The Paleocene–early Eocene interval is punctuated by a series of transient warming events known as hyperthermals that have been associated with changes in the carbon isotope composition of the ocean-atmosphere system. Here we present and discuss a detailed record of calcareous nannofossil and foraminiferal assemblages coupled with high-resolution geochemical, isotopic, and environmental magnetic records across the middle Ypresian at the Contessa Road section (Gubbio, Italy). This allows characterization of the Eocene Thermal Maximum 3 (ETM3, K or X) and recognition of four minor (I1, I2, J, L) hyperthermals. At the Contessa Road section, the ETM3 is marked by short-lived negative excursions in both δ13C and δ18O, pronounced changes in rock magnetic properties, and calcium carbonate reduction. These changes coupled with the moderate to low state of preservation of calcareous nannofossils and planktonic foraminifera, higher FI and agglutinated foraminifera values, along with a lower P/(P + B) ratio (P—planktonic; B—benthic) and coarse fractions provide evidence of enhanced carbonate dissolution during the ETM3. A marked shift toward warmer and more oligotrophic conditions has been inferred that suggests unstable and perturbed environmental conditions both in the photic zone and at the seafloor.

The western Pacific region contains 22 independent island countries and territories spread over an area of 27.8 million km2. Pacific peoples have lived here for as long as 50,000 yr, developing isolated cultures with close relationships to the environment. Although food security is adequate, the region suffers from persistent poverty that places many in a precarious position. Beginning in the 1920s, geological surveys conducted pioneering studies geared toward development. Beginning in the mid-1990s, many aid donors shifted their focus away from science, leading to a depletion of geo-science capacity. Lately, regional organizations have made considerable headway in expanding scientific capacity. The Geoscience Division of the Secretariat of the Pacific Community plays a significant role in helping the region attract geoscience-related aid funding and stitching the dispersed geoscience communities together. Universities in the region, assisted by geoscientists abroad and private employers, are also playing a role. This paper describes three examples of how geoscience can contribute to inclusive sustainable development. One example explores deep-sea minerals as a new source of wealth generation and the challenges the region faces in developing capacity and addressing the environmental concerns of this new revenue stream. A second project in Kiribati has moved aggregate extraction from beaches only 3 m above sea level to sediment-rich lagoons, providing new options for the future. Lastly, the promises and benefits of sustainable geothermal and ocean thermal technology are described.

Past environments of equatorial SE Asia must have played a critical role in determining the timing and trajectory of early human dispersal into and through the region. However, very few reliable terrestrial records are available with which to contextualize human dispersal events. This circumstance, coupled with a sparse archaeological record and the likelihood that much of the archaeological record is now submerged, means we have an incomplete understanding of the role that geography, climate and environment played in shaping human pre-history in this region. From a review of the literature, we conclude that there must have been a substantial environmental barrier resulting in a genetic separation between east and west Sundaland that persisted even though a terrestrial connection was present for most of the Pleistocene. This barrier is likely to be a north–south corridor of open non-forest vegetation, and its existence may have encouraged the rapid dispersal of early humans through the interior of Sundaland and on to Sahul. We conclude that more reliable terrestrial palaeoenvironmental records are required to better understand the links between past environments and dispersal events. We highlight avenues of particular research value, such as focusing on eastern Sumatra, western/southern Borneo and the islands in the Java Sea, where the purported savanna corridor most probably existed, and including edaphic factors in palaeovegetation modelling.

Near-vertical multiple ScS (S waves reflected at the core-mantle boundary) phases are among the cleanest seismic phases traveling over several thousand kilometers in the Earth's mantle and are useful for constraining the average attenuation and shear wave speed in the whole mantle. However, the available multiple ScS pairs are limited. We took advantage of the recent dramatic increase in the number of global broadband stations and made a thorough computer-assisted search for high-quality data of multiple ScS pairs. We could find 220 station-event pairs which provided us with robust local estimates of average Q (quality factor) and two-way shear wave travel times. With the assumption that geometric focusing caused by lateral velocity heterogeneity does not seriously affect the amplitude measurements, the Q values exhibit strong short-range lateral variations, with very high and very low Q regions adjacent to each other. The mantle beneath seismic station KIP (Hawaii) has normal Q and shear wave speed, which supports the result of earlier studies. The mantle beneath station AFI (Samoa Islands) has a very high Q, possibly larger than 1400, and the slowest shear wave speed. The stations on the upper plate of the Tonga and Japan subduction zones yield average to low Q values. In contrast, the stations on the trenchward side of the upper plate of some subduction zones, e.g., station LVC (Chile) and station PET (Kamchatka, Russia), indicate high Q values, larger than 1000. We found no obvious correlation between Q and shear wave speed, which suggests that different factors like temperature, composition, anisotropy, etc., are controlling these properties in the mantle of different tectonic environments.

The association of Hawaiian-Emperor volcanism with a large-scale central Pacific anisotropy anomaly at ~150 km depth can be explained by tapping of shallow melt sources in a perisphere/LLAMA (layer of lateral advection of mass and anisotropy) model. The origin of the anisotropy anomaly can be traced to the formation of a phlogopite-garnet-pyroxenite assemblage in the perisphere beneath an island arc on the Stikine terrane of the North American Cordillera in the Carboniferous. The pyroxenites were formed when subduction-related melts invaded the mantle wedge at ~150–200 km depth. The enriched region inherited the thermal profile of the mantle wedge, along with a solar-like noble gas isotopic composition from earlier fluxing of hydrothermal fluids between interplanetary dust particle–bearing deep-sea sediments and ultramafic layers of the oceanic crust prior to subduction. After termination of subduction, the enriched perisphere was displaced to the northeast beneath the Farallon plate, and then to the northwest beneath the Izanagi and Pacific plates, eventually becoming distorted into the shape of the present-day central Pacific anisotropy anomaly. During the thermal equilibration time, estimated at ~170 m.y., the phlogopite-garnet-pyroxenite assemblage followed a horizontal trajectory in pressure-temperature (P-T) space. As the P-T path crossed the solidi for volatile-bearing pyroxenite compositions, diabatic partial melting generated carbonatitic to alkaline melts which began to ascend and metasomatize shallower levels of the perisphere, carrying with them the geochemical signature of the original pyroxenites. The present central Pacific anisotropy anomaly is the current manifestation of the metasomatized domain. The latter was tapped from the Late Cretaceous to the present, by propagating fractures induced by large-scale plate reorganizations in the northwest of the Pacific Basin, to produce the Hawaiian-Emperor volcanic chain.

Extract from beginning of chapter: ON THE CHINA SEA The many-colored sea was glorious in the splendid weather that favored us—deep blue-green far out; lighter and brighter green toward the coast, turning to yellowish and yellow where it mingled with river waters along the shore. The Yellow Sea1 is well named, colored with the muddy waters of the Yangtze and the Yellow Rivers. In places there were great purplish streaks. On Sunday evening [1910], we were quietly anchored in the Min River, ten miles below Foochow,2 one of the most beautiful spots I was ever in. The entrance to the river is picturesque with mountains on both sides of a tortuous bay. There was a long trip up a fascinating valley with inlets and branches, between steep hills cultivated in horizontal terraces, in places to the highest points, with rice fields on either shore. We stopped in a lake-like expanse with stretches of river in three directions, each presenting a different mountainous scene. Rugged granite peaks formed the skyline in several directions at different distances. A low, reedy island was in one foreground; a wooded hill topped by a tall pagoda formed another. A green terraced ridge with artificially flat crests and scattered pines outlined against distant hills made a third, each view with its peculiar charm. Soon the steamer was surrounded by sampans, the locals climbing up the sides of the ship, struggling to unpack their stocks of all kinds on the lower deck. The whole family came in the sampan, the cleanest

The Northwest Hawaiian Ridge is a classic example of a large igneous province. The morphology and geology of the ridge is poorly characterized, although it constitutes the longest segment (~47%) of the Hawaiian-Emperor Chain. Here we present a new bathymetric compilation, petrographic and X-ray fluorescence (XRF) data for lavas from 12 volcanoes along the Northwest Hawaiian Ridge, and review literature data for the age and isotopic variation of the ridge. The bathymetric compilation revealed that the Northwest Hawaiian Ridge consists of at least 51 volcanoes. The 45 new XRF analyses show that the Northwest Hawaiian Ridge contains tholeiitic and alkalic lavas with compositions typical of lavas from the Hawaiian Islands. The absolute ages and duration of volcanism of individual Northwest Hawaiian Ridge volcanoes are poorly known, with modern 40Ar/39Ar ages for only 10 volcanoes, mostly near the bend in the chain. We infer the initiation age of the Hawaiian-Emperor Bend to be ca. 49–48 Ma, younger than the age for the onset of island arc volcanism in the western Pacific (52–51 Ma). Thus, the kink in the Hawaiian-Emperor Chain and the onset of arc volcanism were not synchronous. Isotopic data are sparse for the Northwest Hawaiian Ridge, especially for Pb and Hf. Two transitional lavas from just south of the bend have Loa trend type Pb and Sr isotopic ratios. Otherwise, the available chemistry for Northwest Hawaiian Ridge lavas indicates Kea-trend source compositions. The dramatic increase in melt flux along the Hawaiian Ridge (~300%) may be related to changes in melting conditions, source fertility, or plate stresses.

The Shatsky Rise is an oceanic plateau consisting of three main massifs that were constructed in the Pacific Ocean by intense volcanism during the Late Jurassic to Early Cretaceous. In order to explore the sources of this oceanic plateau, we present noble gas compositions from fresh quenched glasses cored by ocean drilling at Integrated Ocean Drilling Program Site U1347 on the Tamu Massif and Site U1350 on the Ori Massif. The studied glasses are normal-type basalts, the most abundant of four types of basalts defined by trace element compositions. Possible disturbances of noble gas compositions by posteruption radiogenic ingrowth in aged glasses are assessed by extraction of gases from glass vesicles by stepwise crushing. The 3He/4He ratios in glasses from Site U1347 are lower than atmospheric 3He/4He, presumably owing to magma degassing coupled with radiogenic ingrowth of 4He. In contrast, glasses from Site U1350 exhibit a limited range of 3He/4He (5.5–5.9 Ra). Uniform 3He/4He cannot be achieved if gases in glass vesicles have been affected by secondary contamination or posteruption radiogenic ingrowth. Therefore, the uniform 3He/4He in the normal-type basalts from Site U1350 is ascribed to their source characteristics. Relatively low 3He/4He among oceanic basalts suggests the involvement of recycled slab material in the source of the normal-type basalts. However, the depleted radiogenic isotope signatures are inconsistent with recycled slab being a distinct melting component. Instead, we propose that the normal-type basalts of the Shatsky Rise were sourced from a domain where subducted fertile material is dispersed in the mantle.

Oceanic plateaus are formed by a large volume of basaltic rocks on top of the oceanic lithosphere. Alteration of these basalt lava piles leads to significant chemical element exchanges between mantle and oceans that can strongly influence chemical budget. Here we report boron (B), chlorine (Cl), and other element concentrations in basalt samples from the Shatsky Rise to define alteration processes and to estimate the significance of oceanic plateaus in storing these elements. Sampling includes 121 basaltic lavas and 92 fresh glasses collected at various depths from Holes U1346A, U1347A, U1349A, and U1350A during Integrated Ocean Drilling Program Expedition 324. Loss on ignition (LOI) results indicate that alteration affected basalts from the summit sites (U1346 and U1349) more deeply than those from the flank sites (U1347 and U1350). The positive correlations between B, K, and LOI observed in the basalts indicate that low-temperature seawater-derived alteration was the predominant process affecting Shatsky Rise basalts. This is confirmed by the elevated B/K and modest Cl/K ratios of these altered basalts relative to the fresh glasses. In addition, B concentrations in the summit basalts (~132 ppm) are significantly higher than those in normal altered oceanic crust and are likely related to the presence of illite. This suggests that the Shatsky Rise oceanic plateau may be an important sink for B in the Pacific oceanic crust.

The Shatsky Rise is one of the largest oceanic plateaus, a class of volcanic features whose formation is poorly understood. It is also a plateau that was formed near spreading ridges, but the connection between the two features is unclear. The geologic structure of the Shatsky Rise can help us understand its formation. Deeply penetrating two-dimensional (2-D) multichannel seismic (MCS) reflection profiles were acquired over the southern half of the Shatsky Rise, and these data allow us to image its upper crustal structure with unprecedented detail. Synthetic seismograms constructed from core and log data from scientific drilling sites crossed by the MCS lines establish the seismic response to the geology. High-amplitude basement reflections result from the transition between sediment and underlying igneous rock. Intrabasement reflections are caused by alternations of lava flow packages with differing properties and by thick interflow sediment layers. MCS profiles show that two of the volcanic massifs within the Shatsky Rise are immense central volcanoes. The Tamu Massif, the largest (~450 km × 650 km) and oldest (ca. 145 Ma) volcano, is a single central volcano with a rounded shape and shallow flank slopes (<0.5°–1.5°), characterized by lava flows emanating from the volcano center and extending hundreds of kilometers down smooth, shallow flanks to the surrounding seafloor. The Ori Massif is a large volcano that is similar to, but smaller than, the Tamu Massif. The morphology of the massifs implies formation by extensive and far-ranging lava flows emplaced at small slope angles. The relatively smooth flanks of the massifs imply that the volcanoes were not greatly affected by rifting due to spreading ridge tectonics. Deep intrabasement reflectors parallel to the upper basement surface imply long-term isostasy with the balanced addition of material to the surface and subsurface. No evidence of subaerial erosion is found at the summits of the massifs, suggesting that they were never highly emergent.

The Shatsky Rise, located in the northwest Pacific Ocean, is one of the largest oceanic plateaus. The origin and evolution of the oceanic plateaus are unclear because these features are remote and poorly imaged with geophysical data. Marine multi-channel seismic (MCS) data were collected over the Shatsky Rise to image its upper crustal structure. These data have the potential to improve understanding of the processes of basaltic volcanism and the formation and evolution of oceanic plateaus by providing direct insights into the geometry and distribution of igneous eruptions. In contrast to sedimentary settings, it is often difficult to interpret deeper layers within basaltic crust because of rugged layering and scattering. Reflections in igneous crust are characterized by poor lateral continuity compared with marine sediments and often by weak impedance contrasts, resulting in a lower signal-to-noise ratio and a more challenging interpretation. In this paper we apply the two-dimensional (2-D) anisotropic continuous wavelet transform (CWT) method to improve interpretations of MCS data from the Shatsky Rise oceanic plateau. Applying the transform to the time domain MCS profiles with appropriate values of wavelength and period produces new images with enhanced continuity of reflectors and reduced amplitudes of incoherent noise at different periods. The analysis of the results obtained by using 2-D CWT on the MCS data over the Tamu massif part of the Shatsky Rise also helps reveal features such as dome-like bulges possibly associated with lava intrusion and faults in the deeper part of the crust associated with volcanic rock. These were not readily seen in the original seismic images, but the suppression of random noise and other signals with low coherence makes their interpretation possible. These and similar results provide new insights into the complexity of the igneous processes forming the Tamu massif.

The eruptive history of the Shatsky Rise, a large oceanic plateau in the northwestern Pacific Ocean, is poorly understood. Although it has been concluded that the Shatsky Rise volcanic edifices erupted rapidly, there are few solid chronological data to support this conclusion. Similarly, the Shatsky Rise is thought to have formed near the equator, but paleolatitude data from the plateau are few, making it difficult to assess its plate tectonic drift with time. To understand the formation history of this oceanic plateau, paleomagnetic measurements were conducted on a total of 362 basaltic lava samples cored from the Shatsky Rise at 4 sites (U1346, U1347, U1349, and U1350) during Integrated Ocean Drilling Program Expedition 324. Examining changes in paleomagnetic inclinations, we gain a better understanding of eruptive rates by comparison of observed shifts in inclination with expected paleosecular variation. At three sites (U1346, U1347, and U1349) little change in paleomagnetic directions was observed, implying that the cored sections were mostly erupted rapidly over periods of <~100–200 yr. Only Site U1350 displayed directional changes consistent with significant paleosecular variation, implying emplacement over a period of ~1000 yr. The paleomagnetic data are consistent with the idea that the Shatsky Rise igneous sections were mostly emplaced rapidly, but there were some time gaps and some fl ank locations built up more slowly. Because paleosecular variation was inadequately sampled at all the Shatsky Rise sites, paleolatitudes have large uncertainties, and because of the equatorial location, magnetic polarity is also uncertain. All sites yield low paleolatitudes and indicate that the Shatsky Rise stayed near the equator during its formation. Given that the locus of magmatism moved northward relative to the Pacific plate while staying near the equator, the Pacific plate must have drifted southward relative to the spin axis during the emplacement of the plateau.

Fresh basalts from the Ontong Java Plateau (OJP) and the Shatsky Rise show lithium enrichments comparable to those of mid-oceanic ridge basalts (MORBs) and ocean island basalts (OIBs), with Li contents being significantly higher at a given MgO content. The Li isotopic compositions of the Shatsky Rise basalts (δ7Li = +6‰ to +7‰) are at the higher end of the range exhibited by OIBs, whereas OJP basalts (δ7Li = +3‰ to +5‰) have Li isotopic compositions similar to MORBs. Among all the basalts from the two oceanic large igneous provinces (LIPs), one sample from the Shatsky Rise is isotopically enriched (e.g., low 143Nd/144Nd and 176Hf/177Hf) and has higher K/Ti and lower La/Nb than the other samples. Relationships between δ7Li and K/Ti, La/Nb, and Rb/Nb of this sample indicate that it may have been affected by mantle that was metasomatized by slab-derived fluids. Apart from this isotopically enriched sample, δ7Li values of basalts from the two oceanic LIPs are positively correlated with K/Ti and Rb/Nb. Obvious linear relationships exist between δ7Li and Yb/Li, Y/Li, and Dy/Li for samples from the Shatsky Rise. These geochemical relationships can be explained by magmatic assimilation of hydrothermally influenced crust. The high δ7Li values of the Shatsky Rise basalts imply that the degree of assimilation is high because shallow magma chambers allow greater assimilation of hydrothermally influenced crust. In contrast, the low δ7Li values of the OJP samples may indicate they have undergone little assimilation as compared with the Shatsky Rise basalts.

A substantial portion of the Pacific basin is composed of seafloor formed during the Cretaceous Normal Superchron (CNS). Because this region lacks the magnetic lineations typically required to constrain tectonic reconstructions, we employ additional methods for interpreting CNS Pacific history, involving seafloor fabric, basement paleolatitudes, and age data. We utilize seafloor fabric, including fracture zones and the rift margins of large igneous provinces, to derive quantitative rotations. The timing of such rotations is constrained using rock ages, bounding magnetic isochrons, and estimates of interactions with surrounding terrains. The method relies on high-resolution shipboard bathymetry and rock ages, as much fine-scale seafloor fabric useful for reconstructions is not visible in satellite altimetry data. We show that the Ontong Java, Manihiki, and Hikurangi oceanic plateaus likely originated as one large superplateau, the Ontong Java Nui (OJN). Reconstructions of OJN at 123 Ma reveal large offsets between observed and predicted paleolatitudes. Observed paleolatitudes exhibit a systematic bias, which may be attributed to large-scale rotation of the entire plateau. Such a rotation would imply either that OJN was initially decoupled from the Pacific plate and able to rotate independently or that the orientation of the Pacific plate at 123 Ma differed from conventional model predictions. However, large uncertainties in absolute plate motion models prior to ca. 80 Ma preempt a conclusive interpretation for OJN formation. Given an ~10 km resolution limit for satellite altimetry, continued investments in seagoing research will be needed to investigate tectonic events in magnetic quiet zones.

High-Mg Kroenke-type basalts containing 9–11 wt% MgO from the Ontong Java Plateau (OJP) include spinels. These spinels have nearly identical Cr/(Cr + Al) ratios (0.45–0.54), and are generally hosted by olivine phenocrysts with relatively primitive compositions, with Fo contents [100 × Mg/(Mg + Fe2+) in atomic ratios] as high as 88. This implies that the primary OJP magmas were in equilibrium with refractory peridotites (i.e., harzburgites) and were homogenized by large-scale melting and magmatic evolutionary processes. Oxygen geobarometry indicates that the OJP primary magmas record uniform oxygen fugacity (fO2) conditions and are slightly more oxidized (0.6 log units) than normal mid-ocean ridge basalts, but record less-oxidized fO2 conditions than ocean island basalts. These data are consistent with previous studies that suggest the OJP primary magmas were generated by large-scale and extensive melting of a mantle source region under relatively oxidized conditions.