...W. P. LEEMAN; C. J. VITALIANO Abstract The McKinney Basalt, a composite pahoehoe and pillow lava unit in the Snake River Plain, has been studied by petrographic, chemical, strontium-isotopic, and experimental methods in an attempt to define its origin and evolutionary history. Differences...

...WILLIAM P. LEEMAN Abstract Samples of McKinney Basalt, including a pillow glass, are characterized by light rare-earth element–enriched abundance patterns with small positive Eu anomalies (relative to chondrites) and high Cr/Ni ratios. In particular, the positive Eu anomaly observed in the pillow...

... Shale Members of the Aguja Formation. A second phase of deposition resulted in a retrogradational shoreface succession that includes the upper part of the Abajo Shale, overlying Rattlesnake Mountain Sandstone Member, and lower part of the McKinney Springs Tongue of the Pen Formation, up to a skeletal...

... north of the amphitheater of the giant subaqueous 10 km 3 McKinney Bay landslide, which originated on the west wall of Lake Tahoe. Images from a submersible camera show that the ridges are composed of loose piles of boulders and cobbles that lie directly on poorly consolidated, fine-bedded lake beds...

...Figure 2. Stratigraphic summary of Idaho Group, adapted from Lee et al. (1995) . Comments on placement of Banbury Basalt and Tuana Gravel are in text. Sand Spring Basalt, Yahoo Clay, McKinney Basalt, Crowsnest Gravel, and Melon Gravel are within Snake River Group. An erosional unconformity...

...Figure 2. Simplified geologic map of northwestern part of the Lake Tahoe Basin. Units shown on map are: MPa (brown)—Miocene–Pliocene andesite flows and breccias; QPs (gray)—Pliocene–Pleistocene lacustrine sediments, locally diatomite rich; Qb 1 (apple green)—older (2.3 Ma) basaltic lavas; Qb 2...

... collection of ions of two different masses was invented by Nier (1947) . A description of a Nier-type instrument specifically for measuring precisely small differences in isotope ratios is given by McKinney et al. (1950) . A comprehensive review of the chemistry of oxygen isotopes is given...

... 1980 35 219 41 Leeman W. P. Rogers J. J. Late Cenozoic alkali-olivine basalts of the Basin-Range province, U.S.A Contrib. Mineral Petrol 1970 25 1 24 Leeman W. P. Vitaliano C. F. Petrology of the McKinney basalt, Snake River Plain, Idaho Bull geol Soc Am 1976...

... ontogenetic processes and have been addressed mainly in the context of heterochrony ( Gould 1977 ; McKinney 1988 ; McKinney and McNamara 1991 ; McNamara 1995 , 1997 ; Klingenberg 1998 ). Paleobiological analysis of such evolutionary changes involves caution because of the way ontogenetic information...

... within the intraterrestrial regime or from extraterrestrial impacts. Examples of intraterrestrial evolutionary drivers include flood basalt volcanism, plate tectonics, and Earth’s magnetic field reversals ( Stothers 1986 , 1993 ). Patterns in marine extinctions can be linked to the fluctuation...

... took place during younger, post–10 Ma faulting. A two-part extensional history of the East Range is outlined in Figure 9 . Miocene (17–13 Ma) olivine basalt flows are extrapolated from outcrops east of McKinney Pass to cross section A–A′, resulting in the unconformity beneath these flows having...

... of Pena Mountain; (3) Dawson Creek; (4) Rough Run Creek; (5) north of Paint Gap Hills; (6) north of Grapevine Hills; (7) south of Rosillos Mountains; (8) Tornillo Flat; (9) Canoe Valley; (10) south of Dagger Flat; (11) northwest of McKinney Hills; (12) divide between Hannold Draw and Big Yellow arroyo...

... , located close to the granodiorite contact in a multi-phase, composite, diorite pluton ( McKinney, 1985 ; Moore and Lockwood, 1973 ). F ig . 1. Location and geology map of the Fisher Lake area in northeastern California, USA (silhouette, top right corner). Stippled, rectangular areas mark...

... lavas (Leeman et al. 1977); Atlantic DSDP leg-37 (Blanchard et al. 1976); Atlantic FAMOUS area (Langmuir ct al. 1977), lb. }POD 417-53 basalts (Bor-Ming Jahn et ali 1980); Snake River, McKinney basalts (Leeman and Vitaliano, 1976); Columbia River ba~Blts (Swanson and Wright, 1981); Skye Island basalts...

..., especially mass extinction, as being forced by 26–35 m.y. periodic events, such as bolide impacts (e.g., Rampino and Stothers, 1986 ; Raup, 1992 ) or terrestrial events such as sealevel changes, flood basalt volcanism, and magnetic field reversals (e.g., Hallam, 1989 ; Stothers, 1986 , 1993...

...—Dollar Point; EB—Emerald Bay; ELP—Ellis Peak; EP—Echo Peak; EPF—Echo Peak fault; ES—Echo Summit; FLL—Fallen Leaf Lake; GC—General Creek; MC—Meeks Creek; McK—McKinney Creek; MT—Mt. Tallac; NTFZ—North Tahoe fault zone; OS—Osgood Swamp; RL—Round Lake; RP—Rubicon Peak; RV—Rockbound Valley; SNP—Sierra Nevada...

... and topography on a geologic map of Lake Tahoe highlighting the modern depositional plain, glacial erosional channels and debris aprons, the lacustrine platform and older lacustrine rocks and sediments, Mesozoic granite and metamorphic rocks, as well as the McKinney Bay (MB) debris field and several relatively...

... crust, pp.2165-2172. TAYLOR, S. R. and OTHFRS Rare earth element patterns in Archaean high-grade metasediments and their tectonic significance, pp. 2267·2280. STILLE, P. and OTHERS Pb, Sr. Nd, and Hf isotopic constraints on the origin of Hawaiian basalts and evidence for a unique mantle source, pp. 2303...