Reef and Basin                                  Depositional Model                                                                                                                                           Basinal Siliciclastics and El Capitan Forereef

 

Course:          New Mexico/West Texas Field Seminar

(Carbonate and Siliciclastic Studies/Field Sedimentology with Exercises and Techniques for Analyzing Outcrops and Subsurface Data)

Class Time:      M 1 – 3 p.m in DeLoach 109

Instructor:        Roger D. Shew

Office:              DeLoach 121

Phone:             x7676

Email:              shewr@uncw.edu

Office Hours:    Before and After Class and Tues from 12 - 2

 

Course Description:

Although the focus of the course is the field seminar to the classic outcrops in New Mexico and West Texas, we will also have in-class discussions and exercises on field sedimentologic techniques as well as the interpretation of rocks, cores, logs, and seismic. Our goal is to “put it all together” for a complete description/interpretation of a project, core, field, and/or thesis. You will be expected to be able to describe outcrops and any other data and come to a sound interpretation of its origin, depositional setting, and properties. In other words you will characterize the outcrop etc. and then you will be expected to summarize the data in a presentation and in an Executive Summary.

 

The actual agenda, types of study topics, and projects will vary somewhat depending upon knowledge base, areas visited, and particular interest/excitement with various topics. However, the following rough agenda provides some framework for the course.

Tentative Agenda (subject to change at my whim)

August 27

Introduction: Requirements, Field Trip Discussions/Plans

September 3

Labor Day Holiday

September 10

Basin Scale Interpretation

September 17

Field Scale Interpretation

September 24

Reservoir Scale Interpretation

October 1

Field Trip Review and Logistics

October 5 or 6 - 11

Field Trip

October 15

No Class (Rest up from Field Trip and organize data)

October 22

Summary of Trip, Questions, Expectations for Presentation

October 29

Field Exercise

November 5

Field/Core/Outcrop Exercises: Modern and Ancient

November 12

Writing and Presentations

November 19

Presentation Prep (no formal class)

November 26

Summaries Due and Test

December 3

Presentations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Grading:

Grades will be based on several factors. There will be a general exam toward the end of the semester that will indicate to me how much you learned from the trip and exercises. It will only count 25% but it is the one way to insure that you did acquire “knowledge” and that you processed the information that we covered. The largest part of the course grade is the actual field trip itself (50%). Attendance, participation, doing the exercises, and summarizing the trip upon our return are very important. The other 25% will be determined but much of that will be your putting a presentation together on the field trip and other learnings to indicate that you both again received information and that you know how to assimilate and summarize your data.

 

Comprehensive Test:                  25%

Field Trip Component:                50%

Presentation/Exercises:             25%

 

Academic Honor Code:

It is UNC-W’s stated policy that ‘no form of academic dishonesty will be tolerated by its students or faculty’. I take this very seriously and it applies to plagiarism, copying, and all forms of cheating. Complete details of the code are in the current Student Handbook. UNCW practices a zero-tolerance policy for violence and harassment of any kind.  For emergencies contact UNCW CARE at 962-2273, Campus Police at 962-3184, or Wilmington Police at 911.  For University or community resources visit http://uncw.edu/wrc/crisis.htm.

Etiquette:

NO cell phones or players are acceptable (turn them off before class).This will be a conversational type of class and I encourage discussion but respect the opinions and questions of others.

Brief Description of the Field Area

 

The New Mexico/West Texas Permian outcrops are some of the best exposures in the world that allow for the easy tracing and visualization of sabkha to basin depositional environments. However, the real benefits of this area for study is that it includes large- (basin and sea level cyclicity) and small- (rock to pore structure to fossils) scale geologic data. The outcrops have large vertical and lateral exposures. The types of data that we will consider and that you will become intimately familiar with include:

 

·          Depositional environments

Sabkha – Beach – Intertidal to Subtidal (has stromatolites also) – Shelf and Ramp carbonate settings w/ shoaling upward cycles as well as backreef to reef to forereef – Change from slope to basin.There are carbonates (several modes of deposition as well as diagenesis) as well as siliciclastics.

·          Basin Studies

Evolution from ramp to shelf and reciprocal sedimentation w/ abundant sea level cyclicity. There are 3rd, 4th, and 5th order cycles that are obvious on the shelf as well as in the basin.

The shelf is dominated by carbonates (highstand) w/ thin sandstones and the basin is dominated by siliciclastics (lowstand) w/ thin carbonates.

The basin eventually dried leaving behind gypsum and ultimately halite and sylvite. The WIPP site is in the salts for storage of transuranic materials. I could probably get us a tour of this.

·          Stratigraphy

This section (Leonardian, Guadalupian, Ochoan) is now the type section for the world of these strata. Importantly this area is classic for sequence stratigraphic and biostratigraphic concepts because of the sea level fluctuations (by the way this is a result of the Permian glaciation)

·          Sedimentology/Sedimentary Petrology

Because of the variety of depositional environments, rock types, diagenesis, and basin evolution, there are several courses just in looking at the rocks. I have thin sections already on many of these

·          Structure

The Guadalupe Mountains have been uplifted ~1 mile and the current reef trend and basin are more or less the way they would have looked in the Permian (2000’ of relief between basin and reef). The uplift is associated with the easternmost limits of the Basin and Range Uplift and there are numerous faults (Salt Flat Graben), lineations, and joints to observe/study. The rocks are well exposed because of the faults.

·          Subsurface

Seismic lines and well logs of the subsurface that match stuff on the surface – good visualizations

·          Associated Studies

Caves, Paleontology (Subtidal, backreef, reef, and forereef facies), Maps, Mineralogy (some good collection sites), Igneous side trip (the syenite intrusions are now well-exposed), Natural history (relation of geology to plants, settlements, etc.), Hydrology (springs and falls), meteorology (wind and rain effects w/ mountains), WIPP site (environmental issues), wind energy, petroleum, sylvite from potash mining.

 

This area contains a world class series of sites that will be visited over ~5 days (depending on emphasis and travel). Academics and industry come from all over the world to study this area. Guide books, surface and subsurface data, and other materials for the area will be provided.