Laborcita Formation
The Laborcita Formation is a geologic formation in the Sacramento Mountains of New Mexico. It preserves fossils dating back to the late Pennsylvanian to early Permian.
Description
The formation is composed mostly of marine beds consisting of alternating cycles of limestone and siliciclastic sedimentary beds with a thickness of about at the type section. It is exposed only in a small area of the northernmost Sacramento Mountains, and transitions to mostly continental red mudstones some thick before abruptly pinching out to the southeast. The formation lies on the Holder Formation and is overlain by the Abo Formation.The formation is interpreted as cyclic sequences of terrestrial and shallow marine carbonate rocks deposited on a narrow shelf lying between the Pedernal Uplift to the east and the Orogrande Basin to the west. Cycles are generally transgressive, with basal conglomerate giving way to increasingly fine sandstone, siltstone, and shale and finally limestone. Corresponding regressive sequences are very poorly developed.