(a) With reference to Figure 224, to what do the two geoid...

Name: Problem 10, Chapter 2: The Ocean Basins: Their Structure and Evolution
Uploaded: 2024-12-07T06:15:46-08:00
Channel: Susan Hallstrom
Description: (a) With reference to Figure 224, to what do the two geoid anomaly highs in the extreme north-west of Figure 2.26 correspond? (b) In Figure 2.26, in what way do the expressions of the following differ between the Seasat data (bottom) and the Geosat/ERS-1 data (top): (i) transform faults and fracture zones, (ii) median valleys?

(a) With reference to Figure 224, to what do the two geoid anomaly highs in the extreme north-west of Figure 2.26 correspond? (b) In Figure 2.26, in what way do the expressions of the following differ between the Seasat data (bottom) and the Geosat/ERS-1 data (top): (i) transform faults and fracture zones, (ii) median valleys?

(a) With reference to Figure 224, to what do the two geoid anomaly highs in the extreme north-west of Figure 2.26 correspond?
(b) In Figure 2.26, in what way do the expressions of the following differ between the Seasat data (bottom) and the Geosat/ERS-1 data (top):
(i) transform faults and fracture zones, (ii) median valleys?

Key Concepts

Geoid Anomalies

Geoid anomalies are deviations of the Earth’s actual gravity field from an idealized, uniform model. They arise from variations in mass distribution within the Earth, such as those produced by seafloor topography and crustal features, and are used to infer underlying geological and tectonic structures. In marine geophysics, positive anomalies often correlate with elevated seafloor features or regions of high crustal density, helping to interpret processes like seafloor spreading or mantle convection.

Satellite Altimetry Data

Satellite altimetry involves measuring the sea surface height with high precision to infer the underlying seafloor topography. Different satellite missions, such as Seasat and Geosat/ERS-1, can produce data sets with differing resolutions and data quality. These differences affect how geological features such as transform faults, fracture zones, and median valleys are expressed, with some satellites capturing broader, lower-resolution features and others providing finer detail.

Transform Faults and Fracture Zones

Transform faults are the active, lateral boundaries along mid?ocean ridges where tectonic plates slide past one another. Fracture zones are their inactive extensions that mark the offset in seafloor segments. Both features are significant in understanding plate motion and seafloor spreading, and their signature in gravity and altimetry data helps delineate the plate boundaries and past tectonic events.

Median Valleys

Median valleys are the central depressions found along mid-ocean ridges where active seafloor spreading occurs. These depressions are formed as new crust is generated and subsequently cools and subsides. Variations in the depiction of median valleys in satellite altimetry data can provide insights into the dynamics of ridge processes, with differences in resolution between data sets emphasizing different aspects of their morphology.