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

Figure 11

SEM images showing maceral types and related pores observed in Wufeng-Longmaxi shales. (a–h) Selected samples under SEM at depths of 2481 m, 2503 m, 2513 m, 2534 m, 2567 m, 2573 m, 2576 m, and 2577 m, respectively. The organic matter content increases with deeper depth (a–h) in the studied samples and can be reflected by the area of dark material (a–h). Pyrobitumen is the dominant maceral in samples, and its content shows an obvious increase in samples from 2567 m deep and deeper.

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