New Research Opportunities in the Earth Sciences (2012) / Chapter Skim
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2 New Research Opportunities in the Earth Sciences
2 New Research Opportunities in the Earth Sciences
Pages 13-70
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From page 13... ...
interactions among climate, Earth continents that have led to the current Earth system. surface processes, tectonics, and deep Earth processes; Recent progress on understanding the early Earth has (5)
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From page 14... ...
Accordingly, the assumption that forces that collect dust particles into planetesimals, Earth formed by a continuous influx of small particles typically 1-kilometer-sized objects that were the fun- made of pristine solar system condensates has given damental building blocks of Earth and the other terres- way to a much more dramatic model, in which Earth trial planets. Once a sufficient density of planetesimals was assembled by a relatively small number of traudeveloped in the nebular cloud, increasingly violent matic collisions involving larger objects, some of these collisions began to dominate the accretion process, already having differentiated interiors and well as their forming an ever-smaller number of growing planetary own internal dynamics (Canup and Asphaug, 2001)
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From page 15... ...
, and methane lakes on Titan. These discoveries provide new opportunities to test our understanding of the basic processes that govern planetary evolution and interactions between Earth systems, particularly the interior, the geodynamo, surface environments, and the atmosphere.
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predict that much of the global magma oceans extending to considerable depths preexisting layered structure of Earth was obliterated (Tonks and Melosh, 1993)
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. What is more certain, however, is of a Moon-forming giant impact -- the smoking gun that terrestrial magma oceans and the early atmosphere in Earth's early history -- remains elusive.
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. Another assumes that dispersed metal rained cate lunar magma ocean is reasonably well understood down through the magma ocean, collected at its base, FIGURE 2.3 Schematic evolution of progressive crystallization of surface and basal magma oceans (yellow)
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, and once the magma ocean solidified, liquid process. water could stabilize at the surface with carbon dioxide and methane dominating the climate (Kasting and Ono, 2006)
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. Reprinted by permission from Macmillan Publishers Ltd.
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From page 21... ...
Develop- outer core material and to constrain temporal evoluing a community focus on these topics and coordination tion of the geodynamo, geochemistry to define internal of the interdisciplinary approaches is likely to accelerate chemical variability and timing of fractionation events, progress, much as has been the case for studies of the and geology to decipher the history of crustal formapresent-day deep Earth system. The complexity and tion and plate tectonics recorded by surface rocks.
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From page 22... ...
. outstanding issues will require enhanced resolution of Quantifying the nature and dynamical influence fine-scale structures in the interior beyond what can of deep Earth chemical heterogeneities will require an now be achieved, and efforts to attain higher resolution interaction of multiple Earth science subdisciplines, from seismological, geodynamical, and mineral physics including geodynamics, petrology, mineral physics, geoapproaches will need to be undertaken.
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From page 23... ...
The green curves outline the 20 percent of the core-mantle boundary area with the lowest S-wave velocities, and this corresponds to the two LLSVPs beneath southern Africa and the south-central Pacific that have been characterized by seismic tomography and waveform modeling studies over the past two decades. SOURCE: Reprinted from Thorne et al.
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From page 24... ...
An "Array of Arrays" concept is being ing of thermo-chemical convection throughout the developed in the seismological community as a means upper and lower mantles, including effects of the sub- to achieve the high-resolution capabilities essential ducted lithosphere, deep chemical piles, and thermo- to resolving detailed structures in boundary layers, in chemical plumes. deep subducting slabs, and in deep plumes as well as While near-term progress can be anticipated based for improving models of statistical heterogeneity of on the improved data, analysis techniques, and facilities small-scale structures that cannot be deterministically that support research on the deep Earth system, final imaged.
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From page 25... ...
The overall scope of facilities Likewise, the deep interior plays a critical role in needed to make the next large steps in understand- the global carbon cycle, and carbon can also alter physiing the deep Earth thermo-chemical dynamic system cal properties of the mantle yielding feedbacks between will likely require major instrumentation initiatives carbon cycling and mantle dynamics (see Figure 2.7)
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From page 26... ...
. As the physics characterization of the myriad hydrous phases, core cools, the inner core grows by solidification of dehydration processes, and influence of volatiles on iron at its surface accompanied by a depletion of the rheology and the elastic properties imaged by seismol- light alloy component.
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From page 27... ...
from the mostly solid inner core into the molten outer core provide much of the power for the geodynamo and also influence the rate of inner core growth and the thermo-chemical evolution of the core as a whole. New interpretations of these fluxes center on the significance of the seismic F-layer above the inner-core boundary (ICB)
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From page 28... ...
before demagnetization to identify the magnetic using SQUID (see text) microscope maps but also in the thermal history of the planet; the rate of nications across the disciplines and training of graduate polarity boundaries because of the NRM's gen- of undemagnetized natural remanent mag inner core growth is determined by how rapidly the core netization for thin-sections sMA1 and in the diverse arena of core studies.
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From page 29... ...
Determining the statistical likelihood of NRC report Origin and Evolution of Earth highlighted earthquakes in a region is of particular interest to socithe question of whether earthquakes, volcanic erup- ety because engineering building codes are guided by tions, and their consequences can be predicted, as one the probability of experiencing various levels of ground of 10 Grand Challenges in the Earth sciences. shaking within the lifetime of a building.
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30 NEW RESEARCH OPPORTUNITIES IN THE EARTH SCIENCES Recent Advances -- The Wide Range of Slip Velocities region within the past decade and have been termed either "slow slip" or "slow earthquakes." In Cascadia the The scientific view of how faults slip has evolved slow slip events occur about every 14 months (Miller dramatically in the past decade. Developments in space et al., 2002)
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(2007) by permission from Macmillan Publishers Ltd.
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. Global seismic network to allow the estimation of the relevant parameters (e.g., data are now used to estimate slip distribution for all faults are planar, slip is unidirectional)
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project confor theoretical developments so that 3D wavefields ducted by the Earth sciences, receiving $200 million of can be computed for realistic crustal environments. NSF's MREFC support from outside of the DirectorFurthermore, additional ground displacement records ate for Geosciences (GEO)
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From page 34... ...
. ing deep crustal and upper-mantle structures under The scientific rationale for following through on North America, unveiling as the Transportable Array the EarthScope program in the next decade is compel- sweeps eastward.
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(2009) by permission from Macmillan Publishers Ltd.
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From page 36... ...
sequestration, geothermal energy, fracking for shale- 2018 is equally compelling given the large investment gas recovery, nuclear power plant siting, and building of NSF funds in EarthScope, the superb success of the code development. facilities in achieving the primary data collection goals The economic rationale for sustaining the to date, the exciting scientific results on first-order EarthScope project through the planned program to Earth science problems, and the excellent prospect for
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From page 37... ...
The Alaskan subduction zone provides a second natural laboratory to study fault zone processes. This INTERACTIONS AMONG CLIMATE, zone is complex, with significant variations in geom- SURFACE PROCESSES, TECTONICS, AND etry and locking and more frequent magnitude 7.0 to DEEP EARTH PROCESSES 8.0 earthquakes and volcanic eruptions than Cascadia (see Box 2.5)
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From page 38... ...
Modern research in volcanology relies on integrating complementary approaches: remote sensing from space with InSAR and spectroradiometers; distributed high-frequency monitoring of GPS, tilt, seismic, infrasound, acoustic, and electromagnetic signals; gas sampling; measuring the rheological properties and phase equilibria of magmas in the lab; and numerical simulations of conduit processes, the multiphase dynamics of eruption columns and pyroclastic flows, and the thermal and chemical evolution of magma within the crust. Additionally, large-scale laboratory experiments offer an USGS important opportunity for validating the new generation of numerical models for conditions and properties that are well constrained.
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From page 39... ...
For example, numerous geological, and geomorphological processes. Our under- studies have documented evidence for the opera standing of the dynamics of landscape evolution and tion of a so-called "glacial buzzsaw" through which the linkages between climate, Earth surface processes, efficient glacial erosion above the glacial equilibrium and tectonics across a wide range of spatial and tempo- line altitude (ELA)
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From page 40... ...
. Reprinted by permission from Macmillan Publishers Ltd.
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. Recent recognition of processes, ecosystems, and landscape evolution is a the strong coupling between erosion and surficial mass primary goal of research on Earth surface processes.
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. Courtesy of Macmillan Publishers Ltd.
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From page 43... ...
physical studies that target deeper crustal and mantle Other examples of deeper Earth response to erostructure. sion unloading and sediment loading of Earth's sur face include the impact of sediment distribution on the distribution and magnitudes of subduction zone Linkages Between Climate, Surface Processes, and megathrust earthquakes, with important implications Deeper Earth Processes for the major human population centers located along Although it has long been recognized that lower subducting margins (e.g., Wells et al., 2003)
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From page 44... ...
tions in the distant past remarkably different from • Integrating surface processes and deep Earth those of the Holocene epoch -- the epoch when low studies, including petrological and seismological and relatively stable atmospheric carbon dioxide and studies, and the record of past surface environ- largely benign climatic conditions fostered human ments, to explore connections between deep civilizations. Earth's deep-time record provides numer Earth processes and Earth surface dynamics.
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From page 45... ...
Also, by ice sheets at both poles and atmospheric carbon these diverse data can now be brought together into dioxide partial pressure (pCO2) up to 30 percent less the interpretative framework of small- to large-scale than present-day levels, however, captures only a small numerical approaches ranging from geochemical box part of known climate variability.
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From page 46... ...
. The climate linkage between radiative forcing, Earth surface temperatures, and high-latitude continental glaciation is clearly delineated in the history of the buildup of the Antarctic and Northern Hemisphere ice sheets (see Figure B2.6, bottom)
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From page 47... ...
These in turn have contributed to major greenhouse gas increases such as during mass extinction climate change, ocean acidification and hypoxia, and and ecosystem reorganization events, notably those at consequent large-scale biotic impact. the end-Permian, end-Triassic, Cretaceous-Paleogene, In the tropics, integrated paleoclimate and paleoand PETM.
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From page 48... ...
Genomic data derived from environmental RNA reveal microbial dynamics on scales of minutes, while data derived from DNA allow characterization of geobiological evolution over billions of years. The field is poised to address challenges facing humanity, including increasing soil fertility to aid in feeding the world's growing population, providing novel approaches to managing Earth's resources and waste disposal and attenuating the impacts from human land use and climate change in the critical zone.
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49 NEW RESEARCH OPPORTUNITIES IN THE EARTH SCIENCES time, Ma 10 20 30 40 50 60 0 5,000 CO 2 proxies Boron 4,000 Alkenones Atmospheric CO 2, pCO 2 (p.p.m.v.) Nahcolite Trona 3,000 Anthropogenic peak (5,000 Gt C)
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Recent advances that allow access to this distribution have ushered in a new and rich source of information contained in the stable isotopes. Most notably, Ghosh et al.
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51 NEW RESEARCH OPPORTUNITIES IN THE EARTH SCIENCES specific microbial metabolisms in the very old record limited the evolutionary advance of life. At the same and their environmental implications ( Johnston et al., time, metal isotope systems, such as iron and molyb2008)
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From page 52... ...
cycling and regional drought, and consequent substanExamples include those at the end-Triassic (McElwain tial impact on marine and terrestrial ecosystems. For et al., 1999; Schaller et al., 2011)
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From page 53... ...
Furthermore, intervals of abrupt ent tremendous new opportunities for advancing our c limate change documented by the deep-time geo understanding of Earth surface processes as well as logical record -- most notably, past hyperthermals of providing critical scientific input to managers tasked the early Cenozoic and the last greenhouse-icehouse with finding solutions to problems associated with transition of the Late Paleozoic -- reveal the nonlinear environmental change. This research opportunity difdynamics associated with pushing the climate system fers from the later section on biogeochemical cycles in through critical thresholds.
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From page 54... ...
It is reasonable to assume that soil moisture through its effects on transpiration and long-term trends of warming temperatures will result photosynthesis. Soil moisture variations are regulated in fundamental alterations to polar, glacial, and peri- by external factors like topography and soil composiglacial landscapes and ecosystems, but at what point tion, as well as feedbacks with vegetation, microbial are these changes irreversible?
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From page 55... ...
As such, these large root systems appear Changes in land use and climate can modify pre- Role of Humans in Landscape Change for its ability to identify several large near-surface roots mapped from capable of mechanical soil production with or without turnover pits along our study transects. This threshold valuefavoring some cipitation, runoff, and soil moisture, also had the effect events.
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From page 56... ...
The National processes, and change due to both human activity and Center for Earth-Surface Dynamics (NCED) , an NSF climate change (past and future)
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From page 57... ...
was launched in 2004 to provide barrier islands are linked through potential resort the cyber-infrastructure and protocols for coupling damage by storm over wash and flooding and the and running a suite of numerical models representing resulting efforts to limit physical and economic damdiverse processes and scales across Earth's surface, with age through site location and size and to maximize the goal of facilitating exploration of surface response revenue by renting many rooms at a relatively high to environmental change. CSDMS is moving toward price.
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From page 58... ...
. Globally, trapecological, climatic, and biogeochemical processes ping of sediment in reservoirs and channeling of river shape modern coastal landscapes and dictate their flows by levees and other structures has significantly sensitivity and resilience to short-term disturbance reduced the natural supply of terrestrial sediment to events and longer-term trends in climate, land use, and the coastal zone, resulting in sinking deltas and erodsea level.
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. but neither the monitoring nor the understanding of Technical and methodological advances are also the underlying physical and biological processes is shedding new light on coastal processes.
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Humans are now managing and altering 50 percent of Earth's land Integrated Soil, Water, and Biogeochemical surface -- dubbed the "critical zone" in the Basic Research D ynamics in the Critical Zone Opportunities in Earth Science report (NRC, 2001) -- and, in so doing, are transforming the physical, chemi- The dynamics of the critical zone -- the dynamic cal, and biological states and feedbacks among essential interface between the solid Earth and its fluid envelopes components of the Earth surface system.
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From page 61... ...
These PBO rock breakdown to form soils is needed to understand studies demonstrate how infrastructure developed for the processes of soil formation and how they vary in geophysical studies can simultaneously be used for different landscapes, climates, and tectonic regimes. water cycle studies funded through the hydrological Interdisciplinary studies of the critical zone are sciences within EAR, the Division of Atmospheric and yielding new ideas about the interactions of weather- Geospace Sciences (AGS)
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From page 62... ...
. The integrated watershed studies needed to advance Responses and Feedbacks of Carbon, Nitrogen, and our understanding of the critical zone is a distinctive Water Cycles to Climate Change f eature of the CZO framework and their multidisciplinary science teams.
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From page 63... ...
scales. organisms guarantees that the carbon cycle is coupled Environments in which climate change could with those of nitrogen and phosphorus, while processes trigger relatively rapid vegetation and landscape change, such as biological nitrogen fixation link nitrogen cycles such as permafrost areas and wetlands, are of particular to those of other elements, such as iron (e.g., Finzi et concern to regional and global carbon exchange.
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From page 64... ...
Understanding how all of this additional nitrogen cycles operating in soil-based, freshwater, and marine will affect climate, terrestrial ecosystems, and carbon systems. Quantifying changes in the water cycle associcycling is essential as we attempt to anticipate future ated with climate change is therefore a critical element environmental change and possible mitigation strate- of building an understanding of future changes in gies.
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From page 65... ...
between agricultural land cover in the Mississippi River basin and increased discharge under average precipita- Human Impacts on Water, Carbon, and tion conditions, with agricultural land use accounting Nitrogen Cycles for more of the increase in Mississippi River discharge in the past 50 years than do increases in precipitation Humans have altered the terrestrial water cycle (Raymond et al., 2008)
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From page 66... ...
In this figure, climate change, the nitrogen cycle, process with respect to safe operating conditions. at dangerous levels -- for proc interference and biodiversity loss have crossed the threshold of unacceptable environmental change.
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From page 67... ...
(2010) recently investigated a portion of tions of this chapter is the growing reliance on geo- the early Cambrian period associated with the appearchronology to provide quantitative estimates of the ance of the first calcite biomineralizing organisms and age, duration, and rate of events and processes over an associated dramatic change in global carbon cycling, many different timescales.
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68 NEW RESEARCH OPPORTUNITIES IN THE EARTH SCIENCES FIGURE 2.26 An example of the new insights possible with ages precise to a small fraction of a percent. Chart shows carbon isotope variability in marine carbonate in the early Cambrian period.
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From page 69... ...
ing methods expand, the need for close collaboration Thus, continued and robust advances in geochronology among those who develop techniques and make the will involve a broad cross section of the Earth science measurements with those who select key samples and community. interpret results is becoming increasingly apparent.
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