2010 Alum

Luis Montalvo

Luis Montalvo

Years participated in RESESS:


Diagenetic history of the Ellenburger Group in the Fort Worth Basin, Texas »

An Overview

Diagenetic history of the Ellenburger Group in the Fort Worth Basin, Texas

Academic Affiliation: University of Puerto Rico, at Mayagüez, Geology
Science Mentor: Dr. R. Doug Elmore, University of Oklahoma
Writing and Community Mentors: Rika Burr and Earl Manning, University of Oklahoma


Luis G. Montalvo Lliteras is a native of Puerto Rico and grew up in the southwest corner of the island in a town called Cabo Rojo. He has a love for the outdoors, especially hiking, camping, and snorkeling. Luis collects old records, movies, minerals, and old photographs. He has a strong appreciation for music and plays the bass guitar. He creates music beats and complete tracks using various music software programs. His academic interests are in carbonate sedimentology, carbonate diagenesis, and the effects of sea level changes throughout geologic time.


The Ellenburger group on the subsurface of the Fort Worth Basin, Texas, has undergone several episodes of diagenesis during karstification and burial, which resulted in various phases of dolomitization. Identifying the evolution pattern of the diagenetic processes is required for upcoming studies regarding hydrocarbon exploration and natural gas productivity in the Fort Worth Basin. Core samples used in this study were divided into five different lithologies: dolostone, dolostone breccia, dolomitic mudstone, dolomitic ooid grainstone, and dolomitic wackestone-packstone. Five types of dolomites were also identified using petrography (polarizing microscopy, reflected light microscopy and cathodoluminesence). Dolomite type 1 is characterized by the very fine crystalline dolomite and the preservation of primary sedimentary structures. It was interpreted as forming shortly after deposition of lime mud. After deposition, karstification developed vugs, cavities, and collapse breccias. Freshwater resulted in extensive calcification followed by silicification. Shallow burial of the Ellenburger developed fractures, dissolution seams, and stylolites that were later filled or replaced by dolomite types 2 and 3. Dolomite type 2 is found associated with dissolution seams. Dolomite type 3 is found in fractures and stylolites within the calcites. Type 4 dolomite replaces earlier dolomites and is usually found in dolostones. Type 4 was interpreted as a deep burial dolomite. Dolomite type 5 is a cementing dolomite found in veins and vugs. It is characterized by saddle dolomite that formed at slightly elevated temperatures. A paragenetic sequence (figure 1) that summarizes the events recorded in the core samples was constructed based on the petrographic observations. The resulting paragenesis is consistent with what has been reported from the Permian Basin.