Microfacies Analysis of Paleolake Clarkia Sediments at P-37
Faculty Mentor
Lindsay MacKenzie
Presentation Type
Poster
Start Date
4-14-2026 11:30 AM
End Date
4-14-2026 1:30 PM
Location
PUB NCR
Primary Discipline of Presentation
Geosciences
Abstract
Paleolake Clarkia’s fossil beds, near Clarkia Idaho, is a Fossil-Lagerstätten preservation a large quantity of plant and bug fossils. Many of the plant fossils consist of leaves with original carbon and cellular detail, and insects with original color. The fossil beds represent a lacustrine sequence of siliciclastic clay and silts, interbedded with fine sands and ash and were deposited in a primary anoxic environment. This paleolake formed around 15.4-16 Ma as the Columbia River Basalts dammed the ancestral Saint Maries River. There are 5 localities containing the fossil beds, including P-33, P-34, P-37, P-38, and P-40, located in different embayments. This study aims to analyze the microfacies within the lacustrine sediments at site P-37. Overall stratigraphic measurements and samples were collected in fall 2022 as part of a larger sedimentological study by MacKenzie. The samples were prepped for analysis by first cutting with a hacksaw, then vacuum-impregnated in resin, and finally sanded to a polished surface to reveal small scale (sub-mm details). We will begin initial microfacies analysis using previously-identified microfacies ((1) primary background deposition, (2) proximal turbidites, (3) distal turbidites, (4) ash, and (5) clays). Microfacies will be identified using light and scanning election microscopy, and chemistry and mineralogy will be determined using energy-dispersive X-ray spectroscopy and X-ray diffraction. These data will inform variability of grain size, chemical composition and distribution within and between facies. This will elucidate the different mechanisms depositing the sediments in the lake basin, reflecting possible seasonal and environmental changes as well as clarifying conditions responsible for the high-fidelity plant fossils.
Recommended Citation
Meier-Grolman, Cadence, "Microfacies Analysis of Paleolake Clarkia Sediments at P-37" (2026). 2026 Symposium. 10.
https://dc.ewu.edu/srcw_2026/ps_2026/p2_2026/10
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Microfacies Analysis of Paleolake Clarkia Sediments at P-37
PUB NCR
Paleolake Clarkia’s fossil beds, near Clarkia Idaho, is a Fossil-Lagerstätten preservation a large quantity of plant and bug fossils. Many of the plant fossils consist of leaves with original carbon and cellular detail, and insects with original color. The fossil beds represent a lacustrine sequence of siliciclastic clay and silts, interbedded with fine sands and ash and were deposited in a primary anoxic environment. This paleolake formed around 15.4-16 Ma as the Columbia River Basalts dammed the ancestral Saint Maries River. There are 5 localities containing the fossil beds, including P-33, P-34, P-37, P-38, and P-40, located in different embayments. This study aims to analyze the microfacies within the lacustrine sediments at site P-37. Overall stratigraphic measurements and samples were collected in fall 2022 as part of a larger sedimentological study by MacKenzie. The samples were prepped for analysis by first cutting with a hacksaw, then vacuum-impregnated in resin, and finally sanded to a polished surface to reveal small scale (sub-mm details). We will begin initial microfacies analysis using previously-identified microfacies ((1) primary background deposition, (2) proximal turbidites, (3) distal turbidites, (4) ash, and (5) clays). Microfacies will be identified using light and scanning election microscopy, and chemistry and mineralogy will be determined using energy-dispersive X-ray spectroscopy and X-ray diffraction. These data will inform variability of grain size, chemical composition and distribution within and between facies. This will elucidate the different mechanisms depositing the sediments in the lake basin, reflecting possible seasonal and environmental changes as well as clarifying conditions responsible for the high-fidelity plant fossils.
