Question is in text and preconditions to question are attached in imagesSuppose paleomagnetic data indicate Africa travelled N at 5 cm/yr and collidedwith a stationary North America. Assume continental crust is 35 km thick.Because continents are buoyant relative to the mantle, neither continentsubducts. At steady state, continental crust is moving up to the surface atmountain belts, undergoing weathering and erosion, and the mass is beingredistributed away from the mountain-belt, all at equal rates. What is the massflux? Suppose the pre-collision eroded flux was equal to Earth’s modernsediment flux of 8 km 3 /yr; what is the fractional change in eroded flux (i.e.,mass/volume available for weathering)? Q1. Effect of Supercontinent Formation. The purpose of the question is to think throughthe role of mountains in climate stability. Mountains are important to the global weatheringbudget. This is because mountain uplift increases the amount of material available forweathering per year (the sediment mass flux). Because the total planet-integratedweathering must be constant (averaged over >107 yr timescales) in order to avoid a climaterunaway, the increase in material available for weathering must be compensated by adecrease in the amount of weathering per unit sediment. The easiest way to decrease theamount of weathering per unit sediment is to lower the planet temperature. (The loweringof temperature is accommodated by a transient pulse of increased weathering. Thistransient increase in weathering lowers the CO₂ concentration, which lowers temperature.The planet is now less efficient at weathering each sediment parcel, and so the climate re-equilibrates at a new, lower temperature).The purpose of this question is to work through the order-of-magnitude effect on planetaryclimate of forming new mountain belts.Earth 280 Ma. Credit: Ron Blakey (NAU).The most recent global supercontinent, Pangea, was completed ~280 Ma by collision ofNorth America with Africa. The collision (the Alleghenian orogeny) created a mountainchain, the Central Pangean Mountains. The Appalachian Mountains approximatelycorrespond to a remnant of this mountain belt. In this question, use the paleogeographicreconstruction above (grid spacing 30 degrees) and Earth radius = 6 x 106 m. Assume weathering rate per unit rock (cations/yr/km³) scales asπαρ-E/RTwhere E is activation energy and R is the gas constant, 8.314 J/mol/K, and surfacetemperature T is in K. Assume an effective activation energy for weathering ("effective"including the effect of temperature on rainfall) of E = 74 kJ/mol (West et al., Earth &Planetary Science Letters, 2005).

To calculate the mass flux, we need to first determine the area of the mountain belt created by the…

Answered: Suppose paleomagnetic data indicate…

Applications and Investigations in Earth Science (9th Edition)

9th Edition

ISBN:9780134746241

Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Chapter1: The Study Of Minerals

Section: Chapter Questions

Problem 1LR

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Question is in text and preconditions to question are attached in images

Suppose paleomagnetic data indicate Africa travelled N at 5 cm/yr and collided
with a stationary North America. Assume continental crust is 35 km thick.
Because continents are buoyant relative to the mantle, neither continent
subducts. At steady state, continental crust is moving up to the surface at
mountain belts, undergoing weathering and erosion, and the mass is being
redistributed away from the mountain-belt, all at equal rates. What is the mass
flux? Suppose the pre-collision eroded flux was equal to Earth’s modern
sediment flux of 8 km 3 /yr; what is the fractional change in eroded flux (i.e.,
mass/volume available for weathering)?