�@	Speciation analysis of sediment by selective chemical leaching method-experimental study and its application to granitic conglomerate
		Basin formation and strain partitioning along strike-slip fault zones

Speciation analysis of sediment by selective chemical leaching method-experimental study and its application to granitic conglomerate

Yutaka Kanai, Yasuko Okuyama-Kusunose and Yukio Sakamaki

1996

vol. 47 (8), p. 413-425, 10 figs., 5 tables.

Keywords : speciation analysis, selective chemical leaching, reagent, sedimentaty rock, Tono mine, granitic conglomerate, chemical composition

Abstracts: A selective chemical leaching method was examined for several reagents and applied to a granitic conglomerate. It was shown that neither AcONa nor AcONH₄ solutions dissolves carbonates of heavy metals or alkali earth elemrnts except for some hydroxides and sulfates. AcONa/AcOH solution adjusted to pH 5.0 dissolves carbonates.
�@The results of chemical leaching analysis on the granitic conglomerate demonstrate that the AcONa soluble fraction was rich in Ca and is considered to be in ion exchangeable form. Ca, Mn, Zn, and U were abundant in the AcONa/AcOH soluble fraction which is assumed to be derived from carbonate. NH₂OH�EHCl/AcOH soluble fraction, presumably from iron oxides, contained Fe, Mn, Mg, P, Zn, V, and U, and these elements are considered to have coprecipitated with iron oxides. Adsorption densities were calculated assuming that elements area adsorbed by the iron hydroxide surfaces. Those of Na, Mg, Ca, Mn, Zn, and V are independent on the grain size, while adsorption densities of Al, K, P, Ti, Ba, and Sr decrease and that of U increases with decreasing grain size. These results suggest that there may be some other geochemical actions as well as the adsorption of iron hydroxide.

Basin formation and strain partitioning along strike-slip fault zones

Christopher Parkinson and Tim Dooley

1996

vol. 47 (8), p. 427-436, 5 figs., 1 table.

Keywords : strike-slip fault, pull-apart basin, strain partitioning, geometric analysis

Abstract : Surface traces of large strike-slip fault systems are invariably composed of segments that appear as steps in map-view. In many such fault systems, the dominant sense of step-over of segments (on a reginal scale)is releasing, resulting in the development of pull-apart basins and related structures. Previous attempts to explain this type of fault array have appealed to local heterogeneities, which may be more fortuitous than systematic. Here we propose a simple, geometrical model for the initial development of releasing step-overs based upon geometrical analyses of a number of strike-slip fault zones in various, diverse geological settings. These preliminary analyses indicate that constituent fault segments are considerably straighter than the fault zones, and that basin spacing (fault segment length) has a positive relationship with the radius of curvature of the fault zone. Since straight faults are more efficient at accommodating slip than curved or irregular traces, fault segmentation is necessary to accommodate a curved plate boundary. Net extension along transform/strike-slip systems must be compensated by intra-plate shortening and compression oriented perpendicular to the trend of the primary fault system, resulting in the partitioning of strain.