Kelly meteorite, Logan County, Colorado, USAi

Regional Level Types
Kelly meteorite	Meteorite Fall Location
Logan County	County
Colorado	State
USA	Country

INTRODUCTION

Ordinary chondrite, brecciated & xenolithic (LL4,br; S3; W2)
Find,1937; 44.3 kg, single stone

A single mass was found with both chondritic and recrystallized textures set within an almost completely recrystallized matrix. Within the matrix host olivine (Fa27-32, av. 29) and orthopyroxene dominate along with minor albitic plagioclase. Chondrules include usually well-defined barred olivine (BO) types as well as more poorly defined relic porphyritic olivine (PO) types. Small blebs of Fe-Ni metal and troilite are scattered throughout the meteorite. Several additional minor and accessory opaques were observed by Ramdohr (1973). Different clasts have experienced different levels of shock (e.g., undulose extinction in many, but not all olivines). Low-level and moderate weathering is pervasive.

Kelly was one of the first meteorites to receive critical attention after the first moon rocks were returned by the Apollo astronauts. Its complex and pervasive brecciation structure were described as that of a 'metabreccia' in an oft-cited article by Bunch & Stöffler (1974). The parallels between the battered regolith features of lunar rocks and meteorites are not as startling today as they were four decades ago, but they remain complex and only partially explained.

The LL chondrites (very low in total iron) are the smallest group of ordinary chondrites (~10% of the classified witnessed falls) with the LL4 subgroup falls accounting for only 10% of all LL falls. Kelly's cosmic ray exposure (CRE) age of 13.6 Ma, similar to the ~15 Ma CRE ages of many other LL chondrites, may indicate a recent shared disruptive impact event for many LL chondrites.

Kelly itself is the 2nd most massive of the 300 meteorites and meteorite fragments classified exactly as 'LL4' chondrites at the Meteoritical Bulletin Database (in May 2016). Moderate-sized masses in the 1-5 kg range have been held by the Denver Museum of Nature and Science, the United States National Museum (Washington, DC), Field Museum of Natural History in (Chicago), and Senckenberg-Museum (Frankfurt, Germany).

Other Regions, Features and Areas containing this locality

References