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The trace fossil Rhizocorallium is abundant in the shallow‐marine settings of the Upper Devonian Wangguangou Formation in Xichuan, Henan Province, northern margin of the South China block. Based on its morphological characteristics, the studied Rhizocorallium is attributed to Rhizocorallium commune var. auriforme. There is a significant compositional difference between the fillings of the marginal tube and the spreite. The fillings in the marginal tube are similar to the surrounding rock, with abundant bioclasts. The fillings in the spreite are relatively fine‐grained and obviously affected by biological activities. Four types of pyrite framboids (pyritohedral, octahedron, cube and spherical) have been found within the Rhizocorallium. Moreover, the ratio of pyrite framboids diameter (D) to submicron crystal diameter (d) is <10, suggesting that they were formed by microbial activities. Relatively large pyrite framboids with smooth surface mainly occur in the marginal tube, while small pyrite framboids with sheath are abundant in the spreite. Energy spectrometer (EDS) analysis showed that the S/Fe ratio in the pyrite increased with decreasing crystal diameter, indicating different redox conditions in the marginal tube and the spreite. These features indicate that Rhizocorallium from the Xichuan section is not simply a foraging trace, but is probably a multi‐functional, complex burrow system utilized for living, caching and farming microorganisms. [ABSTRACT FROM AUTHOR]

The carbonate rocks of the Ordovician Majiagou Formation from the northwestern part of Henan Province and their diverse trace fossils provide an outcrop analogue for bioturbated, low porosity and low permeability carbonate reservoirs. Three ichnofabrics can be defined based on the ichnotaxonomy, ichnodiversities, individual abundances and overall bioturbation indices. The Balanoglossites ichnofabric represented medium to relatively high-energy sedimentary environments such as intertidal zone and subtidal shoals in the carbonate platform. The Planolites ichnofabric suggested relatively low-energy, protected sedimentary environments such as lagoons in a restricted carbonate platform, but also occurs in the deeper-water depressions in the open carbonate platform. The Chondrites ichnofabric characterized low-energy and reduced oxygen conditions, with burrows penetrating below a shallow redox interface in deeper-water settings that include the distal slope as well as local depressions in the open carbonate platform. Our analysis suggests that the modifications of petrophysical parameters are controlled or influenced by the ichnofabric characteristics (burrow architecture, burrow cross-cutting relationship, degree of bioturbation and burrow connectivity), the permeability contrast between burrow-fills and matrix, and the dolomitization of burrow-fills. The micritic host sediments have negligible porosity and permeability. The bioturbated sediments have significant differences in fabric, texture, porosity and permeability. The burrow-fills are very commonly dolomitised. Each of the burrow-types can enhance reservoir properties, but the greatest differences are associated with the Balanoglossites ichnofabric, in which porosity and permeability can reach over 2% and 70 mD. Preliminary stratigraphic studies indicate that reservoir potential in the subsurface will be linked to an understanding of the distribution of shoal and intertidal facies as well as their associated Balanoglossites ichnofabrics. [ABSTRACT FROM AUTHOR]