title: The skeletal carbonate contribution to mixed terrigenous-carbonate sediments on the temperate northeastern Northland continental shelf, New Zealand

authors: Rogers, Danielle Claire

abstract: The northeastern Northland continental shelf (NNCS) includes the coastal, shelf and uppermost slope seafloor out to depths of 210 m and over a distance of 150 km between North Cape and Ngurauru Bay slightly north of Whangarei. The nature of the surficial sediments covering NNCS is poorly known and this study uses archived and recently collected samples to begin to address this situation, with special attention to the nature and distribution of the skeletal carbonate fraction. The sediments are mainly neither carbonate-dominated as occurs in the Three Kings area immediately to the north, nor overwhelmingly terrigenous in nature as typifies more southern shelf sectors. Instead, mixed terrigenous-carbonate deposits prevail in an often patchwork mosaic distribution of facies. Carbonate content is often highest nearshore and in bays and harbours (50-80%), and generally decreases into deeper water (few-50%). The NNCS sediments are almost completely dominated by sand-sized components (60-90%) comprising gravelly sand, sand, muddy sand and gravelly muddy sand textures.

A sedimentary facies model is developed for the NNCS identifying five different facies. Facies 1 is siliciclastic quartzofeldspathic sand with minor bivalve contributions, occurring only in the northern sector. Subfacies 1a (quartz>feldspar) occurs at inner- to mid-shelf depths and is mainly derived from reworked Quaternary Karioitahi Group sand deposits and/or podzolisation and reworking of local soils. Subfacies 1b (feldspar>quartz) occurs in mid- to outer-shelf depths and is derived from the erosion of a combination of the Quaternary sand deposits (Katioitahi Group), Mesozoic basement rocks and Northland volcanic and sedimentary rocks. Facies 2 comprises mixed barnacle-siliciclastic gravel and sand at inner-shelf to uppermost slope depths in the northern sector and includes submarine basaltic and type 1 sedimentary rock fragments derived from Mesozoic basement rocks and the Tangihua Complex of the Northland Allochthon. Facies 3 consists of mixed calcareous red algae and bivalve-siliciclastic gravel and sand at inner- to mid-shelf depths in the southern sector and involves a mix of relict and modern skeletal material and sedimentary rock fragments type 2 sourced from Tertiary deposits. Facies 4 is mixed foraminiferal-siliciclastic sand and mud and occurs only in the very southern sector in two subfacies. Subfacies 4a, a mixed benthic foraminiferal-siliciclastic sand, occurs in mid-shelf depths and comprises plagioclase dominated siliciclastic material sourced from Mesozoic basement rocks. Subfacies 4b, a mixed planktic foraminiferal-siliciclastic sand and mud, occurs in mid- to outer-shelf depths and comprises rock fragments derived from Tertiary deposits which could also be a local source of the reworked planktic foraminifera at these depths. Facies 5 consists of mixed bryozoan-siliciclastic sand at mid-shelf depths and in scattered locations across the NNCS associated with rocky outcrops for bryozoan attachment. Siliciclastic material comprises plagioclase sand sourced from reworking of Mesozoic basement rocks, and sedimentary rock fragments type 2 sourced from Tertiary sediments.
The NNCS sedimentary facies model is compared with other temperate carbonate shelf models and carbonate-rich North Island shelf sectors, including Hauraki Gulf, Three Kings platform, north Kaipara continental margin and Wanganui shelf, which serves to both test and expand scenarios of cool-water carbonate sedimentation established for New Zealand. Overall, the mixed terrigenous-carbonate material on the NNCS comprises an often mosaic facies distribution with the skeletal fraction dominated by bivalve and barnacle fragments and a mixture of relict and modern material. These characteristics reflect several environmental controls, including (a) diversified substrate types (rock, shell, sand, mud); (b) variable supply and dispersal routes of terrigenous material linked to positions of hinterland estuaries/harbours and rocky versus sandy coastlines; (c) scattered and discrete areas of primary carbonate generation (the “carbonate factories”) and the subsequent selective transportation of skeletal grains; (d) local effects of nutrient-rich upwelling; and (e) the variable mix of relict and modern sediment associated with the post-glacial rise of sea level since about 20 ka.

text: The skeletal carbonate contribution to mixed terrigenous-carbonate sediments on the temperate northeastern Northland continental shelf, New Zealand The northeastern Northland continental shelf (NNCS) includes the coastal, shelf and uppermost slope seafloor out to depths of 210 m and over a distance of 150 km between North Cape and Ngurauru Bay slightly north of Whangarei. The nature of the surficial sediments covering NNCS is poorly known and this study uses archived and recently collected samples to begin to address this situation, with special attention to the nature and distribution of the skeletal carbonate fraction. The sediments are mainly neither carbonate-dominated as occurs in the Three Kings area immediately to the north, nor overwhelmingly terrigenous in nature as typifies more southern shelf sectors. Instead, mixed terrigenous-carbonate deposits prevail in an often patchwork mosaic distribution of facies. Carbonate content is often highest nearshore and in bays and harbours (50-80%), and generally decreases into deeper water (few-50%). The NNCS sediments are almost completely dominated by sand-sized components (60-90%) comprising gravelly sand, sand, muddy sand and gravelly muddy sand textures.

A sedimentary facies model is developed for the NNCS identifying five different facies. Facies 1 is siliciclastic quartzofeldspathic sand with minor bivalve contributions, occurring only in the northern sector. Subfacies 1a (quartz>feldspar) occurs at inner- to mid-shelf depths and is mainly derived from reworked Quaternary Karioitahi Group sand deposits and/or podzolisation and reworking of local soils. Subfacies 1b (feldspar>quartz) occurs in mid- to outer-shelf depths and is derived from the erosion of a combination of the Quaternary sand deposits (Katioitahi Group), Mesozoic basement rocks and Northland volcanic and sedimentary rocks. Facies 2 comprises mixed barnacle-siliciclastic gravel and sand at inner-shelf to uppermost slope depths in the northern sector and includes submarine basaltic and type 1 sedimentary rock fragments derived from Mesozoic basement rocks and the Tangihua Complex of the Northland Allochthon. Facies 3 consists of mixed calcareous red algae and bivalve-siliciclastic gravel and sand at inner- to mid-shelf depths in the southern sector and involves a mix of relict and modern skeletal material and sedimentary rock fragments type 2 sourced from Tertiary deposits. Facies 4 is mixed foraminiferal-siliciclastic sand and mud and occurs only in the very southern sector in two subfacies. Subfacies 4a, a mixed benthic foraminiferal-siliciclastic sand, occurs in mid-shelf depths and comprises plagioclase dominated siliciclastic material sourced from Mesozoic basement rocks. Subfacies 4b, a mixed planktic foraminiferal-siliciclastic sand and mud, occurs in mid- to outer-shelf depths and comprises rock fragments derived from Tertiary deposits which could also be a local source of the reworked planktic foraminifera at these depths. Facies 5 consists of mixed bryozoan-siliciclastic sand at mid-shelf depths and in scattered locations across the NNCS associated with rocky outcrops for bryozoan attachment. Siliciclastic material comprises plagioclase sand sourced from reworking of Mesozoic basement rocks, and sedimentary rock fragments type 2 sourced from Tertiary sediments.
The NNCS sedimentary facies model is compared with other temperate carbonate shelf models and carbonate-rich North Island shelf sectors, including Hauraki Gulf, Three Kings platform, north Kaipara continental margin and Wanganui shelf, which serves to both test and expand scenarios of cool-water carbonate sedimentation established for New Zealand. Overall, the mixed terrigenous-carbonate material on the NNCS comprises an often mosaic facies distribution with the skeletal fraction dominated by bivalve and barnacle fragments and a mixture of relict and modern material. These characteristics reflect several environmental controls, including (a) diversified substrate types (rock, shell, sand, mud); (b) variable supply and dispersal routes of terrigenous material linked to positions of hinterland estuaries/harbours and rocky versus sandy coastlines; (c) scattered and discrete areas of primary carbonate generation (the “carbonate factories”) and the subsequent selective transportation of skeletal grains; (d) local effects of nutrient-rich upwelling; and (e) the variable mix of relict and modern sediment associated with the post-glacial rise of sea level since about 20 ka.

year: 2012

title: A new approach to fitting linear models in high dimensional spaces

authors: Wang, Yong

abstract: This thesis presents a new approach to fitting linear models, called “pace regression”, which also overcomes the dimensionality determination problem. Its optimality in minimizing the expected prediction loss is theoretically established, when the number of free parameters is infinitely large. In this sense, pace regression outperforms existing procedures for fitting linear models. Dimensionality determination, a special case of fitting linear models, turns out to be a natural by-product. A range of simulation studies are conducted; the results support the theoretical analysis. 

Through the thesis, a deeper understanding is gained of the problem of fitting linear models. Many key issues are discussed. Existing procedures, namely OLS, AIC, BIC, RIC, CIC, CV(d), BS(m), RIDGE, NN-GAROTTE and LASSO, are reviewed and compared, both theoretically and empirically, with the new methods. 

Estimating a mixing distribution is an indispensable part of pace regression. A measure-based minimum distance approach, including probability measures and nonnegative measures, is proposed, and strongly consistent estimators are produced. Of all minimum distance methods for estimating a mixing distribution, only the nonnegative-measure-based one solves the minority cluster problem, what is vital for pace regression.

Pace regression has striking advantages over existing techniques for fitting linear models. It also has more general implications for empirical modeling, which are discussed in the thesis.

text: A new approach to fitting linear models in high dimensional spaces This thesis presents a new approach to fitting linear models, called “pace regression”, which also overcomes the dimensionality determination problem. Its optimality in minimizing the expected prediction loss is theoretically established, when the number of free parameters is infinitely large. In this sense, pace regression outperforms existing procedures for fitting linear models. Dimensionality determination, a special case of fitting linear models, turns out to be a natural by-product. A range of simulation studies are conducted; the results support the theoretical analysis. 

Through the thesis, a deeper understanding is gained of the problem of fitting linear models. Many key issues are discussed. Existing procedures, namely OLS, AIC, BIC, RIC, CIC, CV(d), BS(m), RIDGE, NN-GAROTTE and LASSO, are reviewed and compared, both theoretically and empirically, with the new methods. 

Estimating a mixing distribution is an indispensable part of pace regression. A measure-based minimum distance approach, including probability measures and nonnegative measures, is proposed, and strongly consistent estimators are produced. Of all minimum distance methods for estimating a mixing distribution, only the nonnegative-measure-based one solves the minority cluster problem, what is vital for pace regression.

Pace regression has striking advantages over existing techniques for fitting linear models. It also has more general implications for empirical modeling, which are discussed in the thesis.

year: 2000

title: Systemic racism in clinical psychology: Symposia

authors: Wairoa-Harrison, Sophia

subjects: Racial oppression

abstract: This study constitutes a part of the Working to End Racial Oppression (WERO) project on Systemic Racism in Health Education, Training, and Practice. The focus is on the three dimensions of racism in psychology in Aotearoa New Zealand: its costs, systems and the potential responses that exist. Content: To set the scene, the session will begin with a 30-minute presentation that outlines evidence from three WERO studies on different levels of racism affecting indigenous Māori and minoritised groups. First study presents findings from a desktop analysis of papers across university psychology departments. The findings will be compared with previous studies (Levy, 2007; Levy & Waitoki, 2015) to identify the changes in inclusion of Māori and culturally focused paper at different timepoints. The second study involves semi-structured interviews with Māori students enrolled in clinical psychology training programmes (n = 19) to understand the extent of cultural responsiveness, support, disparities, and representation within programmes. The third study draws on preliminary survey findings with directors of training programmes to depict the progress towards including taha Māori and cultural competency in the psychology curriculum since the studies by Abbott and Durie (1987) and Nathan (1999). The rest of the session will be conducted as a wānanga or a forum that includes a panel discussion amongst WERO research team while allowing for a reciprocal exchange of knowledge with the attendees. Opportunities will be provided for attendees to ask questions, provide feedback to the research analyses and findings, and share their experiences of witnessing or encountering racism in psychology. The session will be opened with a karakia (prayer) and attendees to be offered manaakitanga (hospitality) and tikanga (custom) to ensure cultural safety. Goals: In this session, the research team will bring the evidence derived from robust analyses on existence and ramifications of racism in psychology to the fore. These findings will be integrated with the Waitangi Tribunal claim (Levy, 2018) to shed light on the manifestations of racism across systems and agents responsible for the regulation, training and employment of psychologists. Findings will be used to inform ways for all in psychology to embark on Te Tiriti-focused, culturally-competent and equitable approaches in the quest of indigenising the psychology discipline and advancing it to be relevant to the multicultural nature of Aotearoa populations.

text: Systemic racism in clinical psychology: Symposia This study constitutes a part of the Working to End Racial Oppression (WERO) project on Systemic Racism in Health Education, Training, and Practice. The focus is on the three dimensions of racism in psychology in Aotearoa New Zealand: its costs, systems and the potential responses that exist. Content: To set the scene, the session will begin with a 30-minute presentation that outlines evidence from three WERO studies on different levels of racism affecting indigenous Māori and minoritised groups. First study presents findings from a desktop analysis of papers across university psychology departments. The findings will be compared with previous studies (Levy, 2007; Levy & Waitoki, 2015) to identify the changes in inclusion of Māori and culturally focused paper at different timepoints. The second study involves semi-structured interviews with Māori students enrolled in clinical psychology training programmes (n = 19) to understand the extent of cultural responsiveness, support, disparities, and representation within programmes. The third study draws on preliminary survey findings with directors of training programmes to depict the progress towards including taha Māori and cultural competency in the psychology curriculum since the studies by Abbott and Durie (1987) and Nathan (1999). The rest of the session will be conducted as a wānanga or a forum that includes a panel discussion amongst WERO research team while allowing for a reciprocal exchange of knowledge with the attendees. Opportunities will be provided for attendees to ask questions, provide feedback to the research analyses and findings, and share their experiences of witnessing or encountering racism in psychology. The session will be opened with a karakia (prayer) and attendees to be offered manaakitanga (hospitality) and tikanga (custom) to ensure cultural safety. Goals: In this session, the research team will bring the evidence derived from robust analyses on existence and ramifications of racism in psychology to the fore. These findings will be integrated with the Waitangi Tribunal claim (Levy, 2018) to shed light on the manifestations of racism across systems and agents responsible for the regulation, training and employment of psychologists. Findings will be used to inform ways for all in psychology to embark on Te Tiriti-focused, culturally-competent and equitable approaches in the quest of indigenising the psychology discipline and advancing it to be relevant to the multicultural nature of Aotearoa populations.

year: 2023-03-25