Geophysical characterisation of large silicic volcanic structures in the Coromandel Peninsula, New Zealand

Malengreau, Barbara; Skinner, D. N. B.; Bromley, Chris; Black, Philippa M.

doi:10.1080/00288306.2000.9514879

Cited by 24 publications

(8 citation statements)

References 14 publications

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“…Residual gravity anomaly map (contour interval is 10 gu) showing correlation of residual anomalies with the mapped geology, particularly the Martha (Waihi) and Favona deposits and the mapped and inferred faults. Malengreau et al, 2000). This closely approximates the density of unaltered andesite in the area (e.g., Hatherton and Leopard, 1964;Locke and de Ronde, 1987).…”

Section: Gravity Data Interpretationsupporting

confidence: 59%

“…Regional magnetic data (Stagpoole et al, 2001) have delineated a number of major features, such as calderas and buried intrusions, and a number of distinct structural trends (Bromley and Brathwaite, 1991;Rabone, 1991;Malengreau et al, 2000). Regional gravity studies (Woodward, 1971) show high values in the west of the peninsula reflecting outcropping or near-surface basement and a series of negative anomalies in the east which are interpreted as resulting from buried calderas (Malengreau et al, 2000;Smith et al, 2006).…”

Section: Geologic Settingmentioning

confidence: 99%

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Geophysical Characteristics of Adularia-Sericite Epithermal Gold-Silver Deposits in the Waihi-Waitekauri Region, New Zealand

et al. 2011

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Aeromagnetic, airborne radiometric, and surface gravity data from the adularia-sericite epithermal province of the Hauraki goldfield have delineated distinct anomalies associated with pervasive hydrothermal alteration and gold-silver mineralization. Aeromagnetic derivative images, particularly the analytic signal, define the boundaries of several magnetic quiet zones that result from magnetite destruction in the volcanic host rocks. Six discrete zones, each of ≤10-km 2 areal extent are evident and are comparable in size to modern-day geothermal systems in the Taupo volcanic zone. An extensive (>20-km 2) zone in the Waitekauri Valley is likely to be the result of multiple overlapping systems, for which there are also analogues in the Taupo volcanic zone that form single large-scale alteration zones up to 100 km 2. Low-pass filtering of the analytic signal data reveals still wider zones of relatively low magnetic intensity interpreted as areas of hydrothermally altered rock extending below younger, unaltered cover. Many of these magnetic quiet zones are aligned along a north-northeast-south-southwest structural corridor, indicating that regional-scale structures may have controlled the location of these geophysical features. Radiometric data delineate local high potassium anomalies that reflect up to 12/100 g potassium enrichment in the core of alteration zones in the form of adularia and illite. A broad K/Th anomaly correlates with the extent of the magnetic quiet zones and indicates widespread potassium enrichment in the Waitekauri-Maratoto area. Gravity data in the Waihi district define a unique, double-peaked, 50-gravity unit positive residual anomaly that correlates closely with the extent of the magnetic quiet zone and the locations of the Waihi and Favona deposits. Preliminary modeling indicates that the anomaly source body, beneath the near-surface, low-density altered andesite, has a volume of up to ~11 km 3 and a minimum density of 2,900 kg m-3. The nature of this source body is enigmatic; possible causes include a dense intrusion, uplifted anomalously dense basement, dense sulfide mineralization, or some combination of these. In addition, the correlation of each of the two gravity peaks with a north-northeast-trending fault may indicate some structural focusing process active at the deposit scale. This integration of geophysical data provides an outstanding case study of the district-to regional-scale geophysical characteristics of a classic epithermal province and demonstrates the strengths of geophysical surveys in the exploration for epithermal mineral deposits.

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Section: Gravity Data Interpretationsupporting

confidence: 59%

Section: Geologic Settingmentioning

confidence: 99%

Geophysical Characteristics of Adularia-Sericite Epithermal Gold-Silver Deposits in the Waihi-Waitekauri Region, New Zealand

et al. 2011

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“…Black (1970) reported allanite-(Ce) and allanite-(La) from metasedimentary units of the Manaia Hill Group near Paritu, in the northwestern part of the Coromandel Peninsula, and ascribed their formation to the remobilization of the REE from the Manaia Hill Group sedimentary rocks by ß uids associated with intrusion of the Paritu pluton. The Whitianga quarry is located on the edge of the Whitianga Caldera (Malengreau et al 2000), which may have provided the heat source for ß uid circulation in the present case.…”

Section: Chemical Compositionmentioning

confidence: 97%

“…These have been extensively altered hydrothermally to various propylitic, argillic and siliceous assemblages, and have been dated at 13.9-15.5 Ma (Adams et al 1994). Recent geophysical investigations by Malengreau et al (2000) point to the existence of a major Late Miocene rhyolitic caldera (15 km diameter) in the region, centered on Whitianga.…”

Section: (Traduit Par La Rédaction)mentioning

confidence: 99%

PINK LANTHANITE-(Nd) FROM WHITIANGA QUARRY, COROMANDEL PENINSULA, NEW ZEALAND

Graham¹,

Pogson²,

Colchester³

et al. 2007

The Canadian Mineralogist

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Lanthanite-(Nd) occurs in tuffaceous, altered andesitic agglomerate in the Whitianga quarry, Coromandel Peninsula, New Zealand. The usual platy habit is represented, together with more unusual blocky equant crystals. The former show the new forms {201}, {102} and {111}, and the latter, {111}. ICP-MS analyses show that the distribution of REE (and Ga) is consistent with the formulation (Nd 0.63 La 0.59 Ce 0.35 Pr 0.15 Sm 0.10 Gd 0.069 Y 0.06 Eu 0.03 Dy 0.02 Ga 0.01) ⌺2.04 (CO 3) 3 •8H 2 O; the REE sum of 2.04 is due solely to rounding errors. The Þ nd represents the Þ rst occurrence of this rare mineral in New Zealand. The mineral formed under comparatively oxidizing conditions. The REE are probably scavenged by warm waters circulating through underlying greywackes of the Manaia Hill Group. We also characterized the lanthanite-(Nd) by X-ray diffraction (powder method) and Raman spectroscopy.

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“…The peninsula has a diverse geology, which is related to the remnant of rhyolite and ignimbrite volcanism (Whitianga Group) with four identified calderas spreading from the center to through the SW of the Peninsula. Meanwhile, the basement is Jurassic greywacke, which can be found in the NW part of the field [17,18], while andesite and dacite groups are the most common rock formations throughout the whole territory from Miocene to Pliocene volcanic activity [12,13,16,[19][20][21][22][23]. Additionally, plutonic rocks such as granite-granodiorite commonly referred to as "Coromandel Granite" in the far north of the peninsula at Paritu Bay have been widely used as decorative building stones across New Zealand between 1900-1970s, for example in New Zealand's Parliament Buildings, the Auckland Chief Post Office, and the Auckland War Memorial Museum [12,13,[24][25][26].…”

Section: Geologymentioning

confidence: 99%

Quantitative-Qualitative Method for Quick Assessment of Geodiversity

Zakharovskyi

Németh

2021

Land

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The article demonstrates a method for quantitative-qualitative geodiversity assessment based on core elements of abiotic nature (geology and geomorphology) according to a proposed weight multiplied by the area of spread through the studied region. The territory of the Coromandel Peninsula was selected as a case study due to its diverse geology and geomorphology. The north part of the Peninsula (Port Jackson, Fletcher Bay and Port Charles districts) was chosen because of the variety of rock types (sedimentary and volcanic groups) covering the region, while historical stratovolcano remnants and old sediments provide a good variety of meadow hills and weathered coastal cliffs. Meanwhile, the method utilizes easily accessible data (topographical and geological map) to assess slope angle (morphometry) and rock groups, including their age (geology) to identify areas in the sample region with significant geodiversity values. Moreover, the aim of this research is to make the assessment of geodiversity simpler and more accessible for various parts of the world with minimal required information. In this paper, we provide access to improve and utilize this method in geologically diverse territories to select the best areas for geotourism, geoeducation and geconservation planning.

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Geophysical characterisation of large silicic volcanic structures in the Coromandel Peninsula, New Zealand

Cited by 24 publications

References 14 publications

Geophysical Characteristics of Adularia-Sericite Epithermal Gold-Silver Deposits in the Waihi-Waitekauri Region, New Zealand

Geophysical Characteristics of Adularia-Sericite Epithermal Gold-Silver Deposits in the Waihi-Waitekauri Region, New Zealand

PINK LANTHANITE-(Nd) FROM WHITIANGA QUARRY, COROMANDEL PENINSULA, NEW ZEALAND

Quantitative-Qualitative Method for Quick Assessment of Geodiversity

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