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Strain induced molecular heterogeneity in ancient sedimentary organic matter mapped at nanoscales using optical photothermal infrared spectroscopy

Metadata Updated: July 6, 2024

Here we report ultra-high resolution infrared mapping of organic matter functional group distribution in Tasmanites (algal microfossils) from the Upper Devonian Ohio Shale using optical photothermal infrared spectroscopy (O-PTIR). O-PTIR is capable of rapidly measuring the vibrational response of samples in situ with ~500-nm spatial resolution, well below the infrared diffraction limit. Our results indicate that organic matter within the fold apices regions (zones of greatest deformation) of relatively large Tasmanites is more aliphatic and less oxygen-rich than organic matter in the surrounding Tasmanites body. This contrasts with data from relatively thinner Tasmanites which show statistically invariant chemical differences between the fold apices and body regions. These findings indicate that deformation strain due to mechanical stress during burial can alter the molecular structure of sedimentary organic matter to different degrees across nanometer to micron length scales leading to chemical heterogeneity. However, chemical differences induced to organic matter by this mechanism appear be minor compared to those from thermal alteration. Finally, the data presented here represent the first application of O-PTIR to study sedimentary organic matter highlighting the great promise this analytical approach has for future studies evaluating the molecular composition of geologic materials.

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Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Created Date June 1, 2023
Metadata Updated Date July 6, 2024

Metadata Source

Harvested from DOI EDI

Additional Metadata

Resource Type Dataset
Metadata Created Date June 1, 2023
Metadata Updated Date July 6, 2024
Publisher U.S. Geological Survey
Identifier USGS:635aa238d34ebe44250471a8
Data Last Modified 20230130
Category geospatial
Public Access Level public
Bureau Code 010:12
Metadata Context
Metadata Catalog ID
Schema Version
Catalog Describedby
Harvest Object Id 6726517e-2d94-4655-b212-3c960dd83b27
Harvest Source Id 52bfcc16-6e15-478f-809a-b1bc76f1aeda
Harvest Source Title DOI EDI
Metadata Type geospatial
Old Spatial -82.50288,40.39778
Publisher Hierarchy White House > U.S. Department of the Interior > U.S. Geological Survey
Source Datajson Identifier True
Source Hash e64ee8c9ec72ccfa49f4805fb915b67b1fb89438789d5e47492839f69f8a5d55
Source Schema Version 1.1

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