Fusulinid Biostratigraphy of Bird Spring Formation in Spring Mountains near Mountain Springs Pass, Clark County, Nevada

Mart T. Gamache, Gary D. Webster

Fusulinids from a 955.16 m thick section of Chesterian into Wolfcampian rocks of the Indian Springs and Bird Spring formations exposed near Mountain Springs Pass represent the biozones of Millerella to Pseudoschwagerina. Species of Millerella, Plectofusulina, Staffella, Schubertina, Pseudostaffella, Profusulinella, Fusulinella, Beedeina, Oketaella, Pseudofusulina, Triticites, Schwagerina, Eoparafusulina, and Cuniculinella were described. One new species of Millerella and three new species of Triticites were named.

The Mountain Springs section can be correlated intraregionally with other sections in Clark County using similar cherty limestones or sandstone-dominated strata in association with biozones recognized in the southern Great Basin. The thickening of strata from the Mountain Springs section to the Arrow Canyon and Lee Canyon sections demonstrated by this method reflects each section's position to the northeast-trending Las Vegas-Wasatch hinge line between thin, shallow shelf sediments and thicker sediments to the west after palinspastic reconstruction. The large diversity of fusulinid species in the Mountain Springs section relative to Arrow Canyon and Lee Canyon suggests that a fusulinid diversity index may be useful in correlating similar paleoenvironments.

Fusulinid biozones of the Mountain Springs section can also be correlated regionally with fusulinid subbiozones A through G of the Shasta Lake area in northern California and with fusulinid biozones of the Mid-Continent based on similar species and occurrences.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.