Question

This detrital rock consists of angular grains and is rich in potassium feldspar and quartz. What do the angular grains indicate about the distance the sediment was transported? The source of the sediment in this rock was an igneous mass. Name the likely rock type. Did the sediment in this sample undergo a great deal of chemical weathering? Explain.

Answer 1

The detrital rock with angular grains and rich in potassium feldspar and quartz suggests minimal transport from the source and is likely arkose; the minimal transport also indicates limited chemical weathering.

Step-by-step explanation:

The rock in question, with angular grains, rich in potassium feldspar and quartz, is likely arkose. The angular nature of the grains suggests that the sediment was not transported a great distance because angular grains usually indicate proximity to the source rock.

As such, these sediments have not been subjected to extensive rounding which occurs during a longer transport. The presence of significant amounts of potassium feldspar suggests minimal chemical weathering since feldspar readily alters to clay under extensive chemical weathering conditions.

Given the mineral composition, and the lack of significant rounding or alteration of feldspar, it can be concluded that the sediment did not undergo a great deal of transport or chemical weathering before deposition and lithification into arkose.