Lava Creek Tuff

The Lava Creek Tuff is a voluminous sheet of ash-flow tuff located in Wyoming, Montana and Idaho, United States. It was created during the Lava Creek eruption around 630,000 years ago, which led to the formation of the Yellowstone Caldera. This eruption is considered the climactic event of Yellowstone's third volcanic cycle. The Lava Creek Tuff covers an area of more than 7,500 km² (2,900 sq mi) centered around the caldera and has an estimated magma volume of 1,000 km³ (240 cu mi).

Lava Creek Tuff
Tuff Cliff showing the Lava Creek Tuff formation
Volcano	Yellowstone Caldera
Date	Around 630,000 years ago
Type	Ignimbrite-forming
Location	Wyoming, United States 44°24′N 110°42′W / 44.400°N 110.700°W / 44.400; -110.700
Volume	>1,000 km^3 (240 cu mi)
VEI	8
Extent of the Lava Creek ash bed

The fallout from the eruption blanketed much of North America, depositing as one of the most widespread air-fall pyroclastic layers, formerly known as the Pearlette type O ash bed in the United States and Wascana Creek ash in Canada.

The thick tuff formation resulting from this eruption is well-exposed at various locations within Yellowstone National Park, including Tuff Cliff along the Gibbon River, Virginia Cascade, and along U.S. Highway 20.

Lava Creek Tuff ranges in color from light gray to pale red in some locales. Rock texture of the tuff ranges from fine-grained to aphanitic and is densely welded. The maximum thickness of the tuff layer is approximately 180–200 m (590–660 ft).^[1]

Chronology of tuff

Ash flows of the Lava Creek Tuff are divided among six members, informally named unit 1, unit 2,^[2] member A and B^[3] from bottom to top, with unit 3 and unit 4 having unspecified stratigraphic positions.^[4] The emplacement of the Lava Creek Tuff was not instantaneous and continuous, but rather, there were multiple pauses, and the members were erupted at different times.^[5][6][7][3]

To date the timings of their eruptions, two common methods of radiometric dating are employed: ⁴⁰Ar/³⁹Ar on sanidine and U–Pb on zircon. The interpretation of the two techniques differs in that zircon crystallization occurs early and progressively during magma evolution; therefore, U–Pb ages must predate the instantaneous age of volcanic eruption as recorded by sanidine.^[8]

Two samples from ignimbrite visually closely similar to unit 1 or 2, the oldest ignimbrite units of the Lava Creek Tuff, have ⁴⁰Ar/³⁹Ar ages of 634.5±6.8 kyr and 630.9±4.1 kyr.^{[9] 40}Ar/³⁹Ar dating experiments on sanidine from member B have yielded eruption ages of 627.0±1.7 kyr,^[10] 631.3±4.3 kyr,^[11] and 630.9±2.7.^[12]

U–Pb dating for zircon crystals from both the member A and B yields an age of 626.5±5.8 kyr,^[13] which is indistinguishable from the ⁴⁰Ar/³⁹Ar date of sanidine. Another team reported U–Pb ages of 626.0±2.6 kyr and 629.2±4.3 kyr for zircon from member A and member B, respectively.^[14]

Petrography

The ignimbrite sheet was formed from rhyolite magma^[15] and contains phenocrysts of quartz, sanidine, and subordinate sodic plagioclase, along with minor proportions of magnetite, ilmenite, ferroaugite, fayalite, iron-rich hornblende, zircon, chevkinite, and allanite.^[16] However, the abundance of phenocrysts differs between the members. Hornblende is relatively abundant in member A but rare in other members.^[17][2] Unit 3 is distinguished from unit 1 and 2 by higher crystal content and more plagioclase.^[6] Member A is distinguished from member B primarily by the presence of the mineral amphibole in the former.^[18]

The zircon and phenocrysts rims recorded that the magma of the Lava Creek Tuff was generated from a mix of mantle, Archean crust, and shallow hydrothermally altered intra-caldera rocks. Member A and B were sourced from separate magma reservoirs prior to eruption,^[19] at a depth range of 3–6 km (1.9–3.7 mi)^[20] and a temperature of 790–815 °C (1,454–1,499 °F).^[21] The eruption of member B was probably triggered by a combination of an injection of new silicic magma into the reservoir and volatile exsolution from crystallizing magma.^[22]

Eruption

The eruption of the Lava Creek Tuff has been reconstructed through geological analysis of the deposits. Proximal ignimbrite units of member A and B have been studied in detail^[23] and correlated with distal air-fall.^[24] Meanwhile, the newly identified units 1, 2, 3, and 4 are only known at a few locales, nonetheless, they indicate that the Lava Creek eruption was much more complex than previously thought.^[25][4]

Unit 1 and 2

These ignimbrite units represent the earliest known eruptive events of the Lava Creek episode.^[26]

See also

• Snake River Plain
• Island Park Caldera
• Henry's Fork Caldera

References

1. "U.S. Geological Survey Scientific Investigations Map 2816" (PDF). Retrieved May 20, 2018.
2. Wilson, Stelten & Lowenstern 2018, p. 10.
3. Christiansen 2001, p. 26.
4. Yellowstone Volcano Observatory 2023, pp. 24–29.
5. Wilson, Stelten & Lowenstern 2018, p. 1.
6. Yellowstone Volcano Observatory 2023, pp. 29.
7. Morgan Morzel et al. 2017, p. 11.
8. Schmitt et al. 2023, p. 1008.
9. Wilson, Stelten & Lowenstern 2018, p. 5.
10. Mark et al. 2017, p. 10.
11. Matthews, Vazquez & Calvert 2015, p. 2517.
12. Jicha, Singer & Sobol 2016, p. 62.
13. Matthews, Vazquez & Calvert 2015, p. 2515.
14. Wotzlaw et al. 2015, p. 4.
15. Christiansen 2001, p. 1.
16. Christiansen 2001, p. 31.
17. Matthews, Vazquez & Calvert 2015, p. 2509.
18. Wilson, Stelten & Lowenstern 2018, p. 2.
19. Wotzlaw et al. 2015, p. 6.
20. Maguire et al. 2022, p. 1.
21. Shamloo & Till 2019, p. 1.
22. Shamloo & Till 2019, p. 14.
23. Christiansen 2001, p. 26-38.
24. Izett, G. A.; Wilcox, R. E. (1982). Map showing localities and inferred distributions of the Huckleberry Ridge, Mesa Falls, and Lava Creek ash beds (Pearlette family ash beds) of Pliocene and Pleistocene age in the western United States and southern Canada (Report). IMAP. Vol. 1325. doi:10.3133/i1325.
25. Wilson, Stelten & Lowenstern 2018, pp. 2–10.
26. Wilson, Stelten & Lowenstern 2018, pp. 6–7.

Sources

• Mark, Darren F.; Renne, Paul R.; Dymock, Ross C.; Smith, Victoria C.; Simon, Justin I.; Morgan, Leah E.; Staff, Richard A.; Ellis, Ben S.; Pearce, Nicholas J. G. (2017-04-01). "High-precision 40Ar/39Ar dating of pleistocene tuffs and temporal anchoring of the Matuyama-Brunhes boundary". Quaternary Geochronology. 39: 1–23. doi:10.1016/j.quageo.2017.01.002. hdl:10023/10236. ISSN 1871-1014.

• Matthews, Naomi E.; Vazquez, Jorge A.; Calvert, Andrew T. (2015). "Age of the Lava Creek supereruption and magma chamber assembly at Yellowstone based on 40 Ar/ 39 Ar and U-Pb dating of sanidine and zircon crystals: AGE OF THE LAVA CREEK SUPERERUPTION". Geochemistry, Geophysics, Geosystems. 16 (8): 2508–2528. doi:10.1002/2015GC005881.

• Schmitt, A.K.; Sliwinski, J.; Caricchi, L.; Bachmann, O.; Riel, N.; Kaus, B.J.P.; Cisneros de Léon, A.; Cornet, J.; Friedrichs, B.; Lovera, O.; Sheldrake, T.; Weber, G. (2023-08-01). "Zircon age spectra to quantify magma evolution". Geosphere. 19 (4): 1006–1031. doi:10.1130/GES02563.1. ISSN 1553-040X.

• Wotzlaw, Jörn-Frederik; Bindeman, Ilya N.; Stern, Richard A.; D’Abzac, Francois-Xavier; Schaltegger, Urs (2015-09-10). "Rapid heterogeneous assembly of multiple magma reservoirs prior to Yellowstone supereruptions". Scientific Reports. 5 (1): 14026. doi:10.1038/srep14026. ISSN 2045-2322. PMC 4564848.

• Christiansen, Robert L. (2001). "The Quaternary and Pliocene Yellowstone Plateau volcanic field of Wyoming, Idaho, and Montana". USGS Professional Paper 729G.

• Morgan Morzel, Lisa Ann; Shanks, W. C. Pat; Lowenstern, Jacob B.; Farrell, Jamie M.; Robinson, Joel E. (2017). Geologic field-trip guide to the volcanic and hydrothermal landscape of the Yellowstone Plateau (Report). U.S. Geological Survey.

• Wilson, Colin J. N.; Stelten, Mark E.; Lowenstern, Jacob B. (2018-05-16). "Contrasting perspectives on the Lava Creek Tuff eruption, Yellowstone, from new U–Pb and 40Ar/39Ar age determinations". Bulletin of Volcanology. 80 (6): 53. doi:10.1007/s00445-018-1229-x. ISSN 1432-0819.

• Yellowstone Volcano Observatory (2023). "Yellowstone Volcano Observatory 2022 annual report". U.S. Geological Survey Circular 1508.

• Jicha, Brian R.; Singer, Brad S.; Sobol, Peter (2016). "Re-evaluation of the ages of 40Ar/39Ar sanidine standards and supereruptions in the western U.S. using a Noblesse multi-collector mass spectrometer". Chemical Geology. 431: 54–66. doi:10.1016/j.chemgeo.2016.03.024.

• Maguire, Ross; Schmandt, Brandon; Li, Jiaqi; Jiang, Chengxin; Li, Guoliang; Wilgus, Justin; Chen, Min (2022-12-02). "Magma accumulation at depths of prior rhyolite storage beneath Yellowstone Caldera". Science. 378 (6623): 1001–1004. doi:10.1126/science.ade0347. ISSN 0036-8075.

• Shamloo, Hannah I.; Till, Christy B. (2019-04-19). "Decadal transition from quiescence to supereruption: petrologic investigation of the Lava Creek Tuff, Yellowstone Caldera, WY". Contributions to Mineralogy and Petrology. 174 (4): 32. doi:10.1007/s00410-019-1570-x. ISSN 1432-0967.