Research Interests

Stratigraphic architecture of the Tuscan Formation

The very same sheets of volcanic fragmented rocks, called the Tuscan Formation, which are exposed in Upper Bidwell Park dive under the town of Chico and serve as the city’s main groundwater supply. Despite the paucity of data on how the aquifer works and its recharge mechanism, overly optimistic forecasts believe the upper and lower portions of the Tuscan Formation will continue to supply water resources to the region with excess water to send elsewhere. Recent promises have been made to sell large volumes water to southern California from the lower portion of the Tuscan Formation which has even fewer data available (relative to the upper portion) regarding its storage and flow capacity. tuscan flows

I am beginning a study that focuses on the outcrop stratigraphy and sedimentology of the Tuscan Formation. constrain the geometry of the basal Tuscan surface and document the sedimentary fill of Tuscan deposits. The results will provide a geologic framework for the Tuscan in outcrop and provide others with tools to correlate between outcrops and into the subsurface. If the Tuscan can be better understood in the subsurface, then more realistic groundwater models will better constrain the flowpaths and storage volumes of Butte County’s water supply.

Projects with undergraduate students (M. Smith, T. Geddes, A.E. Carlton, A. Wohletz) have provided a good start to try to address the main problems associated with Tuscan stratigraphy. Thus far, the Department of Water Resources has supplied approximately 20 well-logs from the Chico area along with lithologic information for those wells. An undergraudate student has digitizing the logs for future correlation work. I have also worked with Carlton and Wohletz on micron-scale analyses of Tuscan matrix material on the microprobe lab at UC Davis.

My goal is to create a geologic framework for the Tuscan Formation in outcrop which can then be transferred to the subsurface. Basic field mapping, microscopy, and chemical analyses will characterize: 1) the paleo-topography prior to deposition of the Tuscan, 2) the range of depositional facies and flow types that deposited Tuscan rocks, and 3) vertical trends in composition of mud, sand, and conglomerate recognizable when drilling in the subsurface.

Beyond DWR publications, surprisingly little on Tuscan stratigraphy has been published since 1968. In the past five years, a handful of Chico State Masters theses and posters presented at geology conferences have served as excellent references, but they have not been published in peer-reviewed journals and they have not been assimilated into a unified framework. Fundamental questions still linger about what types of flows deposited Tuscan rocks (rivers vs. volcanic flows vs. mudflows) and the topographic expression before Tuscan sediments were deposited. To address these, I will systematically look at sedimentary textures both in outcrop and microscopic scales documenting percentages of rock types, mineral species, and elemental abundances through time. well sorted top of flow

The underlying objective is to provide a more realistic geologic model for groundwater flow simulators to use so reasonable assessments on water volumes and flowpaths can help dictate regional water policy for the foreseeable future. If more is understood about the Tuscan aquifer system, then the decision to pump large volumes of water out of the lower Tuscan to southern California may be curtailed to a point where local economies can prepare.

Eel River Basin

There are many opportunities for faculty and students at Chico St. to work on projects that will directly benefit operators in the onshore Eel River basin. Two Masters students and three faculty members are involved in projects. price creek outcrop

The onshore Eel River basin in northwestern California contains over 3,000 feet of mud-rich bathyal deposits within the Pliocene lower Rio Dell Formation. The lower Rio Dell Formation contains discrete deep-water sand packages up to 150 feet thick (20-40% net sand) that correlate from outcrops (Eel River and Price Creek) to wells in the Grizzly Bluff Field approximately 5 miles away. Detailed sedimentologic descriptions of correlative units in lower Rio Dell Formation core (distal position) and outcrop (proximal position) reveal many packages of “linked debrites” demonstrating decreasing turbulent energy in the distal direction. These observations can be useful in predicting reservoir quality in linked-debrites as well as serve as an excellent analog for the Late Jurassic North Sea deep-water fan deposits.

Seismic studies

The Tectonics and Sedimentation Lab houses a seismic workstation ready and loaded with a 3-D seismic dataset from the western Gulf of Mexico (courtesy of Anadarko Petroleum Corporation). I am currently working with a graduate student to test whether a relationship exists between seismic facies of deep-water Mass Transport Complexes (MTCs) and pre-MTC emplacement conditions. Specifically, we propose to correlate seismic facies distribution to the following testable initial conditions: 1) proximity to source, 2) degree of bathymetric confinement, 3) slope, and 4) roughness of the seafloor. If research objectives are met, the results could be used to better predict facies in areas that contain MTCs as seals, traps, or possible reservoirs. Additionally, our study could stimulate research of analogous datasets by providing a novel approach that establishes a genetic linkage between the MTC deposit and its boundary conditions.

seismic-MTC

Slice through one of the MTCs in the 3-D seismic dataset showing typical MTC seismic patterns (highlighted in red, yellow, and green) and their confining boundaries in map view. The MTC has traveled from left to right).

MTCs are an important component to deep-water depositional systems, yet little is known about their internal structure at the field scale (1-100 km2). Recently, industry’s willingness to part with shallow portions of high-resolution 3-D seismic datasets has given researchers valuable insight into deep-water processes, and to fill the data gap between outcrop studies and lower resolution seismic data.

Tyee Fm.

The Tyee Formation is a very large deep-water system exposed along the southwestern portion of Oregon. Although mostly covered by "oceans" of douglar-fir trees, the best exposures show excellent examples of a sand-rich turbiditic system from proximal channels (see adjacent photo) to extremely extensive mid-fan sheet sands. It's an excellent laboratory to study sedimentary structures and deep-water facies. Recent interest by oil comapanies to use the Tyee Formation as an outcrop analog has spurned multiple visits, field trips, and possible student projects.

tyee outcrop