Petrographic Characterization and Maceral Controls on Porosity in Overmature Marine Shales: Examples from Ordovician-Silurian Shales in China and the U.S.

<div>Pyrobitumen and zooclast morphology and distribution under SEM and reflected light microscopy in Wufeng-Longmaxi shale. The pairs (a, b), (c, d), (e, f), and (g, h) show the same areas on four different samples. (a–f) Pyrobitumen occurred as speckles disseminated in the shale matrix. (a–d) Graptolite fragments characterized by biological morphologies with sharp outlines. (b, c) Graptolite with a spindle shape. (e, f) Chitinozoan fragment with a scalene shape. (g, h) Acritarch body and its central cavity closed with irregular ruptures.</div>

Geofluids

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Figure 6

Figure 6: Petrographic Characterization and Maceral Controls on Porosity in Overmature Marine Shales: Examples from Ordovician-Silurian Shales in China and the U.S. 

Figure 6 | Petrographic Characterization and Maceral Controls on Porosity in Overmature Marine Shales: Examples from Ordovician-Silurian Shales in China and the U.S. 