ADMAP‐2 (Figure 3) offers the most detailed view to date of the crustal magnetic field over the Antarctic continent and surrounding oceans south of 60°S (e.g., Ferraccioli, Armadillo, Jordan, et al., 2009; Ferraccioli, Armadillo, Zunino, et al., 2009; Golynsky, 2007; Goodge & Finn, 2010; Mieth & Jokat, 2014). It also provides new insights into Antarctica's continent‐ocean transitions (e.g., Davey et al., 2016; Gohl et al., 2013; Granot et al., 2013; König & Jokat, 2006; Leinweber & Jokat, 2012) and the geodynamic evolution of its lithosphere through three cycles of supercontinent assembly and breakup (e.g., Aitken et al., 2014; Aitken, Betts, et al., 2016; Jordan et al., 2017).

ADMAP‐2 compilation of total field magnetic anomalies in shaded‐relief on a polar stereographic projection with central meridian = 0°E longitude and standard parallel = 71°S latitude (Golynsky et al.,). The 1.5‐km grid low‐pass filtered for wavelengths ≥7 km was generated from more than 3.5 million line‐km of airborne and shipborne magnetic observations. Abbreviations include: EBA, Enderby Basin Anomaly; FMA, Forster Magnetic Anomaly; GC, Grunehogna Craton; NC, Napier Craton; PMA, Pacific Margin Anomaly; RC, Ruker Craton; RMA, Robertson Magnetic Anomaly; TOAST, Tonian Oceanic Arc Superterrane; VCB, Valkyrie Cratonic Block. The four white ellipses encircle East Antarctic areas of the strongly negative magnetic anomalies considered in the text.

We provide below selected examples of crustal interpretations of the new aeromagnetic and marine anomaly surveys in ADMAP‐2. They expand previous geological interpretations of the ADMAP‐1 compilation (e.g., Chiappini & von Frese, 1999; von Frese et al., 2002; Ferraccioli et al., 2013) and offer initial starting points for using the new ADMAP‐2 compilation in Antarctic crustal studies.

The Ellsworth‐Whitmore Mountains Block to the east forms the uplifted flank of the WARS that was not affected by widespread Cenozoic magmatism. The aeromagnetic data over the adjacent Möller and Institute Ice Streams' (Figure 2 ) catchments image the inland extent of the older Jurassic Weddell Sea Rift and reveal a major left‐lateral strike‐slip fault that separates East and West Antarctica (Jordan, Ferraccioli, Ross, et al., 2013 ). Prior to the opening of the Weddell Sea Rift, this inferred regional shear zone may have facilitated the emplacement of Jurassic granitic intrusions and accommodated southwards motion of the Ellsworth‐Whitmore Block toward West Antarctica from a position closer to East Antarctica (Jordan, Ferraccioli, Ross, et al., 2013 , 2017 ).

ADMAP‐2 incorporates significant magnetic data sets over much of the West Antarctic Ice Sheet. These new data provide key constraints into the extent of Cenozoic magmatism in the West Antarctic Rift System (WARS), which extends from the Ross Sea Embayment to the Amundsen (Gohl et al., 2013 ; Jordan et al., 2010 ) and possibly Bellingshausen Seas (Eagles et al., 2009 ). As in the Ross Sea sector (Behrendt, 1999 ), the Amundsen Sea Embayment was initially affected by distributed Cretaceous rifting related to New Zealand‐West Antarctica separation (Gohl et al., 2013 ) and subsequent Cenozoic narrow‐mode rifting (Jordan et al., 2010 ). The new aeromagnetic compilation reveals the occurrence of several narrow highly magmatic rift basins between the outcrops of Neogene volcanics in the Hudson Mountains (Figure 2 ), the Pine Island Glacier (Figure 2 ) catchment, and the Marie Byrd Land Dome (Young et al., 2017 ). Some of the proposed subglacial rift basins may also enhance glacial flow into the Amundsen Sea (Smith et al., 2013 ) and Bellingshausen Sea embayments (Bingham et al., 2012 ). Recent Curie depth estimates derived from magnetic data (Gohl et al., 2013 ) provide evidence for high geothermal heat flux offshore of the Thwaites Glacier (Figure 2 ; Dziadek et al., 2017 ) consistent with proposed Cenozoic tectono‐thermal reactivation in this WARS segment (Damiani et al., 2014 ). ADMAP‐2 facilitates extending these results inland into the catchment area of the climatically sensitive glacier and its neighbors.

The Antarctic Peninsula's magnetic data sets contain imprints of a protracted history of crustal growth by Mesozoic arc magmatism along the paleo‐Pacific margin of Gondwana (Ferraccioli et al., 2006 ). The Antarctic Peninsula is a composite crustal block that includes two distinct magmatic arcs, separated by an inferred suture exceeding 1,500 km in length that was likely active during the mid‐Cretaceous Palmer Land event (Vaughan et al., 2012 ). Specifically, combined aeromagnetic, aerogravity, and geological data suggest that a mafic, isotopically juvenile Early Cretaceous western arc marked by the western Pacific Margin Anomaly (Figure 3 ) may have collided against a more felsic eastern continental arc (Ferraccioli et al., 2006 ). This aeromagnetic interpretation, however, is subject to debate, with more recent studies favoring long‐lived in situ arc to back‐arc magmatism in the Antarctic Peninsula throughout the Mesozoic (Burton‐Johnson & Riley, 2015 ). Higher‐resolution aeromagnetic surveys across Adelaide Island (Figure 2 ) also suggest emplacement of extensive Paleogene and Neogene magmatism along part of the inherited Mesozoic arc/fore‐arc boundary (Jordan et al., 2014 ).

3.2 East Antarctica

Joint interpretation of airborne and satellite magnetic anomaly data helps unveil a mosaic of Precambrian provinces in East Antarctica (Ferraccioli et al., 2011). In the absence of outcrop and drilling information, the age of the individual basement provinces and the tectonic processes that led to their assembly remain both uncertain and controversial. A major collisional suture has been postulated to lie between the Archean Ruker Craton and the inferred Proterozoic Gamburtsev Province (Ferraccioli et al., 2011). The inferred suture may correspond to the southern boundary of a Mesoproterozoic‐to‐Neoproterozoic orogenic belt that surrounds the Ruker Province. More speculatively, this orogenic belt may link to eastern Dronning Maud Land, where the Tonian Oceanic Arc Superterrane (TOAST; Figure 3), recognized from geochronological and geochemical studies, may encompass a large sector of East Antarctica (Jacobs et al., 2015). Its subglacial extent has been reevaluated using U‐Pb zircon analyses of glacial drift to also reveal the presence of older Stenian age oceanic arc‐related magmatism (Jacobs et al., 2017).

ADMAP‐2 suggests a possible new interpretation concerning the Gamburtsev Province, in the center of which prominent positive anomalies are comparable to anomalies over the Shackleton Range (SR; Figure 2), which lies more than 1,500 km to the west. The relatively lower resolution aeromagnetic data between the Gamburtsev Province and the SR reveal a sinuous alignment of broadly correlative segmented positive anomalies that, with better future coverage, may prove to be a continuous curvilinear belt.

The positive anomalies of the SR Block reach amplitudes of 500 nT in contrast to the more subdued magnetic anomalies of the neighboring Coats Land Block (Golynsky & Aleshkova, 2000). The Precambrian basement rocks in the SR sustained a strong Ross‐age (ca. 500 Ma) overprint and were thrust over unaltered Paleoproterozoic Read basement (Tessensohn, 1997). The SR hosts exposures of the southeastern margin of the East African‐Antarctic Orogen (Will et al., 2010). Beneath the Recovery, Bailey, and Slessor glaciers (BG, RGl, and SG; Figure 2) that dissect the region along latitudinal trends lie fault‐bounded grabens related to inferred Jurassic and Cretaceous intraplate tectonics (Golynsky & Golynsky, 2012; Paxman et al., 2017) that likely led to reactivation of the inherited basement faults.

Neoproterozoic sedimentary rocks overlying basement in the SR, together with ca. 500 Ma ophiolites (Talarico et al., 1999), high‐pressure (up to eclogite facies) metamorphic rocks (Schmädicke & Will, 2006), and thrust faults suggest the presence of a major suture zone. The inferred suture separates the Coats Land Block (Loewy et al., 2011) from the proposed northernmost edge of the Mawson Continent (Will et al., 2010) and may mark ocean closure linked to left‐lateral transpressional tectonics (Kleinschmidt et al., 2002). Recent aeromagnetic interpretations suggest that the proposed SR suture extends at least 500 km into the interior of East Antarctica, where it changes orientation from E‐W to N‐S in the Recovery Lakes (Figure 2) region (Ferraccioli et al., 2016). However, despite the large magnetic susceptibilities of the exposed ophiolites (e.g., 59.0–350 × 10−3 SI), prominent aeromagnetic anomalies do not overlie the proposed suture in the SR (Sergeyev et al., 1999). This implies that relatively small oceanic crustal remnants are preserved within this part of the suture zone.

To the east of the SR, ADMAP‐2's compilation of the recent ICEGRAV (Gravity measurements over the ice; Forsberg et al., 2018) and Alfred Wegener Institute (Mieth & Jokat, 2014) magnetic data reveals a curvilinear belt of positive magnetic anomalies. It borders the characteristic NW‐trending anomaly fabric of the TOAST on the NE and encircles a poleward‐lying province of more subdued magnetic anomalies that may be related to the presence of cratonic lithosphere (Golynsky, 2007; Ruppel et al., 2018). ADMAP‐2 allows the first relatively complete mapping of the anomaly province labeled the Valkyrie Cratonic Block (Figure 3) for its partial inclusion of the Valkyrie Dome (Herzfeld, 2012). Notably, several different Archean cratonic blocks in East Antarctica exhibit contrasting magnetic signatures, including the Grunehogna Craton (Figure 3; e.g., Golynsky & Aleshkova, 2000; Ferraccioli, Jones, Curtis, Leat, & Riley, 2005; Riedel et al., 2013), the Napier Craton (Figure 3; Golynsky et al., 1996), and the Ruker Craton (Figure 3; e.g., Golynsky, 2007; McLean et al., 2009).

In central Dronning Maud Land, the Forster Magnetic Anomaly (FMA; Figure 3; Riedel et al., 2013) delineates a major tectonic boundary and/or suture zone within the East African‐Antarctic Orogen (Jacobs & Thomas, 2004). The FMA is nearly 400 km long and 65 km wide and consists of segmented linear SW‐NE trending anomalies. The lower amplitude SE‐trending magnetic anomalies between the FMA and Sør Rondane Mountains (Figure 2) may represent sectors of the TOAST that were partially reworked during the inferred Pan‐African age (ca. 600–550 Ma) collision of East Antarctica with Africa and India (e.g., Jacobs et al., 2015; Mieth et al., 2014; Mieth & Jokat, 2014).

Over the eastern shoulder of the Lambert Rift (Harrowfield et al., 2005) that is part of the continental‐scale East Antarctic Rift System (Ferraccioli et al., 2011), a prominent alternating system of linear NE‐SW trending positive and negative magnetic anomalies may be related to outcropping Precambrian gneiss with both igneous and sedimentary protoliths (Laiba & Kudriavtsev, 2006). Although these rocks are virtually identical in age and geochemistry to Beaver Complex rocks on the western side of the rift (Mikhalsky et al., 2013), the two regions have different magnetic anomaly signatures (Golynsky, Masolov, et al., 2006; Golynsky, Golynsky, et al., 2006). Geochemical analyses indicate island arc and volcanic arc settings for the emplacement of the protoliths (Liu et al., 2014), and geochronological data yield protolith ages ranging from ca. 1,347 to 1,020 Ma, indicating long‐lived magmatic accretion within the composite Rayner continental arc. Thus, aeromagnetic surveys over Princess Elizabeth Land image the extent of a continuous Stenian‐age accretional orogen in East Antarctica, which preserves geological records of a protracted accretionary history prior to collision (Liu et al., 2016; Mikhalsky et al., 2015). The prominent Robertson Magnetic Anomaly (Figure 3; Golynsky, Masolov, et al., 2006) reflects amphibolite facies rocks that only crop out at Robertson Nunatak (Figure 2; Mikhalsky et al., 2013). These isotopically juvenile rocks may also represent the remnants of an oceanic arc that crosses the Lambert Rift via a dextral offset of about 50–60 km. This displacement more likely occurred during Phanerozoic transtensional tectonics (Läufer & Phillips, 2007), perhaps during the breakup of India from East Antarctica.

In the Wilkes Land region, Investigating the Cryospheric Evolution of the Central Antarctic Plate (Blankenship et al., 2011) aeromagnetic data enable correlating tectonic provinces of southern Australia with those hidden beneath the East Antarctic Ice Sheet, thereby helping to constrain reconstructions of Australia and Antarctica within the Gondwana, Rodinia, and Nuna supercontinents (Aitken et al., 2014; Aitken, Betts, et al., 2016). These magnetic data also help estimate the thickness of sedimentary fill in the Aurora, Knox, and Sabrina subglacial basins (Aitken et al., 2014; Aitken, Roberts, et al., 2016; Maritati et al., 2016). Further to the east, the new compilation reveals a prominent linear 2,100‐km‐long magnetic minimum that images the edge of the Archean‐to‐Mesoproterozoic Mawson continent, which encompassed Australia's Gawler Craton (Payne et al., 2009) and East Antarctica's Terre Adélie Craton (Gapais et al., 2008).

Within the Wilkes Subglacial Basin (WSB; Figure 2) and Transantarctic Mountains region, the combination of aeromagnetic, airborne radar, and aerogravity observations delineates the regional subglacial geology and deeper crustal architecture at the margin of the composite East Antarctic Craton (e.g., Ferraccioli, Armadillo, Jordan, et al., 2009; Jordan, Ferraccioli, Armadillo, et al., 2013; Studinger et al., 2004). Specifically, aeromagnetic interpretations identify the subglacial distribution of Beacon sediments and Ferrar tholeiites and reveal uplifted, presumed Precambrian and Ross age (ca. 550–460 Ma) basement blocks in the WSB. Magnetic modeling also suggests that post‐Jurassic grabens underlie the central basins of the WSB, perhaps structurally similar to the Rennick Graben (Figure 2) in Northern Victoria Land (Ferraccioli, Armadillo, Jordan, et al., 2009). ADMAP‐2 reveals that these grabens may also extend beneath the ice streams of the Cook Ice Shelf (Figure 2).

A significant tectonic feature identified along the eastern side of the WSB is the Exiles Thrust Fault System under the Matusevich Glacier (Figure 2; Ferraccioli et al., 2003). Combined aeromagnetic data and structural geology indicate that the Exiles Thrust and other thrust faults further to the east were active during the Ross Orogen (Ferraccioli, Bozzo, & Capponi, 2002) and were reactivated during much later intraplate Cenozoic strike‐slip faulting that affected Northern Victoria Land (Ferraccioli & Bozzo, 2003).

ADMAP‐2 also reveals nearly 60 negative anomalies with amplitudes reaching −2,650 nT in East Antarctica (Figure 3, white ellipses). In Northern Victoria Land, these anomalies are possibly related with reversed thermoremanent magnetization of Late Cenozoic McMurdo Volcanics (Ferraccioli, Armadillo, Zunino, et al., 2009; Tonarini et al., 1997). Southward of Law Dome (Figure 2), pronounced negative anomalies form a continuous ~ 650‐km‐long belt consisting of eight anomalies with varying shapes, trends, and intensities in a terrane that Aitken et al. (2014) interpreted as “low‐mag intrusions” linked with Australia's Albany‐Fraser Province and the West Mawson Craton (Figure 2). Three additional anomalies over Law Dome appear to map a continuous source with an extent of about 9,500 km2. These anomalies could potentially mark one of the world's largest mafic/ultramafic intrusions, similar in extent to Norway's Bjerkreim‐Sokndal layered intrusion (McEnroe et al., 2001).