Pub Date : 2022-02-02DOI: 10.1080/00288306.2021.2021955
A. Nicol, J. Begg, V. Saltogianni, V. Mouslopoulou, O. Oncken, A. Howell
ABSTRACT The Kaikōura Earthquake uplifted Kaikōura Peninsula by ≤∼1 m. Uplift in 2016 mainly resulted from slip on an offshore thrust fault (OSTF), modelled to splay from the plate-interface, and was further influenced by slip on two newly identified faults (Armers Beach Fault, ABF; Te Taumanu Fault, TTF) mapped onshore from differential lidar (D-lidar). Forward dislocation modelling indicates that 2016 peninsula uplift can be reproduced by mean slip of ∼2.3 m on the OSTF and 0.25–0.5 m on the ABF and TTF. The variable co-seismic uplift recorded during the 2016 earthquake differs from the near-uniform (1.2 ± 0.2°) northwest tilting of MIS5c (96 ± 5 ka) and MIS5e (123 ± 5 ka) marine terraces; these ages are constrained by Optically Stimulated Luminescence (OSL) dating and correlation to sea-level curves. Tilting of Late Quaternary marine terraces can be primarily reproduced by slip rates of ∼0.8–2.7 mm/yr on the OSTF and 0.3–0.6 mm/yr on the ABF. Slip on the TTF is not required to produce tilting of the marine terraces, suggesting that it may have ruptured less frequently than the OSTF and ABF in the Late Quaternary. The OSTF links 2016 ruptures north and south of Kaikōura, with the earthquake rupturing an interconnected network of faults.
{"title":"Uplift and fault slip during the 2016 Kaikōura Earthquake and Late Quaternary, Kaikōura Peninsula, New Zealand","authors":"A. Nicol, J. Begg, V. Saltogianni, V. Mouslopoulou, O. Oncken, A. Howell","doi":"10.1080/00288306.2021.2021955","DOIUrl":"https://doi.org/10.1080/00288306.2021.2021955","url":null,"abstract":"ABSTRACT The Kaikōura Earthquake uplifted Kaikōura Peninsula by ≤∼1 m. Uplift in 2016 mainly resulted from slip on an offshore thrust fault (OSTF), modelled to splay from the plate-interface, and was further influenced by slip on two newly identified faults (Armers Beach Fault, ABF; Te Taumanu Fault, TTF) mapped onshore from differential lidar (D-lidar). Forward dislocation modelling indicates that 2016 peninsula uplift can be reproduced by mean slip of ∼2.3 m on the OSTF and 0.25–0.5 m on the ABF and TTF. The variable co-seismic uplift recorded during the 2016 earthquake differs from the near-uniform (1.2 ± 0.2°) northwest tilting of MIS5c (96 ± 5 ka) and MIS5e (123 ± 5 ka) marine terraces; these ages are constrained by Optically Stimulated Luminescence (OSL) dating and correlation to sea-level curves. Tilting of Late Quaternary marine terraces can be primarily reproduced by slip rates of ∼0.8–2.7 mm/yr on the OSTF and 0.3–0.6 mm/yr on the ABF. Slip on the TTF is not required to produce tilting of the marine terraces, suggesting that it may have ruptured less frequently than the OSTF and ABF in the Late Quaternary. The OSTF links 2016 ruptures north and south of Kaikōura, with the earthquake rupturing an interconnected network of faults.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"66 1","pages":"263 - 278"},"PeriodicalIF":2.2,"publicationDate":"2022-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45812144","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 : 2022-01-17DOI: 10.1080/00288306.2021.2021956
Yoshihiro Tanaka, Megan Ortega, R. Fordyce
ABSTRACT The major increase in cetacean brain size happened in the middle Miocene, about 15 million years ago, and involved the modern oceanic dolphin lineage Delphinoidea. In this paper, we describe a new specimen of an archaic dolphin, aff. Prosqualodon davidis, from the Gee Greensand, near Oamaru, New Zealand. The specimen is from the early Miocene, approximately 23–19–18 Ma, and includes an incomplete cranium, endocast, teeth, and some postcranial elements. Comparison of the median sulcus among previously reported endocasts and brains of the Cetacea suggests that the cerebrum was expanded incipiently in the Odontoceti from the early Miocene in the Eurhinodelphinidae + Delphinoidea lineage. Conversely, the olfactory fossa has been reduced in Odontoceti, and completely lost in at least two clades (Delphinoidea and Platanista gangetica), because olfaction was most likely no longer an essential sense for animals spending their life in water. Reduction and loss of the olfactory fossa saved energy, which may be related to the expansion of the cerebrum and cortex in an Odontoceti lineage that led to modern oceanic dolphins. The early Miocene appears to have been a transitional period for archaic and modern-type odontocetes, which were possibly and partly separated by these differences.
{"title":"A new early Miocene archaic dolphin (Odontoceti, Cetacea) from New Zealand, and brain evolution of the Odontoceti","authors":"Yoshihiro Tanaka, Megan Ortega, R. Fordyce","doi":"10.1080/00288306.2021.2021956","DOIUrl":"https://doi.org/10.1080/00288306.2021.2021956","url":null,"abstract":"ABSTRACT The major increase in cetacean brain size happened in the middle Miocene, about 15 million years ago, and involved the modern oceanic dolphin lineage Delphinoidea. In this paper, we describe a new specimen of an archaic dolphin, aff. Prosqualodon davidis, from the Gee Greensand, near Oamaru, New Zealand. The specimen is from the early Miocene, approximately 23–19–18 Ma, and includes an incomplete cranium, endocast, teeth, and some postcranial elements. Comparison of the median sulcus among previously reported endocasts and brains of the Cetacea suggests that the cerebrum was expanded incipiently in the Odontoceti from the early Miocene in the Eurhinodelphinidae + Delphinoidea lineage. Conversely, the olfactory fossa has been reduced in Odontoceti, and completely lost in at least two clades (Delphinoidea and Platanista gangetica), because olfaction was most likely no longer an essential sense for animals spending their life in water. Reduction and loss of the olfactory fossa saved energy, which may be related to the expansion of the cerebrum and cortex in an Odontoceti lineage that led to modern oceanic dolphins. The early Miocene appears to have been a transitional period for archaic and modern-type odontocetes, which were possibly and partly separated by these differences.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"66 1","pages":"59 - 73"},"PeriodicalIF":2.2,"publicationDate":"2022-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43746437","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 : 2022-01-12DOI: 10.1080/00288306.2021.2011328
K. L. Maier, A. Orpin, H. Neil
ABSTRACT Enclosed depressions, termed pockmarks, are widespread seafloor morphologies, commonly associated with fluid seepage. This study provides the first detailed documentation of pockmarks offshore the South Westland margin of the South Island/Te Waipounamu, Aotearoa New Zealand. Pockmarks are identified from multibeam bathymetry (25-m grid) through manual and semi-automated selection in water depths of 100–2600 m. Pockmarks are most concentrated at 400–850 m water depth on continental slope areas between submarine canyons. A continuum of pockmark morphologies includes – (1) large (>0.5 km2 area) and irregularly shaped pockmarks above partially infilled channels; (2) small and circular pockmarks (∼100–200 m diameter; ∼0.008–0.03 km2 area) occurring between canyons; and (3) elongated and intermediate size pockmarks, generally oriented along-slope and often occurring above buried sediment waves. Elongated pockmarks appear to have been modified by near-seafloor oceanographic and/or turbidity current flows. Pockmark features occur across many locations around Aotearoa, including both the eastern and western margins. Some similar pockmark morphologies are identified in these different tectonic, sedimentary, and oceanographic settings, suggesting that there may be some similarity in formative mechanisms, but clear mechanisms leading to their formation remain enigmatic.
{"title":"Seafloor pockmarks on the South Westland margin of the South Island/Te Waipounamu, Aotearoa New Zealand","authors":"K. L. Maier, A. Orpin, H. Neil","doi":"10.1080/00288306.2021.2011328","DOIUrl":"https://doi.org/10.1080/00288306.2021.2011328","url":null,"abstract":"ABSTRACT Enclosed depressions, termed pockmarks, are widespread seafloor morphologies, commonly associated with fluid seepage. This study provides the first detailed documentation of pockmarks offshore the South Westland margin of the South Island/Te Waipounamu, Aotearoa New Zealand. Pockmarks are identified from multibeam bathymetry (25-m grid) through manual and semi-automated selection in water depths of 100–2600 m. Pockmarks are most concentrated at 400–850 m water depth on continental slope areas between submarine canyons. A continuum of pockmark morphologies includes – (1) large (>0.5 km2 area) and irregularly shaped pockmarks above partially infilled channels; (2) small and circular pockmarks (∼100–200 m diameter; ∼0.008–0.03 km2 area) occurring between canyons; and (3) elongated and intermediate size pockmarks, generally oriented along-slope and often occurring above buried sediment waves. Elongated pockmarks appear to have been modified by near-seafloor oceanographic and/or turbidity current flows. Pockmark features occur across many locations around Aotearoa, including both the eastern and western margins. Some similar pockmark morphologies are identified in these different tectonic, sedimentary, and oceanographic settings, suggesting that there may be some similarity in formative mechanisms, but clear mechanisms leading to their formation remain enigmatic.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"66 1","pages":"42 - 58"},"PeriodicalIF":2.2,"publicationDate":"2022-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43825933","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 : 2022-01-02DOI: 10.1080/00288306.2021.2011329
D. Ninis, T. Little, N. Litchfield, Ningsheng Wang, K. Jacobs, C. Henderson
ABSTRACT Along the south coast of the North Island of New Zealand, elevated Pleistocene marine terraces provide evidence for vertical deformation associated with active crustal faults and the westward subduction of the Pacific Plate at the southern Hikurangi margin. We have reassessed the age and elevation of these terraces. Optically Stimulated Luminescence (OSL) data of their cover bed sediments (20 new ages) provide the first numerical ages for most of these terraces. Shore platform elevations have been surveyed using differential Global Navigation Satellite System (GNSS) measurements of the wave-cut bedrock straths underlying these terraces. These new data allow the terraces to be temporally correlated across the margin. Seven different-aged terraces were identified and mapped along the Wellington south coast; these are preserved discontinuously between the westernmost site at Tongue Point, and Ngawi near Cape Palliser, to the east. The OSL data indicate that most of these terraces formed at MIS 5a, 5c, 5e (Last Interglacial) and 7a. The terraces are best preserved within the Hikurangi margin forearc, where they decrease in altitude towards the west, indicating long wavelength, westward tectonic tilting. The terraces are locally offset by a number of active crustal faults, most notably the Wairarapa and Ohariu faults.
{"title":"Pleistocene marine terraces of the Wellington south coast – their distribution across multiple active faults at the southern Hikurangi subduction margin, Aotearoa New Zealand","authors":"D. Ninis, T. Little, N. Litchfield, Ningsheng Wang, K. Jacobs, C. Henderson","doi":"10.1080/00288306.2021.2011329","DOIUrl":"https://doi.org/10.1080/00288306.2021.2011329","url":null,"abstract":"ABSTRACT Along the south coast of the North Island of New Zealand, elevated Pleistocene marine terraces provide evidence for vertical deformation associated with active crustal faults and the westward subduction of the Pacific Plate at the southern Hikurangi margin. We have reassessed the age and elevation of these terraces. Optically Stimulated Luminescence (OSL) data of their cover bed sediments (20 new ages) provide the first numerical ages for most of these terraces. Shore platform elevations have been surveyed using differential Global Navigation Satellite System (GNSS) measurements of the wave-cut bedrock straths underlying these terraces. These new data allow the terraces to be temporally correlated across the margin. Seven different-aged terraces were identified and mapped along the Wellington south coast; these are preserved discontinuously between the westernmost site at Tongue Point, and Ngawi near Cape Palliser, to the east. The OSL data indicate that most of these terraces formed at MIS 5a, 5c, 5e (Last Interglacial) and 7a. The terraces are best preserved within the Hikurangi margin forearc, where they decrease in altitude towards the west, indicating long wavelength, westward tectonic tilting. The terraces are locally offset by a number of active crustal faults, most notably the Wairarapa and Ohariu faults.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"65 1","pages":"242 - 263"},"PeriodicalIF":2.2,"publicationDate":"2022-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47831770","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 : 2022-01-02DOI: 10.1080/00288306.2022.2048032
L. Strachan, J. Bailleul, K. J. Bland, A. Orpin, A. McArthur
ABSTRACT This is the first of a two-part New Zealand Journal of Geology and Geophysics Special Issue that focuses on improving our understanding of sedimentary systems of the Hikurangi Subduction Margin, Aotearoa-New Zealand. It is amongst the world’s youngest and most accessible active subduction margins and its sedimentary basins preserve a rich history of inception and ongoing evolution, spanning trench to back-arc positions. These sediments and sedimentary rocks provide a record of surface processes from the latest Paleogene to today, and reflect the spatio-temporal variability of the effects of subduction, seismicity, volcanism, evolving sediment sources, routing systems and processes, all imprinted upon by glacio-eustatic sea-level changes. The papers in this volume focus on the interplay between controlling mechanisms and the dynamics of these systems, from both onshore and offshore sedimentary environments. This issue is divided into two themes, distinguished by geological age: 1. Miocene Sedimentary Systems and intra-slope basin evolution, and 2. Insights from Quaternary Sedimentary Systems from the trench to the inner margin. Collectively, these papers represent significant advances into our understanding of sedimentary systems within the Hikurangi Subduction Margin, with innovative results that may find applications to other convergent settings.
{"title":"Understanding sedimentary systems and processes of the Hikurangi Subduction Margin; from Trench to Back-Arc. Volume 1","authors":"L. Strachan, J. Bailleul, K. J. Bland, A. Orpin, A. McArthur","doi":"10.1080/00288306.2022.2048032","DOIUrl":"https://doi.org/10.1080/00288306.2022.2048032","url":null,"abstract":"ABSTRACT This is the first of a two-part New Zealand Journal of Geology and Geophysics Special Issue that focuses on improving our understanding of sedimentary systems of the Hikurangi Subduction Margin, Aotearoa-New Zealand. It is amongst the world’s youngest and most accessible active subduction margins and its sedimentary basins preserve a rich history of inception and ongoing evolution, spanning trench to back-arc positions. These sediments and sedimentary rocks provide a record of surface processes from the latest Paleogene to today, and reflect the spatio-temporal variability of the effects of subduction, seismicity, volcanism, evolving sediment sources, routing systems and processes, all imprinted upon by glacio-eustatic sea-level changes. The papers in this volume focus on the interplay between controlling mechanisms and the dynamics of these systems, from both onshore and offshore sedimentary environments. This issue is divided into two themes, distinguished by geological age: 1. Miocene Sedimentary Systems and intra-slope basin evolution, and 2. Insights from Quaternary Sedimentary Systems from the trench to the inner margin. Collectively, these papers represent significant advances into our understanding of sedimentary systems within the Hikurangi Subduction Margin, with innovative results that may find applications to other convergent settings.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"65 1","pages":"1 - 16"},"PeriodicalIF":2.2,"publicationDate":"2022-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49298913","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 : 2021-11-22DOI: 10.1080/00288306.2021.1995007
J. Griffin, M. Stirling, D. Barrell, E. J. van den Berg, E. Todd, Ross Nicolls, Ningsheng Wang
ABSTRACT We present the first paleoseismic investigation of the Hyde Fault, one of a series of north-east striking reverse faults within the Otago range and basin province in southern New Zealand. Surface traces of the fault and associated geomorphology were mapped using a lidar digital elevation model and field investigations. Trenches were excavated at two sites across fault scarps on alluvial fan surfaces. The trenches revealed stratigraphic evidence for four surface-rupturing earthquakes. Optically stimulated luminescence dating constrains the timing of these events to around 47.2 ka (37.5–56.7 ka at 95% confidence), 34.6 ka (24.7–46.4 ka), 23.5 ka (19.7–27.3 ka) and 10.5 ka (7.9–13.1 ka). We obtain a mean inter-event time of 12.4 kyr (2.3–23.9 kyr at 95% confidence) and the slip rate is estimated to be 0.22 mm/yr (0.15–0.3 mm/yr). We do not find evidence to suggest that earthquake recurrence on the Hyde Fault is episodic, in contrast to other well-studied faults within Otago, suggesting diverse recurrence styles may co-exist in the same fault system. This poses challenges for characterising the seismic hazard potential of faults in the region, particularly when paleoearthquake records are limited to the most recent few events.
海德断裂是新西兰南部奥塔哥山脉和盆地省一系列东北走向逆断层之一，我们对其进行了首次古地震调查。利用激光雷达数字高程模型和实地调查绘制了断层和相关地貌的表面轨迹。在冲积扇表面断层陡坡上的两个地点开挖了沟槽。这些海沟揭示了四次地表破裂地震的地层证据。光激发发光测年将这些事件的时间限制在47.2 ka(95%置信度37.5-56.7 ka)、34.6 ka (24.7-46.4 ka)、23.5 ka (19.7-27.3 ka)和10.5 ka (7.9-13.1 ka)左右。我们得到的平均事件间时间为12.4 kyr(95%置信度为2.3-23.9 kyr)，滑移率估计为0.22 mm/yr (0.15-0.3 mm/yr)。我们没有发现证据表明Hyde断层的地震复发是幕式的，与奥塔哥其他研究充分的断层相反，这表明不同的地震复发类型可能在同一断层系统中共存。这对描述该地区断层的潜在地震危险性提出了挑战，特别是当古地震记录仅限于最近的几个事件时。
{"title":"Paleoseismology of the Hyde Fault, Otago, New Zealand","authors":"J. Griffin, M. Stirling, D. Barrell, E. J. van den Berg, E. Todd, Ross Nicolls, Ningsheng Wang","doi":"10.1080/00288306.2021.1995007","DOIUrl":"https://doi.org/10.1080/00288306.2021.1995007","url":null,"abstract":"ABSTRACT We present the first paleoseismic investigation of the Hyde Fault, one of a series of north-east striking reverse faults within the Otago range and basin province in southern New Zealand. Surface traces of the fault and associated geomorphology were mapped using a lidar digital elevation model and field investigations. Trenches were excavated at two sites across fault scarps on alluvial fan surfaces. The trenches revealed stratigraphic evidence for four surface-rupturing earthquakes. Optically stimulated luminescence dating constrains the timing of these events to around 47.2 ka (37.5–56.7 ka at 95% confidence), 34.6 ka (24.7–46.4 ka), 23.5 ka (19.7–27.3 ka) and 10.5 ka (7.9–13.1 ka). We obtain a mean inter-event time of 12.4 kyr (2.3–23.9 kyr at 95% confidence) and the slip rate is estimated to be 0.22 mm/yr (0.15–0.3 mm/yr). We do not find evidence to suggest that earthquake recurrence on the Hyde Fault is episodic, in contrast to other well-studied faults within Otago, suggesting diverse recurrence styles may co-exist in the same fault system. This poses challenges for characterising the seismic hazard potential of faults in the region, particularly when paleoearthquake records are limited to the most recent few events.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"65 1","pages":"613 - 637"},"PeriodicalIF":2.2,"publicationDate":"2021-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44450630","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 : 2021-11-14DOI: 10.1080/00288306.2021.1996401
P. Williams
ABSTRACT The hill country of west central North Island, west of Te Kuiti and Otorohanga, is recognised to be slowly uplifting and relatively stable. The New Zealand national seismic hazard model shows the area to be in a low-risk zone and the New Zealand active faults database recognises no active faults in the region. However, dated evidence provided by speleothems in a cave near Waitomo indicates the intermittent movement of the Okohua fault from before the Last Interglacial until around 38 kyrs ago. Evidence of older movement along the Waipa Fault near Te Kuiti is also apparent from the vertical displacement of the Ngaroma ignimbrite (1.55 Myrs) by about 150 m in the interval prior to the deposition of the Ongatiti ignimbrite at 1.21 Myrs. Net uplift in the West Waikato Hills and Ranges, by about 0.1 mm/yr in the Late Quaternary, is accommodated in a series of NNE-trending faults and transverse faults, resulting in a staircase of fault-bound blocks rising westwards from Waitomo to the western watershed of the Waipa basin. Geomorphologically fresh cliffed lineaments on the Okohua and Hikurangi faults convey evidence of mid to late Quaternary fault activity.
{"title":"Quaternary uplift and fault movement near Waitomo, North Island, New Zealand","authors":"P. Williams","doi":"10.1080/00288306.2021.1996401","DOIUrl":"https://doi.org/10.1080/00288306.2021.1996401","url":null,"abstract":"ABSTRACT The hill country of west central North Island, west of Te Kuiti and Otorohanga, is recognised to be slowly uplifting and relatively stable. The New Zealand national seismic hazard model shows the area to be in a low-risk zone and the New Zealand active faults database recognises no active faults in the region. However, dated evidence provided by speleothems in a cave near Waitomo indicates the intermittent movement of the Okohua fault from before the Last Interglacial until around 38 kyrs ago. Evidence of older movement along the Waipa Fault near Te Kuiti is also apparent from the vertical displacement of the Ngaroma ignimbrite (1.55 Myrs) by about 150 m in the interval prior to the deposition of the Ongatiti ignimbrite at 1.21 Myrs. Net uplift in the West Waikato Hills and Ranges, by about 0.1 mm/yr in the Late Quaternary, is accommodated in a series of NNE-trending faults and transverse faults, resulting in a staircase of fault-bound blocks rising westwards from Waitomo to the western watershed of the Waipa basin. Geomorphologically fresh cliffed lineaments on the Okohua and Hikurangi faults convey evidence of mid to late Quaternary fault activity.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"66 1","pages":"1 - 11"},"PeriodicalIF":2.2,"publicationDate":"2021-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42384057","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 : 2021-11-12DOI: 10.1080/00288306.2021.1994425
Kate E. MacDonald, D. Hart, Sebastian J. Pitman
ABSTRACT Along the northeast coast of New Zealand’s South Island, a 7.8 Mw earthquake on the 14th of November 2016 induced instantaneous uplift of approximately 1 m around the Kaikōura Peninsula. This paper documents a unique field study examining short-term responses in the Mixed Sand and Gravel (MSG) beaches of Kaikōura to a relative sea level fall as a result of this event. We present two conceptual response pathway models which consider the pre-earthquake trends of 18 coastal sites, and two surveys taken over a 22 month period following the earthquake to define the short-term response of MSG beaches to instantaneous relative sea level fall. This study found MSG beach responses vary strongly according to their pre-quake sediment supply, source connectivity and open coast exposure characteristics. Overall, there were two predominant trends in which the beaches were responding in the short-term post-earthquake environment: accretionary profiles and erosional profiles. The difference between these two profile response types can be summarised as pre-earthquake erosional profiles were found to be retreating to pre-earthquake extents 22 months post-earthquake, whilst pre-earthquake accretional and dynamic beaches had an increased or stable trend which promoted stability or growth in beach volume post relative sea level fall.
{"title":"Geomorphic responses of uplifted mixed sand and gravel beaches: combining short-term observations from Kaikōura, New Zealand with longer-term evidence","authors":"Kate E. MacDonald, D. Hart, Sebastian J. Pitman","doi":"10.1080/00288306.2021.1994425","DOIUrl":"https://doi.org/10.1080/00288306.2021.1994425","url":null,"abstract":"ABSTRACT Along the northeast coast of New Zealand’s South Island, a 7.8 Mw earthquake on the 14th of November 2016 induced instantaneous uplift of approximately 1 m around the Kaikōura Peninsula. This paper documents a unique field study examining short-term responses in the Mixed Sand and Gravel (MSG) beaches of Kaikōura to a relative sea level fall as a result of this event. We present two conceptual response pathway models which consider the pre-earthquake trends of 18 coastal sites, and two surveys taken over a 22 month period following the earthquake to define the short-term response of MSG beaches to instantaneous relative sea level fall. This study found MSG beach responses vary strongly according to their pre-quake sediment supply, source connectivity and open coast exposure characteristics. Overall, there were two predominant trends in which the beaches were responding in the short-term post-earthquake environment: accretionary profiles and erosional profiles. The difference between these two profile response types can be summarised as pre-earthquake erosional profiles were found to be retreating to pre-earthquake extents 22 months post-earthquake, whilst pre-earthquake accretional and dynamic beaches had an increased or stable trend which promoted stability or growth in beach volume post relative sea level fall.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"66 1","pages":"228 - 243"},"PeriodicalIF":2.2,"publicationDate":"2021-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43222901","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 : 2021-11-08DOI: 10.1080/00288306.2021.1996402
Jamie Cudby, J. Scott, D. Craw, Mark Hesson, C. Rufaut
ABSTRACT The historic Come-In-Time gold mine was developed in a ∼100*100 m area of the >7 km long orogenic Rise and Shine Shear Zone in Otago Schist. The oxidation of hydrothermal ankeritic and auriferous arsenopyrite and pyrite-bearing Otago Schist beneath a regional Miocene unconformity resulted in replacement of sulphides and ankerite by arsenic (As)-bearing ferric oxyhydroxide. The As-bearing ferric oxyhydroxide is mainly concentrated in and near the original mineralisation sites, especially shears, but mobilisation into post-mineralisation joints and fractures has redistributed As on a metre scale. Gold was liberated from sulphides during oxidation and aggregated by supergene oxidation processes into a smaller number of larger particles (mm scale) that are intimately intergrown with As-bearing ferric oxyhydroxide, especially in shears. Eluvial gold in proximal immature debris includes variably rounded supergene particles eroded from nearby, and some externally derived detrital flakes from previously overlying Miocene sediments. Some eluvial gold is trapped in fine sediments by lichen on outcrops. The hydrothermal As-Au relationship has therefore been broadly maintained through oxidation of rocks at the metre scale but Au concentrations have been locally enhanced in the surficial environment.
{"title":"Surficial redistribution of gold and arsenic from the Rise and Shine Shear Zone, Otago, New Zealand","authors":"Jamie Cudby, J. Scott, D. Craw, Mark Hesson, C. Rufaut","doi":"10.1080/00288306.2021.1996402","DOIUrl":"https://doi.org/10.1080/00288306.2021.1996402","url":null,"abstract":"ABSTRACT\u0000 The historic Come-In-Time gold mine was developed in a ∼100*100 m area of the >7 km long orogenic Rise and Shine Shear Zone in Otago Schist. The oxidation of hydrothermal ankeritic and auriferous arsenopyrite and pyrite-bearing Otago Schist beneath a regional Miocene unconformity resulted in replacement of sulphides and ankerite by arsenic (As)-bearing ferric oxyhydroxide. The As-bearing ferric oxyhydroxide is mainly concentrated in and near the original mineralisation sites, especially shears, but mobilisation into post-mineralisation joints and fractures has redistributed As on a metre scale. Gold was liberated from sulphides during oxidation and aggregated by supergene oxidation processes into a smaller number of larger particles (mm scale) that are intimately intergrown with As-bearing ferric oxyhydroxide, especially in shears. Eluvial gold in proximal immature debris includes variably rounded supergene particles eroded from nearby, and some externally derived detrital flakes from previously overlying Miocene sediments. Some eluvial gold is trapped in fine sediments by lichen on outcrops. The hydrothermal As-Au relationship has therefore been broadly maintained through oxidation of rocks at the metre scale but Au concentrations have been locally enhanced in the surficial environment.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"66 1","pages":"12 - 26"},"PeriodicalIF":2.2,"publicationDate":"2021-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46905143","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 : 2021-11-03DOI: 10.1080/00288306.2021.1986727
Thomas Brough, A. Nicol, T. Stahl, J. Pettinga, R. Dissen, D. Clark, N. Khajavi, K. Pedley, R. Langridge, Ningsheng Wang
ABSTRACT The 2016 MW 7.8 Kaikōura Earthquake nucleated on The Humps fault, which ruptured across the Emu Plain in North Canterbury. The paleoearthquake history of the fault was poorly constrained prior to the 2016 earthquake. To determine the timing and single-event displacements (SED) of earthquakes on the fault we use Optically Stimulated Luminescence (OSL) and radiocarbon dates of faulted stratigraphy and analysis of faulting (i.e. geometry and slip) at the McLean-1 trench site. At the trench the fault trace trends east–west and primarily accommodated right-lateral strike-slip in 2016 (2 ± 0.2 m strike slip and 0.35 ± 0.05 m vertical slip northside downthrow). The Humps fault is more seismically active than previously thought and accrued slip during at least six surface rupturing paleoearthquakes. The timing of these earthquakes was: 9.8–15.3 ka BP (Event 1), 8.6–11.5 ka BP (Event 2), 8.1–10.9 ka BP (Event 3), 6.0–8.6 ka BP (Event 4), 1840 AD to 4.5 ka (Event 5), and 2016 AD (Event 6). These earthquakes have a mean recurrence interval of 1.8–3.4 kyr and could have recurrence intervals up to ~9 kyr. Kaikōura-type ruptures could occur as frequently as every ∼2 kyr and maybe longer if The Humps fault rupture geometries are not characteristic.
摘要：2016年凯库拉7.8兆瓦地震以驼峰断层为核，该断层在坎特伯雷北部的埃穆平原断裂。在2016年地震之前，断层的古地震历史受到了很差的约束。为了确定断层上地震的时间和单次事件位移（SED），我们使用了光学激发发光（OSL）和断层地层学的放射性碳年代，以及McLean-1海沟现场断层（即几何结构和滑动）的分析。在海沟处，断层走向为东西走向，主要适应2016年的右侧走滑（2 ± 0.2 m走滑和0.35 ± 0.05 m垂直滑动北侧下降）。Humps断层的地震活动比以前认为的要活跃，在至少六次地表破裂的古地震中发生了滑动。这些地震发生的时间为：9.8–15.3 ka BP（事件1），8.6–11.5 ka BP（事件2），8.1–10.9 ka BP（事件3），6.0–8.6 ka BP（事件4），公元1840年至4.5年 ka（事件5）和2016 AD（事件6）。这些地震的平均重现期为1.8-3.4 kyr，复发间隔可达~9 kyr。Kaikōura型破裂的频率可能高达每2次 kyr，如果驼峰断层破裂几何形状不是特征性的，则可能更长。
{"title":"Paleoseismicity of the western Humps fault on the Emu Plain, North Canterbury, New Zealand","authors":"Thomas Brough, A. Nicol, T. Stahl, J. Pettinga, R. Dissen, D. Clark, N. Khajavi, K. Pedley, R. Langridge, Ningsheng Wang","doi":"10.1080/00288306.2021.1986727","DOIUrl":"https://doi.org/10.1080/00288306.2021.1986727","url":null,"abstract":"ABSTRACT The 2016 MW 7.8 Kaikōura Earthquake nucleated on The Humps fault, which ruptured across the Emu Plain in North Canterbury. The paleoearthquake history of the fault was poorly constrained prior to the 2016 earthquake. To determine the timing and single-event displacements (SED) of earthquakes on the fault we use Optically Stimulated Luminescence (OSL) and radiocarbon dates of faulted stratigraphy and analysis of faulting (i.e. geometry and slip) at the McLean-1 trench site. At the trench the fault trace trends east–west and primarily accommodated right-lateral strike-slip in 2016 (2 ± 0.2 m strike slip and 0.35 ± 0.05 m vertical slip northside downthrow). The Humps fault is more seismically active than previously thought and accrued slip during at least six surface rupturing paleoearthquakes. The timing of these earthquakes was: 9.8–15.3 ka BP (Event 1), 8.6–11.5 ka BP (Event 2), 8.1–10.9 ka BP (Event 3), 6.0–8.6 ka BP (Event 4), 1840 AD to 4.5 ka (Event 5), and 2016 AD (Event 6). These earthquakes have a mean recurrence interval of 1.8–3.4 kyr and could have recurrence intervals up to ~9 kyr. Kaikōura-type ruptures could occur as frequently as every ∼2 kyr and maybe longer if The Humps fault rupture geometries are not characteristic.","PeriodicalId":49752,"journal":{"name":"New Zealand Journal of Geology and Geophysics","volume":"66 1","pages":"279 - 292"},"PeriodicalIF":2.2,"publicationDate":"2021-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42482945","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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