Fig. 3 Late Permian palaeogeography of the Guryul ravine (adapted from as it is, Brookfield et al. 2020)
The Guryul section has been investigated for the possible causes of the mass extinction as well as for the geochemical records for post-depositional alteration (Brookfield et al., 2013). The P–Tr boundary section at Guryul represents a catastrophic event in Earth’s history, in which more than 96% of marine and 70% terrestrial life went extinct (Haas et al. 2007). The Guryul Ravine section retains some of the original geochemical depositional signatures (Williams et al. 2012). Positive cerium anomaly recorded at the Guryul Ravine P–Tr boundary section by Algeo et al., 2007, the formation of pyrite frambroids (Wignall et al. 2004) points towards a wide-spread anoxia event occurring in the Tethys during the late Permian period (Williams et al. 2012). Shukla et al. 2002, also concluded that the ferruginous layer was deposited during anoxia event. Global ocean anoxia is also considered one of the widely accepted theories explaining the End Permian extinction. The other theories of mass extinction during P–Tr include Mercury anomaly (Sanei et al. 2011) and methanogenic bursts from microbes (Rothmana et al. 2014).
Evidence of sea-level rise during the late Permian is found in the lower sections of Guryul Ravine, and the up sections show a decrease in thickness and occurrence of storm beds, and a general reduction in grain size (Baud et al. 1996; Brookfield et al. 2003; Korte et al. 2010). Faunal and lithological change in several sections also suggests that marine transgression occurred (Shen et al. 2006). At Guryul Ravine, there is a depletion of diversity in the benthic community; the reduction in diversity consequences with the appearance of Hindeodusparvus, other nektonic ammonoids, and other Triassic taxa (Brookfield et al. 2003; Bhargava et al. 2020). Marine transgression coincides with, and probably caused the spread of anoxic bottom waters over well-oxygenated shallow shelves (Demaison and Moore 1980; Wignall et al. 2004; Williams et al. 2011). Marine transgression had a minor, if any, role in the End Permian extinction (Brookfield et al. 2003; Nabbefeld et al. 2010; Schoepfer et al. 2012). Many “transgression” researchers believe the End Permian extinction to be gradual (Twitchett et al. 2001; Ward et al. 2005). The transgressive period led to the spread of low O2 waters onto the shallow shelf, which further impacted the species abundance and diversity (Röhl et al. 2001; Harper et al. 2004).
Brookfield et al. (2013) proposed that the Guryul ravine section contains 7m thick seismite-tsunamite successions. The research interprets two, 2-m-thick sandstone to sandy limestone containing liquefaction features as seismites, while three lenticular, graded, hummocky cross-stratified bioclastic grainstones as tsunami deposits. The same research attributes frequent Tsunamis at that time to massive early explosive eruptions of the Siberian Traps large igneous province (Payne and Clapham 2012). The global anoxia and the Tsunami theory at that time are illustrative (Virgili 2008). However, the proposed Tsunamite theory is contested by many workers who believe that local seismic activity seems to be a far more logical explanation of the Guryul formations than the eruption of the Siberian Traps more than 6000 km away (Janbu et al. 2004; Shellnutt 2016).
In July 1984, members of the Permian-Triassic Boundary Working Group (PTBWG) polled it informally as a favored stratotype for the Permo-Triassic. During a workshop at Calgary meeting (1993), the PTBWG again proposed four candidates for the stratotype of this boundary, i.e., Meishan of Zhejiang, Guryul Ravine of Kashmir, Shangsi of Sichuan, and Selong of Tibet (Tewari et al. 2015). In 1996, Guryul was a candidate for the Permian–Triassic Global Stratotype Section and Point (GSSP) by International Commission on Stratigraphy (ICS). But due to political turmoil in Kashmir, and absence of significant work done to satisfy the ICS conditions, Meishan-D in Zhejiang Province, China, was selected as GSSP (Yin et al. 2001). Despite not being a GSSP it continues to be favorite among geoscientists due to the advantage of being intensely condensed to the extent that an interval of early Triassic time recorded in the Southern Alps of Italy, Primorye, or the western United States of 100 m of rock is represented in the Guryul Ravine section by as little as 9m to a maximum of only 29 m (Brookfield et al. 2020). The Proximal inner continental margin conditions are also well preserved in the units at the Guryul Ravine P–Tr boundary section in Kashmir (Algeo et al. 2007).
Conclusion and need for the conservation of Guryul
The above review bears the testimony about the tremendous wealth of knowledge that has got unraveled through Guryul ravine in the field of Pr-Tr event. Hence, Guryul is nature’s living laboratory that holds the lessons not only on Pr-Tr event but on the impact of climate change on the global earth system. It is reported that anoxia during the P-Tr event was due to heating of the Earth’s atmosphere. Mushrooming of cement industries and open-cast and low-intensity mining of limestones in the area has made it imperative to protect Guryul Ravine so that scientists from all over the world keep deriving enthralling facts from its study. Declaration of Guryul Ravine as an international fossil park is an essential step in this direction; however, it must be initiated as soon as possible so that mining and industrial activity, through stringent legislation, ceases in its surroundings. Further, the amount of research that has been done on Guryul can be used as evidence to support the Geoscientific community that strives to certify the guryul as GSSP site. It is also vital that other adjoining complementary P-Tr Sections of Mandakpal, Pahalgam, Barus, and Liam should also be protected in the global scientific interest and spared from mining (Fig. 4). International scientific fraternity must stand for guryul and bring forth its importance to the local policymakers.