PERMIAN NON-MARINE BIVALVES FROM THE COLLIO AND GUNCINA FORMATIONS (SOUTHERN ALPS, ITALY): REVISED BIOSTRATIGRAPHY AND PALAEOBIOGEOGRAPHY

Non-marine bivalves are key fossils in Permian continental stratigraphy and palaeogeography. Although known since the end of 19th century, the occurrences from the continental basins of the Southern Alps have never been extensively studied. The non-marine bivalves from the Lower Permian Collio Formation (Brescian pre-Alps) are herein revised, and those from the Guncina Formation (Athesian District) are described for the first time. These two units yielded non-marine bivalves belonging to the genus Palaeomutela sensu lato, which is widespread in the Permian continental successions of eastern Euramerica. Three Palaeomutela morphotypes have been herein described: oval-subtriangular, subtrapezoidal and elongated. The latter includes several specimens herein assigned to Palaeomutela (Palaeanodonta) berrutii sp. nov. and dominates the Collio Formation association. The Guncina Formation yielded also the genus Redikorella, for the first time co-occurring on the same stratigraphic horizon of Palaeomutela, herein assigned to Palaeomutela (Palaeanodonta) guncinaensis sp. nov. To-date, it was generally accepted that the first members of the genera Palaeomutela and Redikorella occurred during the Ufimian (late Kungurian of the global scale) in the non-marine basins of the Cis-Ural Foredeep and of Angara, respectively. Such new finds in the early-middle Kungurian of southwestern Europe, well constrained by radioisotopic dating, suggest new global first appearance (First Appearance Datum) and a possible new center of origin of these genera. This fact raises new questions on biostratigraphy, palaeobiogeography and palaeoecology, which will require further research. If we assume that the genera Palaeomutela and Redikorella had only one center of origin, we need to hypothesise possible migration routes from SW Europe to the continental basins of Eastern Europe and Angara. Apparently, such migration could be better supported by a Pangaea B palaeogeographic configuration.

Structural setting at the contact of the Southern Alps and Dinarides in western Cerkljansko region (western Slovenia)

The area between the villages of Reka in the Idrijca Valley, Bukovo and Zakriž near Cerkno belongs geographically and geotectonically to the Dinarides. The area consists of two large inner thrust blocks of the Trnovo nappe, which were thrusted for tens of kilometers in the direction of SW to their present position. They are overlain by the Tolmin nappe, the lowest thrust unit of the Southern Alps. The Tolmin nappe was thrusted from N to S and consists of two inner thrust blocks and a smaller intermediate inner sheet. In the western part of the area the contact between Southern Alps and the Dinarides runs along the regional Sovodenj fault.Although the rocks in the considered thrust units are about the same age, different stratigraphic settings could be recognized. The lithostratigraphic features of the Ladinian-Lower Carnian Pseudizilian beds are particularly striking. Succession of clastic and carbonate rocks was deposited in deep-marine Slovenian basin. In both the Trnovo and Tolmin nappe, Pseudozilian beds occur in the lithologically characteristic sequences but, in the Tolmin nappe, they are developed in a much greater thickness than in the Trnovo nappe and pass continuously upwards into Amphyclina beds, while in the Trnovo nappe, on the other hand, the succession of Pseudozilian beds is much thinner and is overlain by the platform Cordevol dolomite.

Climatic effects on rapid chemical and physical denudation rates measured with cosmogenic nuclides in the Ōhau catchment, New Zealand

<p>Understanding how active mountain landscapes contribute to carbon dioxide cycling and influences on long-term climate stability requires measurement of weathering fluxes from these landscapes. The few measured chemical weathering rates in the Southern Alps are an order of magnitude greater than in the rest of the world. Rapid tectonic uplift coupled with extreme orographic precipitation is driving exceptionally fast chemical and physical denudation. These rates suggest that weathering in landscapes such as the Southern Alps could play a significant role in carbon dioxide cycling. However, the relative importance of climate and tectonics driving these fast rates remains poorly understood. To address this gap, in situ ¹⁰Be derived catchment-averaged denudation rates were measured in the Ōhau catchment, Canterbury, New Zealand. Denudation rates in the Dobson Valley within the Ōhau catchment, varied from 474 – 7,570 m Myr⁻¹, aside from one sub-catchment in the upper Dobson Valley that had a denudation rate of 12,142 m Myr⁻¹. The Dobson and Hopkins Rivers had denudation rates of 1,660 and 4,400 m Myr⁻¹ respectively, in these catchments. Dobson Valley denudation rates show a moderate correlation with mean annual precipitation (R²=0.459). This correlation supports a similar trend identified at local and regional scales, and at high rates of precipitation this may be an important driver of erosion and weathering. Sampling of four grain sizes (0.125 to > 8 mm) at one site in the Dobson Valley resulted in variability in ¹⁰Be concentrations up to a factor of 2.5, which may be a result of each grain size recording different erosional processes. These observations demonstrate the importance of assessing potential variability and the need to sample consistent grain sizes across catchments. Chemical depletion fractions measured within soil pits in the upper Dobson Valley indicate chemical weathering contributes 30% of total denudation, and that physical erosion is driving rapid total denudation. Chemical weathering appears to surpass any proposed weathering speed limit and suggests total weathering may not be limited by weathering kinetics. This research adds to the paucity of research in New Zealand, and for the first time presents ¹⁰Be derived denudation rates from the eastern Southern Alps, with estimates of the long-term weathering flux. High weathering fluxes in the Southern Alps uphold the hypothesis that mountain landscapes play an important role in carbon dioxide cycling and long-term climate stability.</p>

Climatic effects on rapid chemical and physical denudation rates measured with cosmogenic nuclides in the Ōhau catchment, New Zealand

<p>Understanding how active mountain landscapes contribute to carbon dioxide cycling and influences on long-term climate stability requires measurement of weathering fluxes from these landscapes. The few measured chemical weathering rates in the Southern Alps are an order of magnitude greater than in the rest of the world. Rapid tectonic uplift coupled with extreme orographic precipitation is driving exceptionally fast chemical and physical denudation. These rates suggest that weathering in landscapes such as the Southern Alps could play a significant role in carbon dioxide cycling. However, the relative importance of climate and tectonics driving these fast rates remains poorly understood. To address this gap, in situ ¹⁰Be derived catchment-averaged denudation rates were measured in the Ōhau catchment, Canterbury, New Zealand. Denudation rates in the Dobson Valley within the Ōhau catchment, varied from 474 – 7,570 m Myr⁻¹, aside from one sub-catchment in the upper Dobson Valley that had a denudation rate of 12,142 m Myr⁻¹. The Dobson and Hopkins Rivers had denudation rates of 1,660 and 4,400 m Myr⁻¹ respectively, in these catchments. Dobson Valley denudation rates show a moderate correlation with mean annual precipitation (R²=0.459). This correlation supports a similar trend identified at local and regional scales, and at high rates of precipitation this may be an important driver of erosion and weathering. Sampling of four grain sizes (0.125 to > 8 mm) at one site in the Dobson Valley resulted in variability in ¹⁰Be concentrations up to a factor of 2.5, which may be a result of each grain size recording different erosional processes. These observations demonstrate the importance of assessing potential variability and the need to sample consistent grain sizes across catchments. Chemical depletion fractions measured within soil pits in the upper Dobson Valley indicate chemical weathering contributes 30% of total denudation, and that physical erosion is driving rapid total denudation. Chemical weathering appears to surpass any proposed weathering speed limit and suggests total weathering may not be limited by weathering kinetics. This research adds to the paucity of research in New Zealand, and for the first time presents ¹⁰Be derived denudation rates from the eastern Southern Alps, with estimates of the long-term weathering flux. High weathering fluxes in the Southern Alps uphold the hypothesis that mountain landscapes play an important role in carbon dioxide cycling and long-term climate stability.</p>

“It’s Beyond You, But You’re A Part of It”: Mountaineering in the Southern Alps of Aotearoa New Zealand

<p>This thesis provides a phenomenological exploration of the lived experience of mountaineering in New Zealand. Based on fieldwork completed in the Southern Alps and Mount Ruapehu, it offers an analysis into how mountaineers construct the mountain environment through their climbing, while also being shaped in turn by the vital mountain. At the heart of this thesis is the movement of mountaineering. I argue that the experience of mountaineering cannot be divorced from our embodied sensory perception. Through climbing, mountaineers build a depth of embodied, living knowledge, making sense of technical information and strengthening their judgement to help them climb and manage the risks. That knowledge transforms the mountains for experienced mountaineers. Furthermore, I argue that the vibrant and potentially deadly fluxes of the mountains form their agency and thus the vitality that my participants sense. To climb in the mountains is therefore to enter into a reciprocal relationship with the vital mountain environment. The mountaineers ultimately become a reflection of the mountains in which they climb. This thesis comprises of a written thesis and immersive podcast recording, which has been attached.</p>

“It’s Beyond You, But You’re A Part of It”: Mountaineering in the Southern Alps of Aotearoa New Zealand

<p>This thesis provides a phenomenological exploration of the lived experience of mountaineering in New Zealand. Based on fieldwork completed in the Southern Alps and Mount Ruapehu, it offers an analysis into how mountaineers construct the mountain environment through their climbing, while also being shaped in turn by the vital mountain. At the heart of this thesis is the movement of mountaineering. I argue that the experience of mountaineering cannot be divorced from our embodied sensory perception. Through climbing, mountaineers build a depth of embodied, living knowledge, making sense of technical information and strengthening their judgement to help them climb and manage the risks. That knowledge transforms the mountains for experienced mountaineers. Furthermore, I argue that the vibrant and potentially deadly fluxes of the mountains form their agency and thus the vitality that my participants sense. To climb in the mountains is therefore to enter into a reciprocal relationship with the vital mountain environment. The mountaineers ultimately become a reflection of the mountains in which they climb. This thesis comprises of a written thesis and immersive podcast recording, which has been attached.</p>

Microseismicity, tectonic stress, and exhumation rates near the central Alpine Fault, New Zealand

<p>This thesis documents a detailed examination of the seismic activity and characteristics of crustal deformation along the central Alpine Fault, a major obliquely convergent plate-boundary fault. Paleoseismic evidence has established that the Alpine Fault produces large to great (M7−8) earthquakes every 250−300 years, in a quasi-periodic manner, with the last surface-rupturing earthquake occurring in 1717. This renders the fault late in its typical earthquake cycle, posing substantial seismic risk to southern and central New Zealand. Understanding the seismic and tectonic character of this fault may yield information of both societal and scientific significance regarding seismic hazard and late-interseismic processes leading up to a large earthquake. However, the central Alpine Fault is currently seismically quiescent when compared to adjacent regions, and therefore requires detailed, long-duration observations to study seismotectonic processes. The work in this thesis addresses the need for a greater understanding of along-strike variations in seismic character of the Alpine Fault ahead of an anticipated large earthquake. To achieve observations with high spatial and temporal resolution across the length of the central Alpine Fault, I use 8.5 years of continuous seismic data from the Southern Alps Microearthquake Borehole Array (SAMBA), and data from four other temporary seismic networks and five local GeoNet permanent sites. Incorporating all of these temporary and permanent seismic sites provides us with a dense composite network of seismometers. Without such a dense network, homogeneous examination of the characteristics of low-magnitude seismicity near the Alpine Fault would be impossible. Using this dataset, I have constructed the most extensive microearthquake catalog for the central Alpine Fault region to date, containing 9,111 earthquakes and covering the time between late 2008 and early 2017. To construct this catalog I created an objective workflow to ensure catalog uniformity. Overall, 7,719 earthquakes were successfully relocated with location uncertainties generally ≤ 0.5 km in both the horizontal and vertical directions. The majority of the earthquakes were found to occur southeast of the Alpine Fault (i.e. in the hanging-wall). I observed a lack of seismicity beneath Aoraki/Mount Cook that has previously been shown to be associated with locally high uplift rates (6–10 mm/yr) and high geothermal gradients (∼60◦C/km). Seismogenic cut-off depths were observed to significantly vary along the strike of the Alpine Fault, ranging from 8 km beneath the highest topography to 20 km in the adjacent areas. To quantify the scale of the seismic deformation, a new local magnitude scale was also derived, corrected for geometric spreading, attenuation and site terms based on individually calculated GeoNet moment magnitude (Mw) values. Earthquake local magnitudes range between ML –1.2 and 4.6 and the catalog is complete above ML 1.1. To examine the stress regime near the central Alpine Fault, I built a new data set of 845 focal mechanisms from earthquakes in our catalog. This was achieved by manually determining P wave arrival polarity picks from all earthquakes larger than ML 1.5. In order to determine the orientations and characteristics of the stress parameters, I grouped these focal mechanisms and performed stress inversion calculations that provided an average maximum horizontal compressive stress orientation, SHmax, of 121±11◦ , which is uniform within uncertainty along the length of the central Southern Alps. I observed an average angle of 65◦ between the SHmax and the strike of the Alpine Fault, which is consistent with results from similar previous studies in the northern and southern sections of the Alpine Fault. This implies that the Alpine Fault is misoriented for reactivation, in the prevailing stress field. Using a 1-D steady-state thermal structure model constrained by seismicity and thermochronology data, I investigated the crustal thermal structure and vertical kinematics of the central Southern Alps orogen. The short-term seismicity data and longer-term thermochronology data impose complementary constraints on the model. I observed a large variation in exhumation rate estimates (1–8 mm/yr) along the length of the Alpine Fault, with maximum calculated values observed near Aoraki/Mount Cook. I calculated the temperature at the brittle-ductile transition zone, which ranges from 440 to 457◦C in the different models considered. This temperature is slightly hotter than expected for crust composed by quartz-rich rocks, but consistent with the presence of feldspar-rich mafic rocks in parts of the crust.</p>

Microseismicity, tectonic stress, and exhumation rates near the central Alpine Fault, New Zealand

<p>This thesis documents a detailed examination of the seismic activity and characteristics of crustal deformation along the central Alpine Fault, a major obliquely convergent plate-boundary fault. Paleoseismic evidence has established that the Alpine Fault produces large to great (M7−8) earthquakes every 250−300 years, in a quasi-periodic manner, with the last surface-rupturing earthquake occurring in 1717. This renders the fault late in its typical earthquake cycle, posing substantial seismic risk to southern and central New Zealand. Understanding the seismic and tectonic character of this fault may yield information of both societal and scientific significance regarding seismic hazard and late-interseismic processes leading up to a large earthquake. However, the central Alpine Fault is currently seismically quiescent when compared to adjacent regions, and therefore requires detailed, long-duration observations to study seismotectonic processes. The work in this thesis addresses the need for a greater understanding of along-strike variations in seismic character of the Alpine Fault ahead of an anticipated large earthquake. To achieve observations with high spatial and temporal resolution across the length of the central Alpine Fault, I use 8.5 years of continuous seismic data from the Southern Alps Microearthquake Borehole Array (SAMBA), and data from four other temporary seismic networks and five local GeoNet permanent sites. Incorporating all of these temporary and permanent seismic sites provides us with a dense composite network of seismometers. Without such a dense network, homogeneous examination of the characteristics of low-magnitude seismicity near the Alpine Fault would be impossible. Using this dataset, I have constructed the most extensive microearthquake catalog for the central Alpine Fault region to date, containing 9,111 earthquakes and covering the time between late 2008 and early 2017. To construct this catalog I created an objective workflow to ensure catalog uniformity. Overall, 7,719 earthquakes were successfully relocated with location uncertainties generally ≤ 0.5 km in both the horizontal and vertical directions. The majority of the earthquakes were found to occur southeast of the Alpine Fault (i.e. in the hanging-wall). I observed a lack of seismicity beneath Aoraki/Mount Cook that has previously been shown to be associated with locally high uplift rates (6–10 mm/yr) and high geothermal gradients (∼60◦C/km). Seismogenic cut-off depths were observed to significantly vary along the strike of the Alpine Fault, ranging from 8 km beneath the highest topography to 20 km in the adjacent areas. To quantify the scale of the seismic deformation, a new local magnitude scale was also derived, corrected for geometric spreading, attenuation and site terms based on individually calculated GeoNet moment magnitude (Mw) values. Earthquake local magnitudes range between ML –1.2 and 4.6 and the catalog is complete above ML 1.1. To examine the stress regime near the central Alpine Fault, I built a new data set of 845 focal mechanisms from earthquakes in our catalog. This was achieved by manually determining P wave arrival polarity picks from all earthquakes larger than ML 1.5. In order to determine the orientations and characteristics of the stress parameters, I grouped these focal mechanisms and performed stress inversion calculations that provided an average maximum horizontal compressive stress orientation, SHmax, of 121±11◦ , which is uniform within uncertainty along the length of the central Southern Alps. I observed an average angle of 65◦ between the SHmax and the strike of the Alpine Fault, which is consistent with results from similar previous studies in the northern and southern sections of the Alpine Fault. This implies that the Alpine Fault is misoriented for reactivation, in the prevailing stress field. Using a 1-D steady-state thermal structure model constrained by seismicity and thermochronology data, I investigated the crustal thermal structure and vertical kinematics of the central Southern Alps orogen. The short-term seismicity data and longer-term thermochronology data impose complementary constraints on the model. I observed a large variation in exhumation rate estimates (1–8 mm/yr) along the length of the Alpine Fault, with maximum calculated values observed near Aoraki/Mount Cook. I calculated the temperature at the brittle-ductile transition zone, which ranges from 440 to 457◦C in the different models considered. This temperature is slightly hotter than expected for crust composed by quartz-rich rocks, but consistent with the presence of feldspar-rich mafic rocks in parts of the crust.</p>