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C.E. Meyer

Publications and source records attributed to C.E. Meyer.

26 records · Page 2Linked to original sources
USGS1985

Ages of tuff beds at East African early hominid sites and sediments in the Gulf of Aden

The early hominids of East Africa were dated by determining the ages of tuff beds at the sites. Despite much research using palaeomagnetic and K/Ar-dating techniques, some of those ages are still controversial 1,2. To obtain independent age estimates for these tephra layers, we have examined cores from DSDP Sites 231 and 232 in the Gulf of Aden (Fig. 1a) which consist mainly of calcareous nannofossil ooze, but also contain rare tephra horizons3 dated by interpolation from the established nannofossil stratigraphy (Fig. 1b). Chemical analysis confirms that the identity and sequence of these horizons is the same as that at the East African sites. We conclude that the age of the Tulu Bor Tuff is <3.4 Myr and hence that the Hadar hominid specimens are also <???3.4 Myr old. ?? 1985 Nature Publishing Group.

Nature↗
USGS1983

Taeniolite, an uncommon lithium-mica from Coyote Peak, Humboldt County, California.

Taeniolite has been found in a late pegmatitic clot in a mafic alkalic diatreme at Coyote Peak; associated species are natrolite, pectolite, aegirine, barytolamprophyllite, rasvumite and sphalerite. The taeniolite is green-brown with sp. gr. (meas.) 2.85(1) and H. 31/2. Optically it is biaxial (-) with alpha 1.541(2), beta = gamma 1.570(2), 2V approx 0o and moderate pleochroism with gamma = beta reddish-brown, alpha pale greenish brown. Single-crystal precession photographs show it to be of the 1M type, with a 5.254(2), b 9.110(4), c 10.187(2) A, beta 99.85(4)o and V = 480.4(1) A3. Combined microprobe and ion probe analyses gave SiO2 53.5, Al2O3 3.00, TiO2 1.06, FeO 3.35, MnO 0.21, MgO 18.3, Li2O 2.4, K2O 11.3, Na2O 0.27, F 6.3 = 99.69; SrO and BaO are both <0.04 wt.%; B, Be, Ca and Cl were not detected. Assuming (F + OH) = 2 and assigning 1.30 wt.% H2O gives 409(K1.01Na0.04)(Al0.01Ti0.06Fe2+0.20Mn0.01Mg1.92Li0.68)(Si3.76Al0.24)O10- (F1.40OH0.60).-G.W.R.

Mineralogical Record↗
USGS1980

Zircon fission-track age of 0.45 million years on ash in the type section of the Merced Formation, west-central California

A zircon fission-track age of 0.45 ± 0.08 million years (weighted average of 15 samples) has been determined on an ash interbedded with Pleistocene marine or littoral strata in the type section of the Merced Formation at two localities south of San Francisco. Separation of zircon crystals into several sample groups based on the presence or absence of glass coats, color, and surface texture has made it possible to identify the pyrogenic, detrital, and inferred accidental (xenocrystic) components in the zircon separates. The age obtained on pyrogenic zircons agrees closely with the youngest (0.45 ± 0.18 million years) of several K-Ar ages run previously on plagioclase and hornblende separates from the same localities. The older K-Ar ages (0.7 to 2.1 million years) on this ash are probably a result of detrital or accidental contamination, as determined by analyses on back-picked and untreated splits of the same feldspar separate.

California↗
USGS1974

The regolith at the Apollo 15 site and its stratigraphic implications

Regolith samples from the Apollo 15 landing site are described in terms of two major fractions, a homogeneous glass fraction and a non-homogeneous glass fraction. The proportions of different components in the homogeneous glass fraction were determined directly by chemical analyses of individual particles. They are mainly green glass, a mare-like glass, and different types of Fra Mauro and Highland type glasses. The proportions of various components in the remainder of each of the soils were determined indirectly by finding the mix of components that best fits their bulk compositions. The mixing model suggests that the Apennine Front consists mainly of rocks of low-K Fra Mauro basalt composition. These may overlie rocks with the composition of anorthositic gabbro. Green glass, which occurs widely throughout the site is believed to be derived from a green glass layer which darkens upland surfaces and lies beneath the local mare surface.

Geochimica et Cosmochimica Acta↗