LUNAR MANTLE HETEROGENEITY IN THE VICINITY OF OR BENEATH THE APOLLO 17 SITE EMPHASIZED BY NEW BASALT CLAST IN 79135
The texture and major/minor element mineral compositions of the clast are distinct from Apollo 17 Type B2, C, and D basalts. While mineral chemistry is similar to Type A and B1 basalts, the 79135 clast could potentially represent a new type of Apollo 17 basalt. At least one Type A basalt fragment (79265) has been identified from trench soils near the drive tube of Station 9 where 79135 was also collected; in contrast, if the clast is a B1 basalt, it would represent the first of its type identified from Station 9 and one of the few found east of Station 1, indicating a more pervasive presence of that basalt type.
Despite some broad similarities to other Apollo 17 basalt types, the 79135,14 clast may represent a unique basalt type, thus further emphasizing the mantle heterogeneity. The clast’s petrology (e.g., texture, modal mineralogy, and estimated bulk Mg#) and trace element chemistry (e.g., olivine Ti/V ratio) indicate that it may have been produced from a different mantle source region and/or via a different set of magmatic processes than previously described in Apollo 17 mare basalts.