Indusium (geology)

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system series step ≈ age ( mya )
higher higher higher younger
Triad Upper Triassic Rhaetium 201.3
⬍
208.5
Norium 208.5
⬍
228
Carnium 228
⬍
235
Middle Triassic Ladinium 235
⬍
242
Anisium 242
⬍
247.2
Lower Triassic Olenekium 247.2
⬍
251.2
Indusium 251.2
⬍
251.9
deeper deeper deeper older

The Indusium (partly also Induum , Induium , Indus stage ) is the first or lowest chronostratigraphic stage of the Lower Triassic and thus the Triassic and the Mesozoic Era in the history of the earth . The stage begins geochronologically about 251.9 million years ago and ends about 251.2 million years ago and thus lasted about 1 million years. It replaces the Changhsingium , the highest level of the Permian ; the indusium is followed by the olenekium . Regionally it is subdivided into the lower griesbachium and dienerium levels. The Indusium used to be part of the Scythian level ( Skythium ) together with the Olenekian , which is no longer an officially recognized international level and is only used regionally (for example in the Alps).

Naming and history

The original type locality is in the Salt Range ( Punjab ), on the upper reaches of the Indus River , which mainly flows through Pakistan; the name is derived from this. The name was proposed by Kiparisova and Popov in 1956. However, the internationally recognized GSSP is located in Changxing County in Zhejiang Province in China .

Definition and GSSP

The beginning of the stage is defined with the first appearance of the conodont species Hindeodus parvus and the end of the negative carbon anomaly after the peak of the upper Permian mass extinction. The first appearance of the ammonite species Meekoceras gracilitatis marks the end of the stage.

Breakdown

Despite the presumably very short absolute duration of the stage, the indusium can be subdivided into five ammonite zones in the boreal region and four in the tethyan region .

Individual evidence

  1. ↑ 252.6 to 251 according to Brack et al. (2005)
  2. ↑ Inaccuracy at the beginning ± 0.5 million years

literature

  • Peter Brack, Hans Rieber, Alda Nicora and Roland Mundil: The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale. Episodes, 28 (4): 233-244, Beijing 2005 ISSN  0705-3797 PDF .
  • Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press 2005, ISBN 978-0-521-78673-7
  • Hans Murawski & Wilhelm Meyer: Geological dictionary . 10., rework. u. exp. Ed., 278, Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .
  • Yin Hongfu, Zhang Kexin, Tong Jinnan, Yang Zunyi and Wu Shunbao: The Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary. Episodes, 24 (2): 102-114, Beijing 2001 ISSN  0705-3797 .
  • Ljubová Dmitrievna Kiparisova & Jurij N. Popov: Subdivision of the lower section of the Triassic system into stages. Doklady Akademii Nauk SSSR, 109 (4): 842-845, Moscow 1956 (in Russian) ISSN  0002-3264

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