Late Paleozoic Sediments Derived From Pedernal Uplift: ABSTRACT

Abstract

The Pedernal uplift, elongated northward from southern Otero County, New Mexico, to the present-day position of Pedernal Hills, was a late Paleozoic feature 40-75 mi wide and about 225 mi long; at the time of maximum development, the uplift connected southward with the Diablo platform and northeastward with Sierra Grande arch and Amarillo-Wichita uplift. This is Hill's (1958) Pedernal-Sacramento-Otero uplift, Adams' (1962) Pedernal arch, and Meyer's (1966) Pedernal uplift, but differs from Galley's (1958) Pedernal massif which he extended northeastward to encompass the southern Sierra Grande arch. The southern Pedernal area was beneath pre-Pennsylvanian seas, which derived their minor detritus from Penasco dome of northern New Mexico and southern Colorado. The Pedernal uplift emerged during Early Pennsylvanian time. Sediments which became sandstone, dark shale, and silty limestone were deposited westward in Orogrande and Estancia basins and eastward in Delaware basin. During Desmoinesian time, there was wide expansion of shallow seas; the Pedernal barely was awash, and provided only silt and clay for the limestone-choked seas, except for some deltaic subgraywacke in the Orogrande basin. Uplift of the northern part of the Pedernal uplift during late Desmoinesian time supplied arkose northeastward to the Rowe-Mora basin and westward to the Joyita-Los Pinos area and Estancia basin Beginning in late Missourian, the uplift took on the aspect of a tilted fault block, with the western edge higher (especially near Ruidoso) and providing more detritus westward into the Orogrande and Estancia basins, whereas only minor amounts of fine-grained materials swept eastward into the Delaware basin. These conditions continued into Virgilian time, culminating during the late Virgilian and early Wolfcampian with the westward dumping of a thick sequence of subgraywacke, arkose, and red to dark shale. Early Wolfcampian sediments derived from the west side of the Pedernal uplift range from quartzite and granite-cobble conglomerate to red shale, but by middle Wolfcampian the major detritus source was the Uncompahgre highland of north-central New Mexico and southwestern Colorado. Reddish clastics from this highland flooded Wolfcampian seas southeastward where Abo redbeds intertongue with Hueco Limestone. By late Wolfcampian time, most of the Pedernal uplift was buried beneath redbeds; only locally, as at the present-day Pedernal Hills and Pajarita Mountain, did remnant Precambrian-rock monadnocks rise above the red clastic flood. Higher remnants supplied minor detritus to lagoonal seas during Leonardian time. End_of_Article - Last_Page 537------------