title: Basin analysis of the late Eocene - Oligocene Te Kuiti Group, western North Island, New Zealand

authors: Tripathi, Anand Ratnakar Prasad

subjects: Te Kuiti Group

abstract: The Late Eocene - Oligocene Te Kuiti Group crops out extensively in central-western North Island between Port Waikato and Awakino, providing a useful window for examination of a broadly transgressive shelfal to upper bathyal mixed carbonate-siliciclastic basin fill succession.  The group accumulated during initiation of Cenozoic glaciations on Antarctica when there may have been associated eustatic changes in sea- level changes, and during the initiation of the Australia-Pacific plate boundary through the New Zealand region, which might also have caused relative changes in sea level in the Waikato Basin.

As part of this study Te Kuiti lithostratigraphy in central-western North Island has been reviewed and rationalized. Special emphasis has been given to correlation of the significant stratigraphic discontinuities (erosional unconformities, depositional hiatuses) between units. Combined with a review of the foraminiferal biostratigraphy and new Sr isotope ages for the group, lithologically diverse formations have been able to be correlated across and along the outcrop belt.   In the revised stratigraphic scheme, seven formations and 24 members of Kaiatian to Waitakian (Late Oligocene to Early Miocene) age are identified.  The Te Kuiti Group is subdivided into two subgroups, a lower Okoko Subgroup, and an upper Castle Craig Subgroup. The Okoko Subgroup is dominated by calcareous siltstone and sandstone members, with limestone members commonly occurring at the base of formations, whereas the Castle Craig Subgroup is almost entirely comprised of limestone in the south and by calcareous siltstone in the northern parts of the basin. 

Six unconformity-bound sequences (TK1 - TK6) have been identified and mapped within the Te Kuiti Group using sequence stratigraphic principles.  For several of these sequences (TK2, TK4, TK5  TK6) detailed facies and sequence analyses have been undertaken based on field characteristics, complemented with laboratory grain size and compositional (carbonate % and thin-section) data.  The depositional paleoenvironments have been interpreted for these sequences, with the basin evolution for all sequences summarised in a series of 13 paleogeographic maps representing multiple horizons within the Te Kuiti Group.

TK1 strata are mostly terrestrial coal measures (Waikato Coal Measures) of Late Eocene to earliest Oligocene age that accumulated in paleovalleys concurrent with minor extensional faulting.  The upper beds are marginal marine and consist primarily of estuarine and shallow shelf mudstone (Mangakotuku Formation). The Early Oligocene (lower Whaingaroan) Glen Massey Formation (TK2) is entirely marine in origin, its lowermost member (Elgood Limestone Member) marking a significant marine flooding event across the basin with a landward shift in the position of stratal onlap.  Whaingaroa Formation (TK3) comprises predominantly siltstone with some limestone (Awaroa Limestone Member) at its base in the south, which reflects expansion of a southern shelf area. 

An extensive subaerial unconformity between Whaingaroa Formation (TK3) and Aotea Formation (TK4), combined with a basinward shift in the position of onlap for sequence TK4, indicates a dramatic mid-upper Whaingaroan (c. 29 Ma) change in stratigraphic development and basin dynamics inferred to result from the start of reverse displacement on Taranaki Fault along the basin's western margin.  Aotea Formation comprises lithologically diverse facies dominated by limestone (Waimai Limestone Member) in the north, calcareous sandstone (Hauturu Sandstone Member) in the southwest and muddy sandstone (Kihi Sandstone Member) in south-central and eastern areas.  A condensed section in the upper parts of Aotea Formation, especially in the north, records relative deepening and reduction of clastic sediment supply into sediment-starved northern parts of the basin. 

A major erosional unconformity at the base of the Castle Craig Subgroup in the south and a depositional hiatus in the north reflects a second phase of inversion along the southwestern margin of the basin and reverse displacement on Manganui Fault at c. 27 Ma.  The rocky shorelines that consequently formed along the eastern side of the Herangi High supported carbonate factories supplying reworked carbonate to the adjacent shelf (Orahiri Formation and Otorohanga Limestone).  These formations pass northward into outer shelf-upper bathyal micritic limestone (Raglan Limestone Member) and calcareous siltstone (marl).  Several additional phases of unconformity development are recorded in the Castle Craig Group, but these unconformities had limited extent in the basin, being mainly restricted to the area immediately west of the Herangi High.

Early Miocene Waitemata Group strata unconformably overlie the Te Kuiti Group in the north, reflecting basin inversion and erosion driven from a developing subduction zone to the northeast, whereas early Miocene Mahoenui Group strata in southern parts of the basin are mostly conformable on the Te Kuiti Group, having accumulated in a piggy-back basin carried westward on underlying Taranaki and related faults.  Tectonic movements and cycles of subsidence and subtle basin inversion driven by the alternate accumulation and release of strain on Taranaki and related fault are regarded as the primary control on relative sea-level changes within the Te Kuiti Group, which led to sequences TK4-TK6.  The accumulation of sequences TK1-TK3 resulted from tectonic subsidence in the Waikato region as the zone of extension widened to the east of Taranaki Basin coupled with progressive landward shifts in the position of coastal onlap.  Glacio-eustatic sea- level changes driven from glaciations in Antarctica are not regarded as having generated sea-level changes of sufficient magnitude to impact upon the dynamics of late Eocene and Oligocene sedimentation in the Waikato Basin when the Te Kuiti Group accumulated.

text: Basin analysis of the late Eocene - Oligocene Te Kuiti Group, western North Island, New Zealand The Late Eocene - Oligocene Te Kuiti Group crops out extensively in central-western North Island between Port Waikato and Awakino, providing a useful window for examination of a broadly transgressive shelfal to upper bathyal mixed carbonate-siliciclastic basin fill succession.  The group accumulated during initiation of Cenozoic glaciations on Antarctica when there may have been associated eustatic changes in sea- level changes, and during the initiation of the Australia-Pacific plate boundary through the New Zealand region, which might also have caused relative changes in sea level in the Waikato Basin.

As part of this study Te Kuiti lithostratigraphy in central-western North Island has been reviewed and rationalized. Special emphasis has been given to correlation of the significant stratigraphic discontinuities (erosional unconformities, depositional hiatuses) between units. Combined with a review of the foraminiferal biostratigraphy and new Sr isotope ages for the group, lithologically diverse formations have been able to be correlated across and along the outcrop belt.   In the revised stratigraphic scheme, seven formations and 24 members of Kaiatian to Waitakian (Late Oligocene to Early Miocene) age are identified.  The Te Kuiti Group is subdivided into two subgroups, a lower Okoko Subgroup, and an upper Castle Craig Subgroup. The Okoko Subgroup is dominated by calcareous siltstone and sandstone members, with limestone members commonly occurring at the base of formations, whereas the Castle Craig Subgroup is almost entirely comprised of limestone in the south and by calcareous siltstone in the northern parts of the basin. 

Six unconformity-bound sequences (TK1 - TK6) have been identified and mapped within the Te Kuiti Group using sequence stratigraphic principles.  For several of these sequences (TK2, TK4, TK5  TK6) detailed facies and sequence analyses have been undertaken based on field characteristics, complemented with laboratory grain size and compositional (carbonate % and thin-section) data.  The depositional paleoenvironments have been interpreted for these sequences, with the basin evolution for all sequences summarised in a series of 13 paleogeographic maps representing multiple horizons within the Te Kuiti Group.

TK1 strata are mostly terrestrial coal measures (Waikato Coal Measures) of Late Eocene to earliest Oligocene age that accumulated in paleovalleys concurrent with minor extensional faulting.  The upper beds are marginal marine and consist primarily of estuarine and shallow shelf mudstone (Mangakotuku Formation). The Early Oligocene (lower Whaingaroan) Glen Massey Formation (TK2) is entirely marine in origin, its lowermost member (Elgood Limestone Member) marking a significant marine flooding event across the basin with a landward shift in the position of stratal onlap.  Whaingaroa Formation (TK3) comprises predominantly siltstone with some limestone (Awaroa Limestone Member) at its base in the south, which reflects expansion of a southern shelf area. 

An extensive subaerial unconformity between Whaingaroa Formation (TK3) and Aotea Formation (TK4), combined with a basinward shift in the position of onlap for sequence TK4, indicates a dramatic mid-upper Whaingaroan (c. 29 Ma) change in stratigraphic development and basin dynamics inferred to result from the start of reverse displacement on Taranaki Fault along the basin's western margin.  Aotea Formation comprises lithologically diverse facies dominated by limestone (Waimai Limestone Member) in the north, calcareous sandstone (Hauturu Sandstone Member) in the southwest and muddy sandstone (Kihi Sandstone Member) in south-central and eastern areas.  A condensed section in the upper parts of Aotea Formation, especially in the north, records relative deepening and reduction of clastic sediment supply into sediment-starved northern parts of the basin. 

A major erosional unconformity at the base of the Castle Craig Subgroup in the south and a depositional hiatus in the north reflects a second phase of inversion along the southwestern margin of the basin and reverse displacement on Manganui Fault at c. 27 Ma.  The rocky shorelines that consequently formed along the eastern side of the Herangi High supported carbonate factories supplying reworked carbonate to the adjacent shelf (Orahiri Formation and Otorohanga Limestone).  These formations pass northward into outer shelf-upper bathyal micritic limestone (Raglan Limestone Member) and calcareous siltstone (marl).  Several additional phases of unconformity development are recorded in the Castle Craig Group, but these unconformities had limited extent in the basin, being mainly restricted to the area immediately west of the Herangi High.

Early Miocene Waitemata Group strata unconformably overlie the Te Kuiti Group in the north, reflecting basin inversion and erosion driven from a developing subduction zone to the northeast, whereas early Miocene Mahoenui Group strata in southern parts of the basin are mostly conformable on the Te Kuiti Group, having accumulated in a piggy-back basin carried westward on underlying Taranaki and related faults.  Tectonic movements and cycles of subsidence and subtle basin inversion driven by the alternate accumulation and release of strain on Taranaki and related fault are regarded as the primary control on relative sea-level changes within the Te Kuiti Group, which led to sequences TK4-TK6.  The accumulation of sequences TK1-TK3 resulted from tectonic subsidence in the Waikato region as the zone of extension widened to the east of Taranaki Basin coupled with progressive landward shifts in the position of coastal onlap.  Glacio-eustatic sea- level changes driven from glaciations in Antarctica are not regarded as having generated sea-level changes of sufficient magnitude to impact upon the dynamics of late Eocene and Oligocene sedimentation in the Waikato Basin when the Te Kuiti Group accumulated.

year: 2008

title: Methanotrophic populations in estuarine sediment from Newport Bay, California

authors: McDonald, Ian R.

subjects: Methanotrophs

abstract: Methanotrophic populations have been studied in Newport Bay estuary, Southern California. Environmental clone banks were generated for 16S rRNA genes specific to methanotrophs and for a diagnostic functional gene, pmoA, encoding a conserved subunit of the particulate methane monooxygenase. These clone banks contained sequences specific to types I and II methanotrophs typically found in aquatic environments including freshwater lake and soda lake sediments, aquifers and rice paddies. However, a group of clones that were divergent (93% identity) from known methanotrophic 16S rRNA genes but represented in 16S rRNA gene libraries from other aquatic environments were detected. A group of pmoA sequences divergent (83% identity) from extant methanotrophs and not previously represented in any environmental clone libraries, were also detected. It is concluded that this environment contains significant methanotroph diversity and that some of these may represent novel groups of methanotrophic bacteria.

text: Methanotrophic populations in estuarine sediment from Newport Bay, California Methanotrophic populations have been studied in Newport Bay estuary, Southern California. Environmental clone banks were generated for 16S rRNA genes specific to methanotrophs and for a diagnostic functional gene, pmoA, encoding a conserved subunit of the particulate methane monooxygenase. These clone banks contained sequences specific to types I and II methanotrophs typically found in aquatic environments including freshwater lake and soda lake sediments, aquifers and rice paddies. However, a group of clones that were divergent (93% identity) from known methanotrophic 16S rRNA genes but represented in 16S rRNA gene libraries from other aquatic environments were detected. A group of pmoA sequences divergent (83% identity) from extant methanotrophs and not previously represented in any environmental clone libraries, were also detected. It is concluded that this environment contains significant methanotroph diversity and that some of these may represent novel groups of methanotrophic bacteria.

year: 2006

title: Treatment and survival disparities by ethnicity in New Zealand women with stage I-III breast cancer tumour subtypes

authors: Lawrenson, Ross

subjects: Science & Technology

abstract: Purpose
This study aims to look at the distribution of different subtypes of stage I–III breast cancer in Māori and Pacific versus non-Māori/Pacific women, and to examine cancer outcomes by ethnicity within these different subtypes.

Method
This study included 9,015 women diagnosed with stage I–III breast cancer between June 2000 and May 2013, recorded in the combined Waikato and Auckland Breast Cancer Registers, who had complete data on ER, PR and HER2 status. Five ER/PR/HER2 subtypes were defined. Kaplan–Meier method and Cox proportional hazards model were used to examine ethnic disparities in breast cancer-specific survival.

Results
Of the 9,015 women, 891 were Māori, 548 were Pacific and 7,576 others. Both Māori and Pacific women were less likely to have triple negative breast cancer compared to others (8.6, 8.9 vs. 13.0%). Pacific women were more than twice as likely to have ER−, PR− and HER2+ cancer than Māori and others (14.2 vs. 6.0%, 6.7%). After adjustment for age, year of diagnosis, stage, grade and treatment, the hazard ratios of breast cancer-specific mortality for Māori and Pacific women with ER+, PR+ and HER2− were 1.52 (95% CI 1.06–2.18) and 1.55 (95% CI 1.04–2.31) compared to others, respectively. Māori women with HER2+ cancer were twice more likely to die of their cancer than others.

Conclusions
Outcomes for Māori and Pacific women could be improved by better treatment regimens especially for those with HER2+ breast cancer and for women with ER+, PR+ and HER2− breast cancer.

text: Treatment and survival disparities by ethnicity in New Zealand women with stage I-III breast cancer tumour subtypes Purpose
This study aims to look at the distribution of different subtypes of stage I–III breast cancer in Māori and Pacific versus non-Māori/Pacific women, and to examine cancer outcomes by ethnicity within these different subtypes.

Method
This study included 9,015 women diagnosed with stage I–III breast cancer between June 2000 and May 2013, recorded in the combined Waikato and Auckland Breast Cancer Registers, who had complete data on ER, PR and HER2 status. Five ER/PR/HER2 subtypes were defined. Kaplan–Meier method and Cox proportional hazards model were used to examine ethnic disparities in breast cancer-specific survival.

Results
Of the 9,015 women, 891 were Māori, 548 were Pacific and 7,576 others. Both Māori and Pacific women were less likely to have triple negative breast cancer compared to others (8.6, 8.9 vs. 13.0%). Pacific women were more than twice as likely to have ER−, PR− and HER2+ cancer than Māori and others (14.2 vs. 6.0%, 6.7%). After adjustment for age, year of diagnosis, stage, grade and treatment, the hazard ratios of breast cancer-specific mortality for Māori and Pacific women with ER+, PR+ and HER2− were 1.52 (95% CI 1.06–2.18) and 1.55 (95% CI 1.04–2.31) compared to others, respectively. Māori women with HER2+ cancer were twice more likely to die of their cancer than others.

Conclusions
Outcomes for Māori and Pacific women could be improved by better treatment regimens especially for those with HER2+ breast cancer and for women with ER+, PR+ and HER2− breast cancer.

year: 2017