ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantl... more ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantle plume produced linear island chain, is 6000 km in length, active for 80 Myr, and tectonically simple. Despite its importance to our understanding of mantle plumes and Cenozoic plate motion, there are large data gaps for the age and geochemistry of lavas from volcanoes along the Hawaiian Ridge (HR) portion of the Chain. Ages: Only volcanoes near the Hawaiian-Emperor bend and in the Hawaiian Islands have modern Ar-Ar ages, leaving a gap of 2000 km where existing K-Ar ages suggest synchronous volcanism over a 1000 km section. Geochemistry: There is a 2900 km gap in high precision geochemical data for the HR. The Emperor Seamounts (>45 Ma) have better regional coverage of recent isotopic data and show a correlation of Sr isotope composition with age of the underlying oceanic lithosphere (Regelous et al. 2003). The HR has an unexplained, exponential increase in magma flux over the last 30 Myr (Vidal & Bonneville 2004). Potential explanations for the increase in magma flux include: changes in melting conditions (temperature and/or pressure), change in source fertility related to rock type (pyroxenite vs. peridotite) or previous melting history, and/or changes in plate stresses resulting from reconfigurations of plate motion. Our new multi-disciplinary project will: 1) Determine 40Ar/39Ar ages, and whole-rock major, trace element, and Pb, Sr, Nd and Hf isotopic geochemistry for lavas from 20 volcanoes spanning ~2150 km of the HR (NW of the Hawaiian Islands). 2) Use the geochemical data to determine the long-term evolution of the Hawaiian mantle plume source components and to evaluate whether there have been systematic variations in mantle potential temperature, melting pressure, and/or source lithology during the creation of the HR. If so, are they responsible for the 300% variation in melt production along the Ridge? Also, we will assess when the more fertile Loa source component appeared. 3) Reassess models for the origin of the HR using the new 40Ar/39Ar ages. 4) Recompute and compare the magma flux rate for the Hawaiian and Louisville Ridges using our new HR ages and IODP results for Louisville Ridge, and updated bathymetric data for both chains. 5) Utilize the new ages to revise Cenozoic Pacific plate motions and to compute differential motions as proxies for stress changes along the HR with time to evaluate the effects of plate motion on magma flux rate. These studies will have fundamental implications for mantle plume sources, plume dynamics, and plate kinematics. Vidal V, Bonneville A, 2004. J. Geophys. Res., 109, B03104, doi:10.1029/2003JB002559 Regelous M, Hofmann AW, Abouchami W, Galer SJG, 2003. Jour. Petrol. 44, 113-140
ABSTRACT The Northwest Hawaiian Ridge extends 2800 km and comprises 47% of the total length of th... more ABSTRACT The Northwest Hawaiian Ridge extends 2800 km and comprises 47% of the total length of the Hawaiian-Emperor (H-E) Chain. The Ridge contains at least 52 volcanoes whose shape, volume, and distance from neighboring volcanoes vary markedly. The temporal melt flux variation of the H-E has been estimated with various geophysical methods involving fluid dynamics and lithospheric modeling. These models show a dramatic increase (up to 300%) in melt flux over the last 30 Myr. A potential explanation for the increase in melt flux is a temporal increase in the temperature of melting. Olivine thermometry offers the best method for evaluating mantle source temperature variations along the Ridge. An olivine-liquid equilibration temperature estimate can then be recast into a mantle potential temperature after accounting for the heat of fusion during mantle melting and decompression of the mantle as it follows an adiabat to the surface. New whole-rock XRF and olivine analyzes for 18 tholeiitic, three transitional tholeiites, and two picro-basalts from 11 volcanoes spanning the entire length of the Ridge from Middle Bank to Yuryaku (just south of the Bend) were made. These data were used to obtain a temperature estimate of the mantle during shield formation of each volcano. After screening samples for those in chemical equilibrium using a Rhodes diagram and assuming a Kdol-liq(Fe-Mg)=0.345 ±0.03, data from six volcanoes were input into the thermometers of Beattie (1993; Contrib. Mineral. Petr., 118, 103-111) and Putirka et al., (2007; Chemical Geology, 241, 177-206). The results were averaged to estimate mantle potential temperatures. These calculations yield mantle potential temperature estimates that vary positively with volcano volume (e.g., 1460oC at Yuryaku vs 1608-1630oC at Gardner Pinnacles, the largest volume seamount in the Ridge). These results suggest that temperature variations may be playing a significant role in modulating the melt flux of the Ridge. Seven more samples from Midway, Hancock, and Gardner Pinnacles will be analyzed in order to obtain additional estimates of temporal variations in mantle potential temperature variations along the Ridge. Other parameters may also be affecting the magmatic productivity such as source heterogeneities (ie: pyroxenite vs peridotite) or melting pressure. These will be investigated using the computational methods of PRIMELT2 to understand significance of temperature, pressure, and compositional variations on the melt flux history of Hawaiian mantle plume.
In October 2013, graduate student members of the University of Hawaii Geophysical Society designe... more In October 2013, graduate student members of the University of Hawaii Geophysical Society designed a small-scale model research vessel (R/V) that uses sonar to create 3D maps of a model seafloor in real-time. This pilot project was presented to the public at the School of Ocean and Earth Science and Technology’s (SOEST) Biennial Open House weekend. An estimated 7,600 people attended the two-day event, including children and teachers from Hawaii’s schools, home school students, community groups, families, and science enthusiasts. Our exhibit demonstrated real-time sonar mapping of a cardboard volcano using a toy size research vessel on a fixed 2D model ship track suspended above a model seafloor. Sound wave travel times were recorded using an unltrasonic emitter/receiver attached to an Arduino microcontroller platform, while the same system measured displacement along the ship track. This data was streamed through a USB connection to a PC running MatLab, where a 3D model was updated ...
The Papahānaumokuākea Marine National Monument (PMNM) is a 362,073 km2 conservation area encompas... more The Papahānaumokuākea Marine National Monument (PMNM) is a 362,073 km2 conservation area encompassing islands and seamounts with prodigious diversity of size and morphologies formed by Hawaiian hotspot volcanism 7-31 Myr ago. During the winter and spring of 2014, we collaborated with the Schmidt Ocean Institute to conduct a detailed bathymetric mapping and geophysical survey of the PMNM on board the R/V Falkor. On two cruises, we collected 14,585 km of gravity data using UNOL's BGM-3 marine gravimeter and magnetic data with the University of Hawaii's G-882 cesium magnetometer. We will present these new data paired with� a select set of �existing NGDC marine geophysical data. Using these new gravity and magnetics data, we will investigate the internal density structures of these seamounts and the oceanic lithosphere upon which they were emplaced. The locations and volumes of the dense intrusive magmatic centers and rift zone dike complexes of these seamounts will be determine...
From March to June 2014, the Schmidt Ocean Institute, along with National Marine Sanctuaries and ... more From March to June 2014, the Schmidt Ocean Institute, along with National Marine Sanctuaries and the National Science Foundation, supported 72 days of mapping surveys on two cruises using R/V Falkor in the Papahānaumokuākea Marine National Monument (PMNM) located within the Northwestern Hawaiian Islands (NWHI). PMNM is one of the largest marine protected areas in the world. Approximately 127,000 km2, 35% of the PMNM, were surveyed using dual multibeam systems from less than 30 to >5000 meters water depth, and thus covering the habitat depth ranges for shallow living corals, mesophotic corals, drowned reefs, to deep-sea corals and sponge communities. A total of 18 seamounts, guyots, banks, or atoll flanks (e.g., Midway and Kure) were mapped in the upper northwestern section of the monument, including the generically named Bank 9 Seamount, which appears to be a composite of a younger Hawaiian seamount and an older Cretaceous guyot. The middle segment of the PMNM consists mostly of ...
ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantl... more ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantle plume produced linear island chain, is 6000 km in length, active for 80 Myr, and tectonically simple. Despite its importance to our understanding of mantle plumes and Cenozoic plate motion, there are large data gaps for the age and geochemistry of lavas from volcanoes along the Hawaiian Ridge (HR) portion of the Chain. Ages: Only volcanoes near the Hawaiian-Emperor bend and in the Hawaiian Islands have modern Ar-Ar ages, leaving a gap of 2000 km where existing K-Ar ages suggest synchronous volcanism over a 1000 km section. Geochemistry: There is a 2900 km gap in high precision geochemical data for the HR. The Emperor Seamounts (>45 Ma) have better regional coverage of recent isotopic data and show a correlation of Sr isotope composition with age of the underlying oceanic lithosphere (Regelous et al. 2003). The HR has an unexplained, exponential increase in magma flux over the last 30 Myr (Vidal & Bonneville 2004). Potential explanations for the increase in magma flux include: changes in melting conditions (temperature and/or pressure), change in source fertility related to rock type (pyroxenite vs. peridotite) or previous melting history, and/or changes in plate stresses resulting from reconfigurations of plate motion. Our new multi-disciplinary project will: 1) Determine 40Ar/39Ar ages, and whole-rock major, trace element, and Pb, Sr, Nd and Hf isotopic geochemistry for lavas from 20 volcanoes spanning ~2150 km of the HR (NW of the Hawaiian Islands). 2) Use the geochemical data to determine the long-term evolution of the Hawaiian mantle plume source components and to evaluate whether there have been systematic variations in mantle potential temperature, melting pressure, and/or source lithology during the creation of the HR. If so, are they responsible for the 300% variation in melt production along the Ridge? Also, we will assess when the more fertile Loa source component appeared. 3) Reassess models for the origin of the HR using the new 40Ar/39Ar ages. 4) Recompute and compare the magma flux rate for the Hawaiian and Louisville Ridges using our new HR ages and IODP results for Louisville Ridge, and updated bathymetric data for both chains. 5) Utilize the new ages to revise Cenozoic Pacific plate motions and to compute differential motions as proxies for stress changes along the HR with time to evaluate the effects of plate motion on magma flux rate. These studies will have fundamental implications for mantle plume sources, plume dynamics, and plate kinematics. Vidal V, Bonneville A, 2004. J. Geophys. Res., 109, B03104, doi:10.1029/2003JB002559 Regelous M, Hofmann AW, Abouchami W, Galer SJG, 2003. Jour. Petrol. 44, 113-140
The Hawaiian Islands extend NW for 625 km from Lō‘ihi to Ka‘ula island. One anomalous feature cro... more The Hawaiian Islands extend NW for 625 km from Lō‘ihi to Ka‘ula island. One anomalous feature cross-cutting the Hawaiian Islands is the Kaua‘i Ridge, a 165 km-long bathymetric high with three well-defined gravity highs. These gravity highs are centered under or near the islands of Ka‘ula, Ni‘ihau and Kaua‘i, and represent the cores of three shield volcanoes whose volumes decrease dramatically with distance from the axis of the Hawaiian Chain (Kaua‘i, 58 x 103 km3, Ni‘ihau x 103 km, Ka‘ula 10 x 103 km; Robinson and Eakins 2006). Ka‘ula Volcano, on the SW end of the Kaua‘i Ridge, is centered 100 km off the axis of the Hawaiian mantle plume. The volcano is capped by a small island, which is a remnant of a nephelinitic tuff cone. The cone contains abundant accidental bombs of lava (tholeiite, phonolite and basanite), peridotite and pyroxenite, and unexploded ordnance from US military bombing. Two JASON dives on the flanks of Ka‘ula recovered only alkalic lavas. Three stage of Ka‘ula vol...
ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantl... more ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantle plume produced linear island chain, is 6000 km in length, active for 80 Myr, and tectonically simple. Despite its importance to our understanding of mantle plumes and Cenozoic plate motion, there are large data gaps for the age and geochemistry of lavas from volcanoes along the Hawaiian Ridge (HR) portion of the Chain. Ages: Only volcanoes near the Hawaiian-Emperor bend and in the Hawaiian Islands have modern Ar-Ar ages, leaving a gap of 2000 km where existing K-Ar ages suggest synchronous volcanism over a 1000 km section. Geochemistry: There is a 2900 km gap in high precision geochemical data for the HR. The Emperor Seamounts (>45 Ma) have better regional coverage of recent isotopic data and show a correlation of Sr isotope composition with age of the underlying oceanic lithosphere (Regelous et al. 2003). The HR has an unexplained, exponential increase in magma flux over the last 30 Myr (Vidal & Bonneville 2004). Potential explanations for the increase in magma flux include: changes in melting conditions (temperature and/or pressure), change in source fertility related to rock type (pyroxenite vs. peridotite) or previous melting history, and/or changes in plate stresses resulting from reconfigurations of plate motion. Our new multi-disciplinary project will: 1) Determine 40Ar/39Ar ages, and whole-rock major, trace element, and Pb, Sr, Nd and Hf isotopic geochemistry for lavas from 20 volcanoes spanning ~2150 km of the HR (NW of the Hawaiian Islands). 2) Use the geochemical data to determine the long-term evolution of the Hawaiian mantle plume source components and to evaluate whether there have been systematic variations in mantle potential temperature, melting pressure, and/or source lithology during the creation of the HR. If so, are they responsible for the 300% variation in melt production along the Ridge? Also, we will assess when the more fertile Loa source component appeared. 3) Reassess models for the origin of the HR using the new 40Ar/39Ar ages. 4) Recompute and compare the magma flux rate for the Hawaiian and Louisville Ridges using our new HR ages and IODP results for Louisville Ridge, and updated bathymetric data for both chains. 5) Utilize the new ages to revise Cenozoic Pacific plate motions and to compute differential motions as proxies for stress changes along the HR with time to evaluate the effects of plate motion on magma flux rate. These studies will have fundamental implications for mantle plume sources, plume dynamics, and plate kinematics. Vidal V, Bonneville A, 2004. J. Geophys. Res., 109, B03104, doi:10.1029/2003JB002559 Regelous M, Hofmann AW, Abouchami W, Galer SJG, 2003. Jour. Petrol. 44, 113-140
ABSTRACT The Northwest Hawaiian Ridge extends 2800 km and comprises 47% of the total length of th... more ABSTRACT The Northwest Hawaiian Ridge extends 2800 km and comprises 47% of the total length of the Hawaiian-Emperor (H-E) Chain. The Ridge contains at least 52 volcanoes whose shape, volume, and distance from neighboring volcanoes vary markedly. The temporal melt flux variation of the H-E has been estimated with various geophysical methods involving fluid dynamics and lithospheric modeling. These models show a dramatic increase (up to 300%) in melt flux over the last 30 Myr. A potential explanation for the increase in melt flux is a temporal increase in the temperature of melting. Olivine thermometry offers the best method for evaluating mantle source temperature variations along the Ridge. An olivine-liquid equilibration temperature estimate can then be recast into a mantle potential temperature after accounting for the heat of fusion during mantle melting and decompression of the mantle as it follows an adiabat to the surface. New whole-rock XRF and olivine analyzes for 18 tholeiitic, three transitional tholeiites, and two picro-basalts from 11 volcanoes spanning the entire length of the Ridge from Middle Bank to Yuryaku (just south of the Bend) were made. These data were used to obtain a temperature estimate of the mantle during shield formation of each volcano. After screening samples for those in chemical equilibrium using a Rhodes diagram and assuming a Kdol-liq(Fe-Mg)=0.345 ±0.03, data from six volcanoes were input into the thermometers of Beattie (1993; Contrib. Mineral. Petr., 118, 103-111) and Putirka et al., (2007; Chemical Geology, 241, 177-206). The results were averaged to estimate mantle potential temperatures. These calculations yield mantle potential temperature estimates that vary positively with volcano volume (e.g., 1460oC at Yuryaku vs 1608-1630oC at Gardner Pinnacles, the largest volume seamount in the Ridge). These results suggest that temperature variations may be playing a significant role in modulating the melt flux of the Ridge. Seven more samples from Midway, Hancock, and Gardner Pinnacles will be analyzed in order to obtain additional estimates of temporal variations in mantle potential temperature variations along the Ridge. Other parameters may also be affecting the magmatic productivity such as source heterogeneities (ie: pyroxenite vs peridotite) or melting pressure. These will be investigated using the computational methods of PRIMELT2 to understand significance of temperature, pressure, and compositional variations on the melt flux history of Hawaiian mantle plume.
In October 2013, graduate student members of the University of Hawaii Geophysical Society designe... more In October 2013, graduate student members of the University of Hawaii Geophysical Society designed a small-scale model research vessel (R/V) that uses sonar to create 3D maps of a model seafloor in real-time. This pilot project was presented to the public at the School of Ocean and Earth Science and Technology’s (SOEST) Biennial Open House weekend. An estimated 7,600 people attended the two-day event, including children and teachers from Hawaii’s schools, home school students, community groups, families, and science enthusiasts. Our exhibit demonstrated real-time sonar mapping of a cardboard volcano using a toy size research vessel on a fixed 2D model ship track suspended above a model seafloor. Sound wave travel times were recorded using an unltrasonic emitter/receiver attached to an Arduino microcontroller platform, while the same system measured displacement along the ship track. This data was streamed through a USB connection to a PC running MatLab, where a 3D model was updated ...
The Papahānaumokuākea Marine National Monument (PMNM) is a 362,073 km2 conservation area encompas... more The Papahānaumokuākea Marine National Monument (PMNM) is a 362,073 km2 conservation area encompassing islands and seamounts with prodigious diversity of size and morphologies formed by Hawaiian hotspot volcanism 7-31 Myr ago. During the winter and spring of 2014, we collaborated with the Schmidt Ocean Institute to conduct a detailed bathymetric mapping and geophysical survey of the PMNM on board the R/V Falkor. On two cruises, we collected 14,585 km of gravity data using UNOL's BGM-3 marine gravimeter and magnetic data with the University of Hawaii's G-882 cesium magnetometer. We will present these new data paired with� a select set of �existing NGDC marine geophysical data. Using these new gravity and magnetics data, we will investigate the internal density structures of these seamounts and the oceanic lithosphere upon which they were emplaced. The locations and volumes of the dense intrusive magmatic centers and rift zone dike complexes of these seamounts will be determine...
From March to June 2014, the Schmidt Ocean Institute, along with National Marine Sanctuaries and ... more From March to June 2014, the Schmidt Ocean Institute, along with National Marine Sanctuaries and the National Science Foundation, supported 72 days of mapping surveys on two cruises using R/V Falkor in the Papahānaumokuākea Marine National Monument (PMNM) located within the Northwestern Hawaiian Islands (NWHI). PMNM is one of the largest marine protected areas in the world. Approximately 127,000 km2, 35% of the PMNM, were surveyed using dual multibeam systems from less than 30 to >5000 meters water depth, and thus covering the habitat depth ranges for shallow living corals, mesophotic corals, drowned reefs, to deep-sea corals and sponge communities. A total of 18 seamounts, guyots, banks, or atoll flanks (e.g., Midway and Kure) were mapped in the upper northwestern section of the monument, including the generically named Bank 9 Seamount, which appears to be a composite of a younger Hawaiian seamount and an older Cretaceous guyot. The middle segment of the PMNM consists mostly of ...
ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantl... more ABSTRACT The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantle plume produced linear island chain, is 6000 km in length, active for 80 Myr, and tectonically simple. Despite its importance to our understanding of mantle plumes and Cenozoic plate motion, there are large data gaps for the age and geochemistry of lavas from volcanoes along the Hawaiian Ridge (HR) portion of the Chain. Ages: Only volcanoes near the Hawaiian-Emperor bend and in the Hawaiian Islands have modern Ar-Ar ages, leaving a gap of 2000 km where existing K-Ar ages suggest synchronous volcanism over a 1000 km section. Geochemistry: There is a 2900 km gap in high precision geochemical data for the HR. The Emperor Seamounts (>45 Ma) have better regional coverage of recent isotopic data and show a correlation of Sr isotope composition with age of the underlying oceanic lithosphere (Regelous et al. 2003). The HR has an unexplained, exponential increase in magma flux over the last 30 Myr (Vidal & Bonneville 2004). Potential explanations for the increase in magma flux include: changes in melting conditions (temperature and/or pressure), change in source fertility related to rock type (pyroxenite vs. peridotite) or previous melting history, and/or changes in plate stresses resulting from reconfigurations of plate motion. Our new multi-disciplinary project will: 1) Determine 40Ar/39Ar ages, and whole-rock major, trace element, and Pb, Sr, Nd and Hf isotopic geochemistry for lavas from 20 volcanoes spanning ~2150 km of the HR (NW of the Hawaiian Islands). 2) Use the geochemical data to determine the long-term evolution of the Hawaiian mantle plume source components and to evaluate whether there have been systematic variations in mantle potential temperature, melting pressure, and/or source lithology during the creation of the HR. If so, are they responsible for the 300% variation in melt production along the Ridge? Also, we will assess when the more fertile Loa source component appeared. 3) Reassess models for the origin of the HR using the new 40Ar/39Ar ages. 4) Recompute and compare the magma flux rate for the Hawaiian and Louisville Ridges using our new HR ages and IODP results for Louisville Ridge, and updated bathymetric data for both chains. 5) Utilize the new ages to revise Cenozoic Pacific plate motions and to compute differential motions as proxies for stress changes along the HR with time to evaluate the effects of plate motion on magma flux rate. These studies will have fundamental implications for mantle plume sources, plume dynamics, and plate kinematics. Vidal V, Bonneville A, 2004. J. Geophys. Res., 109, B03104, doi:10.1029/2003JB002559 Regelous M, Hofmann AW, Abouchami W, Galer SJG, 2003. Jour. Petrol. 44, 113-140
The Hawaiian Islands extend NW for 625 km from Lō‘ihi to Ka‘ula island. One anomalous feature cro... more The Hawaiian Islands extend NW for 625 km from Lō‘ihi to Ka‘ula island. One anomalous feature cross-cutting the Hawaiian Islands is the Kaua‘i Ridge, a 165 km-long bathymetric high with three well-defined gravity highs. These gravity highs are centered under or near the islands of Ka‘ula, Ni‘ihau and Kaua‘i, and represent the cores of three shield volcanoes whose volumes decrease dramatically with distance from the axis of the Hawaiian Chain (Kaua‘i, 58 x 103 km3, Ni‘ihau x 103 km, Ka‘ula 10 x 103 km; Robinson and Eakins 2006). Ka‘ula Volcano, on the SW end of the Kaua‘i Ridge, is centered 100 km off the axis of the Hawaiian mantle plume. The volcano is capped by a small island, which is a remnant of a nephelinitic tuff cone. The cone contains abundant accidental bombs of lava (tholeiite, phonolite and basanite), peridotite and pyroxenite, and unexploded ordnance from US military bombing. Two JASON dives on the flanks of Ka‘ula recovered only alkalic lavas. Three stage of Ka‘ula vol...
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