Pub Date : 2022-07-20DOI: 10.1080/00288306.2022.2101481
M. Crundwell, A. Woodhouse
{"title":"Biostratigraphically constrained chronologies for Quaternary sequences from the Hikurangi margin of north-eastern Zealandia","authors":"M. Crundwell, A. Woodhouse","doi":"10.1080/00288306.2022.2101481","DOIUrl":"https://doi.org/10.1080/00288306.2022.2101481","url":null,"abstract":"","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47126038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-20DOI: 10.1080/00288306.2022.2099432
A. Woodhouse, P. Barnes, Anthony Shorrock, L. Strachan, M. Crundwell, H. Bostock, J. Hopkins, S. Kutterolf, K. Pank, E. Behrens, A. Greve, R. Bell, A. Cook, K. Petronotis, L. Levay, R. A. Jamieson, T. Aze, L. Wallace, D. Saffer, I. Pecher
{"title":"Trench floor depositional response to glacio-eustatic changes over the last 45 ka, northern Hikurangi subduction margin, New Zealand","authors":"A. Woodhouse, P. Barnes, Anthony Shorrock, L. Strachan, M. Crundwell, H. Bostock, J. Hopkins, S. Kutterolf, K. Pank, E. Behrens, A. Greve, R. Bell, A. Cook, K. Petronotis, L. Levay, R. A. Jamieson, T. Aze, L. Wallace, D. Saffer, I. Pecher","doi":"10.1080/00288306.2022.2099432","DOIUrl":"https://doi.org/10.1080/00288306.2022.2099432","url":null,"abstract":"","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44534810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-11DOI: 10.1080/00288306.2022.2089170
P. Otway, F. Illsley‐Kemp, E. Mestel
{"title":"Taupō volcano’s restless nature revealed by 42 years of deformation surveys, 1979–2021","authors":"P. Otway, F. Illsley‐Kemp, E. Mestel","doi":"10.1080/00288306.2022.2089170","DOIUrl":"https://doi.org/10.1080/00288306.2022.2089170","url":null,"abstract":"","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44410803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-30DOI: 10.1080/00288306.2022.2089171
D. Eberhart‐Phillips, M. Reyners
ABSTRACT Here we update a catalogue of 2001–2011 New Zealand earthquakes relocated with a 3-D seismic velocity model, which has recent improvements. We use P- and S-wave arrival times from earthquakes during 2001–2011 as these were manually picked with assigned quality. We demonstrate the usefulness of the catalogue by considering results from the southern South Island where GeoNet seismograph spacing is large. Later phase data used automatic picking and processing of arrival times. We relocate the 2019–2020 data from National Geohazards Monitoring Centre (NGMC) and compare seismicity patterns to consider its usefulness. We find that the auto-detected crustal earthquakes are more sparse in most of the southern South Island compared to the earlier analyst-picked data period, including Fiordland, which is one of the most seismically active areas in New Zealand. The auto-detected seismicity pattern is also problematic at greater depth and does not show a seismicity band in the lower crust across Southland evident in 2001–2011 data. The detection capability could be improved with a much denser permanent network. We recommend that the 2001–2011 relocated catalogues be used in studies of tectonics and seismic hazard across the South Island, and in studies that consider New Zealand wide seismicity patterns.
{"title":"Catalogue of 2001–2011 New Zealand earthquakes relocated with 3-D seismic velocity model and comparison to 2019–2020 auto-detected earthquakes in the sparsely instrumented southern South Island","authors":"D. Eberhart‐Phillips, M. Reyners","doi":"10.1080/00288306.2022.2089171","DOIUrl":"https://doi.org/10.1080/00288306.2022.2089171","url":null,"abstract":"ABSTRACT Here we update a catalogue of 2001–2011 New Zealand earthquakes relocated with a 3-D seismic velocity model, which has recent improvements. We use P- and S-wave arrival times from earthquakes during 2001–2011 as these were manually picked with assigned quality. We demonstrate the usefulness of the catalogue by considering results from the southern South Island where GeoNet seismograph spacing is large. Later phase data used automatic picking and processing of arrival times. We relocate the 2019–2020 data from National Geohazards Monitoring Centre (NGMC) and compare seismicity patterns to consider its usefulness. We find that the auto-detected crustal earthquakes are more sparse in most of the southern South Island compared to the earlier analyst-picked data period, including Fiordland, which is one of the most seismically active areas in New Zealand. The auto-detected seismicity pattern is also problematic at greater depth and does not show a seismicity band in the lower crust across Southland evident in 2001–2011 data. The detection capability could be improved with a much denser permanent network. We recommend that the 2001–2011 relocated catalogues be used in studies of tectonics and seismic hazard across the South Island, and in studies that consider New Zealand wide seismicity patterns.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48185585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-27DOI: 10.1080/00288306.2022.2090386
E. Crouch, C. Clowes, J. Raine, L. Alegret, M. Cramwinckel, R. Sutherland
{"title":"Latest Cretaceous and Paleocene biostratigraphy and paleogeography of northern Zealandia, IODP Site U1509, New Caledonia Trough, southwest Pacific","authors":"E. Crouch, C. Clowes, J. Raine, L. Alegret, M. Cramwinckel, R. Sutherland","doi":"10.1080/00288306.2022.2090386","DOIUrl":"https://doi.org/10.1080/00288306.2022.2090386","url":null,"abstract":"","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47000247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-22DOI: 10.1080/00288306.2022.2087692
D. King, K. Clark, C. Chagué, Xun Li, E. Lane, B. McFadgen, Jarom Hippolite, Peter Meihana, Billy Wilson, J. Dobson, Pene Geiger, Hamuera Robb, D. Hikuroa, Shaun Williams, R. Morgenstern, F. Scheele
ABSTRACT Informed by Māori oral histories that refer to past catastrophic marine inundations, multi-proxy analysis of stratigraphic records from Swamp Bay, Rangitoto ki te Tonga (D’Urville Island) shows evidence of an anomalous deposit extending some 160 m inland. The deposit includes two distinct lithofacies. The lower sand unit is inferred to have been transported from the marine environment, with corresponding increases in the percentages of benthic marine and brackish–marine diatoms, and geochemical properties indicative of sudden changes in environmental conditions. Radiocarbon dating indicates the deposit formation is less than 402 yrs BP, and pollen indicates it is unlikely to be younger than 1870 CE. Core stratigraphy age models and co-seismic chronologies point to the marine unit most likely being emplaced by tsunami transport associated with rupture of the Wairarapa Fault in 1855 CE. The overlying unit of gravel and silt is inferred to be fluvial deposit and slope-wash from the surrounding hills, loosened by ground-shaking following the earthquake. These findings indicate the 1855 CE earthquake may have been more complex than previously thought and, or, available tsunami modelling does not fully capture the local complexities in bathymetry and topography that can cause hazardous and localized tsunami amplification in embayments like Swamp Bay.
{"title":"Tsunami or storm deposit? A late Holocene sedimentary record from Swamp Bay, Rangitoto ki te Tonga/D’Urville Island, Aotearoa – New Zealand","authors":"D. King, K. Clark, C. Chagué, Xun Li, E. Lane, B. McFadgen, Jarom Hippolite, Peter Meihana, Billy Wilson, J. Dobson, Pene Geiger, Hamuera Robb, D. Hikuroa, Shaun Williams, R. Morgenstern, F. Scheele","doi":"10.1080/00288306.2022.2087692","DOIUrl":"https://doi.org/10.1080/00288306.2022.2087692","url":null,"abstract":"ABSTRACT Informed by Māori oral histories that refer to past catastrophic marine inundations, multi-proxy analysis of stratigraphic records from Swamp Bay, Rangitoto ki te Tonga (D’Urville Island) shows evidence of an anomalous deposit extending some 160 m inland. The deposit includes two distinct lithofacies. The lower sand unit is inferred to have been transported from the marine environment, with corresponding increases in the percentages of benthic marine and brackish–marine diatoms, and geochemical properties indicative of sudden changes in environmental conditions. Radiocarbon dating indicates the deposit formation is less than 402 yrs BP, and pollen indicates it is unlikely to be younger than 1870 CE. Core stratigraphy age models and co-seismic chronologies point to the marine unit most likely being emplaced by tsunami transport associated with rupture of the Wairarapa Fault in 1855 CE. The overlying unit of gravel and silt is inferred to be fluvial deposit and slope-wash from the surrounding hills, loosened by ground-shaking following the earthquake. These findings indicate the 1855 CE earthquake may have been more complex than previously thought and, or, available tsunami modelling does not fully capture the local complexities in bathymetry and topography that can cause hazardous and localized tsunami amplification in embayments like Swamp Bay.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49371071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1080/00288306.2022.2080236
Melody G. Whitehead, M. Bebbington, J. Procter, M. Irwin, G. Viskovic
ABSTRACT There are currently no quantitative short-term eruption forecasts based on peer-reviewed and validated models that are operational for New Zealand’s volcanoes. Specific forecasts produced for work-risk assessments are not generally publicised. During a volcanic crisis, eruption forecasts are demanded under high stress and time-restricted conditions. Many forecasting options exist but none are proven as universally viable, with testing and calibration limited to the hindcasting of specific events. Here, we compare the requirements of six methods with currently available data and monitoring capabilities at each of New Zealand’s volcanoes to determine which methods are currently feasible, as well as those options that may be implemented with additional effort or equipment. In New Zealand, the major limiting factor in method selection is the low number of past instrumentally monitored eruptions. This data gap may be filled by carefully selected analogue data from a global volcano set and expert knowledge. Event trees and the failure forecasting method may be set up at most volcanoes with minimal effort, but the latter can only forecast eruption onset time. Expert interpretation is the only method available in New Zealand for any forecast output type.
{"title":"An initial assessment of short-term eruption forecasting options in New Zealand","authors":"Melody G. Whitehead, M. Bebbington, J. Procter, M. Irwin, G. Viskovic","doi":"10.1080/00288306.2022.2080236","DOIUrl":"https://doi.org/10.1080/00288306.2022.2080236","url":null,"abstract":"ABSTRACT There are currently no quantitative short-term eruption forecasts based on peer-reviewed and validated models that are operational for New Zealand’s volcanoes. Specific forecasts produced for work-risk assessments are not generally publicised. During a volcanic crisis, eruption forecasts are demanded under high stress and time-restricted conditions. Many forecasting options exist but none are proven as universally viable, with testing and calibration limited to the hindcasting of specific events. Here, we compare the requirements of six methods with currently available data and monitoring capabilities at each of New Zealand’s volcanoes to determine which methods are currently feasible, as well as those options that may be implemented with additional effort or equipment. In New Zealand, the major limiting factor in method selection is the low number of past instrumentally monitored eruptions. This data gap may be filled by carefully selected analogue data from a global volcano set and expert knowledge. Event trees and the failure forecasting method may be set up at most volcanoes with minimal effort, but the latter can only forecast eruption onset time. Expert interpretation is the only method available in New Zealand for any forecast output type.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46892919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-25DOI: 10.1080/00288306.2022.2078376
D. Pocknall, C. Clowes, D. Jarzen
ABSTRACT The fossil species Monosulcites prominatus was described from Early Eocene sediments in Canterbury, New Zealand. It resembles the pollen of the mangrove palm Nypa fruticans. Subsequently, the new genus Spinizonocolpites was proposed with a type species, S. echinatus, which we consider to be a junior synonym of S. prominatus. However, S. prominatus has not always been recognised as the type species, with many authors deferring to the ‘original’ type, S. echinatus. Some 37 species of Spinizonocolpites have been described, though several are undoubtedly synonyms. Many have an affinity to Nypa and the earliest appeared in the Late Cretaceous, especially in northern South America, Africa, India and Borneo. The Indian subcontinent appears to have been the global centre of diversity of Nypa-like species during the Paleocene with a high diversity of Spinizonocolpites species. Nypa was most widespread globally during the Eocene, but the onset of global cooling in the late Middle Eocene resulted in the ultimate range contraction to Northern Australia, the Indonesian Archipelago, the Philippine Islands and China present day. The presence of Nypa pollen in sediment samples indicates a mangrove environment of muddy, slow moving tidal estuaries or rivers influenced by fresh and brackish waters.
{"title":"Spinizonocolpites prominatus (McIntyre) Stover & Evans: fossil Nypa pollen, taxonomy, morphology, global distribution, and paleoenvironmental significance","authors":"D. Pocknall, C. Clowes, D. Jarzen","doi":"10.1080/00288306.2022.2078376","DOIUrl":"https://doi.org/10.1080/00288306.2022.2078376","url":null,"abstract":"ABSTRACT The fossil species Monosulcites prominatus was described from Early Eocene sediments in Canterbury, New Zealand. It resembles the pollen of the mangrove palm Nypa fruticans. Subsequently, the new genus Spinizonocolpites was proposed with a type species, S. echinatus, which we consider to be a junior synonym of S. prominatus. However, S. prominatus has not always been recognised as the type species, with many authors deferring to the ‘original’ type, S. echinatus. Some 37 species of Spinizonocolpites have been described, though several are undoubtedly synonyms. Many have an affinity to Nypa and the earliest appeared in the Late Cretaceous, especially in northern South America, Africa, India and Borneo. The Indian subcontinent appears to have been the global centre of diversity of Nypa-like species during the Paleocene with a high diversity of Spinizonocolpites species. Nypa was most widespread globally during the Eocene, but the onset of global cooling in the late Middle Eocene resulted in the ultimate range contraction to Northern Australia, the Indonesian Archipelago, the Philippine Islands and China present day. The presence of Nypa pollen in sediment samples indicates a mangrove environment of muddy, slow moving tidal estuaries or rivers influenced by fresh and brackish waters.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45978008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.1080/00288306.2022.2072904
F. Brook, B. Hayward
ABSTRACT Two species of bulimoid land snails, Maoristylus pliocenicus n. sp. and Archaeostylus n. gen. manukauensis n. sp., in family Bothriembryontidae, subfamily Placostylinae, are described here from fossil shells that were recovered from subsurface Kaawa Formation shelly sediments at Māngere, northern New Zealand. These fossils are of late Pliocene age (Waipipian Stage [latest Zanclean-early Piacenzian], 3.7–3.0 Ma), and are the oldest known representatives of the Placostylinae. The associated fossil fauna indicates that the land snail shells were deposited at shallow subtidal depths in a coastal inlet. The teleoconch of Maoristylus pliocenicus n. sp. has highly distinctive rugose sculpture and in this regard is very similar to modern M. etheridgei (Hedley, 1891) from Lord Howe Island. The latter taxon was described as a subspecies of M. bivaricosus (Gaskoin, 1855), but it is here treated as a separate species on account of its distinctive shell morphology. Archaeostylus n. gen. manukauensis n. sp. has apertural morphology that differs markedly from other taxa in Placostylinae. Rather than being ancestral to extant taxa it probably belonged to a sister lineage. Both it and the M. pliocenicus n. sp. lineage went extinct in New Zealand during latest Pliocene or Pleistocene time, possibly as a consequence of a cooling climate. http://zoobank.org/urn:lsid:zoobank.org:pub:68553D05-C54C-4EFE-AF08-C7E4A17E5B0C
{"title":"Taxonomy and taphonomy of Pliocene bulimoid land snails from Māngere, northern New Zealand, with descriptions of a new genus and two new species (Gastropoda: Bothriembryontidae: Placostylinae)","authors":"F. Brook, B. Hayward","doi":"10.1080/00288306.2022.2072904","DOIUrl":"https://doi.org/10.1080/00288306.2022.2072904","url":null,"abstract":"ABSTRACT Two species of bulimoid land snails, Maoristylus pliocenicus n. sp. and Archaeostylus n. gen. manukauensis n. sp., in family Bothriembryontidae, subfamily Placostylinae, are described here from fossil shells that were recovered from subsurface Kaawa Formation shelly sediments at Māngere, northern New Zealand. These fossils are of late Pliocene age (Waipipian Stage [latest Zanclean-early Piacenzian], 3.7–3.0 Ma), and are the oldest known representatives of the Placostylinae. The associated fossil fauna indicates that the land snail shells were deposited at shallow subtidal depths in a coastal inlet. The teleoconch of Maoristylus pliocenicus n. sp. has highly distinctive rugose sculpture and in this regard is very similar to modern M. etheridgei (Hedley, 1891) from Lord Howe Island. The latter taxon was described as a subspecies of M. bivaricosus (Gaskoin, 1855), but it is here treated as a separate species on account of its distinctive shell morphology. Archaeostylus n. gen. manukauensis n. sp. has apertural morphology that differs markedly from other taxa in Placostylinae. Rather than being ancestral to extant taxa it probably belonged to a sister lineage. Both it and the M. pliocenicus n. sp. lineage went extinct in New Zealand during latest Pliocene or Pleistocene time, possibly as a consequence of a cooling climate. http://zoobank.org/urn:lsid:zoobank.org:pub:68553D05-C54C-4EFE-AF08-C7E4A17E5B0C","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43761055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-19DOI: 10.1080/00288306.2022.2076701
D. Craw, C. Rufaut, Dhanashree Pillai, G. Kerr
ABSTRACT Soil-free sodic salt pans with local pH >10 have formed on loess and schist-derived clay surfaces in the semi-arid climate of Central Otago. This study identifies evaporative mineral distributions and associated variations in surface geochemistry, and these results are relevant to survival of rare halophytic plants on some of the pans. Evaporative salts on pan surfaces are dominated by NaCl from marine aerosols, and Na-sulphates and Na-carbonates. Some of the Na in evaporites was derived from alteration of schist-derived albite and Na-bearing smectite formed from albite. The high pH pan surfaces result from a combination of long-term (decades to millennia) albite alteration and short-term (minutes to months) Na-carbonate dissolution and recrystallisation. This muscovite is variably cemented by evaporative salts, and some crusts have abundant salt-dissolution voids. High pH has facilitated dissolution of aluminium and silica from albite and smectite, with evaporative precipitation of Al-oxyhydroxide contributing to crust cementation. Different dissolution rates of evaporative minerals during rain events and damp seasons results in differential mobility of salt components downslope. The salt pans are physically and chemically dynamic features that have formed on time scales of decades to centuries.
{"title":"Geochemical evolution of high-pH sodic salt pans in Central Otago, New Zealand","authors":"D. Craw, C. Rufaut, Dhanashree Pillai, G. Kerr","doi":"10.1080/00288306.2022.2076701","DOIUrl":"https://doi.org/10.1080/00288306.2022.2076701","url":null,"abstract":"ABSTRACT\u0000 Soil-free sodic salt pans with local pH >10 have formed on loess and schist-derived clay surfaces in the semi-arid climate of Central Otago. This study identifies evaporative mineral distributions and associated variations in surface geochemistry, and these results are relevant to survival of rare halophytic plants on some of the pans. Evaporative salts on pan surfaces are dominated by NaCl from marine aerosols, and Na-sulphates and Na-carbonates. Some of the Na in evaporites was derived from alteration of schist-derived albite and Na-bearing smectite formed from albite. The high pH pan surfaces result from a combination of long-term (decades to millennia) albite alteration and short-term (minutes to months) Na-carbonate dissolution and recrystallisation. This muscovite is variably cemented by evaporative salts, and some crusts have abundant salt-dissolution voids. High pH has facilitated dissolution of aluminium and silica from albite and smectite, with evaporative precipitation of Al-oxyhydroxide contributing to crust cementation. Different dissolution rates of evaporative minerals during rain events and damp seasons results in differential mobility of salt components downslope. The salt pans are physically and chemically dynamic features that have formed on time scales of decades to centuries.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48721261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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