Origin of Paleo-Tokyo Bay Sands

晚更新世古东京湾的松散砂记录了沉积环境和物源的重要变量对框架组成的影响。河流砂包括许多岩屑，比浅海砂的石英质和长石质少。近海岸砂的特征是最稳定的单晶石英颗粒，但比滨岸至近海砂的石英石少。连续的近岸动力作用可能造成不稳定岩屑和长石的磨损和破坏，这些岩屑和长石是由从海岸露头上被侵蚀掉的较老的古东京湾沉积物的磨损叠加而成的。滨岸和离岸海岸砂是在风暴波作用下，伴随着洪水的涌入，从近海岸和/或河口环境中间歇性地衍生出来的，其特征是成分介于河流砂和近海岸砂之间。来自火山岩和沉积岩源的沉积物的相对量主要由各省的古河道砂和现代河道砂的组成分来代表，这进一步表现为古东京湾沉积物的古水流、地形和结构的独特组合，以及岩屑总量与石英单晶颗粒的相对丰度，与火山岩碎屑的相对丰度的关系，与流经各省的现代河流系统流域的地质组成相一致。在石英颗粒上的海滩砂与长石颗粒的对比图中，其成分变化也很好地证明了深成岩表面区域的邻近性。这两个分量向花岗岩源的近源区逐渐增加。

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.