The Sutter's Mill meteorite: Thermoluminescence data on thermal and metamorphic history

Abstract

A piece of the Sutter's Mill meteorite, fragment SM2‐1d, has been examined using thermoluminescence techniques to better understand its thermal and metamorphic history. The sample had very weak but easily measureable natural and induced thermoluminescence (TL) signals; the signal‐to‐noise ratio was better than 10. The natural TL was restricted to the high‐temperature regions of the glow curve suggesting that the meteorite had been heated to approximately 300 °C within the time it takes for the TL signal to recover from a heating event, probably within the last 105 years. It is possible that this reflects heating during release from the parent body, close passage by the Sun, or heating during atmospheric passage. Of these three options, the least likely is the first, but the other possibilities are equally likely. It seems that temperatures of approximately 300 °C reached 5 or 6 mm into the meteorite, so that all but one of the small Sutter's Mill stones have been heated. The Dhajala normalized induced TL signal for SM2‐1d is comparable to that of type 3.0 chondrites and is unlike normal CM chondrites, the class it most closely resembles, which do not have detectable TL sensitivity. The shape of the induced TL curve is comparable to other low‐type ordinary, CV, and CO chondrites, in that it has a broad hummocky structure, but does not resemble any of them in detail. This suggests that Sutter's Mill is a unique, low‐petrographic–type (3.0) chondrite.

Primordial and cosmogenic noble gases in the Sutter's Mill CM chondrite

“…This is consistent with the observation reported by Zolensky et al (2014). However, as mentioned below, the temperature range estimated above seems to be higher than those estimated based on our noble gas and thermoluminescence data (Sears and Beauford 2014). Not only in mineralogy but also in noble gas composition, effects of thermal alteration can be seen.…”

“…This means that 3 He and 36 Ar are indigenous to the meteorite. Hence, the temperature experienced during thermal alteration is less than 350°C, which is consistent with the estimate based on the thermoluminescence study (~300°C; Sears and Beauford 2014).…”

“…(). However, as mentioned below, the temperature range estimated above seems to be higher than those estimated based on our noble gas and thermoluminescence data (Sears and Beauford ).…”

X‐ray computed tomography of extraterrestrial rocks eradicates their natural radiation record and the information it contains

“…Sedimentary processes on Mars can be dated by optically stimulated luminescence using either an instrument on landers or returned samples (DeWitt and McKeever ). The extent of thermal alteration of meteorites as they pass through the atmosphere has been determined by thermoluminescence measurements (Sears ; Sears and Beauford ), as have radiation profiles in large meteorites, which provide clues to the preatmospheric size and shape of meteorites (Reedy and Arnold ; Sears ). Such measurements have taken on new interest as NASA tries to understand the details of atmospheric passage in connection with the impact hazard (Sears et al.…”