quartz dioritic sheets. Despite this evidence of direct mantle input into the Tynong magma system, the main granodioritic series do not appear to have been formed by magma mixing processes. Of any I-type granite in the region, the Tynong pluton has perhaps the most direct connection with mantle magmas. Nevertheless, the main mantle connection here is probably in the mantle-derived protolith for these crustal magmas and in the mantle thermal event that gave rise to melting of the deep crust in the Selwyn Block. This degree of mantle connectedness seems typical for I-type granitic rocks worldwide.

Sandstones and siltstones collected from the Siwalik molasse sequence (∼16 to 5 Ma) of the Karnali river section have been studied for their magnetic properties. Behavior of the specimens during demagnetization (of the NRM and IRM) and magnetic susceptibility vs. temperature data suggest that goethite, maghemite/magnetite, and hematite are the main magnetic minerals in the section. Goethite, carrying a recent component, is the dominant magnetic mineral in the fine-grained lithologies from the lower part. Maghemite and magnetite, which also carry a secondary remanence, occur in the sandstones from the upper part. Hematite, mainly of detrital origin, is present in the whole sequence. The magnetic fabric is defined by mainly oblate AMS ellipsoids and a low degree of anisotropy (P < 1.20). The magnetic lineations (declinations: 75• -130• or 245• -310• ; peak orientation: 290• /2.8 • ) are subparallel to the fold axes/bedding strikes/thrust fronts (WNW-ESE). The initial sedimentary-compactional fabric has been overprinted by a secondary tectonic fabric, which was probably induced by mild deformation active in the compressive tectonic setting.

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