Changhsingian

Changhsingian
Ziegler175 · CC BY-SA 3.0 · source
Name	Changhsingian
Color	#FFD700
Time start mya	254.14
Time end mya	251.902
Unit	Age
Period	Lopingian
Epoch	Permian
Lithology	"limestone, shale, chert, siltstone"
Namedfor	Changxing County
Namedby	Chi Chen

Changhsingian The Changhsingian is the uppermost age of the Lopingian Epoch of the Permian Period, representing the final stage of the Paleozoic Era directly preceding the Triassic Period and the Mesozoic Era. It is globally recognized in the International Commission on Stratigraphy timescale and is characterized by distinct biostratigraphic markers, extinction horizons, and lithostratigraphic units that are crucial to correlations between major basins such as the Southern Alps, Tethys Ocean, North China Block, and Karoo Basin. The stage is named after Changxing County in Zhejiang Province and was defined using sections that tie to work by stratigraphers associated with institutions like the Geological Society of America, the Chinese Academy of Sciences, and the International Union of Geological Sciences.

Definition and Stratigraphy

The formal definition of the stage relies on biostratigraphic first and last occurrences of index taxa including species of Conodonts, Ammonoids, and fusulinacean foraminifera found in reference sections such as the Meishan section in Zhejiang and comparable sequences in the Ural Mountains, West Siberian Basin, and Lhasa Terrane. Primary stratotypes integrate magnetostratigraphic data from research groups at University of California, Berkeley, Peking University, and the Natural History Museum, London with chemostratigraphic signatures (stable carbon isotopes, oxygen isotopes) correlated to excursions recognized by teams from University of Oxford and ETH Zurich. Lithostratigraphic units diagnostic of the age include carbonate platforms, pelagic chert successions, and siliciclastic wedges documented in the Moscow Basin, Zagros Mountains, and Andes by geologists affiliated with the Geological Survey of Canada and the United States Geological Survey.

Chronology and Duration

Radiometric constraints using high-precision ^206Pb/^238U zircon dates from volcanic ash beds, obtained by laboratories at Carnegie Institution for Science and Australian National University, place the start of the age near 254.14 million years ago and its end around 251.902 million years ago, bracketing an interval refined by correlation with the GSSP at Meishan, Zhejiang, ratified by panels convened by the International Commission on Stratigraphy and the International Union of Geological Sciences. Time calibration incorporates cyclostratigraphy from cores drilled by consortia including the International Ocean Discovery Program and magnetostratigraphic polarity chrons tied to datasets from Lamont–Doherty Earth Observatory and Swiss Federal Institute of Technology Lausanne.

Paleoenvironments and Climate

Paleoenvironmental reconstructions integrate sedimentology and isotope stratigraphy from shallow-marine shelves of the Tethys Ocean, deeper basins like the Panthalassa margin, and continental basins such as the Karoo Basin and Shaanxi Basin, with climate models produced by teams at NASA Goddard Institute for Space Studies, Max Planck Institute for Meteorology, and University of Leeds indicating elevated greenhouse conditions, episodes of oceanic anoxia, and high-latitude glacio-eustatic signals interpreted by researchers at University of Edinburgh and Columbia University. Proxy records from conodont oxygen isotopes, stomatal indices on plant fossils catalogued at the Smithsonian Institution, and carbonate carbon isotope excursions mapped by groups at California Institute of Technology reveal rapid perturbations in the global carbon cycle coincident with volcanism attributed to the Siberian Traps Large Igneous Province, whose emplacement is documented by petrologists from University of Toronto and Moscow State University.

Biotic Events and Extinctions

The Changhsingian interval culminates in the most severe Phanerozoic mass extinction, the end-Permian event, implicating catastrophic losses among marine clades such as Brachiopoda, Tabulate corals, Rugose corals, Eurypterida, Conodonts, Crinoidea, Trilobita survivors, and major turnovers among Ammonoidea and Bivalvia; terrestrial impacts include dramatic declines in Gondwana floral assemblages, synapsid faunas, and tetrapod diversity evident in fossil assemblages curated at institutions like the Field Museum and Australian Museum. Paleobiological analyses from the Paleobiology Database, macroecological syntheses by teams at University of Chicago and Yale University, and extinction modeling by researchers at Princeton University converge on mechanisms involving euxinia, hypercapnia, acidification, and habitat loss triggered by Siberian Traps volcanism and linked to methane release from clathrate reservoirs and thermogenic carbon from intruded organic-rich sediments, a scenario refined by geochemists at MIT and University of California, Los Angeles.

Regional and Global Correlations

Regional stratigraphic frameworks established in the North China Block, South China Block, Cathaysia, Laurentia, Baltica, and Gondwana are correlated through integrated biostratigraphy (conodonts, ammonoids, foraminifera), chemostratigraphy (δ13C, δ18O), and tephrochronology, with synthesis efforts led by working groups at International Ocean Discovery Program, Society for Sedimentary Geology, and International Association of Sedimentologists. Key correlations draw on sequences from the Meishan GSSP, Permian sections in the Siberian Platform, coal-bearing successions in the Karoo Basin, and carbonate ramps of the Morro da Fumaça Formation, enabling basin-to-basin comparison and global event stratigraphy used by paleoceanographers at Scripps Institution of Oceanography and stratigraphers at University of California, Santa Barbara.

Economic and Geological Significance

Changhsingian successions host source rocks, reservoir intervals, and mineral deposits that are economically important in basins explored by state and private entities including the China National Petroleum Corporation, PetroChina, ExxonMobil, and Shell plc; organic-rich shales and coal measures of late Permian age are exploited for hydrocarbons in the Ordos Basin and Sichuan Basin, while evaporite and carbonate sequences are relevant to mineral extraction and subsurface storage assessed by engineers at Bureau of Economic Geology and energy geoscientists at TotalEnergies. The stratigraphic record also guides modern risk assessments for carbon sequestration projects, informs hydrocarbon exploration workflows used by consulting firms affiliated with Society of Petroleum Engineers, and provides analogs for studying rapid climate perturbations investigated by climate scientists at Intergovernmental Panel on Climate Change and European Commission research initiatives.

Category:Permian