Facies-dependent compositional variation in K-bentonites from lagoonal to littoral environments (Permian-Triassic transition, southwestern China)

Abstract

The alteration pathways of volcanic ashes depend on the physicochemical conditions of the watermass in which they are deposited. Different conditions in terrestrial, paralic, and marine facies may impart recognizable chemical signatures on altered ash beds (i.e., K-bentonites) that are potentially useful for distinguishing depositional facies in ancient ash-bearing stratigraphic successions. Western Guizhou Province in South China contains widespread Permian-Triassic transition strata from terrestrial lacustrine to shallow-marine shelf facies. In this study, factors influencing the mineralogy and geochemistry of K-bentonites accumulating across a spectrum of freshwater facies in Permian-Triassic transition strata of south-western China were comparatively investigated using mineralogical and geochemical data. Our results show that K-bentonites preserve diagnostic information regarding their depositional environment. The clay mineral assemblages of these K-bentonites are facies-dependent, with dominance of mixed-layer illite/smectite (I/S) clays in freshwater lacustrine facies, kaolinite and I/S in lagoonal facies, mixed-layer kaolinite/smectite (K/S) in mixed marine-terrestrial facies, and smectite and I/S in littoral-neritic facies. The lagoonal Chinahe (CNH) K-bentonites exhibit clay mineral compositions dominated by kaolinite (both highly and poorly crystalline forms) and R1 and R3 I/S clays; the CNH-16 K-bentonite additionally contains minor chlorite. The abundance of kaolinite and absence of smectite in the CNH K-bentonites resulted from strong chemical weathering in an organic acid-rich and oxidizing environment characterized by low porewater pH. The littoral Langdai (LD) K-bentonites contain mainly R1 and R3 mixed-layer illite/smectite (I/S) and smectite, with minor poorly crystalline kaolinite, suggesting a higher pH in seawater-derived pore fluids. The littoral LD K-bentonites and their host sediments have Sr/Ba ratios of 0.34−0.49, consistent with deposition in brackish coastal facies, whereas the higher Sr/Ba ratios of the CNH K-bentonites (0.67−1.07) indicate deposition in a marine to slightly hypersaline lagoonal facies linked to warm, arid climate conditions.

Graphical abstract

Keywords

K-bentonites / mixed-layer illite/smectite (I/S) / salinity / porewater pH / sedimentary environment / anatase

References

[1] Algeo T J, Hong H L, Wang C W (2025). The chemical index of alteration (CIA) and interpretation of ACNK diagrams.Chem Geol, 671: 122474

[2] Algeo T J, Tribovillard N (2009). Environmental analysis of paleoceanographic systems based on molybdenum–uranium covariation.Chem Geol, 268(3−4): 211–225

[3] Alizai A, Hillier S, Clift P D, Giosan L, Hurst A, VanLaningham S, Macklin M (2012). Clay mineral variations in Holocene terrestrial sediments from the Indus Basin.Quat Res, 77(3): 368–381

[4] Armstrong-Altrin J S, Machain-Castillo M L, Rosales-Hoz L, Carranza-Edwards A, Sanchez-Cabeza J A, Ruíz-Fernández A C (2015). Provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico unraveled by geochemical analysis.Cont Shelf Res, 95: 15–26

[5] Arslan M, Abdiogğlu E, Kadìr S (2010). Mineralogy, geochemistry, and origin of bentonite in Upper Cretaceous pyroclastic units of the Tirebolu area, Gìresun, Northeast Turkey.Clays Clay Miner, 58(1): 120–141

[6] Bau M, Koschinsky A, Dulski P, Hein J R (1996). Comparison of partitioning behaviors of yttrium, rare earth elements, and titanium between hydrogenetic marine ferromanganese crusts and seawater.Geochim Cosmochim Acta, 60(10): 1709–1725

[7] Bea F (1996). Residence of REE, Y, Th and U in granites and crustal protoliths; implications for the chemistry of crustal melt.J Petrol, 37(3): 521–552

[8] Bercovici A, Cui Y, Forel M B, Yu J X, Vajda V (2015). Terrestrial paleoenvironment characterization across the Permian-Triassic boundary in South China.J Asian Earth Sci, 98: 225–246

[9] Bozkaya Ö, Günal-Türkmenoğlu A, Göncüoğlu M C, Ünlüce Ö, Yilmaz İ Ö, Schroeder P A (2016). Illitization of Late Devonian-Early Carboniferous K-bentonites from Western Pontides, NW Turkey: implications for their origin and age.Appl Clay Sci, 134: 257–274

[10] Caballero E, Reyes E, Delgado A, Huertas F, Linares J (1992). The formation of bentonite: mass balance effects.Appl Clay Sci, 6(4): 265–276

[11] Chamley H (1989). Clay Sedimentology. Berlin: Springer, 1–623

[12] Chanu A K, Manikyamba C, Subramanyam K S V, Raza W, Gangula H R (2023). Geochemistry of the Neoarchean Dodguni carbonates of Chitradurga greenstone belt, Dharwar Craton, India: implications on depositional environment.Geol J, 58(2): 648–661

[13] Chen J, Algeo T J, Zhao L, Chen Z Q, Cao L, Zhang L, Li Y (2015). Diagenetic uptake of rare earth elements by bioapatite, with an example from lower Triassic conodonts of South China.Earth Sci Rev, 149: 181–202

[14] Chen Q, Zhang D, Wang J, Zhao F, Liu Y, Zhang Z, Sun X, Huang C, Bai Y (2020). Geochemical characteristics of carbonate rocks in a salinized lacustrine basin: a case study from Oligocene formation in the Qaidam Basin, northwestern China.Carbonates Evaporites, 35(2): 40

[15] Clauer N, Williams L B, Uysal I T (2022). Boron and lithium isotopic signatures of nanometer-sized smectite-rich mixed-layers of bentonite beds from Campos Basin (Brazil).Clays Clay Miner, 70(1): 72–83

[16] Erkoyun H, Kadir S, Külah T, Huggett J (2017). Mineralogy, geochemistry and genesis of clays interlayered coal seams succession in the Neogene lacustrine Seyitömer coal deposit, Kütahya, western Turkey.Int J Coal Geol, 172: 112–133

[17] Fortey N J, Merriman R J, Huff W D (1996). Silurian and Late-Ordovician K-bentonites as a record of late Caledonian volcanism in the British Isles.Trans R Soc Edinb Earth Sci, 86(3): 167–180

[18] Göncüoğlu M C, Günal-Türkmenoğlu A, Bozkaya Ö, Ünlüce-Yücel Ö, Okuyucu C, Yilmaz İ Ö (2016). Geological features and geochemical characteristics of late Devonian–early Carboniferous K-bentonites from northwestern Turkey.Clay Miner, 51(4): 539–562

[19] Gong N N, Hong H L, Huff W D, Fang Q, Bae C J, Wang C W, Yin K, Chen S L (2018). Influences of sedimentary environments and volcanic sources on diagenetic alteration of volcanic tuffs in South China.Sci Rep, 8(1): 7616

[20] He B, Zhong Y T, Xu Y G, Li X H (2014). Triggers of Permo-Triassic boundary mass extinction in South China: the Siberian Traps or Paleo-Tethys ignimbrite flare-up.Lithos, 204: 258–267

[21] Heintz M L, Yancey T E, Miller B V, Heizler M T (2015). Tephrochronology and geochemistry of Eocene and Oligocene volcanic ashes of east and central Texas.Geol Soc Am Bull, 127(5−6): 770–780

[22] Hints R, Kirsimäe K, Somelar P, Kallaste T, Kiipli T (2008). Multiphase Silurian bentonites in the Baltic palaeobasin.Sediment Geol, 209(1−4): 69–79

[23] Hong H L, Algeo T J, Fang Q, Zhao L L, Ji K P, Yin K, Wang C W, Cheng S (2019). Facies dependence of the mineralogy and geochemistry of altered volcanic ash beds: an example from Permian-Triassic transition strata in southwestern China.Earth Sci Rev, 190: 58–88

[24] Hong H L, Fang Q, Zhao L L, Schoepfer S, Wang C W, Gong N N, Li Z, Chen Z Q (2017). Weathering and alteration of volcanic ashes in various depositional settings during the Permian-Triassic transition in South China: mineralogical, elemental and isotopic approaches.Palaeogeogr Palaeoclimatol Palaeoecol, 486: 46–57

[25] Hong H L, Ji K P, Liu C, Algeo T J, Yin K, Zhao L L, Hochella M F, Fang Q, Wang C W (2022). Authigenic anatase nanoparticles as a proxy for sedimentary environment and porewater pH.Am Mineral, 107(12): 2176–2187

[26] Hong H L, Jin X, Wan M, Ji K, Liu C, Algeo T J, Fang Q (2020). Occurrence of anatase in reworking altered ash beds (K-bentonites and tonsteins) and discrimination of source magmas: a case study of terrestrial Permian–Triassic boundary successions in China.Clay Miner, 55(4): 329–341

[27] Hower J C, Eble C F, O’Keefe J M K, Dai S, Wang P, Xie P, Liu J, Ward C R, French D (2015). Petrology, palynology, and geochemistry of Gray Hawk Coal (early Pennsylvanian, Langsettian) in eastern Kentucky, USA.Minerals (Basel), 5(3): 592–622

[28] Huff W D (2016). K-bentonites: a review.Am Mineral, 101(1): 43–70

[29] Isozaki Y, Shimizu N, Yao J, Ji Z, Matsuda T (2007). End-Permian extinction and volcanism-induced environmental stress: the Permian–Triassic boundary interval of lower-slope facies at Chaotian, South China.Palaeogeogr Palaeoclimatol Palaeoecol, 252(1−2): 218–238

[30] Jones B, Manning D A (1994). Comparison of geochemical indices used for the interpretation of palaeoredox conditions in ancient mudstones.Chem Geol, 111(1−4): 111–129

[31] Kasten S, Barker-Jorgensen B (2000). Sulfate reduction in marine sediments. In: Schulz H D, Zabel M, eds. Marine Geochemistry. Berlin: Springer, 263–282

[32] Kiipli T, Kiipli E, Kallaste T, Hints R, Somelar P, Kirsimäe K (2007). Altered volcanic ash as an indicator of marine environment, reflecting pH and sedimentation rate – Example from the Ordovician Kinnekulle bed of Baltoscandia.Clays Clay Miner, 55(2): 177–188

[33] Kramer W, Weatherall G, Offler R (2001). Origin and correlation of tuffs in the Permian Newcastle and Wollombi Coal measures, NSW, Australia, using chemical fingerprinting.Int J Coal Geol, 47(2): 115–135

[34] Kumar R, Hameed R, Tiwari P, Kumar N, Srivastava P (2024). Major, trace and rare earth element geochemistry of Archaean carbonate sediments of Tanwan Group rocks of the Bhilwara Supergroup, India: implications for seawater geochemistry and depositional environment.Carbonates Evaporites, 39(2): 14

[35] Lei H Y, Wang L, Zhang W D, Jiang M J, Bo Y, Fang Q F (2022). Impact of environmental acidity on the geomechanical and mineralogical behavior of marine clay.Bull Eng Geol Environ, 81(1): 35

[36] Liao Z, Hu W, Cao J, Wang X, Yao S, Wu H, Wan Y (2016). Heterogeneous volcanism across the Permian–Triassic Boundary in South China and implications for the Latest Permian Mass Extinction: new evidence from volcanic ash layers in the Lower Yangtze Region.J Asian Earth Sci, 127: 197–210

[37] Liu C, Fang Q, Hong H L, Song Q, Ji K, Gong N, Shen X, Algeo T J (2024b). Illitization of smectite influenced by chemical weathering and its potential control of anatase formation in altered volcanic ashes.Am Mineral, 109(10): 1691–1704

[38] Liu L, Liu H, Zhang C, Zhang J, Zhai X, Guan N, Wang Z, Liu Q (2024a). Late Carboniferous marine-continental transitional sediments in the Datong Basin, North China: mineralogical and geochemical characteristics and paleoenvironmental significance.Mar Pet Geol, 162: 106714

[39] Liu L, Zhang H, Algeo T J, Zhang K N, Hong H L, Zhang S, Liu Q (2021). Control of coal-bearing claystone composition by sea level and redox conditions: an example from the Upper Paleozoic of the Datong Basin, North China.Appl Clay Sci, 211: 106204

[40] Liu Z R R, Zhou M F, Williams-Jones A E, Wang W, Gao J F (2019). Diagenetic mobilization of Ti and formation of brookite/anatase in early Cambrian black shales, South China.Chem Geol, 506: 79–96

[41] MacRae N D, Nesbitt H W, Kronberg B I (1992). Development of a positive Eu anomaly during diagenesis.Earth Planet Sci Lett, 109(3−4): 585–591

[42] McCarty D K, Sakharov B A, Drits V A (2009). New insights into smectite illitization: a zoned K-bentonite revisited.Am Mineral, 94(11−12): 1653–1671

[43] McLennan S M (1989). Rare earth elements in sedimentary rocks: influence of provenance and sedimentary processes.Rev Mineral Geochem, 21(1): 169–200

[44] McLennan S M (2001). Relationships between the trace element composition of sedimentary rocks and upper continental crust.Geochemistry Geophysics Geosystems, 2: 2000GC000109

[45] Mills M M, Sanchez A C, Boisvert L, Payne C B, Ho T A, Wang Y F (2023). Understanding smectite to illite transformation at elevated (>100 °C) temperature: effects of liquid/solid ratio, interlayer cation, solution chemistry and reaction time.Chem Geol, 615: 121214

[46] Mitchell C E, Goldman D, Delano J W, Samson S D, Bergström S M (1994). Temporal and spatial distribution of biozones and facies relative to geochemically correlated K-bentonites in the Middle Ordovician Taconic foredeep.Geology, 22(8): 715–718

[47] Murray R W (1994). Chemical-criteria to identify the depositional environment of chert-general-principles and applications.Sediment Geol, 90(3−4): 213–232

[48] Nechaev V P, Dai S, Chekryzhov I Y, Tarasenko I A, Zin’kov A V, Moore T A (2022). Origin of the tuff parting and associated enrichments of Zr, REY, redox-sensitive and other elements in the Early Miocene coal of the Siniy Utyes Basin, southwestern Primorye, Russia.Int J Coal Geol, 250: 103913

[49] Nesbitt H W, Markovics G (1997). Weathering of granodioritic crust, long-term storage of elements in weathering profiles, and petrogenesis of siliciclastic sediments.Geochim Cosmochim Acta, 61(8): 1653–1670

[50] Nesbitt H W, Young G M (1982). Early Proterozoic climates and plate motions inferred from major element chemistry of lutites.Nature, 299(5885): 715–717

[51] Núñez M A, Recio J M (2007). Kaolinitic paleosols in the south west of the Iberian Peninsula (Sierra Morena region, Spain). Paleoenvironmental implications.Catena, 70(3): 388–395

[52] Osacký M, Bai Y, Uhlík P, Pálková H, Caplovicová M (2023). Mineralogy, chemistry, and thermal and surface properties of various technological types of K-bentonite from the Dolna Ves deposit (Kremnicke Vrchy Mts. , Western Carpathians, Slovakia). Clays Clay Miner, 71(6): 650-672

[53] Peng Y Q, Zhang S X, Yu T X, Yang F Q, Gao Y Q, Shi G R (2005). High-resolution terrestrial Permian–Triassic eventostratigraphic boundary in western Guizhou and eastern Yunnan, southwestern China.Palaeogeogr Palaeoclimatol Palaeoecol, 215(3−4): 285–295

[54] Pillai S S K, Manoj M C, Mathews R P, Murthy S, Sahoo M, Saxena A, Sharma A, Pradhan S, Kumar S (2023). Lower Permian Gondwana sequence of Rajhara (Daltonganj Coalfield), Damodar Basin, India: floristic and geochemical records and their implications on marine ingressions and depositional environment.Environ Geochem Health, 45(10): 6923–6953

[55] Püspöki Z, Kozák M, Kovács-Pálffy P, Szepesi J, McIntosh R, Kónya P, Vincze L, Gyula G (2008). Geochemical records of a bentonitic acid-tuff succession related to a transgressive systems tract – indication of changes in the volcanic sedimentation rate.Clays Clay Miner, 56(1): 23–38

[56] Renock D, Landis J D, Sharma M (2016). Reductive weathering of black shale and release of barium during hydraulic fracturing.Appl Geochem, 65: 73–86

[57] Reynolds R C Jr, Reynolds R C III (1996). NEWMOD for Windows. The Calculation of One-dimensional X-ray Diffraction Patterns of Mixed-layered Clay Mineral. Hanover: New Hampshire

[58] Schulz H, Wirth R, Schreiber A (2016). Nanocrystal formation of TiO₂ polymorphs brookite and anatase due to organic-inorganic rock-fluid interactions.J Sediment Res, 86(2): 59–72

[59] Sheldon N D, Tabor N J (2009). Quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols.Earth Sci Rev, 95(1−2): 1–52

[60] Shen M, Dai S, Graham I T, Nechaev V P, French D, Zhao F, Shao L, Liu S, Zuo J, Zhao J, Chen K, Xie X (2021). Mineralogical and geochemical characteristics of altered volcanic ashes (tonsteins and K-bentonites) from the latest Permian coal-bearing strata of western Guizhou Province, southwestern China.Int J Coal Geol, 237: 103707

[61] Shu W (2022). Permian–Triassic Floral Successions—Fossil Evidence from North China, South China and Xinjiang. Dissertation for Doctor Degree. Wuhan: China University of Geosciences-Wuhan

[62] Somelar P, Kirsimäe K, Hints R, Kirs J (2010). Illitization of Early Paleozoic K-bentonites in the Baltic Basin: decoupling of burial-and fluid-driven processes.Clays Clay Miner, 58(3): 388–398

[63] Song Q, Hong H L, Algeo T J, Fang Q, Zhao C L, Liu C, Xu Y X (2023). Clay mineralogy mediated by pH and chemical weathering intensity of Permian–Triassic boundary K-bentonites at Dongpan (Guangxi, South China).Chem Geol, 617: 121262

[64] Song T, Tong J, Tian L, Chu D, Huang Y (2019). Taxonomic and ecological variations of Permian-Triassic transitional bivalve communities from the littoral clastic facies in southwestern China.Palaeogeogr Palaeoclimatol Palaeoecol, 519: 108–123

[65] Stampfli G M, Borel G D (2002). A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons.Earth Planet Sci Lett, 196(1−2): 17–33

[66] Šucha V, Kraust I, Gerthofferová H, Peteš J, Sereková M (1993). Smectite to illite conversion in bentonites and shales of the East Slovak Basin.Clay Miner, 28(2): 243–253

[67] Thorpe C L, Lloyd J L, Law G T W, Burke L T, Shaw S, Bryan N D, Morris K (2012). Strontium sorption and precipitation behaviour during bioreduction in nitrate impacted sediments. Chem Geol, 306–307: 114–122

[68] Toulkeridis T, Clauer N, Chaudhuri S, Goldstein S L (1998). Multimethod (K-Ar, Rb-Sr, Sm-Nd) dating of bentonite minerals from the eastern United States.Basin Res, 10(2): 261–270

[69] Ver Straeten C A (2008). Volcanic tephra bed formation and condensation processes: a review and examination from Devonian stratigraphic sequences.J Geol, 116(6): 545–557

[70] Wang A, Wang Z, Liu J, Xu N, Li H (2021). The Sr/Ba ratio response to salinity in clastic sediments of the Yangtze River Delta.Chem Geol, 559: 119923

[71] Wei W, Algeo T J (2020). Elemental proxies for paleosalinity analysis of ancient shales and mudrocks.Geochim Cosmochim Acta, 287: 341–366

[72] Wignall P B, Chu D, Hilton J M, Dal Corso J, Wu Y, Wang Y, Atkinson J, Tong J (2020). Death in the shallows: the record of Permo-Triassic mass extinction in paralic settings, southwest China.Global Planet Change, 189: 103176

[73] Wu Y Y, Chu D, Tong J, Song H, Dal Corso J, Wignall P B, Song H, Du Y, Cui Y (2021). Six-fold increase of atmospheric pCO₂ during the Permian–Triassic mass extinction.Nat Commun, 12(1): 2137

[74] Yin H F, Jiang H S, Xia W C, Feng Q L, Zhang N, Shen J (2014). The end-Permian regression in South China and its implication on mass extinction.Earth Sci Rev, 137: 19–33

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