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End Triassic Extinction: Bibliography

Posted on: December 7, 2018

 

 

 

 

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  1. Millions of years ago (MYA), in the Triassic and Jurassic geological periods, reptiles and dinosaurs ruled the world. The Triassic Period started with the mass extinction that ended the Permian Period 250 MYA and ended with the mass extinction 200 MYA that marks the boundary between the Triassic and Jurassic periods. The mass extinction that ended the Triassic and that marks the beginning of the Jurassic is called the “End Triassic Extinction” or ETE for short. It is one of the most extreme and horrific mass extinctions in the paleo record.
  2. This post is a literature review of paleoclimate evidence and expert interpretations of the data to surmise what happened in that horrific mass extinction that changed the Triassic age of reptiles and small dinosaurs into the Jurassic, the age of the dominance of giant dinosaurs.
  3. The paleo data show that about 200MYA the geochemical evidence indicate a sequential eruption of the Central Atlantic Magmatic Province (CAMP) with a contemporaneous disappearance of a large number of land and oceanic life forms.
  4. This summary of the End Triassic Extinction event is provided by Hames (2003):  “A singular event in Earth’s history occurred roughly 200 million years ago, as rifting of the largest and most recent supercontinent was joined by basaltic volcanism that formed the most extensive large igneous province (LIP) known. A profound and widespread mass extinction of terrestrial and marine genera occurred at about the same time, suggesting a causal link between the biological transitions of the Triassic-Jurassic boundary and massive volcanism. A series of stratigraphic, geochronologic, petrologic, tectonic, and geophysical studies have led to the identification of the dispersed remnants of this Central Atlantic Magmatic Province (CAMP) on the rifted margins of four continents. Current discoveries are generally interpreted to indicate that CAMP magmatism occurred in a relative and absolute interval of geologic time that was brief, and point to mechanisms of origin and global environmental effects. Because many of these discoveries have occurred within the past several years, in this monograph we summarize new observations and provide an up-to-date review of the province.
  5. A bibliography of research in this field is presented below.

 

 

BIBLIOGRAPHY

JESSICA WHITESIDE, JEAN GUEX, ANDREA MARZOLI, BLAIR SCHOENE

 

  1. 1992: Hodych, J. P., and G. R. Dunning. “Did the Manicouagan impact trigger end-of-Triassic mass extinction?.” Geology 20.1 (1992): 51-54.  We use U-Pb zircon dating to test whether the bolide impact that created the Manicouagan crater of Quebec also triggered mass extinction at the Triassic/Jurassic boundary. The age of the impact is provided by zircons from the impact melt rock on the crater floor; we show that the zircons yield a U-Pb age of 214 ±1 Ma. The age of the Triassic/Jurassic boundary is provided by zircons from the North Mountain Basalt of the Newark Supergroup of Nova Scotia; the zircons yield a U-Pb age of 202 ±1 Ma. This should be the age of the end-of-Triassic mass extinction that paleontology and sedimentation rates suggest occurred less than 1 m.y. before extrusion of the North Mountain Basalt. Although the Manicouagan impact could thus not have triggered the mass extinction at the Triassic/Jurassic boundary (impact likely having preceded extinction by 12 ±2 m.y.), the impact may possibly have triggered an earlier mass extinction at the Carnian/Norian boundary in the Late Triassic.  [FULL TEXT]
  2. 1999: Marzoli, Andrea, et al. “Extensive 200-million-year-old continental flood basalts of the Central Atlantic Magmatic Province.” Science 284.5414 (1999): 616-618. The Central Atlantic Magmatic Province (CAMP) is defined by tholeiitic basalts that crop out in once-contiguous parts of North America, Europe, Africa, and South America and is associated with the breakup of Pangea. 40Ar/39Ar and paleomagnetic data indicate that CAMP magmatism extended over an area of 2.5 million square kilometers in north and central Brazil, and the total aerial extent of the magmatism exceeded 7 million square kilometers in a few million years, with peak activity at 200 million years ago. The magmatism coincided closely in time with a major mass extinction at the Triassic-Jurassic boundary[FULL TEXT]
  3. 2000: Pálfy, József, et al. “Timing the end-Triassic mass extinction: First on land, then in the sea?.” Geology 28.1 (2000): 39-42. The end-Triassic marks one of the five biggest mass extinctions, but current geologic time scales are inadequate for understanding its dynamics. A tuff layer in marine sedimentary rocks encompassing the Triassic-Jurassic transition yielded a U-Pb zircon age of 199.6 ± 0.3 Ma. The dated level is immediately below a prominent change in radiolarian faunas and the last occurrence of conodonts. Additional recently obtained U-Pb ages integrated with ammonoid biochronology confirm that the Triassic Period ended ca. 200 Ma, several million years later than suggested by previous time scales. Published dating of continental sections suggests that the extinction peak of terrestrial plants and vertebrates occurred before 200.6 Ma. The end-Triassic biotic crisis on land therefore appears to have preceded that in the sea by at least several hundred thousand years[FULL TEXT]
  4. 2002: Hesselbo, Stephen P., et al. “Terrestrial and marine extinction at the Triassic-Jurassic boundary synchronized with major carbon-cycle perturbation: A link to initiation of massive volcanism?.” Geology 30.3 (2002): 251-254. Mass extinction at the Triassic-Jurassic (Tr-J) boundary occurred about the same time (200 Ma) as one of the largest volcanic eruptive events known, that which characterized the Central Atlantic magmatic province. Organic carbon isotope data from the UK and Greenland demonstrate that changes in flora and fauna from terrestrial and marine environments occurred synchronously with a light carbon isotope excursion, and that this happened earlier than the Tr-J boundary marked by ammonites in the UK. The results also point toward synchronicity between extinctions and eruption of the first Central Atlantic magmatic province lavas, suggesting a causal link between loss of taxa and the very earliest eruptive phases. The initial isotopic excursion potentially provides a widely correlatable marker for the base of the Jurassic. A temporary return to heavier values followed, but relatively light carbon dominated the shallow oceanic and atmospheric reservoirs for at least 600 k.y.
  5. 2002: Hallam, Anthony. “How catastrophic was the end‐Triassic mass extinction?.” Lethaia 35.2 (2002): 147-157. A review of marine and terrestrial animal and plant fossils fails to reveal convincing evidence of a global catastrophe at the Triassic‐Jurassic boundary, although this time marked the final disappearance of ceratite ammonites and conodonts, together with the extinction of most calcareous demosponges; important groups of bivalves and brachiopods went extinct. Because of facies problems, however, there is no stratigraphic section that reveals a clear‐cut disappearance over a short distance. Other marine animal groups except perhaps the radiolarians fail to reveal a notable extinction of global extent immediately across the boundary. On the other hand, there was a substantially higher extinction rate among marine animals in the Rhaetian as compared with the previous stage. On the land, the record is equivocal. Dramatic changes across the T‐J boundary have been claimed for plants in particular areas, such as eastern North America and East Greenland, but only gradual change has been recognized elsewhere. Similarly, claims of a T‐J boundary vertebrate mass extinction have not been supported by others. For the Rhaetian as a whole, however, the turnover rate of reptiles was high. Although much remains to be learned, it seems evident that the fossil record of the latest Triassic is more consistent with a gradual scenario extended over time than a ‘geologically instantaneous’ impact catastrophe.
  6. Hames, Willis, et al. “The Central Atlantic magmatic province: Insights from fragments of Pangea.” Washington DC American Geophysical Union Geophysical Monograph Series 136 (2003).  A singular event in Earth’s history occurred roughly 200 million years ago, as rifting of the largest and most recent supercontinent was joined by basaltic volcanism that formed the most extensive large igneous province (LIP) known. A profound and widespread mass extinction of terrestrial and marine genera occurred at about the same time, suggesting a causal link between the biological transitions of the Triassic-Jurassic boundary and massive volcanism. A series of stratigraphic, geochronologic, petrologic, tectonic, and geophysical studies have led to the identification of the dispersed remnants of this Central Atlantic Magmatic Province (CAMP) on the rifted margins of four continents. Current discoveries are generally interpreted to indicate that CAMP magmatism occurred in a relative and absolute interval of geologic time that was brief, and point to mechanisms of origin and global environmental effects. Because many of these discoveries have occurred within the past several years, in this monograph we summarize new observations and provide an up-to-date review of the province
  7. 2004: Guex, Jean, et al. “High-resolution ammonite and carbon isotope stratigraphy across the Triassic–Jurassic boundary at New York Canyon (Nevada).” Earth and Planetary Science Letters 225.1-2 (2004): 29-41.The Triassic–Jurassic boundary is generally considered as one of the major extinctions in the history of Phanerozoic. The high-resolution ammonite correlations and carbon isotope marine record in the New York Canyon area allow to distinguish two negative carbon excursions across this boundary with different paleoenvironmental meanings. The Late Rhaetian negative excursion is related to the extinction and regressive phase. The Early Hettangian  δ13Corg negative excursion is associated with a major floristic turnover and major ammonite and radiolarian radiation. The end-Triassic extinction–Early Jurassic recovery is fully compatible with a volcanism-triggered crisis, probably related to the Central Atlantic Magmatic Province. The main environmental stress might have been generated by repeated release of SO2 gas, heavy metals emissions, darkening, and subsequent cooling. This phase was followed by a major long-term CO2accumulation during the Early Hettangian with development of nutrient-rich marine waters favouring the recovery of productivity and deposition of black shales
  8. 2004: Marzoli, Andrea, et al. “Synchrony of the Central Atlantic magmatic province and the Triassic-Jurassic boundary climatic and biotic crisis.” Geology 32.11 (2004): 973-976. The evolution of life on Earth is marked by catastrophic extinction events, one of which occurred ca. 200 Ma at the transition from the Triassic Period to the Jurassic Period (Tr-J boundary), apparently contemporaneous with the eruption of the world’s largest known continental igneous province, the Central Atlantic magmatic province. The temporal relationship of the Tr-J boundary and the province’s volcanism is clarified by new multidisciplinary (stratigraphic, palynologic, geochronologic, paleomagnetic, geochemical) data that demonstrate that development of the Central Atlantic magmatic province straddled the Tr-J boundary and thus may have had a causal relationship with the climatic crisis and biotic turnover demarcating the boundary.
  9. 2004: Hautmann, Michael. “Effect of end-Triassic CO 2 maximum on carbonate sedimentation and marine mass extinction.” Facies50.2 (2004): 257-261. Correlation of stratigraphic sections from different continents suggests a worldwide interruption of carbonate sedimentation at the Triassic–Jurassic boundary, which coincided with one of the most catastrophic mass extinctions in the Phanerozoic. Both events are linked by a vulcanogenic maximum of carbon dioxide, which led to a temporary undersaturation of sea water with respect to aragonite and calcite and a corresponding suppression of carbonate sedimentation including non-preservation of calcareous skeletons. Besides the frequently cited climatic effect of enhanced carbon dioxide, lowering the saturation state of sea water with respect to calcium carbonate was an additional driving force of the end-Triassic mass extinction, which chiefly affected organisms with thick aragonitic or high-magnesium calcitic skeletons. Replacement of aragonite by calcite, as found in the shells of epifaunal bivalves, was an evolutionary response to this condition.
  10. 2004: Knight, K. B., et al. “The Central Atlantic Magmatic Province at the Triassic–Jurassic boundary: paleomagnetic and 40 Ar/39 Ar evidence from Morocco for brief, episodic volcanism.” Earth and Planetary Science Letters 228.1 (2004): 143-160. The Central Atlantic Magmatic Province (CAMP), one of the largest known flood basalt provinces formed in the Phanerozoic, is associated with the pre-rift stage of the Atlantic Ocean at the Triassic–Jurassic boundary ca. 200 Ma. Paleomagnetic sampling targeted packages of CAMP lava flows in Morocco’s High Atlas divided into four basic units (the lower, intermediate, upper, and recurrent units) from sections identified on the basis of field observations and geochemistry. Oriented cores were demagnetized using both alternating field (AF) and thermal techniques. Paleomagnetic results reveal wholly normal polarity interrupted by at least one brief reversed chron located in the intermediate unit, and reveal distinct pulses of volcanic activity identified by discrete changes in declination and inclination. These variations in magnetic direction are interpreted as a record of secular variation, and they may provide an additional correlative tool for identification of spatially separated CAMP lava flows within Morocco. 40Ar/39Ar analyses of Moroccan CAMP lavas yield plateau ages indistinguishable within 2σ error limits, sharing a weighted mean age of 199.9±0.5 Ma (2σ), reinforcing the short-lived nature of these eruptions despite the presence of sedimentary horizons between them. Correlation of our sections with the E23n, E23r, E24 sequence reported in the Newark basin terrestrial section and St. Audrie’s Bay marine section is suggested. Brief volcanism in sudden pulses is a potential mechanism for volcanic-induced climatic changes and biotic disruption at the Triassic–Jurassic boundary. Combination of our directional group (DG) poles yields an African paleomagnetic pole at 200 Ma of λ(°N)=73.0°, ϕ(°E)=241.3° (Dp=5.0°, Dm=18.5°).
  11. 2007: Nomade, S., et al. “Chronology of the Central Atlantic Magmatic Province: implications for the Central Atlantic rifting processes and the Triassic–Jurassic biotic crisis.” Palaeogeography, Palaeoclimatology, Palaeoecology 244.1-4 (2007): 326-344. The Central Atlantic Magmatic Province (CAMP) is among the largest igneous provinces on Earth, emplaced synchronously with or just prior to the Triassic–Jurassic (T–J) boundary ca. 200 Ma. In great part due to the controversial connection between the occurrence of CAMP and the events of the T–J boundary, the demand for better constraints on the duration and eruptive chronology of this province has increased. More than 100 new 40Ar/39Ar ages have been published in the last 15 years, with more than half of these in the last 3 years. A careful review and selection of available ages, as well as the publication of 16 new ages from the Carolinas, Newark Basin (USA), French Guyana and Morocco are presented. Judicious selection yields a total of 58 accepted age determinations for CAMP magmatism, ranging from 202 to 190 Ma covering every part of the CAMP. A more complete picture develops with intrusive CAMP magmatism commencing as early as 202 Ma. Extrusive activity initiated abruptly ∼ 200 Ma, reaching peak volume and intensity around 199 Ma on the African margin. The main period of CAMP magmatism is confirmed as brief, but is suggested to consist of at least two phases over ∼ 1.5 Ma, with magmatism commencing along the Africa–North American margins and slightly later along the South American margin. Two volumetrically minor, but distinctive magmatic peaks centered at 195 and 192 Ma are mirrored in data from all three continents and highlighted by our statistical approach. Models describing rifting and thermal input and magma production on these timescales are explored. Despite significant advances in our understanding of the chronology of CAMP, more data of better quality and broader geographical coverage are needed to completely characterize the evolution of the CAMP and infer its geodynamic origin. In addition, lack of a well-defined T–J boundary age, as well as the absence of a relevant basis for comparison between U/Pb and 40Ar/39Ar data for this time period remain limiting factors to unambiguously linking CAMP in time with the events of the T–J boundary.
  12. 2008: Schaltegger, Urs, et al. “Precise U–Pb age constraints for end-Triassic mass extinction, its correlation to volcanism and Hettangian post-extinction recovery.” Earth and Planetary Science Letters 267.1-2 (2008): 266-275. New precise zircon U–Pb ages are proposed for the Triassic–Jurassic (Rhetian–Hettangian) and the Hettangian–Sinemurian boundaries. The ages were obtained by ID-TIMS dating of single chemical-abraded zircons from volcanic ash layers within the Pucara Group, Aramachay Formation in the Utcubamba valley, northern Peru. Ash layers situated between last and first occurrences of boundary-defining ammonites yielded 206Pb/238U ages of 201.58 ± 0.17/0.28 Ma (95% c.l., uncertainties without/with decay constant errors, respectively) for the Triassic–Jurassic and of 199.53 ± 0.19 / 0.29 Ma for the Hettangian–Sinemurian boundaries. The former is established on a tuff located 1 m above the last local occurrence of the topmost Triassic genus Choristoceras, and 5 m below the Hettangian genus Psiloceras. The latter sample was obtained from a tuff collected within the Badouxia canadensis beds. Our new ages document total duration of the Hettagian of no more than c. 2 m.y., which has fundamental implications for the interpretation and significance of the ammonite recovery after the topmost Triassic extinction.The U–Pb age is about 0.8 ± 0.5% older than 40Ar–39Ar dates determined on flood basalts of the Central Atlantic Magmatic Province (CAMP). Given the widely accepted hypothesis that inaccuracies in the 40K decay constants or physical constants create a similar bias between the two dating methods, our new U–Pb zircon age determination for the T/J boundary corroborates the hypothesis that the CAMP was emplaced at the same time and may be responsible for a major climatic turnover and mass extinction. The zircon 206Pb/238U age for the T/J boundary is marginally older than the North Mountain Basalt (Newark Supergroup, Nova Scotia, Canada), which has been dated at 201.27 ± 0.06 Ma [Schoene et al., 2006. Geochim. Cosmochim. Acta 70, 426–445]. It will be important to look for older eruptions of the CAMP and date them precisely by U–Pb techniques while addressing all sources of systematic uncertainty to further test the hypothesis of volcanic induced climate change leading to extinction. Such high-precision, high-accuracy data will be instrumental for constraining the contemporaneity of geological events at a 100 kyr level.
  13. 2009: Cirilli, S., et al. “Latest Triassic onset of the Central Atlantic magmatic province (CAMP) volcanism in the Fundy basin (Nova Scotia): new stratigraphic constraints.” Earth and Planetary Science Letters 286.3-4 (2009): 514-525. In this paper we investigate the stratigraphic relationship between the emplacement of the CAMP basalts and the Triassic–Jurassic (Tr–J) boundary in the Fundy Basin (Nova Scotia, Canada). This is one of the best exposed of the synrift basins of eastern North America (ENA) formed as a consequence of the rifting that led to the formation of the Atlantic Ocean. The Triassic palynological assemblages found in the sedimentary rocks below (uppermost Blomidon Formation) and just above the North Mountain Basalt (Scots Bay Member of the McCoy Brook Formation) indicate that CAMP volcanism, at least in Nova Scotia, is entirely of Triassic age, occurred in a very short time span, and may have triggered the T–J boundary biotic and environmental crisis. The palynological assemblage from the Blomidon Formation is characterised by the dominance of the Circumpolles group (e.g. Gliscopollis meyeriana, Corollina murphyae, Classopollis torosus) which crosses the previously established Tr–J boundary. The Triassic species Patinasporites densus disappears several centimetres below the base of the North Mountain basalt, near the previously interpreted Tr–J boundary. The lower strata of the Scots Bay Member yielded a palynological assemblage dominated by Triassic bisaccate pollens (e.g Lunatisporites acutus, L. rhaeticus Lueckisporites sp., Alisporites parvus) with minor specimens of the Circumpolles group. Examination of the state of preservation and thermal alteration of organic matter associated with the microfloral assemblages precludes the possibility of recycling of the Triassic sporomorphs from the older strata. Our data argue against the previous definition of the Tr–J boundary in the ENA basins, which was based mainly on the last occurrence of P. densus. Consequently, it follows that the late Triassic magnetostratigraphic correlations should be revised considering that chron E23r, which is correlated with the last occurrence of P. densus in the Newark basin, does not occur at the Tr–J boundary but marks rather a late Triassic (probably Rhaetian) reversal.
  14. 2010: Schoene, Blair, et al. “Correlating the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level.” Geology 38.5 (2010): 387-390.  New high-precision U/Pb geochronology from volcanic ashes shows that the Triassic-Jurassic boundary and end-Triassic biological crisis from two independent marine stratigraphic sections correlate with the onset of terrestrial flood volcanism in the Central Atlantic Magmatic Province to <150 ka. This narrows the correlation between volcanism and mass extinction by an order of magnitude for any such catastrophe in Earth history. We also show that a concomitant drop and rise in sea level and negative δ13C spike in the very latest Triassic occurred locally in <290 ka. Such rapid sea-level fluctuations on a global scale require that global cooling and glaciation were closely associated with the end-Triassic extinction and potentially driven by Central Atlantic Magmatic Province volcanism.  [FULL TEXT]
  15. 2010: Whiteside, Jessica H., et al. “Compound-specific carbon isotopes from Earth’s largest flood basalt eruptions directly linked to the end-Triassic mass extinction.” Proceedings of the National Academy of Sciences 107.15 (2010): 6721-6725. A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO2. The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie’s Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO2 super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date.
  16. 2010: Deenen, Martijn HL, et al. “A new chronology for the end-Triassic mass extinction.” Earth and Planetary Science Letters291.1-4 (2010): 113-125. The transition from the Triassic to Jurassic Period, initiating the ‘Age of the dinosaurs’, approximately 200 Ma, is marked by a profound mass extinction with more than 50% genus loss in both marine and continental realms. This event closely coincides with a period of extensive volcanism in the Central Atlantic Magmatic Province (CAMP) associated with the initial break-up of Pangaea but a causal relationship is still debated. The Triassic–Jurassic (T–J) boundary is recently proposed in the marine record at the first occurrence datum of Jurassic ammonites, post-dating the extinction interval that concurs with two distinct perturbations in the carbon isotope record. The continental record shows a major palynological turnover together with a prominent change in tetrapod taxa, but a direct link to the marine events is still equivocal. Here we develop an accurate chronostratigraphic framework for the T–J boundary interval and establish detailed trans-Atlantic and marine–continental correlations by integrating astrochronology, paleomagnetism, basalt geochemistry and geobiology. We show that the oldest CAMP basalts are diachronous by 20 kyr across the Atlantic Ocean, and that these two volcanic pulses coincide with the end-Triassic extinction interval in the marine realm. Our results support the hypotheses of Phanerozoic mass extinctions resulting from emplacement of Large Igneous Provinces (LIPs) and provide crucial time constraints for numerical modelling of Triassic–Jurassic climate change and global carbon-cycle perturbations.  [FULL TEXT]
  17. 2011: Schaller, Morgan F., James D. Wright, and Dennis V. Kent. “Atmospheric pCO2 perturbations associated with the Central Atlantic magmatic province.” Science 331.6023 (2011): 1404-1409. The effects of a large igneous province on the concentration of atmospheric carbon dioxide (PCO2) are mostly unknown. In this study, we estimate PCO2 from stable isotopic values of pedogenic carbonates interbedded with volcanics of the Central Atlantic Magmatic Province (CAMP) in the Newark Basin, eastern North America. We find pre-CAMP PCO2 values of ~2000 parts per million (ppm), increasing to ~4400 ppm immediately after the first volcanic unit, followed by a steady decrease toward pre-eruptive levels over the subsequent 300 thousand years, a pattern that is repeated after the second and third flow units. We interpret each PCO2 increase as a direct response to magmatic activity (primary outgassing or contact metamorphism). The systematic decreases in PCO2 after each magmatic episode probably reflect consumption of atmospheric CO2 by weathering of silicates, stimulated by fresh CAMP volcanics.
  18. 2011: Ruhl, Micha, et al. “Atmospheric carbon injection linked to end-Triassic mass extinction.” Science 333.6041 (2011): 430-434. The end-Triassic mass extinction (~201.4 million years ago), marked by terrestrial ecosystem turnover and up to ~50% loss in marine biodiversity, has been attributed to intensified volcanic activity during the break-up of Pangaea. Here, we present compound-specific carbon-isotope data of long-chain n-alkanes derived from waxes of land plants, showing a ~8.5 per mil negative excursion, coincident with the extinction interval. These data indicate strong carbon-13 depletion of the end-Triassic atmosphere, within only 10,000 to 20,000 years. The magnitude and rate of this carbon-cycle disruption can be explained by the injection of at least ~12 × 103 gigatons of isotopically depleted carbon as methane into the atmosphere. Concurrent vegetation changes reflect strong warming and an enhanced hydrological cycle. Hence, end-Triassic events are robustly linked to methane-derived massive carbon release and associated climate change[FULL TEXT]
  19. 2013: Blackburn, Terrence J., et al. “Zircon U-Pb geochronology links the end-Triassic extinction with the Central Atlantic Magmatic Province.” Science 340.6135 (2013): 941-945. Correlating a specific triggering event, such as an asteroid impact or massive volcanism, to mass extinction events is clouded by the difficulty in precisely timing their occurrence in the geologic record. Based on rock samples collected in North America and Morocco, Blackburn et al. (p. 941, published online 21 March) acquired accurate ages for events surrounding the mass extinction that occurred ∼201 million years ago, between the Triassic and Jurassic Periods. The timing of the disappearance of marine and land fossils and geochemical evidence of the sequential eruption of the Central Atlantic Magmatic Province imply a strong causal relationship[FULL TEXT]

 

 

 

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