Bedload composition, transport and modification in rivers of Westland, New Zealand, with implications for the distribution of alluvial pounamu (jade)

摘要: River bedload surveyed at 50 sites in Westland is dominated by Alpine Schist or Torlesse Greywacke from the Fault hanging wall, with subordinate Pounamu Ultramafics footwall-derived Western Province rocks. Tumbling experiments found ultramafics to have lowest attrition rates, compared greywacke sandstone and granite (which abrade produce silt medium-sand), incompetent schist fragments). Arahura has greater total concentrations (103–105 t/km2) proportions (5–40%) of ultramafic Hokitika Taramakau catchments (101–104 t/km2, mostly <10%), matching relative areas mapped Ultramafic bedrock, but enriched absolute areal proportions. rocks downthrown are under-represented bedload. Enriched decrease rapidly distance downstream source rock outcrops, changing near prominent ice-limit moraines. Bedload evolution transport involves both d...