Within the Himalayan Foreland Basin, the axial Yamuna River with Himalayan headwaters lies along the northern margin of the Indian Craton, giving the impression that cratonic rivers have contributed little to the basin compared with Himalayan drainages. However, the Betwa, Chambal, and other rivers , which drain northward into the Yamuna , are vigorous monsoonal rivers with large catchments. Stratigraphic and petrographic evidence shows that sediment derived largely from these rivers extends north of the axial Yamuna River. Red feldspathic sand and gravel underlie much of the southern foreland basin at shallow depth (>25 m), where its topmost strata are dated at ca. 119 ka ago, and extend at deeper levels (>500 m) to about onethird of the distance across the foreland basin. Petrographic analysis confi rms a match with modern Betwa River sands, which derive their feldspar from granitic gneisses of the Bundelkhand Complex.Along the Yamuna Valley the red alluvium is overlain by gray alluvium dated at 82-35 ka ago, which also yields a cratonic signature, with large amounts of smectite derived from the Deccan Traps. Cratonic contributions are evident in alluvium as young as 9 ka ago in a section 25 km north of the Yamuna. This gray cratonic sediment was probably deposited in part by the Chambal River, which transports high-grade metamorphic minerals from the Banded Gneiss Complex of the Aravalli belt. Cratonic sediment appears to interfi nger with Himalayan detritus farther north below the Ganga-Yamuna Interfl uve.With its headwaters in the tectonically unstable Indus-Ganga watershed area, the Yamuna River may have occupied its present course late in the Quaternary, and if so, cratonic rivers may have provided the basin's axial drainage for prolonged periods. The penetration of Himalayan sediment to the distal foreland basin may refl ect avulsion of orogenic rivers along the craton margin, in addition to dynamic transverse drainage systems from the Himalaya that pushed the axial drainage to the basin's feather edge. The wide spread of cratonic sediment would have been enhanced by slow subsidence in the distal foreland basin and focusing of rivers into a basin reentrant.

Red coloured Middle Eocene Gercus Formation is a widely exposed rock unit in northern Iraq, southeastern Turkey, and northwestern Iran. Siliciclastic rocks (mudstones and sandstones) are the predominant rocks of this formation which were studied petrographically and geochemically. The Gercus Formation also contains a few beds of limestone, gypsum, and conglomerate. The sandstones are of two types, red and white, mostly immature litharenites, consisting of lithics (85%), quartz (12%), and feldspars (3%). The rock fragments consist dominantly of angular chert and rounded limestone and smaller amounts of sedimentary, magmatic, volcanic, and metamorphic lithics indicating proximity of their source rocks. The provenance discrimination diagrams of the detrital grain counts in sandstones show recycled and collision orogen sources. Petrographic, heavy minerals and major and immobile trace element (e.g. La, Th, Sc, Zr, Hf, and Ti) discrimination diagrams indicated that the Gercus Formation was originated under a collision tectonic setting above a subduction zone as part of an Oceanic Island Arc (OIA), where its sediments were derived from mixed sources, including recycled sediments of chert-and carbonate-rich formations and igneous-metamorphic ophiolitic complexes of north to north-east Iraq and adjacent Iranian and Turkish counterparts. The results also indicated a mixed marine (lacustrine and deltaic) and non-marine (fluviatile) origin for the Gercus Formation. The red sandstones, white sandstones, and mudstones show minor differences in their major, trace, and rare-earth element (REE) contents and have generally similar Post Archean Australian Shale (PAAS)-, Upper Continental Crust (UCC)-, and CI-chondrite-normalized distribution patterns indicating their common origin. The average of elements in the siliciclastic rocks is depleted in the high-field-strength elements (HFSE), the large-ion lithophile elements (LILE), and REE; and enriched in some rock-forming elements (RFE) and mantle rock-forming elements (MRFE) (Mg, Ca, Cr, Co, Ni) and depleted in others (Si, Al, Fe, Cu, Zn, Ga) relative to PAAS and UCC; whereas, they are depleted in Fe, Mn, Mg, Co, Ni, Cu, Zn, Ga, Na, and P, and enriched in all other RFE, MRFE, LILE, HFSE, and REE compared to CI-Chondrite. The REE content of these rocks is very low (23-34 ppm) and their LREEs are enriched six times relative to HREEs. These geochemical characteristics suggest a provenance dominated by basic/ultrabasic rocks. The U/Th, V/Cr ratios and the authigenic U values show an oxic depositional environment for the studied siliciclastic rocks.

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