Permian Changes Research Articles

Evolution of Insect Diversity in the Permian and Triassic

The global warming that occurred during the Permo-Triassic transition, following the end of the Late Paleozoic glaciation, and the resulting responses of the biota to the changing environment, are considered important analogs for understanding rapid future warming scenarios. While there has been extensive research on the patterns and extent of diversity in plants, tetrapods, and marine invertebrates during the Permo-Triassic, the study of insect diversity and the evolution of their faunal composition has been relatively limited. The question of whether there were insect extinctions during this period continues to be a subject of debate. Here, we present a statistical study on taxonomic diversity of insects—at specific, generic and familial levels—throughout the Permian and Triassic, with subsampled context on the reported global occurrences. Our result show that more than one insect extinction events, accompanied by significant diversity drop and turnovers of faunal compositional, occurred in the Permian and Triassic. All the uncovered insect diversity crises exhibit strong correspondence with the well-known marine mass extinction events in the Middle Permian, Permo-Triassic transition, Carnian, and Rhaetian, whilst the marine correspondence with the Early Permian insect crisis is less pronounced. Insects, being a major component of terrestrial ecosystems, demonstrate varied diversity responses to climatic changes in Permian and Triassic. Our study sheds new light on the intricate interplay between insect diversity evolution and the changing environmental conditions during these critical geohistorical periods.

Tracing the sedimentary response to the rifting and opening of the Meso‐Tethys Ocean

ABSTRACTKnowledge of the rifting and opening process of the Meso‐Tethys Ocean is important for understanding the evolution of the Tethys tectonic domain and for an in‐depth understanding of Tethys dynamics. Sedimentary rocks are faithful recorders of surface expressions of tectonic events and are thus expected to have recorded the rifting and opening of the Meso‐Tethys Ocean. This study presents petrography, sedimentology, zircon U–Pb geochronological data and Hf isotope data for the Carboniferous–Permian Shiquanhe stratigraphic succession in the Lhasa Terrane of the Tibetan Plateau. The data indicate that the 300 to 273 Ma Lagar and Angjie formations in the lower section of the Carboniferous–Permian Shiquanhe succession were deposited in the stable passive margin of northern Gondwana with sediment sources in Gondwanaland. However, the 273 to 252 Ma Xiala Formation in the upper section of the Carboniferous–Permian Shiquanhe succession was deposited in a tectonically active setting characterized by intense magmatic activity. Considering the transition from the Lagar and Angjie formations to the Xiala Formation, a significant change in depositional setting from tectonically stable to tectonically active occurred at ca 273 Ma. Similar Early–Middle Permian changes in depositional setting have also been identified in the South Qiangtang, Baoshan and Oman regions in the Tethyan tectonic domain. These widespread changes in depositional setting, together with Early–Middle Permian tectonic uplift and episodes of subsidence, as well as rift‐related magmatism in the South Qiangtang, Baoshan, Himalayan, Zagros, Oman and Turkey regions once located in northern Gondwana, constitute a complete record of continental rifting–ocean opening associated with the diachronous opening of the Meso‐Tethys Ocean during the Early–Middle Permian.

Late permian changes in conditions of the atmosphere and environments caused by halogenated gases

There are periods in the Earth’s history when environmental conditions and the climate sharply changed. Some of such changes were accompanied by mass extinction of living organisms and a decrease in the species diversity. At present, there exist numerous hypotheses and conflicting scenarios of terrestrial and extraterrestrial events which led to such consequences. In particular, the most striking such episode belonging to the Late Permian is related to eruption of volcanoes in Siberia, the impact of a large asteroid, and climatic fluctuations caused by a decrease in the ozone concentration in the atmosphere (see for instance, [1]). By the ratio of isotopes in sedimentary rocks, there was revealed a degradation of vegetation in that period, which was accompanied by an appreciable decrease in productivity of photosynthesis [2]. The photosynthesis reduction resulted in a decrease in O 2 and an increase in CO 2 concentrations in the atmosphere and oceans. Volcanic emission of CO 2 in Siberia in the Late Permian also contributed to a general increase in the CO 2 concentration on the Earth. The change in the radiation budget, the warmed-up climate of the Earth, and aridization of some regions on the planet could cause mass extinction of living organisms [1]. The mass extinction of living organisms on the Earth at the boundary between the Permian and Triassic is known to have lasted over a million years (within the interval of 252.3 ± 0.3‐251.4 ± 0.3 Ma ago), i.e., in a very short period of time in terms of geology. Died out during this period were 90% of sea species, 60% of reptile and amphibian families, 30% of insect varieties, and most terrestrial plants [3]. The gradual and continuous changes in the species diversity of living organisms indicate that the mass extinction was caused by a gradual effect rather than a geologically instantaneous event spanning over several years or centuries. This suggests that such global changes began due to terrestrial causes, and later other, probably, extraterrestrial factors came into play. This work discusses a new possible cause of changes in the state of the Earth’s system and mass extinction of living organisms at the boundary between the Permian and Triassic, which was related to an increased emission of volatile phytotoxicological halogenated hydrocarbons (HHCs) from hypersalt lakes and seas. The possibility for HHC to form actively in water and bottom sediments of such water bodies was revealed in recent years in the course of studying aridization processes during climatic warming [4, 5].

Early Permian bioevent in the fusulinacean fauna of South China

Analysis of a large database of the stratigraphic distribution of fusulinacean Foraminifera reveals an Early Permian event of significant decline of species diversity in South China. Data from Late Carboniferous to Early Permian sections without apparent unconformity in southwest China were evaluated to determine if the apparent pattern of species disappearance was caused by bias in fossil preservation associated with Early Permian sea-level changes. Statistical analysis suggests that the Early Permian event started in the Late Sakmarian with a significant drop of species diversity in the Robustoschwagerina ziyunensis Zone and continued through the Pamirina darvasica Zone of the Artinskian and into the Brevaxina dyhrenfurthi Zone of the Early Kungarian, resulted in a total loss of about 40% species diversity in the fusulinacean fauna. The Early Permian event is the most extensive bioevent in the history of fusulinacean Foraminifera at the species level although it is less significant at the generic level. Because a similar faunal change has been found among the fusulinacean assemblages in North America and in various regions of Tethys, this event may represent a major faunal turn-over in response to the Early Permian changes in sea level and could be of a global nature. Previous recognition of this event was hampered by Early Permian unconformities in North America and other regions of Tethys.

Geochemistry of Early Triassic seawater as indicated by study of the Röt halite in the Netherlands, Germany, and Poland

Study of three halite sections in the Röt Basin from the eastern Netherlands (Twente-Rijn 382 borehole), central Germany (Mardorf 6 borehole) and western Poland (Ośno IG2 borehole) shows that the δ 34S values in Röt sulphates of studied samples (27.14–31.98‰) are characteristic of marine sulphates of late Early Triassic. These values fit in the Röt event shift described in the literature. The bromine content in halite is 32–158 ppm. In the Dutch and Polish sections, relics of sedimentary structures—chevron and hopper—are recorded in halite grains. These structures contain fluid inclusions that were analysed using the ultramicrochemical method of Petrichenko (Petrichenko, O.I. 1973. Metody doslidzhennya vkluchen' v mineralakh galogennykh porid. Kiev, Naukova Dumka, 92 pp.). In the German section, no sedimentary halite structures occur. Because the pressure in the inclusions in recrystallized halite is only slightly greater than atmospheric pressure, these inclusions are presumed to be early diagenetic in origin. The analysis of individual brine inclusions, both in sedimentary and diagenetic forms of halite, shows that the Röt brines correspond to the Na-K-Mg-Cl-SO 4 (SO 4-rich) chemical type, i.e. the same type that characterises modern seawater. However, the Röt brines differ from the composition characteristic of modern concentrated seawater by a decrease in the content of sulphate ion and an increase in the content of potassium ion. On a Jänecke diagram, the points of the brine composition during deposition of Röt halite in Poland, Germany and the Netherlands only show a small range. This suggests a stable composition of basinal brines during the deposition of the halite. At the same time, the relative content of sulphate ion in the Lower Triassic Röt Basin was slightly lower than that in Upper Permian evaporite basins, but higher than that in Lower and Middle Permian and Middle and Upper Triassic evaporite basins. The implication is that the content of sulphate ion in seawater was subject to changes in Permian and Triassic times.