Origin of Paleo-Tokyo Bay Sands

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Unconsolidated loose sands of the Late Pleistocene Paleo-Tokyo Bay document the effects of important variables of depositional environment and provenance on framework composition. Fluvial sands include many lithic fragments, and are less quartzose and less feldspathic than shallow marine sands. Near shore sands are characterized by the most stable monocrystalline quartz grains but are less feldspathic than shoreface to offshore sands. Continual nearshore dyrnamic action may have caused abrasion and destruction of unstable lithic fragments and feldspar, overprinted by recydling of the older Paleo-Tokyo Bay sediments which were eroded away grom the coastal outcrops. shoreface and off shore sands are derived intermittently grom nearshore and/or river mouth environments by storm waves, accompanied by the influx of flood water, and are characterized by the intermediate composition between that of fluvial and nearshore sands.The relative amounts of contributed sediments from volvanic and sedimentary rock sources are largely represented by group compositions of ancient and recent fluvial channel sands in each province, which is further represented by unique combination of paleocurrents, topography and architecture of the Paleo-Tokyo Bay sediments, on the relative abundance of total lithic fragments to monocrystalline quartz grains, plotted against the relative abundance of volcanic rock fragments, refering to the geological composition of drainage areas of the recent fluvial systems which have been runing through the each province. The proximity of plutonic rock surce areas are also well documented by compositional variation of beach sands on the quartz grains plotted against the feldspar grains. The two components gradually increase towards the proximal provinces to the granitic rock sources.