Data from International Ocean Discovery Program (IODP) Expedition 371 reveal vertical movements of 1–3 km in northern Zealandia during early Cenozoic subduction initiation in the western Pacific Ocean. Lord Howe Rise rose from deep (∼1 km) water to sea level and subsided back, with peak uplift at 50 Ma in the north and between 41 and 32 Ma in the south. The New Caledonia Trough subsided 2–3 km between 55 and 45 Ma. We suggest these elevation changes resulted from crust delamination and mantle flow that led to slab formation. We propose a “subduction resurrection” model in which (1) a subduction rupture event activated lithospheric-scale faults across a broad region during less than ∼5 m.y., and (2) tectonic forces evolved over a further 4–8 m.y. as subducted slabs grew in size and drove plate-motion change. Such a subduction rupture event may have involved nucleation and lateral propagation of slip-weakening rupture along an interconnected set of preexisting weaknesses adjacent to density anomalies.

lieh, obwohl der Vorgang geographisch diachron ist. Sein Verschwinden aus dem Südatlantik ist frühzeitig, grob korrelierbar mit Schätzungen aus tropischen Regionen. Kurze Intervalle starker Häufigkeit von C. reticulatum und C. protoannula können darauf hindeuten, daß ihr letztes Erscheinen (jeweils 37.86 Ma und 38.18 Ma) einen begrenzeten biochronologischen Wert hat. Für die Eozän/Oligozän-Grenze wird anhand des Hole 522 und des Aussterbens von Hantkenina ein Alter von 36.15 Ma bis 36.20 Ma vorgeschlagen. Das nächstliegende Nannofos-Silienereignis ist das erste häufige Erscheinen von E. obruta (36.07 Ma) oder, regional (?), der scharfe Umschlag im Verhältnis R. umbilicus/C. formosus (36.10 Ma).

The Middle to Late Ordovician was a time of profound biotic diversification, paleoecological change, and major climate shifts. Yet studies examining speciation mechanisms and drivers of dispersal are lacking. In this study, we use Bayesian phylogenetics and maximum likelihood analyses in the R package BioGeoBEARS to reanalyze ten published data matrices of brachiopods and trilobites and produce time-calibrated species-level phylogenetic hypotheses with estimated biogeographic histories. Recovered speciation and biogeographic patterns were examined within four time slices to test for changes in speciation type across major tectonic and paleoclimatic events. Statistical model comparison showed that biogeographic models that ACCEPTED MANUSCRIPTA C C E P T E D M A N U S C R I P T 2 incorporate long-distance founder-event speciation best fit the data for most clades, which indicates that this speciation type, along with vicariance and traditional dispersal, were important for Paleozoic benthic invertebrates. Speciation by dispersal was common throughout the study interval, but notably elevated during times of climate change. Vicariance events occurred synchronously among brachiopod and trilobite lineages, indicating that tectonic, climate, and ocean processes affected benthic and planktotrophic larvae similarly. Middle Ordovician interoceanic dispersal in trilobite lineages was influenced by surface currents along with volcanic island arcs acting as "stepping stones" between areas, indicating most trilobite species may have had a planktic protaspid stage. These factors also influenced brachiopod dispersal across oceanic basins among Laurentia, Avalonia, and Baltica. These results indicate that gyre spin-up and intensification of surface currents were important dispersal mechanisms during this time. Within Laurentia, surface currents, hurricane tracks, and upwelling zones controlled dispersal among basins. Increased speciation during the Middle Ordovician provides support for climatic facilitators for diversification during the Great Ordovician Biodiversification Event. Similarly, increased speciation in Laurentian brachiopod lineages during the Hirnantian indicates that some taxa experienced speciation in relation to major climate changes. Overall, this study demonstrates the substantial power and potential for likelihood-based methods for elucidating biotic patterns during the history of life.

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A basic means to establish and understand variations in climate and ocean water properties is through sediment mass accumulation rates (MARs), which are quantified measurements of solid material flux to the seabed (mass Abstract Sediment mass accumulation rate (MAR) is a proxy for paleoceanographic conditions, especially if biological productivity generated most of the sediment. We determine MAR records from pelagic calcareous sediments in Tasman Sea based on analysis of 11 boreholes and >3 million seismic reflection horizon picks. Seismic data from regions of 10,000-30,000 km 2 around each borehole were analyzed using data from International Ocean Discovery Program Expedition 371 and other boreholes. Local MAR was affected by deepwater currents that winnowed, eroded, or deposited seafloor sediment. Therefore, it is necessary to average MARs across regions to test paleoceanographic and productivity models. MARs during the Miocene Climate optimum (18-14 Ma) were slightly lower than Quaternary values but increased on southern Lord Howe Rise at 14-13 Ma, when global climate became colder. Intensification of the Indian and East Asian monsoons at ∼8 Ma and ∼3.6 Ma approximately corresponds to the start and end, respectively, of the Biogenic Bloom, which had MARs at least double Quaternary values. On northern Lord Howe Rise, we recognize peak MARs at∼7 Ma and ∼5 Ma. There is no correlation between Neogene MAR and ocean pH or atmospheric CO 2 concentration. Neogene MARs are on average higher than Quaternary values. We posit that future long-term productivity in the southwest Pacific could be higher than Quaternary values, but new computer models that can fit our observations are required to test this hypothesis. Plain Language SummaryGlobal climate is likely to get warmer, and we want to know what will happen to marine life. We can study ancient warm periods to better predict the future. The ocean is a global carbon sink, because some organisms form shells by combining calcium with carbon dioxide dissolved in seawater. Once dead, their calcium carbonate shells sink to the seabed. Over millions of years, the southwest Pacific accumulated huge deposits. We used geophysical surveying and drilling to measure this history of deposition, which is a proxy for ancient biological productivity (how much marine life existed). A warm period 18-14 million years ago had high atmospheric carbon dioxide (2-4 times preindustrial levels) and slightly lower ocean productivity. In contrast, 8-4 million years ago, atmospheric carbon dioxide was similar to predicted 21st century levels and productivity was much higher: more than double recent values. Rates of calcium carbonate deposition in the past do not correlate with ocean acidity or atmospheric carbon dioxide; but they were mostly higher than today. Hence, long-term biological productivity and carbon sequestration in the southwest Pacific might increase in future, but computer models that fit our observations are needed to test this idea.