Low-latitude arc–continent collision as a driver for global cooling

Abstract

New constraints on the tectonic evolution of the Neo-Tethys Ocean indicate that at ∼90-70 Ma and at ∼50-40 Ma, vast quantities of mafic and ultramafic rocks were emplaced at low latitude onto continental crust within the tropical humid belt. These emplacement events correspond temporally with, and are potential agents for, the global climatic cooling events that terminated the Cretaceous Thermal Maximum and the Early Eocene Climatic Optimum. We model the temporal effects of CO 2 drawdown from the atmosphere due to chemical weathering of these obducted ophiolites, and of CO 2 addition to the atmosphere from arc volcanism in the Neo-Tethys, between 100 and 40 Ma. Modeled variations in net CO 2 -drawdown rates are in excellent agreement with contemporaneous variation of ocean bottom water temperatures over this time interval, indicating that ophiolite emplacement may have played a major role in changing global climate. We demonstrate that both the lithology of the obducted rocks (mafic/ultramafic) and a tropical humid climate with high precipitation rate are needed to produce significant consumption of CO 2 . Based on these results, we suggest that the low-latitude closure of ocean basins along east-west trending plate boundaries may also have initiated other long-term global cooling events, such as Middle to Late Ordovician cooling and glaciation associated with the closure of the Iapetus Ocean.climate change | climate-tectonic connection | arc-continent collision O ver geologic time, atmospheric pCO 2 is regulated by a balance between sources and sinks (1-5), including the products of volcanism (6), metamorphism (7, 8), and silicate weathering (4), which are fundamentally the results of plate tectonic processes (9-11). However, attempts to relate particular episodes of Cretaceous to recent climate change to specific tectonic events remain controversial (1,9,(12)(13)(14)(15).Studies of present-day chemical weathering document an important control of lithology and paleogeography on weathering rates and associated CO 2 drawdown (16,17). Highly active regions of intense chemical weathering account for >50% of the consumed CO 2 per year, yet the proportion of this land area is <10% (18, 19). In these areas, high CO 2 consumption rates are the consequence of elevated physical and chemical weathering rates, which result from a combination of significant topographic relief, high rates of precipitation (20), elevated surface temperatures, and exposure of large volumes of highly weatherable mafic and ultramafic) rocks (16,17,21). Such conditions are characteristic of tectonically active (or recently active) regions located at low latitude, within the Intertropical Convergence Zone (ITCZ) and adjacent regions of humid tropical climate and high precipitation (6,9,16). Based on these observations, we propose that the obduction of mafic and ultramafic rocks at low latitude that resulted from arc-continent collision during the closure of the Neo-Tethys Ocean exerted important controls on Late Cretaceous to Eocene (100-40 Ma) g...

Continental igneous rock composition: A major control of past global chemical weathering

“…This progressive decrease in Sr flux from radiogenic continental areas combined with the increase in mid-oceanic ridge magmatism associated with the Tethys opening might explain the lower ( 87 Sr/ 86 Sr) seawater values during the Permian period ( 57 ). Changes in the isotopic signature of the Sr flux exported from continents are associated with the uplift of metamorphic rocks, ophiolites, and LIPs ( 22 ) can also play a significant role in the Sr isotope budget ( 56 ). The rapid weathering of these isotopically distinct rocks in favorable paleogeographic or tectonic configuration likely contributes to some of the ( 87 Sr/ 86 Sr) seawater variations over the last 1000 My (Fig.…”

Paleoclimate Constraints on Terrestrial Hydroclimate, Silicate Weathering, and the Carbon Cycle

“…These effects are likely to be greater than those caused by changes in the global average runoff given that spatially runoff varies substantially. Indeed, previous studies have suggested that changes in global silicate weathering fluxes could be driven by the interaction of continental configuration and sea level with the overlying runoff distribution, as determined by atmospheric circulation, over both short (10 3 -10 5 yr) and long (>10 6 yr) timescales (e.g., Gibbs and Kump, 1994;Gibbs et al, 1999;Ludwig et al, 1999;Munhoven, 2002;Donnadieu et al, 2004;Goddéris et al, 2008;Kent and Muttoni, 2008;Le Hir et al, 2009;Mills et al, 2011Mills et al, , 2013Jagoutz et al, 2016).…”

“…For example, basaltic catchments weather faster than other silicates and account for approximately 20-35% of the modern global silicate weathering and CO2 consumption flux, while occupying less than 5% of sub-aerial continental area (Gíslason et al, 1996(Gíslason et al, , 2009 have been critically important in controlling past levels of atmospheric CO2 (pCO2) (Li and Elderfield, 2013;Kent and Muttoni, 2013;Molnar and Cronin, 2015;Jagoutz et al, 2016). However, scaling modern observations of weathering fluxes from catchments to both large spatial and temporal scales (e.g., Wallmann, 2001;Lefebvre et al, 2013;Li and Elderfield, 2013;Kent andMuttoni, 2008, 2013;Mills et al, 2014a;Li et al, 2016;Jagoutz et al, 2016;Cox et al, 2016) remains a challenge due to the lack of phenomenological modeling frameworks that predict weathering fluxes at both catchment and global scales under different climate states.…”

Arc volcanism, carbonate platform evolution and palaeo-atmospheric CO&lt;sub&gt;2&lt;/sub&gt;: Components and interactions in the deep carbon cycle

“…According to the Accumulation model, the dramatic change that characterised the reduction in CIA 15 lengths ~75 Ma included the termination of a ~3 000-km-long section of a north-dipping intra-oceanic subduction zone in the Northern Tethys ocean, corresponding to the Trans-Tethyan Subduction System (Jagoutz et al, 2016), and the cessation of subduction along the Sundaland margin (McCourt et al, 1996;Zahirovic et al, 2016) (Figs. 5c, 5d).…”

“…The intra-oceanic subduction in the Neo-Tethys in our model would not be classified as a carbonate-intersecting arc due to the overriding plate (in this case largely oceanic 20 lithosphere) lacking extensive carbonate platforms. In any case, this intra-oceanic subduction zone in the Accumulation Model corresponds to the emplacement of the peri-Arabian ophiolite belt along the AfroArabian continental margin between 80-70 Ma rather than an Andean-style arc, the erosion of which has been posited as a cause of global cooling following the EECO (Jagoutz et al, 2016) (Figs. 5c, 5d).…”