A digital rock density map of New Zealand

Tenzer, Róbert; Sirguey, Pascal; Rattenbury, Mark; Nicolson, Julia

doi:10.1016/j.cageo.2010.07.010

Cited by 65 publications

(39 citation statements)

References 22 publications

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“…Semantic indecision around using the term 'sandstone' rather than 'greywacke' in the middle stages of the QMAP project resulted in some inconsistency in rock name usage between the maps' digital data. These inconsistencies were compensated for by Tenzer et al (2011) who used greywacke as a general term encompassing older, more lithified and weakly metamorphosed sandstone-dominated basement terranes, but including also lithified mudstone, conglomerate and other minor rock types. By this definition greywacke forms 20.5% of New Zealand's surface rock, eclipsed only by unconsolidated sediment and tephra (28.3%).…”

Section: New Zealand's Dominant Rocksmentioning

confidence: 99%

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The QMAP 1:250 000 Geological Map of New Zealand project

Rattenbury¹,

Isaac²

2012

New Zealand Journal of Geology and Geophysics

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In 1994 the QMAP 1:250 000 Geological Map of New Zealand project began with compilation of the Dunedin sheet. Nearly 18 years later, publication of the Hawke's Bay sheet marks the completion of all 21 maps. The adoption of geographic information systems (GIS) software for data capture, data management and map production has not only produced high cartographic quality maps, but also built the attribute-rich, nationally consistent QMAP GIS spatial database. The project cost about NZD $24M, and the results are now being used by government, industry and research organisations across infrastructure, geological hazard, resource and environmental areas. QMAP has added significantly to general knowledge of New Zealand's geological composition and history due to new discoveries and validation of concepts. Notable advances include work on the allochthons of Northland and East Coast; rationalisation of the Taupo Volcanic Zone and East Coast stratigraphic successions; differentiation of the Torlesse basement terranes; clarification of the transition from Otago Schist to Alpine Schist; determining the complex spatial and temporal history of igneous intrusions in Fiordland and Stewart Island; and mapping Quaternary sediments by oxygen isotope stage and depositional processes.

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Section: New Zealand's Dominant Rocksmentioning

confidence: 99%

“…6;Tenzer et al 2011). Many of these rocks belong to the Torlesse composite terrane, a unit that is difficult to subdivide using conventional lithostratigraphy.…”

Section: Greywacke Geologymentioning

confidence: 99%

The QMAP 1:250 000 Geological Map of New Zealand project

Rattenbury¹,

Isaac²

2012

New Zealand Journal of Geology and Geophysics

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“…A mean density of 1685 kg m 23 is reflective of the dominance of recent deposits of relatively unconsolidated sediments in the area. These results are comparatively lower than the mean density of 2670 kg m 23 for materials in the upper continental crust that is commonly used in geological, geophysical, and geodetic applications (Robert et al 2011). Since the soils are dominated by lighter materials, then raindrop impact can easily detach the soil particles from their parent materials.…”

Section: Data Analysis Results and Discussion Of Resultsmentioning

confidence: 94%

An Assessment of the Influences of Surface and Subsurface Water Level Dynamics in the Development of Gullies in Anambra State, Southeastern Nigeria

et al. 2014

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Gully erosion-induced problems have been challenging the people and government of Anambra State in southeastern Nigeria for a long time. In spite of the numerous geoscientific and engineering studies so far conducted in the area, the underlying causes of these problems still remain poorly understood. In an attempt to contribute to the understanding of the underlying processes responsible for the persistent gully erosion problems in Anambra State, an integrated study utilizing hydrological, geomorphological, and geophysical data was undertaken. Results of the analyses show that bulk density, pH, and organic matter content of the soil range from 1610 to 1740 kg m 23 , 5.10 to 5.30, and 0.32% to 0.46%, respectively. Particle size analyses results show that the soils are dominated by coarse sand materials (50%-68%). Variations in the Atterberg limit parameters (liquid limit, plastic limit, and plasticity index) also point to the dominance of coarse materials in the shallow subsurface. Vertical electrical sounding results capture the shallow surface as being dominated by resistive sandy materials that are underlain by lowly resistive clayey materials. Thus, the area is dominated by porous, friable, and poorly cemented coarse materials that are located on a long and steeply sloping terrain of the tectonically elevated Awka-Orlu cuesta. Both overland and subsurface flow processes are responsible for the gully erosion problems confronting the area. Human activities (e.g., deforestation, uncontrolled urbanization, and absence of requisite legislation to protect the environment) and the high elevation of the Awka-Orlu cuesta have aggravated the severity of the problems. An aggressive reforestation program particularly with native trees, promulgation of necessary legislation to protect the environment, and setting up and empowering an enforcement agency should be vigorously pursued. Also, necessary enlightenment campaigns on best agricultural practices that can reduce surface runoff in soil and water conservation may also be helpful in changing the mindset of people.

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“…Some measured density data are available from previous work (King 2002;Cook 2005) but in general, density values used in the models were guided by data from similar rock types (e.g. Tenzer et al 2011).…”

Section: Methodsmentioning

confidence: 99%

“…The relatively high density (and susceptibility) suggests an abundance of mafic metavolcanic rocks (e.g. Tenzer et al 2011). This basement source broadly represents the metamorphic rocks (both metasedimentary and meta-igneous) of the Port aux Basques subzone in southwestern Newfoundland.…”

Section: Correlation Of Major Faults and Terrane Boundaries Across Thmentioning

confidence: 99%

Connecting Cape Breton Island and Newfoundland, Canada: Geophysical Modeling of pre-Carboniferous 'Basement' Rocks in the Cabot Strait Area

Barr

Dehler

Zsámboki³

2014

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Magnetic and gravity data from northeastern Cape Breton Island, southwestern Newfoundland, and the intervening Cabot Strait area were compiled and used to generate a series of maps displaying magnetic (filtered total field, first and second derivative) and gravity (Bouguer anomaly onshore, free-air anomaly offshore) information to enhance the anomaly pattern associated with regional geology. With further constraints from previously published seismic reflection interpretations and detailed maps of onshore geology, five two-dimensional subsurface models were generated. Potential field anomalies in the offshore can be correlated with onshore faults, rock units, and pre-Carboniferous terranes. In Newfoundland, the Cabot – Long Range Fault separates Grenvillian basement to the northwest from peri-Gondwanan Port aux Basques subzone basement in the southeast and can be traced to the Wilkie Brook Fault on Cape Breton Island. The Cape Ray Fault/Red Indian Line merges offshore with the Cabot – Long Range Fault so that Notre Dame subzone rocks do not extend across the Cabot Strait area. The Port aux Basques – Exploits subzone boundary crosses the strait but is likely buried by younger rocks onshore in Cape Breton Island. Magnetic halos in the Exploits subzone are probably caused by Silurian – Devonian plutons like those in the Burgeo Intrusive Suite. The Exploits – Bras d’Or terrane boundary is located within the Ingonish magnetic anomaly, which was resolved into four overlapping components representing basement sources intruded into metasedimentary rocks and dioritic and granodioritic plutons of the Bras d’Or terrane. The Bras d’Or terrane can be traced to the Cinq-Cerf block and Grey River areas in southern Newfoundland. The interpretations suggest that Bras d’Or terrane ‘basement’ may underlie all of Exploits subzone, and that the Aspy terrane of Cape Breton Island is part of that subzone. SOMMAIRELes données magnétométriques et gravimétriques du nord-est de l’île du Cap-Breton, dans le sud-ouest de Terre-Neuve, et de la région du détroit de Cabot contigu, ont été compilées et utilisées pour produire une série de cartes affichant les particularités magnétiques (champ total filtré, dérivé première et seconde) et gravimétriques (anomalie de Bouguer de la côte, anomalie à l’air libre extracôtière) pour ajouter à la compréhension des motifs d’anomalie de la géologie régionale. En tenant compte des limitations imposées par les interprétations de données de levés de sismique réflexion déjà publiées et de cartes détaillées de géologie continentale, cinq modèles 2D du sous-sol ont été produits. Des anomalies de champ potentiel en zone extracôtière peuvent être corrélées avec des failles, des unités lithologiques et des terranes pré-carbonifères sur la côte. Sur l’île de Terre-Neuve, la faille de Cabot-Long Range qui sépare le socle grenvillien au nord-ouest de la sous-zone de socle péri-gondwanienne, de Port-aux- Basques au sud-est, peut être reliée à la faille de Wilkie Brook sur l’île du Cap-Breton. La faille du Cap Ray et la linéation de Red Indian se fondent au large avec la faille de Cabot – Long Range, ce qui signifie que les roches de la sous-zone de Notre-Dame ne traversent pas la région du détroit de Cabot. La limite de la sous-zone de Port aux Basques-Exploits traverse le détroit, mais elle est vraisemblablement enfouie sous des roches plus jeunes sur l’île du Cap-Breton. Les halos magnétiques dans la sous-zone Exploits sont probablement causés par des plutons siluro-dévoniens comme c’est le cas de ceux de la séquence intrusive de Burgeo. La limite du terrane Exploits-Bras d’Or est située dans l’anomalie magnétique Ingonish, laquelle s’est révélée être constituée de quatre composantes superposées représentant des sources de socle engoncées dans des roches métasédimentaires, et dans des plutons dioritiques et granodioritiques du terrane de Bras d’Or. On peut suivre le terrane de Bras d’Or jusque dans les régions du bloc de Cinq-Cerf et de Grey River dans le sud de Terre-Neuve. Les interprétations permettent de penser que le « socle » du terrane de Bras d’Or pourrait constituer l’assise rocheuse de la sous-zone Exploits, et que le terrane Aspy de l’île du Cap-Breton ferait partie de cette sous-zone.

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A digital rock density map of New Zealand

Cited by 65 publications

References 22 publications

The QMAP 1:250 000 Geological Map of New Zealand project

The QMAP 1:250 000 Geological Map of New Zealand project

An Assessment of the Influences of Surface and Subsurface Water Level Dynamics in the Development of Gullies in Anambra State, Southeastern Nigeria

Connecting Cape Breton Island and Newfoundland, Canada: Geophysical Modeling of pre-Carboniferous 'Basement' Rocks in the Cabot Strait Area

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