title: Nature, Distribution, Origin and Economics of Glauconite in Carbonate-Phosphate-Glauconite Surficial Deposits on Central Chatham Rise, Southwest Pacific

authors: Lawless, Anna Shanti

subjects: Glauconite

abstract: Chatham Rise is a broad, elongated submarine platform that extends 1100 km out into the Southwest Pacific off eastern South Island. The surficial sediments on the central portion of the Rise at depths of 200-500 m include significant concentrations of the mineral glauconite (10-80 wt%) associated with skeletal carbonate, fine terrigenous material and locally abundant phosphatic nodules. This is the first study to fully analyse the nature, origin and economic potential of the glauconite component. Sub-bottom 3.5 kHz profiles have established the distribution, geometry and thickness (10-200 cm) of the surficial deposits, which overlie partially indurated Oligocene chalk of probable Whaingaroan age (~34-27 Ma). 137 grab, dredge or piston core samples have been analysed for their texture, mineralogy and geochemistry, which has produced a new surficial sediment map for the central Chatham Rise.

Glauconite most commonly occurs as dark green to black, very fine to fine sand-sized (0.2 mm), polished ovoidal and lobate pellets, and less commonly as infills within foraminiferal tests or as variably replaced rock fragments and phosphatic clasts. Full physical analysis reveals seven morphological types of glauconite including, in order of decreasing abundance, ovoidal, lobate, composite, internal molds, fossil casts, pigmentary, tabular and pellets within rock fragments. Their internal fabrics are dominated by random microcrystalline varieties with some oriented fibroradiating rim and skeletal infill types. Other notable features of some glauconite pellets include their expansion cracks, opaque inclusions and variable degrees of limonitisation. XRF/XRD analyses reveal mainly diagenetically mature varieties having elevated K2O (7-9 wt%) and Fe2O3 (19-23 wt%) values, and a dominant 10Å glauconitic mica structure involving from 10-20% expandable smectite layers.

K-Ar dates on pellets indicate a Late Miocene age (av. 5.75 Ma). This “old” age, as well as the clear evidence of reworking shown by the dominance of smooth polished ovoidal grains, mean that the central Chatham Rise glauconites are predominantly allogenic (i.e. derived/reworked), and neither strictly authigenic nor in situ, despite occurring in “modern” seafloor deposits. The formation of glauconite is linked to prominent upwelling within the Subtropical Front (STF) zone over the Rise in the Late Miocene, and the attendant heightened primary productivity, bacterial activity and nutrients associated with widespread biogenic blooms at that time. The source of the smectite required for glauconite formation could have been from the devitrification of volcanic ash from diverse eruptive centres, or through “neoformation”/authigenic precipitation within pore water solutions of carbonate-rich waters in the Oligocene/Miocene chalk substrate. Glauconite formation largely ceased after the Late Miocene due to an increase in terrigenous input, a reduced smectite source, and a major period of lowered sea level associated with Antarctic ice sheet growth. The “modern” Chatham glauconite pellets were sourced from submarine erosion of the former Late Miocene sediments and have been dispersed by intensified bottom current circulation at times of lowered sea level within the complex STF over Chatham Rise, and possibly ice scouring. Effectively there exists a widespread “Chatham unconformity” (mid-Oligocene to Recent) which cuts out most of the last 30 myr of the sedimentary record on central Chatham Rise, except for the highly condensed surficial deposits whose glauconite grains formed 5-6 Ma, in the Late Miocene. This long-lasting “Chatham unconformity” is a greatly extended version of the well documented Oligocene Marshall Paraconformity.

The thickness of the surficial sediment cover on central Chatham Rise ranges from 0.06-1.35 m. By using a conservative estimate of 0.5 m thick, and the wt% of glauconite within the sediment cover, a resource estimate of the glauconite has been made for various areas. In the most glauconite-rich area (>50 wt% glauconite) in the vicinity of Reserve Bank in 200-300 m water depths, which has an aerial extend of 4,500 km2, the glauconite resource amounts to about 2 Bt. The Chatham Rise glauconites have substantial economic potential as a potash fertiliser in support of the strong agricultural-based economy of New Zealand.

Glauconite is widespread in many Late Cretaceous-Cenozoic sedimentary deposits in the New Zealand rock record and the Chatham Rise occurrences provide a useful uniformitarian analogue for at least some of these.

text: Nature, Distribution, Origin and Economics of Glauconite in Carbonate-Phosphate-Glauconite Surficial Deposits on Central Chatham Rise, Southwest Pacific Chatham Rise is a broad, elongated submarine platform that extends 1100 km out into the Southwest Pacific off eastern South Island. The surficial sediments on the central portion of the Rise at depths of 200-500 m include significant concentrations of the mineral glauconite (10-80 wt%) associated with skeletal carbonate, fine terrigenous material and locally abundant phosphatic nodules. This is the first study to fully analyse the nature, origin and economic potential of the glauconite component. Sub-bottom 3.5 kHz profiles have established the distribution, geometry and thickness (10-200 cm) of the surficial deposits, which overlie partially indurated Oligocene chalk of probable Whaingaroan age (~34-27 Ma). 137 grab, dredge or piston core samples have been analysed for their texture, mineralogy and geochemistry, which has produced a new surficial sediment map for the central Chatham Rise.

Glauconite most commonly occurs as dark green to black, very fine to fine sand-sized (0.2 mm), polished ovoidal and lobate pellets, and less commonly as infills within foraminiferal tests or as variably replaced rock fragments and phosphatic clasts. Full physical analysis reveals seven morphological types of glauconite including, in order of decreasing abundance, ovoidal, lobate, composite, internal molds, fossil casts, pigmentary, tabular and pellets within rock fragments. Their internal fabrics are dominated by random microcrystalline varieties with some oriented fibroradiating rim and skeletal infill types. Other notable features of some glauconite pellets include their expansion cracks, opaque inclusions and variable degrees of limonitisation. XRF/XRD analyses reveal mainly diagenetically mature varieties having elevated K2O (7-9 wt%) and Fe2O3 (19-23 wt%) values, and a dominant 10Å glauconitic mica structure involving from 10-20% expandable smectite layers.

K-Ar dates on pellets indicate a Late Miocene age (av. 5.75 Ma). This “old” age, as well as the clear evidence of reworking shown by the dominance of smooth polished ovoidal grains, mean that the central Chatham Rise glauconites are predominantly allogenic (i.e. derived/reworked), and neither strictly authigenic nor in situ, despite occurring in “modern” seafloor deposits. The formation of glauconite is linked to prominent upwelling within the Subtropical Front (STF) zone over the Rise in the Late Miocene, and the attendant heightened primary productivity, bacterial activity and nutrients associated with widespread biogenic blooms at that time. The source of the smectite required for glauconite formation could have been from the devitrification of volcanic ash from diverse eruptive centres, or through “neoformation”/authigenic precipitation within pore water solutions of carbonate-rich waters in the Oligocene/Miocene chalk substrate. Glauconite formation largely ceased after the Late Miocene due to an increase in terrigenous input, a reduced smectite source, and a major period of lowered sea level associated with Antarctic ice sheet growth. The “modern” Chatham glauconite pellets were sourced from submarine erosion of the former Late Miocene sediments and have been dispersed by intensified bottom current circulation at times of lowered sea level within the complex STF over Chatham Rise, and possibly ice scouring. Effectively there exists a widespread “Chatham unconformity” (mid-Oligocene to Recent) which cuts out most of the last 30 myr of the sedimentary record on central Chatham Rise, except for the highly condensed surficial deposits whose glauconite grains formed 5-6 Ma, in the Late Miocene. This long-lasting “Chatham unconformity” is a greatly extended version of the well documented Oligocene Marshall Paraconformity.

The thickness of the surficial sediment cover on central Chatham Rise ranges from 0.06-1.35 m. By using a conservative estimate of 0.5 m thick, and the wt% of glauconite within the sediment cover, a resource estimate of the glauconite has been made for various areas. In the most glauconite-rich area (>50 wt% glauconite) in the vicinity of Reserve Bank in 200-300 m water depths, which has an aerial extend of 4,500 km2, the glauconite resource amounts to about 2 Bt. The Chatham Rise glauconites have substantial economic potential as a potash fertiliser in support of the strong agricultural-based economy of New Zealand.

Glauconite is widespread in many Late Cretaceous-Cenozoic sedimentary deposits in the New Zealand rock record and the Chatham Rise occurrences provide a useful uniformitarian analogue for at least some of these.

year: 2012

title: Negative political communication on social media and the gender gap: A study of men's and women's reactions to presidential candidate attacks on facebook in 2012 and 2016

authors: Phillips, Justin B.

subjects: Social Sciences

abstract: Do men and women respond differently to negative political communication? Only a limited collection of studies into the effects of negative campaigns have investigated this research question, and the conflicting results produced from such studies have prevented the development of a widely accepted answer. As campaigns transition to new media environments, further problems arise, as any potential gender gap may be magnified on the new political communication battlefield of social media. The present article contributes to this sparsely investigated area through an empirical study of men's and women's reactions on Facebook to US presidential candidate attacks during two general election campaigns (2012 and 2016) and two primaries (2016 Democratic and Republican). Across nearly 400 million reactions and 40 million unique users, women demonstrate lower receptivity to candidate attacks than men. Two potential explanatory factors for the gap are examined, but neither fully captures the magnitude of the differences observed. Conceptualizing the gender gap composition in terms of differential receptivity most accurately explains these findings and potentially resolves the competing explanations for the gap within the existing literature.

text: Negative political communication on social media and the gender gap: A study of men's and women's reactions to presidential candidate attacks on facebook in 2012 and 2016 Do men and women respond differently to negative political communication? Only a limited collection of studies into the effects of negative campaigns have investigated this research question, and the conflicting results produced from such studies have prevented the development of a widely accepted answer. As campaigns transition to new media environments, further problems arise, as any potential gender gap may be magnified on the new political communication battlefield of social media. The present article contributes to this sparsely investigated area through an empirical study of men's and women's reactions on Facebook to US presidential candidate attacks during two general election campaigns (2012 and 2016) and two primaries (2016 Democratic and Republican). Across nearly 400 million reactions and 40 million unique users, women demonstrate lower receptivity to candidate attacks than men. Two potential explanatory factors for the gap are examined, but neither fully captures the magnitude of the differences observed. Conceptualizing the gender gap composition in terms of differential receptivity most accurately explains these findings and potentially resolves the competing explanations for the gap within the existing literature.

year: 2021-09-01

title: Housing, mental health, and homelessness: Exploring lived experiences of homelessness to identify barriers to sustainable housing for vulnerable populations

authors: Cresswell, Caitlin Grace

subjects: Homelessness

abstract: Homelessness has become a much talked about topic in Aotearoa New Zealand in 2018 and the preceding years. This thesis explores the experiences of five people who have mental illness and have lived experience of homelessness in Aotearoa New Zealand, and two staff members who work closely with people who experience both mental illness and homelessness. The theoretical frameworks that inform this thesis are narrative research, social constructionism and humanistic psychology. Particular attention was paid to using theoretical frameworks and interview methods that suited Māori (the indigenous population of Aotearoa New Zealand) due to the inequities experienced by Māori in mental health and homelessness, and the majority of participants identifying as New Zealand Māori. Participants’ narratives were gathered using semi- structured interviews. This study argues the importance of a humanistic perspective being used for research on homelessness. In contrast to traditional psychology, humanistic psychology emphasises respecting individual participants’ voice and narratives about their personal experiences of homelessness while considering the environment that influence these narratives. The participants’ narratives reflected their desire to be viewed as more than their life circumstances and illness through the sharing of their life stories. While there has been growing public awareness about mental illness, stigma still exists about mental illness which influences social narratives and how people who have mental illness understand their experiences. I argue that people who are vulnerable to homelessness, like those who experience mental illness, should have better protection from homelessness. To achieve this, I argue that structural barriers to finding, gaining and sustaining housing need to be addressed,
iii
including the design of welfare and housing services. Additionally, there needs to be recognition that the solutions to homelessness are complex and require a whole of system approach to effectively address and prevent homelessness. Recognising the complex nature of homelessness and it’s solutions will help bring a focus to establishing predominantly preventative solutions while also providing emergency housing for people in need.

text: Housing, mental health, and homelessness: Exploring lived experiences of homelessness to identify barriers to sustainable housing for vulnerable populations Homelessness has become a much talked about topic in Aotearoa New Zealand in 2018 and the preceding years. This thesis explores the experiences of five people who have mental illness and have lived experience of homelessness in Aotearoa New Zealand, and two staff members who work closely with people who experience both mental illness and homelessness. The theoretical frameworks that inform this thesis are narrative research, social constructionism and humanistic psychology. Particular attention was paid to using theoretical frameworks and interview methods that suited Māori (the indigenous population of Aotearoa New Zealand) due to the inequities experienced by Māori in mental health and homelessness, and the majority of participants identifying as New Zealand Māori. Participants’ narratives were gathered using semi- structured interviews. This study argues the importance of a humanistic perspective being used for research on homelessness. In contrast to traditional psychology, humanistic psychology emphasises respecting individual participants’ voice and narratives about their personal experiences of homelessness while considering the environment that influence these narratives. The participants’ narratives reflected their desire to be viewed as more than their life circumstances and illness through the sharing of their life stories. While there has been growing public awareness about mental illness, stigma still exists about mental illness which influences social narratives and how people who have mental illness understand their experiences. I argue that people who are vulnerable to homelessness, like those who experience mental illness, should have better protection from homelessness. To achieve this, I argue that structural barriers to finding, gaining and sustaining housing need to be addressed,
iii
including the design of welfare and housing services. Additionally, there needs to be recognition that the solutions to homelessness are complex and require a whole of system approach to effectively address and prevent homelessness. Recognising the complex nature of homelessness and it’s solutions will help bring a focus to establishing predominantly preventative solutions while also providing emergency housing for people in need.

year: 2018