Article
Engineering, Environmental
Meret Aeppli, Geoffrey Schladow, Juan S. Lezama Pacheco, Scott Fendorf
Summary: Increased periods of bottom water anoxia in deep temperate lakes due to decreasing frequency and depth of water column mixing in a warming climate may result in the reductive dissolution of iron minerals and increased flux of nutrients from the sediment into the water column.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Geology
Uwe Balthasar, Stephen Kershaw, Anne-Christine Da Silva, Barbara Seuss, Maggie Cusack, Kilian Eichenseer, Peter Chung
Summary: This study used electron backscatter diffraction (EBSD) to analyze the skeletal structure of Silurian and Devonian stromatoporoids, proposing that the original microstructure of stromatoporoids comprised distinct bundles of single-crystal fibres. The presence of fibrous structures suggests a possible link to inclusions of hydrated amorphous calcium carbonate (ACC center dot H2O) in the skeleton during early diagenesis, similar to modern calcified sponges. The high-Mg calcite (HMC) skeletal composition of Palaeozoic stromatoporoids supports the idea that the mineral composition of hypercalcifying reef builders is influenced by Phanerozoic oscillations in the ratio of Mg:Ca.
Article
Chemistry, Physical
Nathalie Fagel, Isabel Israde-Alcantara, Reza Safaierad, Marttiina Rantala, Sabine Schmidt, Gilles Lepoint, Pierre Pellenard, Nadine Mattielli, Sarah Metcalfe
Summary: Environmental conditions significantly influence clay minerals, and studying clay sediments in tropical lakes can provide valuable insights into past environmental conditions. In this study, multiproxy records from sediment cores of three crater lakes in central Mexico were analyzed. The results showed that disordered kaolinite, formed through hydrolysis and hydrothermal alteration, was the predominant mineral in the sediments. The abundance of kaolinite varied in relation to organic carbon and organic matter-related elements, and showed opposite trends with lithogenic elements. Geochemical data suggested that the increase in kaolinite abundance is linked to the formation of organo-mineral aggregates and lake level changes in closed basins.
APPLIED CLAY SCIENCE
(2024)
Article
Geosciences, Multidisciplinary
Stephanie Scheidt, Ramon Egli, Matthias Lenz, Christian Rolf, Karl Fabian, Martin Melles
Summary: The Levinson-Lessing Lake in northern Central Siberia is characterized by continuous sedimen-tation at high rates for over 32,000 years. The study found that the lake's sediments are suitable for paleomagnetic analyses, with magnetic properties indicating remanence carriers originating likely from magnetotactic bacteria. The research provides important insights into the magnetic mineralogy of the lake sediments, demonstrating the presence of detrital origin remanence carriers.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Review
Fisheries
Abigail M. Smith, David F. Freeman, Ian S. Dixon-Anderson, Daphne E. Lee
Summary: We conducted a study to investigate the patterns and controls on the carbonate mineralogy of brachiopods using published and new mineralogical data. The results reveal that calcareous brachiopods mainly consist of low-Mg calcite, but there are also some unusual species that precipitate calcite with higher Mg content. We also discovered bimineralic brachiopods, which is a new finding in this study. The variability in brachiopod mineralogy is influenced by individual, environmental, and phylogenetic factors.
NEW ZEALAND JOURNAL OF MARINE AND FRESHWATER RESEARCH
(2023)
Article
Multidisciplinary Sciences
Leanne A. A. Melbourne, Juliet Brodie, Emily J. J. Rayfield, Danna Titelboim, Oliver T. T. Lord, Daniela N. N. Schmidt
Summary: Coralline algae form complex habitats and are biodiversity hotspots. Climate change may decrease their structural integrity, particularly for southern species. Cellular and mineral properties vary greatly within species, between sites, and over time, with smaller temporal differences compared to spatial differences. Future anthropogenic climate change may result in a loss of habitat complexity in the south and expansion of weaker southern species into northern sites.
SCIENTIFIC REPORTS
(2023)
Article
Geology
Maliheh Pourali, Adel Sepehr, Ziba Hosseini, Mohammad Ali Hamzeh
Summary: This study investigated the geomorphology, bulk and clay mineralogy, and geochemistry of core sediments from Sabzevar playa in the northeast of the Great Kavir. The results showed that the playa is composed of clastic components, with increasing proportions towards the depth, but the trend is reversed for evaporite minerals. The mineralogical and geochemical evidence suggests an evolution of the brine to a Na-SO4-Cl type. Granulometry studies revealed fluctuations and higher energy costs during sediment deposition at a depth of 1 m. The research also explored the hydrological characteristics and revealed higher groundwater levels in the west compared to the center and east of the playa.
CARBONATES AND EVAPORITES
(2023)
Proceedings Paper
Computer Science, Interdisciplinary Applications
Jacob Taggart, Theron Miller, Alexis Navarre-Sitchler, Gregory Carling
Summary: Restoration efforts for Utah Lake should take into account the lake's internal processes, particularly the quantification of coprecipitation rate of phosphorus with calcite.
2022 INTERMOUNTAIN ENGINEERING, TECHNOLOGY AND COMPUTING (IETC)
(2022)
Article
Geochemistry & Geophysics
Paola Gravina, Alessandro Ludovisi, Beatrice Moroni, Riccardo Vivani, Roberta Selvaggi, Chiara Petroselli, David Cappelletti
Summary: Lake systems are crucial for the environment and humans, but they are greatly impacted by anthropogenic activities and climate change. This study focuses on investigating the effects of human activities and climate change on the Trasimeno lake in Central Italy through high-resolution sedimentary archives. By analyzing geochemical proxies stored in the sediment records, the study aims to reconstruct the lake's history and assess past anthropogenic impact. This research is important for monitoring and addressing pollution related to soil and water compartments in line with the objectives of the European Green Deal.
AQUATIC GEOCHEMISTRY
(2022)
Article
Multidisciplinary Sciences
R. M. Doyle, Z. Liu, J. T. Walker, R. Hladyniuk, K. A. Moser, F. J. Longstaffe
Summary: This article presents geochemical measurements and stable isotope compositions of 145 modern water samples and sediment cores collected from Barry Lake, Ontario, Canada. These data provide valuable insights into the changes in effective moisture in southern Ontario over the past 900 years and offer important information for researchers studying eutrophication-induced increases in primary production.
Article
Geology
Stanko Ruzicic, Goran Durn, Ivan Sondi, Lucija Mihaljevic, Maja Ivanic
Summary: The study found similarities in particle size, mineral composition, and other characteristics between marine lake sediment in Veliko Jezero and Calcocambisol/colluvium soil, mainly due to weathering of surrounding soils and deposition of aeolian minerals.
Article
Construction & Building Technology
Hongdan Yu, Kai Zhang, Haifeng Lu, Qingzhao Zhang
Summary: The disposal of lake sediment is a major problem in dredging and lakeside construction projects. Previous research has shown that alkaline-activated reactions can improve the mechanical properties of silicon-and aluminum-rich solid waste. This study analyzed the physical and mechanical properties of dried sediment from a lake in Wuhan, China, and investigated the solidification effects of different alkaline materials used alone or in combination with the lake sediment.
Article
Fisheries
Matthew R. D. Cobain, Rona A. R. McGill, Clive N. Trueman
Summary: Seasonal variations in the availability of resources can affect the structure of food webs. This study used stable isotope analysis to investigate the temporal dynamics of a fish community in a temperate estuary. The results showed limited seasonal variation in sulphur isotope values, indicating little change in the consumption of different resources by the fish community. However, carbon and nitrogen isotope values exhibited seasonality, reflecting changes in phytoplankton biomass and nitrogen sources. Isotope shifts in fish muscle occurred rapidly during periods of high phytoplankton production. This study emphasizes the importance of considering temporal variability in stable isotope-based studies.
JOURNAL OF FISH BIOLOGY
(2022)
Article
Paleontology
Ruben Garcia-Artigas, Ramon Mercedes-Martin, Joan Cartanya, Arnau Bolet, Marc Riccetto, Josep Fortuny
Summary: The study identified a well-preserved marine Ladinian-Carnian carbonate succession in the South Central Pyrenees, with diverse vertebrate and invertebrate faunas. Sedimentological and textural analyses indicate deposition in shallow subtidal coastal settings, suggesting the age of the site to be late Ladinian-middle Carnian. Refinement of paleontological, sedimentological, and biostratigraphic data can better constrain the paleoenvironmental conditions impacting ecosystem diversity during the late Ladinian-Carnian interval in the Tethys domain.
JOURNAL OF PALEONTOLOGY
(2022)
Article
Geology
Laura Bastianini, Mike Rogerson, Ramon Mercedes-Martin, Timothy J. Prior, William M. Mayes
Summary: This study compares anthropogenic carbonates downstream of lime and steel disposal sites with natural systems to explore potential drivers, precipitation mechanisms, and depositional models. The research reveals differences in carbonate precipitation zones and microfabrics, showing that calcite mineral formation is complex and influenced by factors beyond thermodynamic processes.
DEPOSITIONAL RECORD
(2022)
Article
Environmental Sciences
William F. Mills, Andres E. Ibanez, Paco Bustamante, Ana P. B. Carneiro, Stuart Bearhop, Yves Cherel, Rocio Mariano-Jelicich, Rona A. R. McGill, Diego Montalti, Stephen C. Votier, Richard A. Phillips
Summary: Antarctic marine ecosystems are often considered pristine, but wildlife may still be exposed to high levels of environmental contaminants. This study found that blood mercury concentrations increased from the Antarctic Peninsula towards the Antarctic Polar Front, with the highest contamination at Bird Island. Blood mercury concentrations also showed a weak positive correlation with delta N-15 values, likely indicating biomagnification. Males had higher mercury burdens than females, possibly due to differences in their trophic ecology.
ENVIRONMENTAL POLLUTION
(2022)
Editorial Material
Geology
John J. G. Reijmer
Article
Geology
Christian Betzler, Sebastian Lindhorst, John J. G. Reijmer, Juan Carlos Braga, Thomas Luedmann, Or M. Bialik, Jesus Reolid, Anna-Lena Gessner, Dagmar Hainbucher, Dass Bissessur
Summary: In this study, the sedimentary environments of the Saya de Malha Bank were investigated using a multidisciplinary approach. The results showed that ocean currents and internal waves are the major controlling factors for sedimentation, leading to the coexistence of mesophotic coral and red algal facies, as well as hemipelagic and bioclastic sands, and a hardground. These findings can be applied to other drowning examples, improving the interpretation of the stratigraphic record.
Article
Geochemistry & Geophysics
P. Staudigel, A. J. Davies, M. Bernecker, M. Tagliavento, H. J. L. van der Lubbe, C. Nooitgedacht, N. Looser, S. M. Bernasconi, H. Vonhof, J. Fiebig
Summary: Geochemical analyses of carbonate minerals provide insight into temperature and water composition during formation, while fluid trapped in minerals can be used to reconstruct paleotemperatures and diagenetic processes. The Delta(47)-Delta(48) dual-clumped isotope thermometer is highly sensitive to water/carbonate ratio and behaves differently in rock-buffered and water-dominated systems. Heating experiments and evaluation of sampling methods demonstrate the potential of this approach in understanding kinetic processes in biomineralization and resolving ambiguities in climate records.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Article
Biochemistry & Molecular Biology
Ashlie N. Walker, Megan A. Ayala, Somrita Mondal, Mackenzie C. Bergagnini, Phuong John D. Bui, Stephanie N. Chidester, Chad I. Doeden, Louise Esjornson, Brian R. Sweany, Leslie Garcia, Jeanette A. Krause, Allen G. Oliver, Timothy J. Prior, Timothy J. Hubin
Summary: Tetraazamacrocycles are cyclic molecules with four nitrogen atoms known for producing highly stable transition metal complexes. Cross-bridging these molecules with two-carbon chains further enhances the stability of these complexes, making them suitable for various applications. In this study, unbridged dibenzyl tetraazamacrocycle complexes were synthesized to directly compare their stability with known cross-bridged tetraazamacrocycles. UV-Visible spectroscopy and cyclic voltammetry were used for chemical characterization, revealing differences in electronic properties between the bridged and unbridged versions. Results showed that the stability of cyclen-based complex did not benefit from cross-bridging, while cyclam-based complexes greatly benefited. It was concluded that ligand-metal complementarity is crucial for the contribution of topological and rigidity constraints to complex robustness.
Article
Fisheries
Georgina L. Hunt, Matthew R. D. Cobain, Rona A. R. McGill, John K. Pinnegar, Georg H. Engelhard, Benjamin D. Wigham, Nicholas V. C. Polunin
Summary: Sympatric flatfish predators in coastal environments may partition their resources to reduce competition and increase foraging efficiency. However, the consistency in their feeding habits over time and space is not well understood. This study uses stomach content and stable isotope analysis to investigate the feeding habits of two flatfish predators across different temporal scales, revealing changes in resource partitioning and diet switching in response to prey availability.
JOURNAL OF FISH BIOLOGY
(2023)
Article
Environmental Sciences
Isabella Mele, Rona A. R. McGill, Jordan Thompson, James Fennell, Susan Fitzer
Summary: Molluscs are affected by ocean acidification, which can alter their metabolic and environmental sourcing pathways for carbon and negatively impact shell development. However, supplementary feeding can help offset these effects.
MARINE ENVIRONMENTAL RESEARCH
(2023)
Article
Environmental Sciences
Tessa Plint, Mariel T. I. ten Doeschate, Andrew C. Brownlow, Nicholas J. Davison, Georg Hantke, Andrew C. Kitchener, Fred J. Longstaffe, Rona A. R. McGill, Cornelia Simon-Nutbrown, Clayton R. Magill
Summary: Dolphins are highly mobile marine predators that have expanded their range and abundance in British waters. While warm-water adapted species are increasing, cold-water adapted species are decreasing, potentially due to the impact of ocean warming. Competition for prey and the decline in available habitat are important factors that should be considered in the management of dolphin populations.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
Claire B. Rubbelke, Tripti Bhattacharya, Ran Feng, Natalie J. Burls, Scott Knapp, Erin L. Mcclymont
Summary: Future projections of southwestern African hydroclimate are highly uncertain. Insights from past warm climates, like the Pliocene, can reveal mechanisms of future change and help benchmark models. This study reconstructs precipitation in Namibia over the past 5 million years and finds a long-term depletion trend linked to sea surface temperatures. The influence of SSTs on regional hydroclimate is similar to that observed during modern extreme flooding events. Capturing this mechanism is key to accurately simulating past and future regional hydroclimate. The findings have implications for the future climate of the region and the associated risks to ecosystems and industries.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Biochemistry & Molecular Biology
Leslie Garcia, Makynna R. Koper, Somrita Mondal, Joshua T. Priddle, William A. Truong, Elisabeth M. A. Allbritton, Ashtyn G. Mcadoo, Desiray J. Cannon-Smith, Neil L. Funwie, Tuyet Hoang, Inseo Kim, David J. Hubin, Jeanette A. Krause, Allen G. Oliver, Timothy J. Prior, Timothy J. Hubin
Summary: Twenty novel Mn, Fe, and Cu complexes of ethylene cross-bridged tetraazamacrocycles with potentially copolymerizable allyl and benzyl pendant arms were synthesized and characterized. The study demonstrated that these complexes have good stability under harsh acidic and high-temperature conditions, and showed potential for catalytic oxidation. These complexes can be used to produce future heterogeneous water purification materials.
Article
Geography, Physical
James A. Smith, Louise Callard, Michael J. Bentley, Stewart S. R. Jamieson, Maria Luisa Sanchez-Montes, Timothy P. Lane, Jeremy M. Lloyd, Erin L. McClymont, Christopher M. Darvill, Brice R. Rea, Colm O'Cofaigh, Pauline Gulliver, Werner Ehrmann, Richard S. Jones, David H. Roberts
Summary: This study reconstructs the Holocene dynamics of the Nioghalvfjerdsbrae ice shelf, the largest marine-terminating glacier in Northeast Greenland. The results indicate that the ice shelf retreated between 8.5 and 4.4 thousand years ago following a period of enhanced atmospheric and ocean warming. The ice shelf reformed after 4.4 thousand years ago, coinciding with decreasing atmospheric temperatures and the increased dominance of Polar Water.
Article
Chemistry, Multidisciplinary
Shang-Wei Yuan, Pei-Hui Shan, Mao-Xiao Yang, Pei-Hua Ma, Timothy J. Prior, Carl Redshaw, Gang Wei, Zhu Tao, Xin Xiao
Summary: In this study, the host-guest inclusion complexes formed by the symmetric tetramethyl-substituted cucurbit[6]uril with glycine were investigated under different conditions. The interactions were studied in solution and in the solid state, and two molecular structures were reported.
Article
Geosciences, Multidisciplinary
Bin Zhang, Jiaqi Liu, Wen Chen, Zhiliang Zhang, Li Yang, Lei Zhang, Zeyang Zhu, Chunqing Sun, Zhihao Sun
Summary: The eastern Tibetan Plateau is a region with unique topography and active tectonics, making it crucial for studying geodynamics and lithosphere-atmosphere interaction. By integrating new and reported thermochronological data, as well as paleo-crustal thickness reconstruction, this study sheds light on the tectonic deformation, climate-tectonic coupling, and geodynamics of the area.
Article
Geosciences, Multidisciplinary
Zhenhua Tian, Shangwen Zhou, Songtao Wu, Sai Xu, Junping Zhou, Jianchao Cai
Summary: This paper presents a modified method for calculating the lost gas content of shale by analyzing the coring and on-site desorption processes. The method accurately depicts the loss characteristics of free and adsorbed gas and identifies parameters that influence the calculation of in-situ shale gas content. The results demonstrate that the method shows satisfactory applicability in gas loss curve prediction and in-situ gas content estimation.
Article
Geosciences, Multidisciplinary
Pengcheng Li, Jaffar Abbas, Daniel Balsalobre-Lorente, Qingren Wang, Qianxiao Zhang, Syed Ale Raza Shah
Summary: This study explores the factors contributing to sustainability in Pakistan from 1974 to 2018 and finds that emissions from industrial and agriculture sectors have significantly decreased, while the financial sector has not effectively reduced environmental pressure. Therefore, Pakistan needs to adjust its economic policies and ensure the green allocation of financial resources.
Article
Geosciences, Multidisciplinary
Shi Zhou, Ting Zhou, Duo Guan, Yong Yao, Huimin Sun, Ahmed Ali Mosa, Yajie Zuo, Xianqiang Yin
Summary: Graphitic carbon nitride (g-C3N4) has been widely used due to its excellent optical properties and physicochemical stability. The risk of g-C3N4 transport in the environment has been overlooked, but this study investigated its transport behavior in various media. The results showed that flow rate and ionic strength influenced the transport, and the presence of lead (Pb) affected the outflow of g-C3N4. The unique structure of g-C3N4 particles allowed them to deposit in certain media and act as carriers for Pb release.
Article
Geosciences, Multidisciplinary
Xiaolong Qiao, Muntasir Murshed, Mohammad Mahtab Alam, Narasingha Das, Kurshid Khudoykulov, Salman Tariq
Summary: This study examines how macroeconomic factors influence India's carbon emission intensity levels and confirms the impact of factors such as foreign remittance receipts, energy consumption, urbanization, and technological progress. The findings provide policy recommendations for India's carbon emission reduction targets.
Article
Geosciences, Multidisciplinary
Wei Liu, Bo Wan
Summary: Magmatic-hydrothermal systems play a crucial role in transporting materials and potentially affecting Earth's long-term environment. This study investigates the duration of prograde metamorphism induced by fluid infiltration and the amount of carbon released by skarn ore deposits. The findings reveal that skarn ore deposits can efficiently decarbonize CO2 at a high rate, surpassing volcanism in different tectonic settings. The CO2 flux of skarn deposits increases over time and reaches a maximum value at the J/K boundary, providing an important previously unquantified source of outgassing in the subduction zone.
Article
Geosciences, Multidisciplinary
Haikuan Nie, Pei Li, Qing Chen, Zhijun Jin, Quanyou Liu, Wei Dang, Qian Chen, Jianghui Ding, Changbo Zhai
Summary: This study investigates the shale quality and shale gas potential in the upper Ordovician to lower Silurian formations in the Sichuan Basin of southern China. The distribution and characteristics of organic-rich shale are analyzed, aiding in the assessment of shale gas potential and identification of sweet spots.
Article
Geosciences, Multidisciplinary
Najia Saqib, Shujaat Abbas, Ilhan Ozturk, Muntasir Murshed, Malgorzata Tarczynska-Luniewska, Mohammad Mahtab Alam, Waldemar Tarczynski
Summary: This study examines the impact of economic growth, financial development, eco-friendly ICT, renewable energy, and human capital on lowering carbon footprint in the world's top polluting economies from 1993 to 2020. The findings suggest that eco-friendly ICT has the potential to effectively alleviate pollution, and financial development, renewable energy, and environmental technology are proposed as potential solutions for reducing carbon emissions.
Article
Geosciences, Multidisciplinary
Hikmat Salam, Syed Ali Turab, Asghar Ali, M. Qasim Jan, Norasiah Sulaiman, Mohd Basril Iswadi Basori
Summary: The Kahi melange complex in NW Pakistan is an important record of the tectonic evolution between the Indian plate and the Afghan block, consisting of highly dismembered ophiolitic and sedimentary units.
Article
Geosciences, Multidisciplinary
Er-Kun Xue, Wei Wang, David Chew, Manoj K. Pandit, Xin Deng, Yang Tian, Xi-Run Tong, Jun-Hong Zhao
Summary: The study reveals the presence of water-fluxed melting during the Wuyi-Yunkai Orogeny in South China. These water-fluxed melting quartzo-feldspathic migmatites formed during the early Paleozoic and were melted through reactions involving water-saturated quartz, feldspar, biotite, and K-feldspar. The findings highlight the significance of water-fluxed anatexis in the differentiation of the continental crust during orogenesis.
Article
Geosciences, Multidisciplinary
Hadi Shafaii Moghadam, Qiu-Li Li, William L. Griffin, Xian-Hua Li, Orhan Karsli, Christopher J. Spencer, Jose F. Santos, Maria Kirchenbaur, Sobhi Nasir, Suzanne Y. O'Reilly
Summary: Understanding the crustal growth, reworking, and geodynamics of the northern continental margin of Gondwana during the Ediacaran to Silurian times is crucial for the paleogeographic reconstruction of Gondwana. This study uses various analytical methods to evaluate the magmatic history of this region and obtain relevant detrital zircon data. The results provide valuable insights into the crustal evolution and tectonic activities in the northern Gondwana region.
Article
Geosciences, Multidisciplinary
Laura Petrescu, Felix Borleanu, Emanuel Kaestle, Randell Stephenson, Anica Placinta, Oleksandr Ivanovich Liashchuk
Summary: This study investigates the seismic structure of the Eastern European lithosphere and the transition from Precambrian to Phanerozoic Europe. The results show that the crust thickens across the Trans European Suture Zone boundary and the mantle is seismically faster beneath younger terranes. The Precambrian building blocks exhibit contrasting seismic fabrics, with the Baltic orogens characterized by uniform crust and the Sarmatia region showing alternating high and low velocity layers.
Article
Geosciences, Multidisciplinary
Dongya Zou, Hongfu Zhang
Summary: This study analyzes the U-Pb-Hf-O isotopes of zircons in felsic granulite xenoliths from the Fuxin late Cretaceous basalts in the North China Craton to evaluate the role of magma underplating in modifying the Archean lower crust. The results show that long-lived magma underplating occurred beneath the Fuxin region during the Mesozoic, with underplated magmas originating from the lithospheric mantle and later from the depleted asthenospheric mantle. This study concludes that magma underplating not only provided heat for remelting, but also added exotic material and weakened the lower crust, leading to its destruction.
Article
Geosciences, Multidisciplinary
Yu Han, Yingchang Cao, Chao Liang, Keyu Liu, Fang Hao
Summary: A paleoclimate reconstruction based on high-resolution records from lacustrine shale in the Bohai Bay Basin reveals a shift in orbital variability and a humidification event at -41.9 Ma in East Asia. The intensification of the East Asian monsoons at this time was likely a response to the elevated atmospheric pCO2 during the concurrent global warming.
Article
Geosciences, Multidisciplinary
Francesca Innocenzi, Sara Ronca, Stephen Foley, Samuele Agostini, Michele Lustrino
Summary: This study investigates two volcanic provinces in the western branch of the East African Rift and finds that the volcanic products show wide variability in chemical and mineralogical characteristics. Petrographic and geochemical analysis reveals enriched and heterogeneous sub-lithospheric mantle sources. The differences in isotopic features between the two volcanic provinces may indicate changes in the composition, mineralogy, and depth of melting in the lithospheric mantle source.