Yanjiahe Formation

Geologic formation in Hubei, China From Wikipedia, the free encyclopedia

The Yanjiahe Formation is an Ediacaran to Cambrian fossiliferous geologic formation found in South China.^[2]^[3]

Sub-unitsSee: Beds

OverliesDengying Formation

PrimaryShale, limestone, dolomite

Quick facts Type, Sub-units ...

Yanjiahe Formation
Stratigraphic range: Ediacaran - Fortunian ~542–529 Ma PreꞒ Ꞓ O S D C P T J K Pg N ^[1]
View of Yanjiahe River in Macheng, Huanggang, Hubei, the locality after which the formation is named.
Type	Formation
Sub-units	See: Beds
Overlies	Dengying Formation
Lithology
Primary	Shale, limestone, dolomite
Other	Chert, phosphorite
Location
Coordinates	30.8°N 111.3°E / 30.8; 111.3
Approximate paleocoordinates	27.6°N 160.2°E / 27.6; 160.2
Region	Hubei
Country	China
Extent	Yangtze Gorges
Type section
Named for	Yanjiahe River
Yanjiahe Formation (China) Show map of China Yanjiahe Formation (Hubei) Show map of Hubei

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Dating

The Yanjiahe Formation has been dated through various methods. The top of the formation is dated at 526.5±1.1 Ma and 526.4±5.3 Ma using radiometric dating on ash beds within the area. Likewise, the base of the formation has been dated to between 542±0 Ma to 526±0 Ma through carbon isotopic correlations.^[1]

Beds

The Yanjiahe Formation consists of five beds. Every bed within the formation contains fossil material.^[4]

The beds are as follows, in ascending stratigraphic order (lowest to highest):

Bed 1 is characterized by basal dolomitic conglomerates, with banded black cherts.^[4]
Bed 2 is mostly consists of siliceous phosphatic dolostone, with flat pebble conglomerates.^[4]
Bed 3 is characterized by various shales, with the presence of siliceous-phosphatic nodules.^[4]
Bed 4 is composed of carbonaceous limestones.^[4]
Bed 5 is characterized by cherts and siliceous phosphatic dolostone, with flat pebble conglomerates.^[4]

Paleobiota

The Yanjiahe Formation contains a wide range of unique organisms from the base of the Cambrian, from Yanjiahella to Beretella, alongside a lot of early molluscs, like Watsonella.^[3]

Color key

Taxon	Reclassified taxon	Taxon falsely reported as present	Dubious taxon or junior synonym	Ichnotaxon	Ootaxon	Morphotaxon

Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.

Cnidaria

More information Genus, Species ...

Genus	Species	Notes	Images
Octapyrgites^[5]	O. elongatus	Olivooid Medusozoan, larger than any known Olivooid.
Quadrapyrgites^[6]^[7]	O. quadratacris	Olivooid Medusozoan.
Olivooides^[6]^[7]	Olivooides sp. O. multisulcatus O. mirabilis	Olivooid Medusozoan.
Pseudooides^[6]^[7]	Pseudooides sp.	Medusozoan.
Septuconularia^[8]^[9]	S. yanjiaheensis S. crassiformis	Hexangulaconulariid Medusozoan.
Decimoconularia^[10]	D. isofacialis	Hexangulaconulariid Medusozoan.
Carinachites^[6]^[7]	C. spinatus	Cnidarian sclerite, related to the conulariids.
Cambrorhytium^[11]	C. major	Elongated cone-like cnidarian.

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Chancelloriida

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Genus	Species	Notes	Images
Chancelloria^[7]	Chancelloria sp.	Sponge-like eumetazoan.

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Deuterostome

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Genus	Species	Notes	Images
Protohertzina^[12]^[7]	P. unguliformis P. anabarica P. robusta	Possibly a Protoconodont, Paraconodont, or a Chaetognath.
Tarimspira^[6]	T. plana	Possible Paraconodont.
Yunnanodus^[12]^[1]	Yunnanodus sp. Y. yanjiahensis	Possible Paraconodont.
Yanjiahella^[13]	Y. biscarpa	Possibly earliest stem group echinoderm.
Yuknessia^[14]	Yuknessia sp.	Unbranched pterobranch.
Hertzina^[12]	H. guizhouensis H. tenuis	Furnishinid Paraconodont.

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Ecdysozoa

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Genus	Species	Notes	Images
Beretella^[15]	B. spinosa	Possibly adult or larval ecdysozoan.
Saccorhytus^[6]^[7]	Saccorhytus sp.	Possibly adult or larval ecdysozoan.

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Lophotrochozoa

More information Genus, Species ...

Genus	Species	Notes	Images
Conotheca^[14]^[12]	C. subcurvata C. obesa C. nana C. transulcata	Hyolith lophotrochozoan.
Hyolithellus^[12]	H. tenuis? H. decorus	Annelid lophotrochozoan, previously thought to be a Hyolith.
Lapworthella^[14]	Lapworthella sp.	Tommotid lophotrochozoan.
Spinulitheca^[12]	S. billingsi	Hyolith lophotrochozoan.
Microcornus^[12]	M. parvulus?	Hyolith lophotrochozoan.
Cupitheca^[12]	C. mira	Hyolith lophotrochozoan.
Turcutheca^[12]	T. crasseocochlia T. lubrica	Hyolith lophotrochozoan.
Lophotheca^[12]	L. costellata	Hyolith lophotrochozoan.
Circotheca^[12]^[1]	C. longiconica C. longiconica	Circothecid Hyolith.
Aldanella^[14]^[12]	A. attleborensis A. yanjiaheensis	Mollusc with a coiled shell.
Eohalobia^[16]^[6]^[1]	E. diadongensis Eohalobia sp.	Halkieriid mollusc.
Ocruranus^[6]^[16]^[7]^[1]	Ocruranus sp. O. trulliformis O. finial	Halkieriid mollusc.
Scenella^[12]	S. jijiapoensis	Scenellid mollusc.
Siphogonuchites^[12]	S. triangularis	Siphogonuchitid mollusc.
Xianfengella^[12]	X. ovata X. prima	Mollusc.
Tuberoconus^[6]^[1]	T. paucipapillae	Mollusc.
Watsonella^[17]	W. crosbyi	Mollusc.
Anabarella^[17]	A. plana	Helcionelloid mollusc.
Igorella^[12]^[17]	I. emeiensis I. maidipingensis Igorella sp.	Helcionelloid mollusc.
Oelandiella^[12]^[1]	O. korobkovi	Helcionelloid mollusc.
Ceratoconus^[6]^[1]	C. bucers	Helcionelloid mollusc.

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Porifera

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Genus	Species	Notes	Images
Blastulospongia^[18]	Blastulospongia sp.	Globular demosponge, previously postured to be a radiolarian.
Hexactinellid spicules^[4]	???	A collection of monaxons, diaxons and triaxons.

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incertae sedis

More information Genus, Species ...

Genus	Species	Notes	Images
Anabarites^[2]^[12]^[7]	A. trisulcatus A. tianzhushanensis A. gracilis A. ternarius	Anabaritid small shelly fossil.
Tiksitheca^[12]	T. korobovi	Anabaritid small shelly fossil.
Cambrotubulus^[6]^[7]	C. decurvatus	Anabaritid small shelly fossil.
Protoconites^[14]	P. minor	Curved conical organism, possible relations to Cnidaria.
Purella^[14]^[12]	P. antiqua P. lepidites	Small shelly fossil.
Emeiconus^[14]	E. antiqua	Small shelly fossil.
Rugatotheca^[7]	Rugatotheca sp.	Small shelly fossil.
Coleolella^[6]	C. recta	Small shelly fossil.
Vendotaenid^[14]	Vendotaenia sp.	Ribbon-like organism.
Torellella^[1]	T. lentiformis	Tubicolous fossil.

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Flora

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Genus	Species	Notes	Images
Archaeophycus^[2]^[19]^[7]	A. yunnanensis	Either a cyanobacteria or the early developmental stage of an alga.	(J)
Konglingiphyton^[14]	Konglingiphyton sp.	Macroalgae.
Megathrix^[2]^[20]^[19]	M. longus	Filamentous cyanobacterium.
Myxococcoides^[19]	Myxococcoides spp.	Cyanobacteria.
Archaeooides^[7]	A. granulates	Microalgae.

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Microorganisms

More information Genus, Species ...

Genus	Species	Notes	Images
Asteridium^[20]	A. tornatum	Acritarch.
Comasphaeridium^[2]^[20]	C. annulare	Acritarch.
Heliosphaeridium^[2]^[20]	H. ampliatum	Acritarch.
Micrhystridium^[14]	M. regulare	Acritarch.
Yurtusia^[19]	Y. uniformis	Acritarch.
Dictyotidium^[19]	Dictyotidium sp.?	Acritarch.

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Undescribed

More information Genus, Species ...

Genus	Species	Notes	Images
Unnamed probable cnidarian^[11]	???	Curved tubular organism, possible affinities to cnidarians.

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See also

Ediacaran biota

References

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Liu, Zhanhong; Algeo, Thomas J. (June 2025). "Appearance of SSFs in earliest Cambrian seas of South China linked to salinity conditions". Chemical Geology. 683 122761. doi:10.1016/j.chemgeo.2025.122761.
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Dong, Lin; Xiao, Shuhai; Shen, Bing; Zhou, Chuanming; Guoxiang, Li; Yao, Jinxian (2009), "Basal Cambrian Microfossils from the Yangtze Gorges Area (South China) and the Aksu Area (Tarim Block, Northwestern China)", Chemical Geology, 83 (1): 30–34, Bibcode:2009JPal...83...30D, doi:10.1666/07-147R.1, retrieved 2014-08-15
[3]
Yanjiahe Formation at Fossilworks.org
[4]
Chang, Shan; Feng, Qinglai; Clausen, Sébastien; Zhang, Lei (May 2017). "Sponge spicules from the lower Cambrian in the Yanjiahe Formation, South China: The earliest biomineralizing sponge record". Palaeogeography, Palaeoclimatology, Palaeoecology. 474: 36–44. Bibcode:2017PPP...474...36C. doi:10.1016/j.palaeo.2016.06.032.
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Guo, Junfeng; Han, Jian; Van Iten, Heyo; Song, Zuchen; Qiang, Yaqin; Wang, Wenzhe; Zhang, Zhifei; Li, Guoxiang; Sun, Yifei; Sun, Jie (May 2020). "A new tetraradial olivooid (Medusozoa) from the lower Cambrian (Stage 2) Yanjiahe Formation, South China". Journal of Paleontology. 94 (3): 457–466. Bibcode:2020JPal...94..457G. doi:10.1017/jpa.2019.101.
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Steiner, Michael; Yang, Ben; Hohl, Simon; Zhang, Lei; Chang, Shan (September 2020). "Cambrian small skeletal fossil and carbon isotope records of the southern Huangling Anticline, Hubei (China) and implications for chemostratigraphy of the Yangtze Platform". Palaeogeography, Palaeoclimatology, Palaeoecology. 554 109817. Bibcode:2020PPP...55409817S. doi:10.1016/j.palaeo.2020.109817.
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Guo, Junfeng; Han, Jian; Van Iten, Heyo; Song, Zuchen; Qiang, Yaqin; Wang, Wenzhe; Zhang, Zhifei; Li, Guoxiang (September 2021). "A ten-faced hexangulaconulariid from Cambrian Stage 2 of South China". Journal of Paleontology. 95 (5): 957–964. Bibcode:2021JPal...95..957G. doi:10.1017/jpa.2021.25.
[11]
Chang, Shan; Clausen, Sébastien; Zhang, Lei; Feng, Qinglai; Steiner, Michael; Bottjer, David J.; Zhang, Yan; Shi, Min (September 2018). "New probable cnidarian fossils from the lower Cambrian of the Three Gorges area, South China, and their ecological implications". Palaeogeography, Palaeoclimatology, Palaeoecology. 505: 150–166. Bibcode:2018PPP...505..150C. doi:10.1016/j.palaeo.2018.05.039.
[12]
Guo, Junfeng; Li, Yong; Li, Guoxiang (April 2014). "Small shelly fossils from the early Cambrian Yanjiahe Formation, Yichang, Hubei, China". Gondwana Research. 25 (3): 999–1007. Bibcode:2014GondR..25..999G. doi:10.1016/j.gr.2013.03.007.
[13]
Topper, Timothy P.; Guo, Junfeng; Clausen, Sébastien; Skovsted, Christian B.; Zhang, Zhifei (2019), "A stem group echinoderm from the basal Cambrian of China and the origins of Ambulacraria", Nature Communications, 10 (1): 1366, Bibcode:2019NatCo..10.1366T, doi:10.1038/s41467-019-09059-3, ISSN 2041-1723, PMC 6433856, PMID 30911013
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[18]
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[19]
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[20]
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