td>121073</td><td>1578</td><td>521</td><td>6</td><td>351</td><td>6</td><td>7232</td><td>58</td><td>4.88</td><td>0.17</td><td>0.00</td><td>0.00</td><td>0.25</td><td>0.01</td></tr><tr><td>Arkose soil-10</td><td>1.37</td><td>10</td><td>1800</td><td></td><td></td><td>10104</td><td>58</td><td>2002</td><td>29</td><td>60521</td><td>763</td><td>42099</td><td>1407</td><td>80432</td><td>711</td><td>329</td><td>1</td><td>214</td><td>1</td><td>3313</td><td>37</td><td>7.74</td><td>0.49</td><td>0.09</td><td>0.00</td><td>5.41</td><td>0.06</td></tr><tr><td>Arkose soil-6</td><td>1.49</td><td>60</td><td>1800</td><td></td><td></td><td>3788</td><td>44</td><td>2434</td><td>36</td><td>71814</td><td>1631</td><td>32034</td><td>855</td><td>88909</td><td>1437</td><td>389</td><td>8</td><td>189</td><td>3</td><td>3697</td><td>56</td><td>3.04</td><td>0.33</td><td>0.01</td><td>0.00</td><td>0.88</td><td>0.02</td></tr><tr><td>Arkose soil-2</td><td>1.47</td><td>120</td><td>1800</td><td></td><td></td><td>6912</td><td>70</td><td>4726</td><td>43</td><td>132644</td><td>1016</td><td>24313</td><td>856</td><td>104984</td><td>3967</td><td>907</td><td>8</td><td>432</td><td>4</td><td>9201</td><td>180</td><td>4.78</td><td>0.35</td><td>0.02</td><td>0.01</td><td>N/A</td><td>N/A</td></tr><tr><td>Arkose soil-19</td><td>1.26</td><td>1</td><td>2000</td><td></td><td></td><td>6979</td><td>77</td><td>2666</td><td>28</td><td>68512</td><td>965</td><td>37637</td><td>1669</td><td>115117</td><td>928</td><td>516</td><td>4</td><td>213</td><td>2</td><td>3520</td><td>28</td><td>3.15</td><td>0.19</td><td>0.01</td><td>0.00</td><td>1.02</td><td>0.02</td></tr><tr><td>Arkose soil-15</td><td>1.63</td><td>5</td><td>2000</td><td>1.22</td><td>0.04</td><td>12004</td><td>207</td><td>2529</td><td>36</td><td>65814</td><td>768</td><td>39095</td><td>2841</td><td>97579</td><td>702</td><td>401</td><td>7</td><td>208</td><td>3</td><td>3510</td><td>39</td><td>6.20</td><td>0.22</td><td>0.11</td><td>0.01</td><td>5.57</td><td>0.05</td></tr><tr><td>Arkose soil-11</td><td>1.86</td><td>10</td><td>2000</td><td>1.42</td><td>0.04</td><td>16777</td><td>165</td><td>5079</td><td>98</td><td>110919</td><td>2207</td><td>38858</td><td>701</td><td>95643</td><td>860</td><td>470</td><td>6</td><td>758</td><td>5</td><td>5686</td><td>67</td><td>6.23</td><td>0.16</td><td>0.15</td><td>0.01</td><td>8.11</td><td>0.11</td></tr><tr><td>Arkose soil-7</td><td>1.51</td><td>60</td><td>2000</td><td></td><td></td><td>534</td><td>7</td><td>3043</td><td>34</td><td>79493</td><td>1342</td><td>8397</td><td>467</td><td>101514</td><td>1099</td><td>586</td><td>18</td><td>224</td><td>2</td><td>3682</td><td>37</td><td>2.73</td><td>0.22</td><td>0.01</td><td>0.00</td><td>0.27</td><td>0.01</td></tr><tr><td>Arkose soil-3</td><td>1.18</td><td>120</td><td>2000</td><td></td><td></td><td>71</td><td>2</td><td>4210</td><td>47</td><td>128939</td><td>1315</td><td>131</td><td>14</td><td>159622</td><td>1315</td><td>661</td><td>12</td><td>331</td><td>3</td><td>2756</td><td>21</td><td>2.33</td><td>0.32</td><td>0.02</td><td>0.00</td><td>0.55</td><td>0.06</td></tr><tr><td>Arkose soil-16</td><td>1.72</td><td>5</td><td>2200</td><td></td><td></td><td>7506</td><td>107</td><td>2951</td><td>38</td><td>70856</td><td>723</td><td>34456</td><td>914</td><td>91656</td><td>564</td><td>415</td><td>7</td><td>268</td><td>3</td><td>4928</td><td>30</td><td>5.90</td><td>0.18</td><td>0.13</td><td>0.01</td><td>6.20</td><td>0.05</td></tr><tr><td>Arkose soil-12</td><td>1.11</td><td>10</td><td>2200</td><td></td><td></td><td>86</td><td>1</td><td>4762</td><td>33</td><td>96558</td><td>1588</td><td>792</td><td>20</td><td>132273</td><td>1246</td><td>654</td><td>15</td><td>265</td><td>4</td><td>5245</td><td>51</td><td>1.65</td><td>0.26</td><td>0.00</td><td>0.00</td><td>0.34</td><td>0.03</td></tr><tr><td>Arkose soil-8</td><td>0.82</td><td>60</td><td>2200</td><td></td><td></td><td>172</td><td>4</td><td>5292</td><td>50</td><td>168984</td><td>1583</td><td>316</td><td>25</td><td>223170</td><td>2008</td><td>1032</td><td>16</td><td>89</td><td>1</td><td>1560</td><td>11</td><td>7.18</td><td>0.64</td><td>0.02</td><td>0.01</td><td>1.07</td><td>0.04</td></tr><tr><td>Rhyolite soil</td><td></td><td></td><td></td><td>0.28</td><td>0.02</td><td>34964</td><td>1469</td><td>3338</td><td>107</td><td>67170</td><td>2346</td><td>46329</td><td>2918</td><td>6472</td><td>206</td><td>1518</td><td>48</td><td>811</td><td>24</td><td>24791</td><td>654</td><td>153.0</td><td>6.0</td><td>0.69</td><td>0.03</td><td>25.25</td><td>1.12</td></tr><tr><td>Rhyolite soil-21</td><td>3.2</td><td>1</td><td>1600</td><td></td><td></td><td>35867</td><td>1054</td><td>3376</td><td>54</td><td>68482</td><td>1038</td><td>46257</td><td>831</td><td>6812</td><td>127</td><td>1551</td><td>28</td><td>819</td><td>5</td><td>25195</td><td>355</td><td>172.2</td><td>2.4</td><td>0.53</td><td>0.04</td><td>22.35</td><td>0.52</td></tr><tr><td>Rhyolite soil-20</td><td>3.2</td><td>5</td><td>1600</td><td></td><td></td><td>35544</td><td>851</td><td>3337</td><td>65</td><td>67628</td><td>1658</td><td>45836</td><td>2888</td><td>6554</td><td>158</td><td>1552</td><td>41</td><td>805</td><td>19</td><td>24678</td><td>668</td><td>161.6</td><td>4.5</td><td>0.56</td><td>0.02</td><td>23.01</td><td>0.84</td></tr><tr><td>Rhyolite soil-19</td><td>1.67</td><td>10</td><td>1600</td><td>0.57</td><td>0.02</td><td>34744</td><td>655</td><td>3434</td><td>48</td><td>68757</td><td>1198</td><td>45154</td><td>1296</td><td>7770</td><td>92</td><td>1577</td><td>19</td><td>839</td><td>13</td><td>24798</td><td>351</td><td>135.4</td><td>3.2</td><td>0.38</td><td>0.01</td><td>18.19</td><td>0.33</td></tr><tr><td>Rhyolite soil-18</td><td>2.42</td><td>60</td><td>1600</td><td>0.42</td><td>0.02</td><td>35276</td><td>1156</td><td>3374</td><td>73</td><td>67832</td><td>2140</td><td>46566</td><td>1299</td><td>6505</td><td>151</td><td>1544</td><td>53</td><td>809</td><td>18</td><td>24976</td><td>686</td><td>143.2</td><td>4.8</td><td>0.53</td><td>0.03</td><td>24.06</td><td>0.64</td></tr><tr><td>Rhyolite soil-17</td><td>2.18</td><td>120</td><td>1600</td><td>0.40</td><td>0.02</td><td>35313</td><td>1118</td><td>3395</td><td>43</td><td>69084</td><td>859</td><td>45753</td><td>1599</td><td>6648</td><td>79</td><td>1608</td><td>19</td><td>828</td><td>13</td><td>25453</td><td>354</td><td>149.5</td><td>5.3</td><td>0.53</td><td>0.02</td><td>22.65</td><td>1.13</td></tr><tr><td>Rhyolite soil-2</td><td>2.79</td><td>1</td><td>1800</td><td>0.26</td><td>0.02</td><td>34558</td><td>761</td><td>3371</td><td>74</td><td>67590</td><td>1469</td><td>45212</td><td>1043</td><td>6763</td><td>140</td><td>1548</td><td>35</td><td>824</td><td>16</td><td>24912</td><td>633</td><td>167.1</td><td>4.6</td><td>0.66</td><td>0.02</td><td>24.29</td><td>0.86</td></tr><tr><td>Rhyolite soil-5</td><td>3.08</td><td>5</td><td>1800</td><td>0.33</td><td>0.02</td><td>34950</td><td>695</td><td>3425</td><td>33</td><td>67865</td><td>1395</td><td>46947</td><td>1395</td><td>6766</td><td>84</td><td>1594</td><td>14</td><td>834</td><td>9</td><td>25287</td><td>541</td><td>172.4</td><td>2.7</td><td>0.63</td><td>0.01</td><td>23.45</td><td>0.23</td></tr><tr><td>Rhyolite soil-3</td><td>2.46</td><td>10</td><td>1800</td><td></td><td></td><td>34530</td><td>803</td><td>3472</td><td>110</td><td>68678</td><td>2139</td><td>44823</td><td>1503</td><td>6703</td><td>210</td><td>1603</td><td>50</td><td>826</td><td>25</td><td>25344</td><td>828</td><td>121.2</td><td>4.5</td><td>0.42</td><td>0.01</td><td>21.86</td><td>0.49</td></tr><tr><td>Rhyolite soil-1</td><td>1.81</td><td>60</td><td>1800</td><td>0.30</td><td>0.03</td><td>34743</td><td>882</td><td>3465</td><td>77</td><td>69822</td><td>2175</td><td>45871</td><td>2108</td><td>6757</td><td>144</td><td>1605</td><td>36</td><td>842</td><td>17</td><td>25880</td><td>705</td><td>153.2</td><td>5.2</td><td>0.46</td><td>0.01</td><td>21.73</td><td>0.49</td></tr><tr><td>Rhyolite soil-4</td><td>1.74</td><td>120</td><td>1800</td><td>0.54</td><td>0.02</td><td>33312</td><td>476</td><td>3481</td><td>43</td><td>69480</td><td>1767</td><td>44552</td><td>1379</td><td>6700</td><td>74</td><td>1631</td><td>27</td><td>829</td><td>8</td><td>25430</td><td>601</td><td>122.5</td><td>1.9</td><td>0.31</td><td>0.01</td><td>17.98</td><td>0.25</td></tr><tr><td>Rhyolite soil-11</td><td>1.95</td><td>5</td><td>2000</td><td>0.51</td><td>0.02</td><td>35477</td><td>1168</td><td>3478</td><td>79</td><td>69608</td><td>1529</td><td>46330</td><td>2284</td><td>6757</td><td>143</td><td>1528</td><td>37</td><td>841</td><td>18</td><td>25438</td><td>635</td><td>135.6</td><td>3.0</td><td>0.38</td><td>0.01</td><td>19.83</td><td>0.41</td></tr><tr><td>Rhyolite soil-7</td><td>1.26</td><td>60</td><td>2000</td><td></td><td></td><td>26475</td><td>762</td><td>3951</td><td>116</td><td>80346</td><td>2680</td><td>41135</td><td>828</td><td>8484</td><td>229</td><td>1804</td><td>71</td><td>911</td><td>21</td><td>26416</td><td>671</td><td>166.6</td><td>4.6</td><td>0.13</td><td>0.02</td><td>13.47</td><td>0.32</td></tr><tr><td>Rhyolite soil-8</td><td>1.93</td><td>120</td><td>2000</td><td>0.85</td><td>0.02</td><td>26412</td><td>737</td><td>3607</td><td>75</td><td>72195</td><td>2001</td><td>42093</td><td>889</td><td>6957</td><td>145</td><td>1337</td><td>32</td><td>865</td><td>19</td><td>25097</td><td>697</td><td>102.7</td><td>2.6</td><td>0.13</td><td>0.01</td><td>24.92</td><td>0.43</td></tr><tr><td>Rhyolite soil-13</td><td>1.59</td><td>1</td><td>2200</td><td>0.65</td><td>0.02</td><td>32683</td><td>627</td><td>3394</td><td>59</td><td>68539</td><td>1314</td><td>45145</td><td>2472</td><td>6902</td><td>146</td><td>1565</td><td>29</td><td>825</td><td>20</td><td>25263</td><td>434</td><td>119.3</td><td>3.5</td><td>0.32</td><td>0.01</td><td>17.27</td><td>0.61</td></tr><tr><td>Rhyolite soil-10</td><td>1.96</td><td>5</td><td>2200</td><td>0.70</td><td>0.02</td><td>31622</td><td>1137</td><td>3525</td><td>46</td><td>69094</td><td>1472</td><td>45553</td><td>2274</td><td>6974</td><td>170</td><td>1624</td><td>13</td><td>834</td><td>10</td><td>24942</td><td>591</td><td>116.5</td><td>1.2</td><td>0.28</td><td>0.01</td><td>16.11</td><td>0.32</td></tr><tr><td>Rhyolite soil-6</td><td>1.76</td><td>10</td><td>2200</td><td>0.79</td><td>0.03</td><td>28351</td><td>814</td><td>3703</td><td>69</td><td>72964</td><td>1242</td><td>42810</td><td>1607</td><td>7333</td><td>127</td><td>1660</td><td>32</td><td>865</td><td>16</td><td>25690</td><td>420</td><td>117.7</td><td>3.7</td><td>0.21</td><td>0.01</td><td>14.79</td><td>0.53</td></tr><tr><td>Rhyolite soil-15</td><td>1.89</td><td>60</td><td>2200</td><td>1.49</td><td>0.02</td><td>10079</td><td>332</td><td>4284</td><td>51</td><td>85745</td><td>1226</td><td>32994</td><td>900</td><td>8506</td><td>112</td><td>1914</td><td>56</td><td>925</td><td>12</td><td>25595</td><td>528</td><td>83.33</td><td>2.98</td><td>0.09</td><td>0.01</td><td>10.50</td><td>0.42</td></tr><tr><td>Rhyolite soil-12</td><td>0.81</td><td>90</td><td>2200</td><td></td><td></td><td>698</td><td>10</td><td>9480</td><td>134</td><td>261996</td><td>6522</td><td>6537</td><td>349</td><td>19204</td><td>328</td><td>2776</td><td>42</td><td>1698</td><td>36</td><td>30059</td><td>721</td><td>9.72</td><td>0.50</td><td>0.00</td><td>0.01</td><td>0.48</td><td>0.04</td></tr></tbody></table>
<table><caption>**Table 2** – Major and trace element concentrations and zinc isotope ratios in fallout melt glass and tektite samples. All concentrations are ppm.

ªUpper Continental Crust (UCC) values from Rudnick & Gao (2003).</caption><thead><tr><th></th><th>δ<sup>66</sup>Zn<br>(‰)</th><th>2σ</th><th>Na</th><th>2σ</th><th>Mg</th><th>2σ</th><th>Al</th><th>2σ</th><th>K</th><th>2σ</th><th>Ca</th><th>2σ</th><th>Ti</th><th>2σ</th><th>Mn</th><th>2σ</th><th>Fe</th><th>2σ</th><th>Zn</th><th>2σ</th><th>Tl</th><th>2σ</th><th>Pb</th><th>2σ</th></tr></thead><tbody><tr><td>Fallout-1</td><td>0.59</td><td>0.02</td><td>19379</td><td>467</td><td>3887</td><td>46</td><td>62987</td><td>788</td><td>25281</td><td>1107</td><td>10578</td><td>154</td><td>1728</td><td>23</td><td>691</td><td>12</td><td>21516</td><td>226</td><td>45.77</td><td>1.08</td><td>0.22</td><td>0.00</td><td>8.60</td><td>0.14</td></tr><tr><td>Fallout-2</td><td>0.33</td><td>0.02</td><td>22117</td><td>335</td><td>4724</td><td>38</td><td>67610</td><td>674</td><td>30663</td><td>2753</td><td>15518</td><td>162</td><td>2179</td><td>30</td><td>692</td><td>12</td><td>23529</td><td>260</td><td>77.22</td><td>2.56</td><td>0.34</td><td>0.01</td><td>13.67</td><td>0.30</td></tr><tr><td>Fallout-3</td><td>0.47</td><td>0.02</td><td>23496</td><td>343</td><td>2613</td><td>39</td><td>60427</td><td>1267</td><td>29537</td><td>4203</td><td>8860</td><td>206</td><td>1360</td><td>25</td><td>786</td><td>20</td><td>20631</td><td>395</td><td>86.89</td><td>3.31</td><td>0.34</td><td>0.01</td><td>12.87</td><td>0.21</td></tr><tr><td>Fallout-4</td><td>0.67</td><td>0.02</td><td>21324</td><td>124</td><td>3311</td><td>70</td><td>59096</td><td>1265</td><td>26109</td><td>1954</td><td>13639</td><td>312</td><td>1531</td><td>37</td><td>692</td><td>14</td><td>20227</td><td>418</td><td>55.81</td><td>1.10</td><td>0.21</td><td>0.01</td><td>10.04</td><td>0.14</td></tr><tr><td>Fallout-5</td><td>0.40</td><td>0.02</td><td>26205</td><td>283</td><td>2892</td><td>77</td><td>59613</td><td>1551</td><td>32576</td><td>2628</td><td>10919</td><td>360</td><td>1418</td><td>42</td><td>672</td><td>18</td><td>20912</td><td>542</td><td>89.99</td><td>1.62</td><td>0.27</td><td>0.00</td><td>14.13</td><td>0.14</td></tr><tr><td>Fallout-6</td><td>0.33</td><td>0.02</td><td>26076</td><td>208</td><td>3178</td><td>83</td><td>56967</td><td>1483</td><td>30487</td><td>1394</td><td>11012</td><td>310</td><td>1479</td><td>39</td><td>680</td><td>18</td><td>20582</td><td>577</td><td>79.22</td><td>2.32</td><td>0.21</td><td>0.01</td><td>13.41</td><td>0.14</td></tr><tr><td>Fallout-7</td><td>0.40</td><td>0.02</td><td>22670</td><td>263</td><td>3113</td><td>64</td><td>54878</td><td>1143</td><td>29409</td><td>3367</td><td>12328</td><td>271</td><td>1465</td><td>42</td><td>607</td><td>15</td><td>19783</td><td>565</td><td>75.09</td><td>1.94</td><td>0.19</td><td>0.01</td><td>11.49</td><td>0.12</td></tr><tr><td>Australite 1</td><td>1.26</td><td>0.01</td><td>7801</td><td>62</td><td>11063</td><td>119</td><td>63618</td><td>687</td><td>20282</td><td>592</td><td>13251</td><td>154</td><td>4479</td><td>78</td><td>642</td><td>3</td><td>34025</td><td>504</td><td>22.22</td><td>0.22</td><td>0.14</td><td>0.00</td><td>6.65</td><td>0.18</td></tr><tr><td>Australite 2</td><td>1.02</td><td>0.12</td><td>6932</td><td>183</td><td>8620</td><td>78</td><td>51823</td><td>829</td><td>17853</td><td>264</td><td>10140</td><td>69</td><td>3709</td><td>33</td><td>536</td><td>9</td><td>27850</td><td>279</td><td>25.78</td><td>1.43</td><td>0.15</td><td>0.00</td><td>7.24</td><td>0.06</td></tr><tr><td>Australite 3</td><td>1.19</td><td>0.01</td><td>6709</td><td>122</td><td>9724</td><td>86</td><td>53934</td><td>227</td><td>17292</td><td>118</td><td>12209</td><td>56</td><td>3869</td><td>42</td><td>545</td><td>6</td><td>29227</td><td>509</td><td>20.00</td><td>1.28</td><td>0.10</td><td>0.00</td><td>5.04</td><td>0.05</td></tr><tr><td>Australite 4</td><td>2.03</td><td>0.02</td><td>9111</td><td>115</td><td>11826</td><td>40</td><td>61682</td><td>753</td><td>19889</td><td>127</td><td>18726</td><td>221</td><td>4470</td><td>39</td><td>625</td><td>4</td><td>32403</td><td>168</td><td>14.65</td><td>0.37</td><td>0.04</td><td>0.00</td><td>2.89</td><td>0.02</td></tr><tr><td>Australite 5</td><td></td><td></td><td>10027</td><td>78</td><td>12864</td><td>193</td><td>66855</td><td>776</td><td>21558</td><td>535</td><td>20176</td><td>266</td><td>4850</td><td>72</td><td>682</td><td>1</td><td>35569</td><td>277</td><td>11.96</td><td>0.85</td><td>0.04</td><td>0.00</td><td>2.83</td><td>0.05</td></tr><tr><td>Australite 6</td><td>2.04</td><td>0.16</td><td>8094</td><td>34</td><td>10674</td><td>167</td><td>55117</td><td>463</td><td>17611</td><td>70</td><td>16520</td><td>23</td><td>3964</td><td>51</td><td>550</td><td>5</td><td>28713</td><td>402</td><td>10.51</td><td>0.75</td><td>0.03</td><td>0.00</td><td>2.03</td><td>0.04</td></tr><tr><td>Australite 7</td><td></td><td></td><td>5975</td><td>55</td><td>7079</td><td>64</td><td>37314</td><td>522</td><td>12327</td><td>47</td><td>12454</td><td>139</td><td>2583</td><td>38</td><td>353</td><td>1</td><td>18934</td><td>356</td><td>27.87</td><td>3.19</td><td>0.04</td><td>0.00</td><td>2.46</td><td>0.06</td></tr><tr><td>Australite 8</td><td>1.30</td><td>0.02</td><td>9587</td><td>115</td><td>12150</td><td>112</td><td>63597</td><td>369</td><td>21015</td><td>374</td><td>20248</td><td>117</td><td>4522</td><td>27</td><td>623</td><td>15</td><td>33270</td><td>133</td><td>20.30</td><td>0.54</td><td>0.05</td><td>0.01</td><td>4.11</td><td>0.76</td></tr><tr><td>Australite 9</td><td></td><td></td><td>10584</td><td>131</td><td>12875</td><td>93</td><td>67508</td><td>567</td><td>22456</td><td>404</td><td>21960</td><td>430</td><td>4857</td><td>109</td><td>666</td><td>3</td><td>35532</td><td>419</td><td>28.19</td><td>1.94</td><td>0.06</td><td>0.00</td><td>4.69</td><td>0.03</td></tr><tr><td>Australite 10</td><td>1.83</td><td>0.03</td><td>8980</td><td>122</td><td>11828</td><td>66</td><td>61839</td><td>1398</td><td>20030</td><td>296</td><td>18583</td><td>85</td><td>4440</td><td>8</td><td>620</td><td>9</td><td>32317</td><td>608</td><td>10.49</td><td>1.50</td><td>0.04</td><td>0.00</td><td>3.27</td><td>0.04</td></tr><tr><td>Australite 11</td><td>1.94</td><td>0.03</td><td>8625</td><td>112</td><td>11207</td><td>186</td><td>58786</td><td>200</td><td>19173</td><td>96</td><td>17658</td><td>81</td><td>4216</td><td>10</td><td>587</td><td>5</td><td>30700</td><td>117</td><td>9.98</td><td>0.86</td><td>0.04</td><td>0.00</td><td>2.88</td><td>0.04</td></tr><tr><td>Australite 12</td><td>1.49</td><td>0.02</td><td>9116</td><td>31</td><td>12034</td><td>144</td><td>62712</td><td>389</td><td>20137</td><td>52</td><td>19036</td><td>141</td><td>4522</td><td>14</td><td>623</td><td>4</td><td>32912</td><td>217</td><td>11.55</td><td>0.29</td><td>0.04</td><td>0.00</td><td>2.92</td><td>0.03</td></tr><tr><td>Upper Cont. Crust<sup>a</sup></td><td>0.28</td><td>0.03</td><td>24261</td><td>3561</td><td>14880</td><td>2100</td><td>81529</td><td>3971</td><td>23333</td><td>1917</td><td>25643</td><td>1429</td><td>3840</td><td>480</td><td>765</td><td>76</td><td>39200</td><td>4122</td><td>67.00</td><td>6.00</td><td>0.90</td><td>0.50</td><td>17.00</td><td>0.50</td></tr></tbody></table>
<table><caption>**Table 3** – Relative enrichment factors in experimental samples, fallout melt glass and tektites. All enrichment factors are calculated by normalizing the concentrations to aluminium and comparing the x/Al ratio in the sample to the ratio in the precursor soil. The fallout melt glass shares the same rhyolitic soil precursor that was used in the laser heating experiment. We have no strong constraints over the precursor composition of the tektites, and so here have assumed an average upper continental crustal (UCC) composition (Rudnick & Gao 2003).</caption><thead><tr><th></th><th>Zn</th><th>2σ</th><th>Na</th><th>2σ</th><th>Mg</th><th>2σ</th><th>K</th><th>2σ</th><th>Ca</th><th>2σ</th><th>Ti</th><th>2σ</th><th>Mn</th><th>2σ</th><th>Fe</th><th>2σ</th><th>Tl</th><th>2σ</th><th>Pb</th><th>2σ</th></tr></thead><tbody><tr><td>Arkose soil-17</td><td>-68.6</td><td>1.7</td><td>26.3</td><td>3.7</td><td>-72.7</td><td>2.1</td><td>110.7</td><td>16.1</td><td>42.5</td><td>4.8</td><td>-86.1</td><td>3.6</td><td>-60.6</td><td>3.6</td><td>-80.0</td><td>1.9</td><td>6.2</td><td>5.6</td><td>-18.8</td><td>2.6</td></tr><tr><td>Arkose soil-13</td><td>-76.0</td><td>1.6</td><td>29.3</td><td>2.8</td><td>-64.9</td><td>2.0</td><td>94.5</td><td>15.8</td><td>40.6</td><td>4.1</td><td>-78.8</td><td>3.6</td><td>-61.8</td><td>3.6</td><td>-78.9</td><td>1.8</td><td>-3.7</td><td>5.1</td><td>-21.2</td><td>2.1</td></tr><tr><td>Arkose soil-9</td><td>-72.3</td><td>1.7</td><td>28.6</td><td>3.2</td><td>-68.7</td><td>2.2</td><td>77.9</td><td>15.8</td><td>68.7</td><td>5.9</td><td>-85.3</td><td>3.6</td><td>-32.7</td><td>3.8</td><td>-80.1</td><td>1.8</td><td>-17.9</td><td>5.3</td><td>-23.7</td><td>2.5</td></tr><tr><td>Arkose soil-5</td><td>-83.8</td><td>1.6</td><td>24.5</td><td>2.8</td><td>-72.5</td><td>2.1</td><td>-19.4</td><td>14.9</td><td>-15.1</td><td>4.4</td><td>-82.7</td><td>3.6</td><td>-54.3</td><td>3.6</td><td>-81.8</td><td>1.8</td><td>-64.2</td><td>5.0</td><td>-57.5</td><td>2.0</td></tr><tr><td>Arkose soil-1</td><td>-83.4</td><td>1.6</td><td>5.5</td><td>3.3</td><td>-71.2</td><td>2.0</td><td>3.2</td><td>14.8</td><td>24.8</td><td>5.4</td><td>-79.3</td><td>3.6</td><td>-51.7</td><td>3.8</td><td>-77.2</td><td>1.8</td><td>-82.9</td><td>5.0</td><td>-72.7</td><td>2.0</td></tr><tr><td>Arkose soil-18</td><td>-75.5</td><td>1.8</td><td>40.5</td><td>4.3</td><td>-71.8</td><td>2.2</td><td>60.8</td><td>16.8</td><td>68.9</td><td>6.5</td><td>-82.9</td><td>3.7</td><td>-60.4</td><td>3.7</td><td>-71.8</td><td>2.0</td><td>-32.0</td><td>5.3</td><td>-40.9</td><td>2.6</td></tr><tr><td>Arkose soil-14</td><td>-94.6</td><td>1.5</td><td>-97.6</td><td>1.9</td><td>-75.7</td><td>2.0</td><td>-91.3</td><td>13.5</td><td>51.4</td><td>4.5</td><td>-86.7</td><td>3.6</td><td>-51.9</td><td>3.6</td><td>-75.6</td><td>1.8</td><td>-99.7</td><td>4.9</td><td>-99.4</td><td>1.9</td></tr><tr><td>Arkose soil-10</td><td>-86.1</td><td>1.8</td><td>-14.9</td><td>2.2</td><td>-74.7</td><td>2.0</td><td>46.3</td><td>14.5</td><td>63.3</td><td>4.4</td><td>-86.3</td><td>3.6</td><td>-52.4</td><td>3.6</td><td>-81.8</td><td>1.8</td><td>-87.3</td><td>5.0</td><td>-79.0</td><td>2.0</td></tr><tr><td>Arkose soil-6</td><td>-95.4</td><td>1.6</td><td>-73.1</td><td>2.0</td><td>-74.1</td><td>2.1</td><td>-6.2</td><td>13.9</td><td>52.1</td><td>5.6</td><td>-86.4</td><td>3.6</td><td>-64.5</td><td>3.6</td><td>-82.9</td><td>1.9</td><td>-98.7</td><td>4.9</td><td>-97.1</td><td>1.9</td></tr><tr><td>Arkose soil-2</td><td>-96.1</td><td>1.5</td><td>-73.4</td><td>1.9</td><td>-72.8</td><td>2.0</td><td>-61.4</td><td>13.6</td><td>-2.8</td><td>5.2</td><td>-82.8</td><td>3.6</td><td>-56.1</td><td>3.5</td><td>-77.0</td><td>1.9</td><td>-98.5</td><td>4.9</td><td>-96.5</td><td>13.4</td></tr><tr><td>Arkose soil-19</td><td>-95.0</td><td>1.5</td><td>-48.1</td><td>2.1</td><td>-70.3</td><td>2.0</td><td>15.6</td><td>14.5</td><td>106.4</td><td>4.9</td><td>-81.1</td><td>3.6</td><td>-58.0</td><td>3.6</td><td>-82.9</td><td>1.8</td><td>-98.9</td><td>4.9</td><td>-96.5</td><td>1.9</td></tr><tr><td>Arkose soil-15</td><td>-89.8</td><td>1.6</td><td>-7.1</td><td>2.7</td><td>-70.7</td><td>2.1</td><td>25.0</td><td>16.3</td><td>82.1</td><td>4.4</td><td>-84.7</td><td>3.6</td><td>-57.5</td><td>3.6</td><td>-82.3</td><td>1.8</td><td>-86.3</td><td>4.9</td><td>-80.1</td><td>1.9</td></tr><tr><td>Arkose soil-11</td><td>-93.9</td><td>1.5</td><td>-22.9</td><td>2.6</td><td>-65.0</td><td>2.2</td><td>-26.3</td><td>13.7</td><td>5.9</td><td>4.3</td><td>-89.3</td><td>3.6</td><td>-8.0</td><td>4.0</td><td>-83.0</td><td>1.8</td><td>-88.4</td><td>5.0</td><td>-82.8</td><td>2.0</td></tr><tr><td>Arkose soil-7</td><td>-96.3</td><td>1.5</td><td>-96.6</td><td>1.9</td><td>-70.8</td><td>2.1</td><td>-77.8</td><td>13.6</td><td>56.9</td><td>4.8</td><td>-81.5</td><td>3.7</td><td>-62.0</td><td>3.6</td><td>-84.6</td><td>1.8</td><td>-99.4</td><td>4.9</td><td>-99.2</td><td>1.9</td></tr><tr><td>Arkose soil-3</td><td>-98.0</td><td>1.5</td><td>-99.7</td><td>1.9</td><td>-75.1</td><td>2.0</td><td>-99.8</td><td>13.5</td><td>52.1</td><td>4.1</td><td>-87.1</td><td>3.6</td><td>-65.4</td><td>3.5</td><td>-92.9</td><td>1.8</td><td>-98.8</td><td>4.9</td><td>-99.0</td><td>1.9</td></tr><tr><td>Arkose soil-16</td><td>-91.0</td><td>1.5</td><td>-46.0</td><td>2.1</td><td>-68.2</td><td>2.0</td><td>2.3</td><td>13.8</td><td>58.9</td><td>4.1</td><td>-85.3</td><td>3.6</td><td>-49.0</td><td>3.6</td><td>-76.9</td><td>1.8</td><td>-84.6</td><td>5.0</td><td>-79.4</td><td>1.9</td></tr><tr><td>Arkose soil-12</td><td>-98.1</td><td>1.5</td><td>-99.5</td><td>1.9</td><td>-62.3</td><td>2.1</td><td>-98.3</td><td>13.5</td><td>68.3</td><td>4.8</td><td>-83.0</td><td>3.6</td><td>-63.0</td><td>3.6</td><td>-82.0</td><td>1.8</td><td>-99.6</td><td>4.9</td><td>-99.2</td><td>1.9</td></tr><tr><td>Arkose soil-8</td><td>-95.4</td><td>1.6</td><td>-99.5</td><td>1.9</td><td>-76.1</td><td>2.0</td><td>-99.6</td><td>13.5</td><td>62.2</td><td>4.2</td><td>-84.6</td><td>3.6</td><td>-92.9</td><td>3.5</td><td>-96.9</td><td>1.8</td><td>-99.2</td><td>4.9</td><td>-98.5</td><td>1.9</td></tr><tr><td>Rhyolite soil-21</td><td>10.4</td><td>5.7</td><td>0.6</td><td>6.4</td><td>-0.8</td><td>5.2</td><td>-2.1</td><td>7.6</td><td>3.2</td><td>5.3</td><td>0.2</td><td>5.3</td><td>-1.0</td><td>4.9</td><td>-0.3</td><td>4.8</td><td>-25.6</td><td>8.3</td><td>-13.2</td><td>6.1</td></tr><tr><td>Rhyolite soil-20</td><td>4.9</td><td>6.5</td><td>1.0</td><td>6.5</td><td>-0.7</td><td>5.7</td><td>-1.7</td><td>9.8</td><td>0.6</td><td>5.9</td><td>1.6</td><td>6.0</td><td>-1.4</td><td>5.7</td><td>-1.1</td><td>5.7</td><td>-19.9</td><td>6.9</td><td>-9.5</td><td>6.9</td></tr><tr><td>Rhyolite soil-19</td><td>-13.6</td><td>5.8</td><td>-2.9</td><td>6.0</td><td>0.5</td><td>5.2</td><td>-4.8</td><td>7.9</td><td>17.3</td><td>5.3</td><td>1.5</td><td>5.2</td><td>1.0</td><td>5.2</td><td>-2.3</td><td>4.9</td><td>-46.8</td><td>6.3</td><td>-29.6</td><td>5.9</td></tr><tr><td>Rhyolite soil-18</td><td>-7.4</td><td>6.8</td><td>-0.1</td><td>7.1</td><td>0.1</td><td>6.1</td><td>-0.5</td><td>8.3</td><td>-0.5</td><td>6.1</td><td>0.7</td><td>6.7</td><td>-1.2</td><td>5.9</td><td>-0.2</td><td>6.0</td><td>-24.1</td><td>7.5</td><td>-5.6</td><td>6.9</td></tr><tr><td>Rhyolite soil-17</td><td>-5.0</td><td>6.3</td><td>-1.8</td><td>6.4</td><td>-1.1</td><td>5.0</td><td>-4.0</td><td>8.0</td><td>-0.1</td><td>5.0</td><td>3.0</td><td>5.0</td><td>-0.8</td><td>5.0</td><td>-0.2</td><td>4.8</td><td>-25.8</td><td>6.7</td><td>-12.7</td><td>7.2</td></tr><tr><td>Rhyolite soil-2</td><td>8.5</td><td>6.5</td><td>-1.8</td><td>6.3</td><td>0.4</td><td>5.7</td><td>-3.0</td><td>7.8</td><td>3.9</td><td>5.7</td><td>1.3</td><td>5.7</td><td>1.0</td><td>5.4</td><td>-0.1</td><td>5.5</td><td>-4.7</td><td>7.2</td><td>-4.4</td><td>6.9</td></tr><tr><td>Rhyolite soil-5</td><td>11.5</td><td>6.0</td><td>-1.1</td><td>6.2</td><td>1.6</td><td>5.3</td><td>0.3</td><td>8.1</td><td>3.5</td><td>5.3</td><td>3.9</td><td>5.3</td><td>1.7</td><td>5.1</td><td>1.0</td><td>5.3</td><td>-10.1</td><td>6.7</td><td>-8.0</td><td>6.0</td></tr><tr><td>Rhyolite soil-3</td><td>-22.6</td><td>8.2</td><td>-3.4</td><td>6.6</td><td>1.7</td><td>6.5</td><td>-5.4</td><td>8.4</td><td>1.3</td><td>6.5</td><td>3.3</td><td>6.6</td><td>-0.4</td><td>6.3</td><td>0.0</td><td>6.3</td><td>-40.6</td><td>6.5</td><td>-15.3</td><td>6.5</td></tr><tr><td>Rhyolite soil-1</td><td>-3.7</td><td>6.9</td><td>-4.4</td><td>6.7</td><td>-0.1</td><td>6.1</td><td>-4.7</td><td>8.9</td><td>0.4</td><td>6.1</td><td>1.7</td><td>6.1</td><td>-0.1</td><td>5.9</td><td>0.4</td><td>6.0</td><td>-36.7</td><td>6.7</td><td>-17.2</td><td>6.5</td></tr><tr><td>Rhyolite soil-4</td><td>-22.6</td><td>5.7</td><td>-7.9</td><td>6.1</td><td>0.8</td><td>5.5</td><td>-7.0</td><td>8.1</td><td>0.1</td><td>5.5</td><td>3.9</td><td>5.7</td><td>-1.2</td><td>5.3</td><td>-0.8</td><td>5.6</td><td>-57.4</td><td>6.5</td><td>-31.1</td><td>6.0</td></tr><tr><td>Rhyolite soil-11</td><td>-14.5</td><td>5.9</td><td>-2.1</td><td>6.7</td><td>0.6</td><td>5.7</td><td>-3.5</td><td>8.9</td><td>0.7</td><td>5.6</td><td>-2.9</td><td>5.7</td><td>0.0</td><td>5.5</td><td>-1.0</td><td>5.5</td><td>-47.0</td><td>6.6</td><td>-24.2</td><td>6.1</td></tr></tbody></table>
<table><tr><td>Rhyolite soil-7</td><td>-9.0</td><td>6.6</td><td>-36.7</td><td>6.1</td><td>-1.0</td><td>6.5</td><td>-25.8</td><td>7.8</td><td>9.6</td><td>6.7</td><td>-0.7</td><td>7.0</td><td>-6.1</td><td>6.0</td><td>-10.9</td><td>5.8</td><td>-84.7</td><td>6.5</td><td>-55.4</td><td>5.9</td></tr><tr><td>Rhyolite soil-8</td><td>-37.6</td><td>5.7</td><td>-29.7</td><td>6.1</td><td>0.5</td><td>5.9</td><td>-15.5</td><td>7.8</td><td>0.0</td><td>5.9</td><td>-18.1</td><td>5.6</td><td>-0.8</td><td>5.8</td><td>-5.8</td><td>5.7</td><td>-81.9</td><td>6.3</td><td>-8.1</td><td>6.4</td></tr><tr><td>Rhyolite soil-13</td><td>-23.6</td><td>5.9</td><td>-8.4</td><td>6.0</td><td>-0.3</td><td>5.4</td><td>-4.5</td><td>9.1</td><td>4.5</td><td>5.6</td><td>1.0</td><td>5.4</td><td>-0.4</td><td>5.5</td><td>-0.1</td><td>5.1</td><td>-54.3</td><td>6.2</td><td>-33.0</td><td>6.3</td></tr><tr><td>Rhyolite soil-10</td><td>-26.0</td><td>5.5</td><td>-12.1</td><td>6.6</td><td>2.7</td><td>5.4</td><td>-4.4</td><td>8.9</td><td>4.8</td><td>5.8</td><td>4.0</td><td>5.3</td><td>-0.1</td><td>5.2</td><td>-2.2</td><td>5.4</td><td>-60.1</td><td>6.3</td><td>-38.0</td><td>5.9</td></tr><tr><td>Rhyolite soil-6</td><td>-29.2</td><td>5.8</td><td>-25.4</td><td>6.0</td><td>2.1</td><td>5.4</td><td>-14.9</td><td>8.0</td><td>4.3</td><td>5.4</td><td>0.6</td><td>5.4</td><td>-1.9</td><td>5.2</td><td>-4.6</td><td>4.9</td><td>-71.7</td><td>6.2</td><td>-46.1</td><td>6.0</td></tr><tr><td>Rhyolite soil-15</td><td>-57.3</td><td>5.5</td><td>-77.4</td><td>5.5</td><td>0.5</td><td>5.1</td><td>-44.2</td><td>7.4</td><td>3.0</td><td>5.1</td><td>-1.2</td><td>5.7</td><td>-10.7</td><td>4.9</td><td>-19.1</td><td>4.8</td><td>-90.2</td><td>6.2</td><td>-67.4</td><td>5.8</td></tr><tr><td>Rhyolite soil-12</td><td>-98.4</td><td>5.2</td><td>-99.5</td><td>5.5</td><td>-27.2</td><td>5.2</td><td>-96.4</td><td>7.2</td><td>-23.9</td><td>5.3</td><td>-53.1</td><td>4.9</td><td>-46.4</td><td>4.9</td><td>-68.9</td><td>4.5</td><td>-100.0</td><td>6.1</td><td>-99.5</td><td>5.6</td></tr></table>

<table><tr><td>Fallout-1</td><td>-68.1</td><td>5.3</td><td>-40.9</td><td>5.7</td><td>24.2</td><td>5.2</td><td>-41.8</td><td>7.7</td><td>74.3</td><td>5.8</td><td>21.4</td><td>5.2</td><td>-9.2</td><td>5.0</td><td>-7.4</td><td>4.6</td><td>-65.6</td><td>6.2</td><td>-63.7</td><td>5.7</td></tr><tr><td>Fallout-2</td><td>-49.9</td><td>5.5</td><td>-37.2</td><td>5.6</td><td>40.6</td><td>5.1</td><td>-34.2</td><td>9.3</td><td>138.2</td><td>5.8</td><td>42.6</td><td>5.3</td><td>-15.2</td><td>4.9</td><td>-5.7</td><td>4.6</td><td>-50.9</td><td>6.3</td><td>-46.2</td><td>5.8</td></tr><tr><td>Fallout-3</td><td>-36.9</td><td>5.9</td><td>-25.3</td><td>5.8</td><td>-13.0</td><td>5.2</td><td>-29.1</td><td>12.5</td><td>52.2</td><td>6.7</td><td>-0.4</td><td>5.5</td><td>7.7</td><td>5.8</td><td>-7.5</td><td>5.1</td><td>-45.6</td><td>6.3</td><td>-43.3</td><td>5.8</td></tr><tr><td>Fallout-4</td><td>-58.5</td><td>5.4</td><td>-30.7</td><td>5.7</td><td>12.7</td><td>5.8</td><td>-35.9</td><td>8.8</td><td>139.5</td><td>8.9</td><td>14.6</td><td>6.0</td><td>-3.1</td><td>5.4</td><td>-7.3</td><td>5.2</td><td>-66.1</td><td>6.3</td><td>-54.8</td><td>5.8</td></tr><tr><td>Fallout-5</td><td>-33.7</td><td>5.7</td><td>-15.5</td><td>6.0</td><td>-2.4</td><td>6.0</td><td>-20.8</td><td>9.8</td><td>90.1</td><td>9.3</td><td>5.3</td><td>6.3</td><td>-6.7</td><td>5.8</td><td>-5.0</td><td>5.6</td><td>-55.8</td><td>6.2</td><td>-36.9</td><td>5.9</td></tr><tr><td>Fallout-6</td><td>-39.0</td><td>5.8</td><td>-12.1</td><td>6.0</td><td>12.3</td><td>6.3</td><td>-22.4</td><td>8.3</td><td>100.6</td><td>9.0</td><td>14.9</td><td>6.3</td><td>-1.2</td><td>5.8</td><td>-2.1</td><td>5.8</td><td>-64.3</td><td>6.4</td><td>-37.4</td><td>5.9</td></tr><tr><td>Fallout-7</td><td>-39.9</td><td>5.6</td><td>-20.6</td><td>5.8</td><td>14.1</td><td>5.8</td><td>-22.3</td><td>11.6</td><td>133.2</td><td>8.5</td><td>18.1</td><td>6.3</td><td>-8.5</td><td>5.5</td><td>-2.3</td><td>5.6</td><td>-66.3</td><td>6.2</td><td>-44.3</td><td>5.8</td></tr></table>

<table><tr><td>Australite 1</td><td>-57.5</td><td>5.9</td><td>-58.8</td><td>9.1</td><td>-4.7</td><td>0.7</td><td>11.4</td><td>1.1</td><td>-33.8</td><td>2.6</td><td>49.5</td><td>6.7</td><td>7.6</td><td>0.9</td><td>11.2</td><td>1.3</td><td>-80.5</td><td>45.0</td><td>-49.8</td><td>3.2</td></tr><tr><td>Australite 2</td><td>-39.5</td><td>4.6</td><td>-55.0</td><td>8.7</td><td>-8.9</td><td>1.3</td><td>20.4</td><td>2.0</td><td>-37.8</td><td>2.9</td><td>51.9</td><td>7.0</td><td>10.3</td><td>1.2</td><td>11.8</td><td>1.4</td><td>-73.1</td><td>40.8</td><td>-33.0</td><td>2.0</td></tr><tr><td>Australite 3</td><td>-54.9</td><td>6.6</td><td>-58.2</td><td>9.1</td><td>-1.2</td><td>0.2</td><td>12.0</td><td>1.2</td><td>-28.0</td><td>2.1</td><td>52.3</td><td>7.0</td><td>7.7</td><td>0.9</td><td>12.7</td><td>1.5</td><td>-82.6</td><td>46.1</td><td>-55.2</td><td>3.2</td></tr><tr><td>Australite 4</td><td>-71.1</td><td>7.5</td><td>-50.4</td><td>7.8</td><td>5.1</td><td>0.8</td><td>12.7</td><td>1.2</td><td>-3.5</td><td>0.3</td><td>53.9</td><td>7.3</td><td>8.1</td><td>0.9</td><td>9.3</td><td>1.1</td><td>-93.8</td><td>52.3</td><td>-77.5</td><td>4.6</td></tr><tr><td>Australite 5</td><td>-78.2</td><td>9.8</td><td>-49.6</td><td>7.7</td><td>5.4</td><td>0.8</td><td>12.7</td><td>1.3</td><td>-4.0</td><td>0.3</td><td>54.0</td><td>7.3</td><td>8.7</td><td>1.0</td><td>10.7</td><td>1.2</td><td>-94.6</td><td>52.8</td><td>-79.7</td><td>4.9</td></tr><tr><td>Australite 6</td><td>-76.8</td><td>9.6</td><td>-50.7</td><td>7.8</td><td>6.1</td><td>0.9</td><td>11.6</td><td>1.1</td><td>-4.7</td><td>0.4</td><td>52.7</td><td>7.1</td><td>6.5</td><td>0.7</td><td>8.3</td><td>1.0</td><td>-95.7</td><td>53.4</td><td>-82.4</td><td>5.0</td></tr><tr><td>Australite 7</td><td>-9.1</td><td>1.4</td><td>-46.2</td><td>7.2</td><td>3.9</td><td>0.6</td><td>15.4</td><td>1.5</td><td>6.1</td><td>0.5</td><td>46.9</td><td>6.4</td><td>0.9</td><td>0.1</td><td>5.5</td><td>0.7</td><td>-90.2</td><td>50.4</td><td>-68.3</td><td>4.3</td></tr><tr><td>Australite 8</td><td>-61.2</td><td>6.5</td><td>-49.3</td><td>7.7</td><td>4.7</td><td>0.7</td><td>15.5</td><td>1.5</td><td>1.2</td><td>0.1</td><td>51.0</td><td>6.8</td><td>4.5</td><td>0.5</td><td>8.8</td><td>1.0</td><td>-92.3</td><td>55.3</td><td>-69.0</td><td>13.4</td></tr><tr><td>Australite 9</td><td>-49.2</td><td>6.1</td><td>-47.3</td><td>7.4</td><td>4.5</td><td>0.7</td><td>16.2</td><td>1.6</td><td>3.4</td><td>0.3</td><td>52.8</td><td>7.2</td><td>5.1</td><td>0.6</td><td>9.5</td><td>1.1</td><td>-91.4</td><td>51.0</td><td>-66.7</td><td>3.9</td></tr><tr><td>Australite 10</td><td>-79.4</td><td>14.0</td><td>-51.2</td><td>8.0</td><td>4.8</td><td>0.7</td><td>13.2</td><td>1.3</td><td>-4.5</td><td>0.3</td><td>52.5</td><td>7.1</td><td>7.0</td><td>0.8</td><td>8.7</td><td>1.0</td><td>-93.7</td><td>52.4</td><td>-74.6</td><td>4.7</td></tr><tr><td>Australite 11</td><td>-79.3</td><td>10.6</td><td>-50.7</td><td>7.9</td><td>4.5</td><td>0.7</td><td>14.0</td><td>1.3</td><td>-4.5</td><td>0.3</td><td>52.3</td><td>7.0</td><td>6.5</td><td>0.7</td><td>8.6</td><td>1.0</td><td>-94.4</td><td>52.7</td><td>-76.5</td><td>4.5</td></tr><tr><td>Australite 12</td><td>-77.6</td><td>8.2</td><td>-51.1</td><td>7.9</td><td>5.1</td><td>0.8</td><td>12.2</td><td>1.2</td><td>-3.5</td><td>0.3</td><td>53.1</td><td>7.1</td><td>6.0</td><td>0.7</td><td>9.1</td><td>1.1</td><td>-94.7</td><td>52.8</td><td>-77.7</td><td>4.5</td></tr></table>