Leaf metallome preserved over 50 million years

Area of Science:

• Paleobotany
• Geochemistry
• Biogeochemistry

Background:

• Spatially resolved chemical data for fossil plants is limited.
• Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) has previously identified preserved elements in fossil animals.
• Understanding the preservation of chemical inventories in fossil plants is crucial for paleobotanical studies.

Purpose of the Study:

• To investigate the chemical composition and preservation of fossil leaf material using advanced synchrotron techniques.
• To determine if original organometallic and organosulfur compounds are preserved in fossil leaves.
• To compare the chemical signatures of fossil leaves with extant plant material.

Main Methods:

• Application of large-scale Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) elemental mapping.
• Utilizing X-ray absorption spectroscopy on fossil leaf material from the Green River Formation.
• Analysis of multiple fossil leaf specimens to ensure consistent findings.

Main Results:

• SRS-XRF data revealed discrete chemical inventories of organometallic and organosulfur compounds within fossil leaves.
• These chemical distributions mapped fine biological structures and were distinct from the surrounding sedimentary matrix.
• Chemical patterns in fossil leaves were directly comparable to those observed in extant leaves.

Conclusions:

• Original bioaccumulated elements and organometallic/organosulfur compounds are preserved in situ in fossil leaves for at least 50 million years.
• The chemical inventory of fossil leaves is largely derived from the living organism.
• This study pioneers the study of the metallome of extinct flora, providing unprecedented chemical insights.