Spongy-looking microfabrics in the earliest named stromatolite represent deep burial alteration and incipient metamorphism
| Title | Spongy-looking microfabrics in the earliest named stromatolite represent deep burial alteration and incipient metamorphism |
| Publication Type | Journal Article |
| Year of Publication | 2024 |
| Authors | Neuweiler, F, Mueller, M, Walter, BF, Landing, E, Beranoaguirre, A, Sendino, C, Amati, L, Kershaw, S |
| Journal | Scientific Reports |
| Volume | 14 |
| Issue | 1 |
| Abstract | The earliest named stromatolite Cryptozoon Hall, 1884 (Late Cambrian, ca. 490 Ma, eastern New York State), was recently re-interpreted as an interlayered microbial mat and non-spiculate (keratosan) sponge deposit. This “classic stromatolite” is prominent in a fundamental debate concerning the significance or even existence of non-spiculate sponges in carbonate rocks from the Neoproterozoic (Tonian) onwards. Cryptozoon has three types of microbially-induced carbonate layers: clotted-pelletoidal micrite with microbial filaments, clotted-pelletoidal micrite with vesicular structure, and dense microcrystalline laminae. A fourth, stratiform to patchy fabric comprises suspect sponges. Using contextual fabric analysis, elemental mapping, cathodoluminescence, fluid inclusions, electron backscatter diffraction, U–Pb dating, and burial history, the sponge interpretation is denied. Neither a distinct sponge body outline nor a canal system is identifiable. Instead, the suspect fabric is secondary in origin, and best explained as a product of Carboniferous (Mississippian) deep burial alteration associated with basement reactivation. Key petrographic observations include heterogenous recrystallization via aggrading Ostwald ripening with interfingering reaction fronts typical for partially miscible fluids, a granoblastic calcite texture (incipient metamorphism), and subsequent hypidioblastic white mica (arguably Carboniferous/Permian, Alleghenian orogeny). Topotype Cryptozoon is a stromatolite altered to sub-greenschist metacarbonate. The published Tonian to Phanerozoic record of interpreted non-spiculate |
| URL | https://www.nature.com/articles/s41598-024-83359-7 |
| DOI | 10.1038/s41598-024-83359-7 |
| Short Title | Sci Rep |
