Three-Layer Sediment Model Overview - Earth Crustal Model 1 (ECM1)
Three-layer P- velocity model overview for ECM1.
Three-layer S- velocity model overview for ECM1.
Statistics
Average seismic velocity-depth and Vp-Vs-depth models for the eight continental crustal types. (A) P-wave velocities (Vp), (B) S-wave velocities (Vs), and (C) Vp/Vs ratio. The maximum depth for each crustal type depends on the average crustal thickness for that crustal type. Orogens show lower Vp and Vs compared with the other continental provinces, and island arcs show the highest Vp and Vs at any given Depth.
Density-depth curves for (A) continental crustal types and (B) oceanic crustal types. These curves are derived from the Vp values using Equation 2 of Brocher, 2005.
Average Vp-depth models for the three oceanic crustal types. There are an insufficient number of measurements of Vs to calculate reliable Vs-depth curves. Oceanic large igneous provinces have lower P-wave velocities than normal oceanic crust or mid-ocean ridges due to hydrothermal alteration of the crust.
ECM1 crustal types show their average thickness and Vp value for the crystalline crust. Each crustal type is composed of 8 layers, corresponding to ice, water, three layers for the sediments (here combined to one layer), and the upper, middle, and lower crystalline crust. Only Vp values are displayed.
Sub-Moho seismic velocities of P-waves (Vpn) for (A) continental and (B) oceanic crustal types and S-waves (Vsn) for (C) Continental and (D) oceanic crustal types. Both Vpn histograms show a secondary peak around 7.75 km/s corresponding to continental and island arcs (A) and mid-ocean ridges (B).
Area
Pie chart of the global areal percentage of each crustal type. Approximately 60% of the world’s crust is oceanic by area and 40% is continental by area. The submerged continental margin crust comprises 10% by area, therefore 70% of the Earth’s crust is below sea level.
Pie chart of the percentage of the oceanic crustal types by area. The mid-ocean ridge crust is defined as crust <2 Myr in ag and comprises approximately 2% of the ocean crust. The geographical distribution of oceanic large igneous provinces (oceanic LIPs) is from Coffin and Eldholm (1994). Oceanic LIPs represent nearly 6% of the ocean crust. Although the largest category is “normal” ocean crust, this crustal type includes seamounts, unclassified oceanic islands, and subduction zones
Pie chart of the areal percentage of the eight continental crustal types. The continental margin comprises the largest areal percentage of the continental crust, whereas Island arcs and continental arcs contribute the smallest areal percentage.
Volume
Pie chart of the volumetric percentage of each crustal type with respect to the total volume of the Earth’s crust. This volumetric pie chart may be compared with the surface area pie chart. Normal oceanic crust covers 54.6% of the Earth but comprises only 27.3% of the total crust by volume. The continental crust comprises 72.7% of the volume of the Earth’s crust. Continental margins, platforms, shields, and orogens have comparable volumetric percentages, ranging from 12.0% to 16.1%.
Pie chart of the volumetric percentage of the three oceanic crustal types with respect to the total volume of oceanic crust. Normal oceanic crust comprises 89.2% of all oceanic crust by volume, and oceanic large igneous provinces (LIPs) represent almost 10% of the volume of ocean crust. Mid-ocean ridges only represent around 1% of the oceanic volume.
Pie chart of the volumetric percentage of continental crustal types. Approximately half (49%) of the continental crust is composed of stable shields, platforms, and cratonic basins. The remaining half (51%) has undergone deformed by Mesozoic/Cenozoic compression, extension, or magmatic activity.
Comparison with previous models
Total sediment thickness of (A) CRUST1.0, (B) ECM1, and (C) CRUST1.0 minus ECM1. The differences fluctuate between +/-10 km and in some regions the difference is >15 km. The largest differences are located within continental margins.
Comparison with previous models
Total crustal thickness of (A) CRUST2.0 and (B) ECM1 and (C) ECM1 minus CRUST2.0.
Total crustal thickness of (A) CRUST1.0 and (B) ECM1 and (C) ECM1 minus CRUST1.0. The differences fluctuate between +/- 5 km and in some regions can differ by 10 km.
Total crustal thickness of (A) Litho1.0, (B) ECM1 and (C) ECM1 minus Litho1.0 model.
Total crustal thickness of (A) Szwillus model, (B) ECM1 and (C) ECM1 minus Szwillus et al., 2019 model. The differences fluctuate between +/-10 km and in some regions can differ by >15 km.
The difference in total crustal thickness of model ECM1 in comparison with three other 1º x 1º models.(A) ECM1 minus Cru ECM 1 minus Crust 1.0; (B) ECM1 minus Litho 1.0; (C)ECM1 minus Szwillus et al. (2019).
The difference in crystalline crustal thickness of model ECM1 in comparison with three other 1º x 1º models.(A) ECM 1 minus Crust 1.0; (B) ECM1 minus Litho 1.0; (C)ECM1 minus Szwillus et al. (2019).