Geological correlation of magnetic susceptibility and profiles from Nordre Strømfjord, southern West Greenland

Nielsen, Bo Møller; Rasmussen, Thorkild Maack

doi:10.34194/ggub.v191.5128

Cited by 5 publications

(3 citation statements)

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“…Supracrustal rocks within the Nordre Isortoq steep belt are reflected by an aeromagnetic low (c. -300 to -500 nT), while short-wave elongate anomalies with higher amplitude within the steep belt may reflect sheets of orthogneiss or more magnetite-rich supracrustal rocks. This is in agreement with data from more detailed magnetic surface profiles and measured magnetic susceptibilities in the area (Nielsen & Rasmussen 2002). Small, isolated highly magnetic anomalies (c. -100 to 50 nT) within the lows of the steep belt are thought to relate to bodies of granitic or mafic to ultramafic rocks which are not necessarily all exposed.…”

Section: Aeromagnetic Data By Bo Møller Stensgaardsupporting

confidence: 88%

“…The vertical gradient enhances shallow features and sharpens the boundaries/flanks of the anomalies, and is very useful in the interpretation of geological structures and patterns at the surface. Aeromagnetic data and interpretations that include the Ussuit map area are also presented in Rasmussen & van Gool (2000), Nielsen & Rasmussen (2002, Nielsen (2004), and Sørensen et al (2006).…”

Section: Aeromagnetic Data By Bo Møller Stensgaardmentioning

confidence: 99%

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Explanatory notes to the Geological Map of Greenland, 1:100 000, Ussuit 67 V.2 Nord

Gool

Marker

2007

geusm

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NOTE: This Map Description was published in a former series of GEUS Bulletin. Please use the original series name when citing this series, for example: van Gool, J. A., & Marker, M. (2007). Explanatory notes to the Geological Map of Greenland, 1:100 000, Ussuit 67 V.2 Nord. Geological Survey of Denmark and Greenland Map Series 3, 1-40. https://doi.org/10.34194/geusm.v3.4596 _______________ The Ussuit map area is situated around the inner Nassuttooq (Nordre Strømfjord) in central West Greenland, in the core of the Palaeoproterozoic Nagssugtoqidian orogen. The orogen largely consists of reworked Archaean gneisses, as well as Palaeoproterozoic ortho- and paragneisses in its central part. Easy access through the branched fjord system and good exposures along its coastlines, combined with less intense reworking compared to neighbouring areas to the west and south, have made the Ussuit map area the most intensely studied and best known part of the orogen. The most recent research and mapping projects were organised by the Danish Lithosphere Centre (1994–1999) and the Geological Survey of Denmark and Greenland (2000–2001). The predominant rocks are late Archaean tonalitic and granodioritic orthogneisses, intruded by postkinematic granites. Archaean supracrustal rocks are predominantly of mafic composition, but only few have been recognised. Palaeoproterozoic rocks occur as tectonic sheets (the Ussuit unit) which are always in tectonic contact with the Archaean orthogneisses. The most abundant Palaeoproterozoic rock types are biotite schist and biotite-bearing paragneiss, besides orthogneiss of the Arfersiorfik intrusive suite. The latter rocks are mainly deformed quartz diorites intrusive into the metasedimentary rocks and interpreted as remnants of a magmatic arc above a subduction zone. The Ussuit unit also includes amphibolite, marble and calc-silicate rocks, and lenses of ultrabasic rocks. Small bodies of younger syn- and post-tectonic granites occur throughout the map area. The interleaved Palaeoproterozoic and Archaean rocks form a major anticlinal fold structure between two crustal-scale shear zones, the Nordre Strømfjord shear zone in the north and the Nordre Isortoq steep belt in the south. These shear zones formed during the latest ductiledeformation event (D4), following ductile thrusting (D1) and kilometre-scale folding (D2 and D3). The deformation and high grade metamorphism are the result of collision of two Archaean blocks at c. 1850 Ma, with a presumed strongly deformed suture rooted in the southern Ussuit area. No economically feasible mineral occurrences have been discovered to date within the Ussuit map area. Minor sulphide mineralisation related to hydrothermal activity occurs in faults and shear zones, and minor stratabound iron formations have been observed. The most promising industrial mineral deposits are minor diopside occurrences and potential dimension stone in migmatised orthogneiss.

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Section: Aeromagnetic Data By Bo Møller Stensgaardsupporting

confidence: 88%

Section: Aeromagnetic Data By Bo Møller Stensgaardmentioning

confidence: 99%

Explanatory notes to the Geological Map of Greenland, 1:100 000, Ussuit 67 V.2 Nord

Gool

Marker

2007

geusm

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“…mineral content (Nielsen and Rasmussen, 2002). Magnetic susceptibility has been applied in paleoceanography and paleoclimate studies to correlate sedimentary sequence, determine sediment condition (missing or disturb layer), and reconstruct past climate and oceanography conditions (Verosub and Roberts, 1995;Hounslow andMaher, 1999 in Larrasoana et al, 2008).…”

Section: Methodsmentioning

confidence: 99%

Sediment Characteristics of Mergui Basin, Andaman Sea based on Multi-proxy Analyses

Zuraida

Troa

Hendrizan

et al. 2018

BoMG

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This paper presents the characteristics of sediment from core BS-36 (6°55.85’ S and 96°7.48’ E, 1147.1 m water depth) that was acquired in the Mergui Basin, Andaman Sea. The analyses involved megascopic description, core scanning by multi-sensor core logger, and carbonate content measurement. The purpose of this study is to determine the physical and chemical characteristics of sediment to infer the depositional environment. The results show that this core can be divided into 5 lithologic units that represent various environmental conditions. The sedimentation of the bottom part, Units V and IV were inferred to be deposited in suboxic to anoxic bottom condition combined with high productivity and low precipitation. Unit III was deposited during high precipitation and oxic condition due to ocean ventilation. In the upper part, Units II and I occurred during higher precipitation, higher carbonate production and suboxic to anoxic condition.Keywords: sediment characteristics, Mergui Basin, Andaman Sea, suboxic, anoxic, oxic, carbonate content Makalah ini menyajikan karakteristik sedimen contoh inti BS-36 (6°55,85’ LS dan 96°7,48’ BT, kedalaman 1147,1 m) yang diambil di Cekungan Mergui, Laut Andaman. Metode analisis meliputi pemerian megaskopis contoh inti, pemindaian contoh inti dengan menggunakan multi-sensor core logger, dan pengukuran kandungan karbonat. Tujuan penelitian adalah untuk mengetahui karakteristik fisik dan kimiawi sedimen untuk menafsirkan kondisi lingkungan pengendapan. Hasil penelitian menunjukkan bahwa contoh inti ini dapat dibagi menjadi 5 unit litologi yang mewakili kondisi lingkungan yang berbeda. Pada bagian bawah sedimen, Unit V dan IV ditafsirkan sebagai hasil endapan pada kondisi suboksik hingga anoksik pada saat produktivitas tinggi dan curah hujan rendah. Unit III diendapkan pada saat curah hujan tinggi dan kondisi oksik yang diperkirakan berkaitan dengan ventilasi samudera. Pada bagian atas, Unit II dan I diendapkan pada saat curah hujan cukup tinggi dengan produksi karbonat yang cukup besar dan kondisi dasar laut suboksik hingga anoksik. Kata kunci: karakteristik sedimen, Cekungan Mergui, Laut Andaman, suboksik, anoksik, oksik, kandungan karbonat

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Magnetic susceptibilities of rocks of the Antarctic Peninsula: Implications for the redox state of the batholith and the extent of metamorphic zones

et al. 2013

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Geological correlation of magnetic susceptibility and profiles from Nordre Strømfjord, southern West Greenland

Cited by 5 publications

References 10 publications

Explanatory notes to the Geological Map of Greenland, 1:100 000, Ussuit 67 V.2 Nord

Explanatory notes to the Geological Map of Greenland, 1:100 000, Ussuit 67 V.2 Nord

Sediment Characteristics of Mergui Basin, Andaman Sea based on Multi-proxy Analyses

Magnetic susceptibilities of rocks of the Antarctic Peninsula: Implications for the redox state of the batholith and the extent of metamorphic zones

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