--------------------------------------------------

 

Department of Geosciences

Texas Tech University

Lubbock, TX 79409-3131

 

--------------------------------------------------

 

Office: Science 318

 

Email:dustin.sweet@ttu.edu

 

--------------------------------------------------

 

 

 

 

 

 

 

 

 

Research

 

 

 

 

Research Project Areas

 

Ancestral Rocky Mountains: Tectonic and Climatic Evolution

An overarching theme of the majority of my research involves the Ancestral Rocky Mountains (ARM), specifically, attempting to refine tectonic and climatic understanding. The core of ARM resides in Colorado, New Mexico, Utah and Oklahoma; a region largely overprinted by younger tectonic events. As a result, studies of the ARM attempt to peer through younger events predominantly using sedimentary basin fill. Data sets I predominantly utilize are field-based, such as measured sections and structural mapping, however I strive to integrate laboratory based data, including geochemical, SEM analysis of grain textures, and grain-size distributions.

The classic portrayal of ARM tectonic evolution is the mountains uplifted and then slowly eroded away after uplift ceased. However, recent work by myself and others have shown that hints of multiple episodes of uplift exist indicated by syn-tectonic unconformities. Moreover, that basin fill in numerous spots appears to show a late phase of post-tectonic fill. Accordingly, many of my current students are working on projects aimed to test these new thoughts.

The ARM was located in equatorial western Pangea and although many climatic studies have argued over whether it was wet or dry, most agreed it was ever warm, largely based on the low-latitude position. Recently, however, a growing body of work collected largely by colleagues and myself has suggested the uplands of the ARM were episodically glaciated. Yet, many more unknowns exist, such as: What was the elevation of the ice? How often might they have been glaciated? What are the effects in the marine realm? I am interested in projects aimed at addressing these questions.

 

SEM Analysis of Quartz Grains: Transport Histories Revealed

Detrital grains are conveyed through a suite of transport processes en route to final deposition. Stress conditions imposed during transport, however, can vary widely, and impart environmentally distinctive textures in some cases. For example, ice transport exacts much higher and sustained stresses on grains than fluvial saltation. These suites of process-specific microtextures have been well studied and defined from modern and Quaternary systems, but less so in the ancient record. Future projects in this larger theme include calibration from studying modern systems and application to older sediments as a proxy. Specifically, can you determine glacially transported quartz grains during fluvially overprinting? If so, how far or long in a fluvial system will those textures exist?

 

Quaternary Climate Records of the Southern High Plains

A new area of research for me is deciphering climate change on the Southern High Plains (SHP). The SHP is broad topographic plateau and largely been a site of aggradation for the past 1.6 Ma. Thus, the region is akin to a continental version of an atoll. Current projects utilize cores recovered from the Quaternary cover the SHP to geochemically and sedimentologically characterize buried soil profiles. Future projects are aimed at recovering deeper cores to assess buried soil types and associated chemical weathering signatures which when coupled with high-resolution age dating techniques, such as cosmogenic nuclides, optical stimulation luminescence, tephrochronology and magnetic polarity studies, a detailed climate reconstruction of the SHP is possible.

Digitally Archiving Permian Basin Biostratgraphic Data

In the Fall of 2011, a collection of biostratigraphic well reports from west Texas and New Mexico was donated to the Department of Geosciences. Since then, I have been curator of that donation and have undertaken a project to digitally capture the biostratigraphic information from the numerous wells in the collection. The wells were drilled from as early as the 1920's up to the early 1970's. This project began in the fall of 2014 and will likely take numerous years to finish. Once completed, it is my hope that a sortable, online database with GIS interface will allow quick assembly of isopach and structural maps of a wide variety of time intervals within the greater Permian basin region.