Petrology of the Indian eucrite Piplia Kalan

Piplia Kalan is an equilibrated eucrite consisting of 60-80 vol% lithic cla sts in a subordinate brecciated matrix. Ophitic/subophitic clasts fall into two groups: finer-grained lithology A and coarser-grained lithology B. Ver y fine-grained clasts with equigranular textures (lithology C) also occur a nd originally were hypocrystalline in texture. The variety of materials rep resented in Piplia Kalan suggests cooling histories ranging from quenching to slower crystallization. Despite textural differences, clasts and matrix have similar mineral and bulk compositions. Thus, Piplia Kalan is probably best classified as a genomict breccia that could represent fragments of a s ingle lava flow or shallow intrusive body, including fine-grained or glassy outer margin and more slowly cooled coarser-grained interior. Bulk composi tion suggests that the meteorite is most closely related to the main group eucrites, but it probably was affected by minor amounts of fractional cryst allization. Piplia Kalan displays evidence of an early shock event, includi ng brecciated matrix and areas of lithic clasts that contain very fine-grai ned, granular pyroxene between deformed feldspar laths. The meteorite also displays evidence of at least one episode of extensive thermal metamorphism : hypocrystalline materials are recrystallized to hornfelsic textures and m inerals throughout the meteorite contain abundant inclusions that are relat ively large in size. Veins of brown glass transect both clasts and matrix a nd indicate a second, postmetamorphism shock event.