The Deep Earth Engine Driving Major Surface Events

experienced environmental changes that drastically impacted habitability. The changes have been mostly attributed to near-surface processes or astronomical events with little consideration of Earth’s deep interior. Recent progresses in high-pressure geochemistry and geophysics, however, indicate that deep Earth processes may have played a dominant role in the surface (Mao and Mao, 2020). Systematic observations of the Earth’s surface by the geoscience community around the world have collected a gigantic amount of data and deduced a series of major catastrophic events, that dictate the evolution in the biosphere throughout the Earth’s history, including the great oxidation event (GOE), snowball Earth, five mass extinctions, large igneous provinces (LIP), converging and rifting of supercontinents, and starting of the plate tectonics. These events are closely correlated in their geological timeline, yet their proposed origins diverge widely among surficial effects, such as photosynthesis of cyanobacteria, environmental changes, ocean chemistry changes, sedimentary carbon sequestration, orogenic processes, volcanic activities, etc., and astronomical effects, such as asteroid impacts, Earth’s spin axis wobbling, and gamma-ray burst (GRB). The most likely effects of the massive deep Earth interior, however, have been hardly considered due to the lack of information. Our samplings of the deep Earth, including the deepest core drilling, volcanic eruptions, and diamond inclusions, are limited to less than ten percent of the Earth’s radius. Most information of the depth comes from geophysical explorations, including seismic, gravitational, geomagnetic, and geothermal observations. These findings have limited variables. Moreover, they do not contain the time dimension; they only represent the present Earth, and that is difficult to record the Earth’s past nor predict the future. Therefore the most powerful tool for studying the deep Earth is to use in-laboratory high pressuretemperature (P-T) experimentation to simulate the behaviour of minerals and rocks in the depth. Recent advances of the high P-T technology with diamond-anvil cell (DAC) (Mao et al., 2020) and multianvil device (MA) (Walker and Li, 2020), and the integration with analytical probes at synchrotron x-ray facilities (Hirao et al., 2020; Ji et al., 2020) have led to surprising and unexpected discoveries in chemistry (Yoo, 2020) and geochemistry (Zhang et al., 2014), and a unified theory based on deep internal engine-driven surface effects begins to emerge and consolidate (Fig. 1). Oxygen as an essential bioelement is the most abundant element on Earth. Recent discoveries on the pressurealtered chemistry revealed that the oxygen cycles through Earth’s deep interior could also be the origin of the mantle dynamics and that could cause the disruptive evolution of the life on surface. Subducting slab injects the oxidized crust down into the reduced deep lower mantle. H2O severs as a strong oxidant and oxygen transporter (Katsura and Fei, 2020; Lin et al., 2020; Walter, 2020) to meet Fe at the core-mantle boundary (CMB), Fe can be oxidized to produce superoxide FeO2 with the cubic pyrite structure (Hu et al., 2016). At the middle of the lower mantle, Hu et al. (2020) show that H2O can also react with ferropericlase (Mg, Fe)O, a major lower-mantle mineral, to form pyritestructured superoxide. At shallower depth, Liu et al. (2020) found that H2O induced oxidation of ferropericlase to form Fe2O3+δ with a new hexagonal structure. The subducting process may compile substantial oxygen-rich materials to form oxygen reservoirs at the CMB. The basic form of reaction is: MOn + H2O ⇆ MOn+1 + H2 (1) oxides oxygen-rich material where M stands for metal cation (Fe, Mg, Ca, Si.). In addition to oxygen-rich materials, the Reaction (1) The Deep Earth Engine Driving Major Surface Events