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Ghost Ranch, New Mexico, Project Overview – GEO 660, Summer 20006. Physical Response of Aeolian Sands Seas to Changes in Wind Regime Over the Last 100,000 Years – An Approach From System Self-Organization. Gary Kocurek. Overview of project Your preparation
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Ghost Ranch, New Mexico, Project Overview – GEO 660, Summer 20006 Physical Response of Aeolian Sands Seas to Changes in Wind Regime Over the Last 100,000 Years – An Approach From System Self-Organization Gary Kocurek
Overview of project Your preparation More time in field looking at the geology and less lecture Objectives of Pre-Class Meeting
Regional paleogeography Review of aeolian systems and their rock record Ghost Ranch Project Middle Jurassic Entrada & Todilto Formations What is unique about Entrada dune record Some parts of the explanation Project assignment Topics Addressed
Western North America • Subduction complex • Interior seaway • Entrada Desert
Todilto Formation Facies • Inland sea • Bull’s eye facies pattern • Surrounded by Entrada dunes • Marine and sabkha facies to north and west
Ancient Aeolian Record • Sets of dune cross-strata • Each set is produced by one migrating dune • Transport direction determined by foreset dip directions • Interdune surface and overlying flat interdune strata
Stratification Types of Dune Foresets • Lee-face deposits • Grainflow • Grainfall • Wind ripples • Textural differences reflected in diagensis
Ghost Ranch Outcrop: What Is Special Regarding Dune Preservation?
Entrada/Todilto Outcrop • L & G are Todilto facies • M represents subaqueous mass flow deposits • D is the last Entrada dune • Compare D to underlying Entrada strata
Explain the occurrence of preserved Entrada dune paleo-topography (one of 3 known examples globally!) Components Draw for yourself the outcrop walls of the Entrada & Todilto By a series of connected measured sections, document the relationship of the Todilto facies to the Entrada paleotopography Interpret/contrast depositional settings of Entrada dune, mass flows, and Todilto facies What to hand in Two drawings No more than 2 pages of text that gives your interpretation with support (exclude irrelevant material!) Ghost Ranch Project