The U-Pb systematics for the Allende carbonaceous chondrite are reexamined and shown to be incapable of explanation by conventional one-, two- or three- stage episodic models. A full and consistent description of the systematics is demonstrated to be possible in terms of a new two-stage model; a similar model can explain the Rb-Sr systematics. The model is consistent with the initial Pb isotopic composition of Allende being closely similar to the Canon Diablo composition, implies that Allende was subjected to a shock event about 0.15 Ga ago and provides a simple explanation of the phenomenon of apparent excess radiogenic lead.

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The concentrations of ²²⁸Ra and ²²⁶Ra in the surface and subsurface sea water samples collected from the East Indian and the West Pacific Ocean were determined. Radium isotopes were analyzed by γ-ray spectrometry or ²²⁸Th milking method. Surface waters of the northern Indian Ocean to the north of latitude 30°S contained higher concentrations of ²²⁸Ra (63-32dpm/1, 000l) than those of southern area and the West Pacific Ocean (less than 8dpm/1, 000l). The samples from near shore water of Indonesia and the South China Sea showed high ²²⁸Ra contents, 629-164dpm/1, 000l. The concentrations of ²²⁸Ra in subsurface waters were very low except for the South China Sea. A major source of ²²⁸Ra in the Indian Ocean may be coastal sediments of Indonesia. The mixing rate of surface water masses across the subtropical convergence was calculated by using a simple box model to be about 41 km/y.

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The Precambrian Virginia Dale ring dike complex, centered on the Colorado-Wyoming border, consists of four ring zones and a central stock. Three of the ring zones and the central stock are granitic; the fourth is a composite of gabbro, diorite, and older metamorphic rocks. Forty-seven samples from the ring dike complex and surrounding igneous rocks were analyzed for major elements, Rb, Sr, Zr, Ba, Cu, and Zn, by X-ray fluorescence and atomic absorption. Chemical variations suggest that the complex was formed during two magmatic events, probably separated by a short period of time: (1) an earlier event involving the gabbro-diorite association and the Trail Creek granite; and (2) a later event involving the Cap Rock and Log Cabin (central core) lithologies, which are apparently related by crystal fractionation. In that portion of the ring dike associated with the younger event, ages seem generally to decrease toward the center of the complex while the degree of fractionation increases inward, suggesting a “classic” ring dike sequence. Although there is abundant field evidence for magma mixing/assimilation, these processes had no apparent major effects on chemical trends in the major lithologic units of the ring dike complex.

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Distribution of copper and cadmium between manganese oxide and solution has been investigated through the laboratory experiment. The amount of copper coprecipitated with manganese oxide is almost equal to that of cadmium. However, the amount of copper adsorbed on ferro-manganese nodule suspended in seawater medium is greater than that of cadmium. The experimental results suggest that almost all copper in manganese oxide is contained as an adsorbed form on the surface of manganese oxide, and that manganese oxide may not be a good scavenger to remove cadmium discharged to seawater.

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The influence of borate-boron on the crystal form of calcium carbonate has been studied experimentally. And it has been found that borate ions in a parent solution favor the formation of calcite. This experimental result is in good agreement with the prediction from the trend that chemical species which are more easily coprecipitated with calcite or aragonite favor the formation of aragonite or calcite respectively, because the authors reported previously that borate ions are more easily coprecipitated with aragonite than with calcite.

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