Chapter 5 Regional analysis of spiculite faunas in the permian phosphoria basin: Implications for paleoceanography

Middle Permian radiolarians from Anmenkou, Chaohu, Northeastern Yangtze platform, China

“… The radiolarian chert of the Gufeng Formation was deposited in an outer shelf environment under sulphate‐reducing conditions. Three Wordian–Capitanian radiolarian assemblages are present in the SRM of Gufeng Formation: Pseudoalbaillella longtanensis – Pseudoalbaillella fusiformis , Follicucullus monacanthus , and Follicucullus scholasticus – Ruzhencevispongus uralicus . Sponge spicules from the Gufeng Formation are comparable to those of the Central Belt of the western USA (Murchey 2004), indicating deposition in a basin of moderate depth (150–1000 m). Radiolarian faunas of the SRM suggest deposition in a basin of depth shallower than 500 m. However, other factors also appear to affect the occurrence of radiolarian fauna, and the depositional environment thus remains debatable. Radiolarians from the SRM are representative of the relatively shallow, tropical radiolarian fauna of the Middle Permian eastern Paleotethys. …”

“…Murchey & Jones (1994) reported quantitative analyses of the populations of Albaillellacea, Ruzhencevispongacea (Latentifistularia), and sponge spicules from the western USA. The proportion of Albaillellacea was later reported to increase from the Eastern to Western belts (Murchey 2004), also indicating that Albaillellacea are more abundant in deep basins. Kuwahara (1999) showed a quantitative analysis of Permian radiolarian faunas from pelagic, hemipelagic, and neritic environments of Japan and China, and suggested that the proportion of stauraxon radiolarians (Latentifistularia) is broadly indicative as an index of the paleoenvironment.…”

“…The fauna of sponge spicule from the Gufeng Formation consists of abundant monaxons and triaxons with rare tetraxons. The triaxons and anadiaene originate from hexactinellids, whereas tetraxons originate from demosponges (Rigby 1987; Murchey 2004). Thus, the sponge fauna of the Gufeng Formation mainly consists of hexactinellids with minor demosponges.…”

“…According to those results, sponges and radiolarian fauna are well‐correlated with water depth; from the shallow Eastern Belt to the deep Western Belt, the sponge/(sponge + radiolarian) ratio decreases and sponge spicules originating from demosponges decrease. The sponge fauna of the Eastern Belt includes abundant rhax derived from demosponges, and includes very sparse or no radiolarians, whereas the sponge fauna of the Central Belt consists of hexactinellids and demosponges, and the sponge/(sponge + radiolarian) ratio varies (Murchey 2004). From the results of Murchey (2004), the sponge fauna of the Gufeng Formation appears most similar to that of the Central Belt, which Murchey 2004 inferred to reside in a bathymetric range of 150–1000 m, below the Eastern Belt (<150 m).…”

“…The sponge fauna of the Eastern Belt includes abundant rhax derived from demosponges, and includes very sparse or no radiolarians, whereas the sponge fauna of the Central Belt consists of hexactinellids and demosponges, and the sponge/(sponge + radiolarian) ratio varies (Murchey 2004). From the results of Murchey (2004), the sponge fauna of the Gufeng Formation appears most similar to that of the Central Belt, which Murchey 2004 inferred to reside in a bathymetric range of 150–1000 m, below the Eastern Belt (<150 m). Therefore, based on sponge fauna, the depth of the Gufeng Basin is considered to also be in this range (150–1000 m), which is consistent with the outer shelf interpretation in Kametaka et al.…”