The Jiangshanian is the middle
stage of the
Furongian series. It follows the
Paibian Stage and is succeeded by the still unnamed
Stage 10 of the
Cambrian
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...
. The base is defined as the
first appearance of the
trilobite ''
Agnostotes orientalis''
which is estimated to be million years ago. The Jiangshanian lasted until approximately million years ago.
The Jiangshanian stage was named after
Jiangshan, a city in China's
Zhejiang
)
, translit_lang1_type2 =
, translit_lang1_info2 = ( Hangzhounese) ( Ningbonese) (Wenzhounese)
, image_skyline = 玉甑峰全貌 - panoramio.jpg
, image_caption = View of the Yandang Mountains
, image_map = Zhejiang i ...
province, where its GSSP was defined.
Stratigraphy
The
Global boundary Stratotype Section and Point (GSSP) of the Jiangshanian is the "Duibian B Section" (), west of the village of
Duibian (碓边), and 10 km north of
Jiangshan. The outcrop belongs to the
Huayansi Formation (华严寺组).
The upper boundary (the base of the
Stage 10) is not formally defined by
ICS, but there is a proposal to set the first appearance of an agnostoid ''
Lotagnostus americanus'' as its marker.
In 2012, international research group proposed the Kyrshabakty section in the Malyi Karatau Range, southern
Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
, as a candidate for the Auxiliary boundary Stratotype Section and Point (ASSP) of the Jiangshanian. The proposal was approved by an overwhelming majority of votes by the International Subcommission on Cambrian
Stratigraphy (ISCS). The section is situated near Kyrshabakty River, about 28 km north-east of the
Zhanatas town. The
first appearance datum (FAD) of ''Agnostotes orientalis'' is located at an altitude of 259 m above the base of the section, in the
Zhumabay Formation, also known as Bestogai Formation.
In 2021, the
International Union of Geological Sciences
The International Union of Geological Sciences (IUGS) is an international non-governmental organization devoted to global cooperation in the field of geology. As of 2023, it represents more than 1 million geoscientists around the world.
About
Fo ...
(IUGS) proposed to deny the use of specific points and replace them by Standard Auxiliary Boundary Stratotypes (SABS) for more "flexible" correlations with GSSPs.
Major events
At the beginning of the Jiangshanian, there was a peak in species diversity, comparable to that observed in the middle
Guzhangian, before the Guzhangian–
Paibian extinction. Jiangshanian extinction, which lasted approximately from 493.9 to 491.3 Ma, reduced species diversity by 55.2%. It was followed by an interval of relatively small fluctuations in species richness, which ended shortly after the beginning of the
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...
.
Paleontology
Nearly 50
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
genera were found in the Jiangshanian deposits of the
Sandu Formation in
Guangxi
Guangxi,; officially the Guangxi Zhuang Autonomous Region, is an Autonomous regions of China, autonomous region of the China, People's Republic of China, located in South China and bordering Vietnam (Hà Giang Province, Hà Giang, Cao Bằn ...
, South China. Organisms presented by the
algae
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
,
graptolites, the
cnidarian
Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...
''
Sphenothallus'', one species of
Palaeoscolecida, and
arthropod
Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s, which include
aglaspidid,
mollisoniid, and "bivalved" forms.
Rare
hurdiids were discovered in the Jiangshanian strata in Sandu Formation and
Wiśniówka Sandstone Formation in Poland.
Tasmania
Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...
.Wichita Mountains
The Wichita Mountains are located in the southwestern portion of the U.S. state of Oklahoma. It is the principal relief system in the Southern Oklahoma Aulacogen, being the result of a failed continental rift. The mountains are a northwest-south ...
, Oklahoma
Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...
, USA.
References
External links
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Cambrian geochronology
Geological ages
{{cambrian-stub