Making a Better Magnetic Map

Self Cite

179

388

Antarctica is the largest reservoir of ice on Earth. Understanding its ice sheet dynamics is crucial to unraveling past global climate change and making robust climatic and sea level predictions. Of the basic parameters that shape and control ice flow, the most poorly known is geothermal heat flux. Direct observations of heat flux are difficult to obtain in Antarctica, and until now continent‐wide heat flux maps have only been derived from low‐resolution satellite magnetic and seismological data. We present a high‐resolution heat flux map and associated uncertainty derived from spectral analysis of the most advanced continental compilation of airborne magnetic data. Small‐scale spatial variability and features consistent with known geology are better reproduced than in previous models, between 36% and 50%. Our high‐resolution heat flux map and its uncertainty distribution provide an important new boundary condition to be used in studies on future subglacial hydrology, ice sheet dynamics, and sea level change.

Section: Methodsmentioning

confidence: 99%

Heat Flux Distribution of Antarctica Unveiled

Martos

Catalán

Jordan

et al. 2017

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179

388

“…We used an analysis window size of 350 km with an overlap of 57%, see supporting information and Figures S1–S4. We applied this method to a modified version of the World Digital Magnetic Anomaly Map 2 (Catalán et al, ; Lesur et al, ). This compilation is provided as 5‐km raster resolution grid and includes satellite, airborne, and shipborne data (Figure a), which we upward continued to a uniform altitude of 5 km above sea level on a 5‐km grid.…”

Section: Methodsmentioning

confidence: 99%

Geothermal Heat Flux Reveals the Iceland Hotspot Track Underneath Greenland

Martos

Jordan

Catalán

et al. 2018

Self Cite

153

Curie depths beneath Greenland are revealed by spectral analysis of data from the World Digital Magnetic Anomaly Map 2. A thermal model of the lithosphere then provides a corresponding geothermal heat flux map. This new map exhibits significantly higher frequency but lower amplitude variation than earlier heat flux maps and provides an important boundary condition for numerical ice‐sheet models and interpretation of borehole temperature profiles. In addition, it reveals new geologically significant features. Notably, we identify a prominent quasi‐linear elevated geothermal heat flux anomaly running northwest–southeast across Greenland. We interpret this feature to be the relic of the passage of the Iceland hotspot from 80 to 50 Ma. The expected partial melting of the lithosphere and magmatic underplating or intrusion into the lower crust is compatible with models of observed satellite gravity data and recent seismic observations. Our geological interpretation has potentially significant implications for the geodynamic evolution of Greenland.

“…To help mitigate some of these limitations, localized spherical harmonic Slepian functions (Kim & von Frese, ) are also being developed to integrate the south polar cap's crustal magnetic anomalies from ADMAP‐2 and the Swarm satellite mission (Thébault et al, ). The Slepian coefficients can also directly update global spherical harmonic coefficients, and thus, ADMAP‐2 is poised to substantially upgrade the Antarctic components of the World Digital Magnetic Anomaly Map (Catalán et al, ; Meyer et al, ). In addition, ADMAP‐2 includes magnetic data to extend the Antarctic core field model through 2013 that was developed for extracting crustal anomalies over the 1960–2002 survey period from the ADMAP‐1 compilation (Gaya‐Piqué et al, ; von Frese et al, ).…”

Section: Compilation Proceduresmentioning

confidence: 99%

New Magnetic Anomaly Map of the Antarctic

Golynsky

Ferraccioli

Hong

et al. 2018

104

The second generation Antarctic magnetic anomaly compilation for the region south of 60°S includes some 3.5 million line-km of aeromagnetic and marine magnetic data that more than doubles the initial map's near-surface database. For the new compilation, the magnetic data sets were corrected for the International Geomagnetic Reference Field, diurnal effects, and high-frequency errors and leveled, gridded, and stitched together. The new magnetic data further constrain the crustal architecture and geological evolution of the Antarctic Peninsula and the West Antarctic Rift System in West Antarctica, as well as Dronning Maud Land, the Gamburtsev Subglacial Mountains, the Prince Charles Mountains, Princess Elizabeth Land, and Wilkes Land in East Antarctica and the circumjacent oceanic margins. Overall, the magnetic anomaly compilation helps unify disparate regional geologic and geophysical studies by providing new constraints on major tectonic and magmatic processes that affected the Antarctic from Precambrian to Cenozoic times.Plain Language Summary Given the ubiquitous polar cover of snow, ice, and seawater, the magnetic anomaly compilation offers important constraints on the global tectonic processes and crustal properties of the Antarctic. It also links widely separated areas of outcrop to help unify disparate geologic studies and provides insights on the lithospheric transition between Antarctica and adjacent oceans, as well as the geodynamic evolution of the Antarctic lithosphere in the assembly and breakup of the Gondwana, Rodinia, and Columbia supercontinents and key piercing points for reconstructing linkages between the protocontinents. The magnetic data together with ice-probing radar and gravity information greatly facilitate understanding the evolution of fundamental large-scale geological processes such as continental rifting, intraplate mountain building, subduction and terrane accretion processes, and intraplate basin formation.