2. feldspar chemistry draw and explain the ternary phase diagram for feldspars (as shown in class). your explanation should make reference to exchange vectors, miscibility gaps, the rock types that might contain specific feldspars and, in turn, the formative plate tectonic environments. [30 pts] 3. magma viscosity 3a) calculate and plot the velocity profile through a 2 m-thick basaltic lava flow with a viscosity of 300 pa. s and density 275o kg mo descending a 2° slope. what is the shape of the profile? [20 pts] 3b) calculate the maximum velocity in the flow. do the same for a similar flow of rhyolite with a viscosity of 10° pa. s and density 2500 kg m*, and a lunar basalt from the sea of tranquility (moon, where g is 1.62 m s*) having a viscosity 9 pa. s and density 30oo kg m*. for comparison, calculate your own walking velocity (~4 miles/hour) in the same units. are these accurate estimates of lava flow rates? think of factors that might complicate the calculation. [3o pts]