July 2018 LIP of the Month

Lessons from Earth’s Large Igneous Province (LIP) Record for Modern Climate Change

Richard. E Ernst ^(1,2), Nasrrddine Youbi ^(3,4), Simon M. Jowitt ⁽⁵⁾, & Yulia Mishenina ⁽²⁾

¹Department of Earth Sciences, Carleton University, Ottawa, Canada; richard.ernst@ernstgeosciences.com,

²Faculty of Geology and Geography, Tomsk State University, Tomsk, Russia; j.a.selezneva29@gmail.com

³Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco; youbi@uca.ac.ma

⁴Instituto Dom Luiz, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal

⁵Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, Nevada, USA; simon.jowitt@unlv.edu

Introduction

Connections between large historic basaltic eruptions, and changes in the global environment have been long recognized. Dramatic examples include the eruptions of Laki, Iceland in 1783, and Eldgjá, Iceland in 934, both of which were followed in subsequent years by historically cold summers in the northern hemisphere with severe environmental consequences (Stothers, 1998; Thordarson and Self, 2003; Oman et al., 2006; Bressan, 2015; Fig. 1). For instance, the Laki eruption was followed by plague and famine in 1783-1784, during which an estimated nine thousand people died, one-fifth of the population of Iceland. More recently the 2010 volcanic eruptions of Eyjafjallajokull, Iceland, although relatively small, caused havoc for airline travel in western and northern Europe in April 2010 (https://en.wikipedia.org/wiki/2010_eruptions_of_Eyjafjallajökull). Taking a longer perspective, over the past few thousand years, human civilization has been dramatically influenced by volcanic-induced climate change (e.g. Harris and Mann, 2018) with periods of increased volcanic activity often leading to decreased global temperatures and linked to famine, population collapse, and wars.

Role of Large Igneous Provinces (LIPs) and Silicic LIPs (SLIPs) in climate change through Earth History

These climate-changing volcanic events of Iceland are dwarfed by Large Igneous Provinces (LIPs) which represent much larger outpourings of basaltic magmas, up to millions of cubic kilometres (e.g. Coffin and Eldholm, 1994; Ernst, 2014). There is an increasing recognition of the role of LIPs and their silicic counterparts, Silicic LIPs (SLIPs), in rapid environmental and climate changes, including global warming (Hothouse events), global cooling (Icehouse events, i.e. Snowball Earth or regional glaciations), anoxia, stepwise oxygenation, acid rain/ocean acidification, enhanced hydrothermal and terrestrial nutrient fluxes, and mercury poisoning and leading to mass extinctions (e.g. Courtillot, 1999; Saunders, 2005; Wignall, 2005; Kerr, 2005; Self et al., 2005; Neal et al., 2008; Ernst and Youbi, 2017; Bond and Grasby, 2017). Specifically, the largest mass extinction events at 360, 252, 201, 66 Ma and probably also at 440 Ma can be linked to LIPs with an additional input from a meteorite impact only associated with the end Cretaceous (66 Ma) mass extinction.

In this brief contribution, we discuss the emerging recognition of the role of LIPs as a major driver of climate change throughout Earth history. We then consider ways in which the historical record of climate change can be useful in modern studies of climate change. This is an initial commentary, and is meant to stimulate discussion on how lessons from Earth’s geological history and the LIP record throughout time can be potentially informative for modern climate change research.

Overview of Large Igneous Provinces (LIPs)

The precise definition of a LIP has varied, but generally emphasizes a huge volume of mafic magma emplaced in a short period and which is of intraplate style (e.g. Coffin and Eldholm, 1994; Bryan and Ernst, 2008; Bryan and Ferrari, 2013; Ernst, 2014; Ernst and Youbi, 2017). The following definition is modified after Ernst (2014) and Ernst and Youbi (2017). LIPs represent large volume (>0.1 Mkm³; frequently above 1 Mkm³), mainly mafic (-ultramafic) magmatic events of intraplate affinity (based on tectonic setting and/or geochemistry) that occur in both continental and oceanic settings, and are typically either of short duration (<5 Ma) or consist of multiple short pulses that occur over a maximum of a few 10s of Ma. LIPs consist of volcanic packages (flood basalts) and a plumbing system of regional dyke swarms (linear, radiating and a newly identified circumferential type), sill complexes, layered mafic-ultramafic (M-UM) intrusions, and crustal magmatic underplates. Continental LIPs can also be associated with major silicic magmatic events termed Silicic LIPs (SLIPs), as well as carbonatites and kimberlites. LIP events occur at variable rates through time. Since 2500 Ma, there has been an average of one LIP event every 20–30 Ma, with higher numbers of LIPs occurring during supercontinent breakup (Ernst and Bleeker, 2010). The rate of LIP occurrences in the Archean, however, is less certain due to poorer preservation. 

Large Igneous Provinces (LIPs) have been the focus of a significant amount of recent research not only for their role in dramatic climate change (the focus of this contribution), but also given their growing importance in constraining paleocontinental reconstructions (e.g., via magmatic bar-coding, Bleeker and Ernst, 2006; Ernst et al., 2013; and via paleomagnetism of mafic rocks; Buchan, 2014), as a tool in exploration targeting (e.g. Ernst and Jowitt, 2013, 2017), and as analogues for voluminous planetary intraplate magmatism (e.g. Head and Coffin, 1997; Ernst et al., 2017).

The environmental effects of LIPs are caused by gas release both via volcanism, and also from interaction of the intrusive component with host sediments that leads to hydrothermal venting (e.g. Svensen et al. 2009). Additional factors include chemical weathering, ash clouds affecting Earth’s albedo, and the release of reductants, nutrients, and metals to the ocean. It is also important to consider the interactions between the effects of LIPs and SLIPs (both direct and indirect) and other proposed drivers of climatic change (such as new ocean formation, erosion of mountain belts, meteorite impact, biological evolution, obliquity cycles, and changes in planetary albedo, ocean circulation, and solar luminosity).

Integrating LIP and sedimentary records

A key research frontier is the systematic integration of the LIP record (e.g. volume, magma eruption rates, distribution, duration, paleolatitude, gas composition, etc.) with environmental consequences as recorded in the sedimentary record (in compositional and isotopic environmental proxies). The context is that although the distribution of LIP events is regional, the environmental effects that are recorded in the sedimentary record are global (Ernst and Youbi, 2017). In support of this theme of integration of magmatic and sedimentary histories, we are organizing a LIPs conference in Sept 2019 (Tomsk State University, Siberia, Russia), with that as a main theme. The provisional conference title is: “Large Igneous Provinces Through Earth History: Links with Mantle Plumes, Climate Change, Metallogeny and Oil-Gas”; Tomsk, Siberia, Russia, 2-5 September 2019 (with field trips before and after) http://geoconf.tsu.ru/lip2018/english/

Implications for the Precambrian Time Scale

Publications such as Okulitch (1987, 2002) and Bleeker (2004a, 2004b) as well as the comprehensive review by Van Kranendonk et al. (2012) have argued for a revised Precambrian time scale based on natural chronostratigraphic boundaries (in some cases correlated with LIPs) to replace the current chronometric scale (e.g. Ogg et al., 2016) that uses numbers rounded mainly to the nearest 100 Myr.

The robust array of LIP-related environmental effects (as demonstrated in the Phanerozoic record) suggests that LIP events represent useful time markers in the Precambrian as proxies for significant global environmental changes that are preserved in the sedimentary record. The potential of LIP events to cause severe global environmental impacts means they can represent proxies for “golden spike” horizons in the sedimentary record. One contribution toward the identification of appropriate natural boundaries is provided by an examination of the Proterozoic record for LIP candidates to mark such boundaries (Table 1 in Ernst and Youbi 2017). LIPs at 2500–2450, 2100, 2060, 1880, 1790–1750, 1525–1500, 1460, 1380, 1270, 1110, 825, 720, 615–560, 510 Ma (Table 1) are of particular significance both for their scale and extent. Although LIP size is not the only factor in their potential impact on climate it remains an important first-order parameter.

Lessons from other planets

In terms of the range of possible LIP-climate links there are lessons from other planets, both within our solar system and also extra-solar planets.

Modelling by Way et al. (2016) inferred that Venus had a habitable climate at equatorial latitudes from about 3 Ga to 700 Ma, at which point dramatic global climate change occurred, with surface temperatures increasing to c. 450°C and atmospheric pressures to 90 bar (dominated by CO₂).  This runaway climate change was linked to voluminous basaltic volcanism and associated CO₂ release (e.g. Solomon et al. 1999).  On Mars, intense volcanism and associated release of CO₂, H₂O and SO₂ led to episodic global warming early in Mars history (e.g. Grott et al. 2011; Halevy and Head 2014; Wordsworth, 2016).

Extrasolar planets are of increasing importance in understanding climate change  (https://exoplanets.nasa.gov/,  http://astrobiology.ucr.edu/exoplanets.html,  https://www.space.com/17738-exoplanets.html, http://www.planetary.org/explore/space-topics/exoplanets/,  http://astrobiology.ucr.edu/). Currently over three thousand extrasolar planets have been discovered through spacecraft such as Kepler Space Telescope, launched in 2009, and the Transiting Exoplanet Survey Satellite (TESS) launched in April 2018. For instance, Gillon et al. (2017), discovered seven Earth-sized planets in orbit around the nearby dwarf star TRAPPIST-1 (Fig. 4)

The atmospheres of extrasolar planets will be revealed through future space missions, such as the upcoming James Webb Space Telescope mission which will be launched in 2021 (https://jwst.nasa.gov/index.html), and strategies for detecting volcanism on extrasolar planets are also being developed (e.g. Kaltenegger et al., 2010). Thus, future data from extrasolar planets on climate and volcanism will represent another source of information for better understanding the parameter space for climate, volcanism and conditions for maintaining life.

Carbon sequestration

One of the aspects of the LIP record that is most relevant to understanding modern climate change relates to role of LIPs as carbon sinks. Weathering of basalts is known to be an efficient mechanism for CO₂ drawdown (Pollyea et al. 2014) and suggest the role of mafic units of  LIPs in carbon sequestration (e.g. Tollefson, 2013; Giacomel et al., 2018). It is also now recognized that the ultramafic components of LIP can even more efficiently sequester CO₂ during mineralogical changes associated with serpentinisation (Wilson and Jowitt 2014; Wilson et al. 2009, 2014).  One example of this is the natural sequestration of CO₂ by ultramafic mine tailings, as exemplified by the tailings associated with the komatiitic Mount Keith nickel mine in Western Australia, which is part of the Kambalda sequence of the 2700 Ma Eastern Goldfields LIP. Natural sequestration of CO₂ is a result of the passive weathering and carbonation of these Mount Keith mine tailings and offsets some 11% of the annual greenhouse gas emissions associated with mining and nickel production (Wilson et al., 2014). The CO₂ sequestration potential of LIP intrusions is also being actively investigated, with research currently underway to make use of pyroxene-rich mafic tailings from PGM mines in the Bushveld LIP as a feedstock for industrial carbonation reactors (e.g., Meyer et al., 2014).

Implications for modern climate change 

Earth’s history of dramatic climate change, linked to LIPs, provides some lessons for modern climate change.

• Research integrating LIPs and environmental consequences contributes to a fuller characterization of how the Earth responds and recovers from severe environmental stressors, with implications for understanding and mitigating modern climate change. More broadly, Earth’s history of climate change (regardless of cause) can provide a robust context for modern climate change without diminishing the impact of anthropogenic drivers in the latter.
• One example of this is the weathering of mafic and ultramafic rocks, processes that act as powerful sinks for atmospheric CO₂, and thus have suggested a role for these rock types in carbon sequestration efforts.
• A simple cautionary tale is that the Earth has experienced many periods of dramatic climate change, some of which resulted in mass extinction events where a majority of life on Earth was wiped out. Many of these dramatic climatic shifts are linked to LIPs, but in the context of this essay, the more important message is that Earth’s climate is continually changing, sometimes dramatically, with catastrophic effects on life, and therefore, the risk to humanity is real.