... were performed at the outcrop scale to evaluate the impact of the ~100 Ma McAfee Creek intrusion on the Barcroft background magnetic susceptibility. The combined data sets display a broad positive correlation between K m and elevation. Pluton mineralogy also appears to vary with elevation but is more...

...TABLE 4. ISOTOPIC DATA FOR THE BARCROFT AND MCAFEE CREEK INTRUSIVE SERIES ...

... °C at a depth of 4–5 km. Mineral assemblages of stages 1 → 4 are disposed progressively inward, indicating that the Barcroft pluton lost heat along intrusive contacts with the wall rocks, cooling, annealing, and re-equilibrating in the process. The Cretaceous McAfee Creek Granite transected this ENE...

... and carbonate metasedimentary section on the south. The Middle Jurassic Barcroft granodioritic pluton later intruded the Barcroft break; the Middle Jurassic Cottonwood, and Late Cretaceous McAfee Creek + Pellisier Flat granitoids also invaded the superjacent section on the NE. Heating of the White Mountain Peak...

... to be upright and the oldest part of the Mesozoic section. The McAfee Creek Granite, which has a 100 ±1 Ma U/Pb zircon age, postdates thrusting; therefore, the Barcroft structural break is primarily Early Cretaceous in age. Geological Society of America 1987 *Present addresses: Hanson—Department...

... to exclude. It is impossible to guage the extent to which water intrusion has affected the production of oil in the Gulf Coast fields for they have always been afflicted by water troubles, but if water conditions could be improved it appears certain that operating expenses would be reduced and probable...

... environments. The Vinini Formation ( Figs. 2 and 4 ; Table 1 ) was first mapped in the Roberts Mountains by Merriam and Anderson (1942) along Vinini Creek. Merriam and Anderson (1942) recognized two informal units (upper and lower) based on lithology and graptolite fauna and described the extreme...

...-type hydrothermal systems. If true, then across Nevada three sedimentary packages may have contributed Au to a hydrothermal system. Furthermore, Au may have been emplaced in the thermal aureole in, or in veins, cutting the sedimentary rocks during intrusion of Jurassic and Cretaceous intrusive...

... history with the Sierra Nevada, of which they were a part, prior to Basin and Range extension. Pre-Cenozoic rocks in the southern White Mountains, south of Mount Barcroft ( Fig. 3 ), consist of sedimentary rocks of late Precambrian and early Paleozoic age as well as several Mesozoic granitic intrusions...

... as either quartz or carbonate. Many large areas disturbed by active mining have high quartz index values (Fig. 6) , especially along the Carlin Trend (CN), the Independence Trend (IN), the Twin Creeks mine at the northeast end of the Getchell Trend (GT), the Lone Tree (LT) and Marigold (MG) mines along...

...I. H. Crick; C. J. Boreham; A. C. Cook; T. G. Powell ABSTRACT Five potential source rocks have been discovered in the middle Proterozoic of the McArthur basin. The lacustrine Barney Creek Formation (McArthur Group) and the marine Velkerri Formation (Roper Group) compare favorably in thickness...

... rarer are very thick intrusive bodies that have cooled sufficiently slowly to allow a layered complex to develop. It is generally accepted that they are the result of multiple intrusions that occurred prior to a significant degree of crystallization of the previous magma body. The Karoo Large Igneous...

... Valley, Tehachapi, Monolith, and Back Canyon pendants. However, the Lebec granodiorite-hosted Salt Creek pendant does not likely correlate with Brite Valley and Tehachapi pendants since they are intruded by 99–105 Ma tonalites, diorites, and gabbroids of the intrusive suite of Bear Valley ( Saleeby et al...

.... These are commonly, but not necessarily, expressed topographically. Some lineaments are suggested by lines of igneous intrusive or extrusive centers or alignments of ore bodies. Finally, others are revealed only by regional gravity ( Cook and Montgomery, 1972 ) and magnetic ( Zietz et al ., 1969 ) patterns related...

... and volcanism. The basement, composed of layered intrusions, granitic plutons, and gneissic rocks, served as the source for the quartz arenite with detrital chromite. Mesoarchean Slave stratigraphic sections contain fining-upward (FU) and coarsening-upward (CU) sequences, with the former predominant at craton...

... of a ca. 527 ± 12 (2σ) Ma maximum depositional age. These features, in addition to abundant detrital magnetite-ilmenite grains, reflect a distal source for these rocks, most likely from the ca. 1.1 Ga Pikes Peak batholith and/or the Midcontinent rift and ca. 0.53 Ga bimodal intrusions of the Oklahoma...