Hikurangi Subduction Margin Coring, Logging, and Observatories最新文献

{"title":"Data report: early Late Cretaceous radiolarians from IODP Site U1520 (Expedition 375, Hikurangi subduction margin)","authors":"C. Hollis","doi":"10.14379/iodp.proc.372b375.208.2021","DOIUrl":"https://doi.org/10.14379/iodp.proc.372b375.208.2021","url":null,"abstract":"Poorly preserved radiolarians of early Late Cretaceous age have been recovered from International Ocean Discovery Program (IODP) Hole U1520C, which was drilled as part of IODP Expedition 375 (Hikurangi Subduction Margin Coring, Logging, and Observatories). Seven radiolarian-rich samples from Cores 375-U1520C42R and 43R (1027.8–1037.5 meters below seafloor) contain a relatively uniform assemblage that includes species indicative of a middle Cenomanian age (~97 Ma).","PeriodicalId":403414,"journal":{"name":"Hikurangi Subduction Margin Coring, Logging, and Observatories","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124358299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Data report: reconnaissance of bulk sediment composition and clay mineral assemblages: inputs to the Hikurangi subduction system","authors":"M. Underwood","doi":"10.14379/iodp.proc.372b375.203.2020","DOIUrl":"https://doi.org/10.14379/iodp.proc.372b375.203.2020","url":null,"abstract":"This report provides a reconnaissance-scale assessment of bulk mineralogy and clay mineral assemblages in sediments and sedimentary rocks that are entering the Hikurangi subduction zone, offshore North Island, New Zealand. Samples were obtained from three sites drilled during Leg 181 of the Ocean Drilling Program (Sites 1123, 1124, and 1125) and 38 piston/gravity cores that are distributed across the strike-length of the margin. Results from bulkpowder X-ray diffraction show large variations in normalized abundances of total clay minerals and calcite. The typical lithologies range from clay-rich hemipelagic mud (i.e., mixtures of terrigenous silt and clay with lesser amounts of biogenic carbonate) to calcareous mud, muddy calcareous ooze, and nearly pure nannofossil ooze. Basement highs (Chatham Rise and Hikurangi Plateau) are dominated by biocalcareous sediment, whereas most deposits in the trench (Hikurangi Trough and Hikurangi Channel) and on the insular trench slope are hemipelagic. Clay mineral assemblages (<2 μm) change markedly as a function of geographic position. Sediment entering the southwest side of the Hikurangi subduction system is enriched in detrital illite (>60 wt%) relative to chlorite, kaolinite, and smectite. Normalized proportions of detrital smectite increase significantly toward the northeast to reach values of 40–55 wt% offshore Hawkes Bay and across the transect area for Expeditions 372 and 375 of the International Ocean Discovery Program. Introduction Expeditions 372 and 375 of the International Ocean Discovery Program (IODP) drilled five sites on the overriding and subducting plates of the Hikurangi convergent margin, offshore North Island, New Zealand (Figure F1). The project’s overarching goal is to understand the behavior and spatial distribution of slow slip events (SSE) along the plate interface (Saffer et al., 2017). Drilling focused on recovery of sediments, rocks, and pore fluids, acquisition of logging-while-drilling data, and installation of long-term borehole observatories. Interpretations of new compositional results from the transect area are challenging, however, because comparable information is almost nonexistent from other sectors along the strikelength of the margin. The closest Ocean Drilling Program (ODP) sites (1123, 1124, and 1125) are located far seaward of the Hikurangi Trough (Figure F1). Shipboard X-ray diffraction (XRD) measurements were not completed during that expedition, and only one published report contains postcruise compositional data (Winkler and Dullo, 2002). Far to the southwest, XRD data from the Canterbury Basin and Canterbury slope (Land et al., 2010; Villaseñor et al., 2015) are of limited value to Hikurangi studies because those sites capture a different system of detrital sources and dispersal routes off the South Island of New Zealand (Figure F1). The motivation for regional-scale reconnaissance of sediment composition is to provide better context for forthcoming interpretati","PeriodicalId":403414,"journal":{"name":"Hikurangi Subduction Margin Coring, Logging, and Observatories","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124651935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Data report: clay mineral assemblages within biocalcareous and volcaniclastic inputs to the Hikurangi subduction zone, IODP Expedition 372B/375 Sites U1520 and U1526, offshore New Zealand","authors":"M. Underwood","doi":"10.14379/iodp.proc.372b375.207.2021","DOIUrl":"https://doi.org/10.14379/iodp.proc.372b375.207.2021","url":null,"abstract":"Inputs to the Hikurangi subduction zone, offshore North Island, New Zealand, include volcaniclastic conglomerates that were deposited during the Late Cretaceous on the flanks of the subducting basement of Hikurangi Plateau. The overlying succession of pelagic carbonates is early Paleocene to early Pleistocene in age and ranges in composition from calcareous mudstone to muddy chalk and chalk. A thick wedge of Quaternary trench sediments occupies the top of the stratigraphic succession. International Ocean Discovery Program Expedition 375 cored those subduction inputs at two sites. Site U1520 is located on the distal edge of the trench, and Site U1526 is located near the crest of Tūranganui Knoll, where a highly condensed section of pelagic-hemipelagic sediment covers the basalt basement. This report provides the results of 128 X-ray diffraction analyses of the clay-sized fraction (<2 μm spherical settling equivalent), where smectite + illite + undifferentiated (chlorite + kaolinite) + quartz = 100%. Clay minerals in the altered volcaniclastic conglomerates and basalt consist almost exclusively of smectite. At Site U1520, the normalized abundance of smectite in overlying biocalcareous sediments ranges from 28.3 to 72.9 wt% (mean = 54.2 wt%), whereas the abundance of illite ranges from 16.1 to 49.0 wt% (mean = 32.0 wt%). The range for undifferentiated chlorite + kaolinite is 0.3–17.8 wt% (mean = 7.4 wt%), and the range for clay-sized quartz is 2.7–20.5 wt% (mean = 6.4 wt%). Upsection depletion of smectite in those sediments is balanced by upsection enrichment of illite. That same age-dependent trend is evident in coeval biocalcareous drift sediments from Ocean Drilling Program Sites 1123 (North Chatham drift) and 1124 (Rekohu drift). Moving downsection at Site U1520, indicators of clay diagenesis are inconsistent. Values of illite crystallinity index increase (i.e., peak broadening), whereas the proportion of illite within illite/smectite mixed-layer clays increases with depth.","PeriodicalId":403414,"journal":{"name":"Hikurangi Subduction Margin Coring, Logging, and Observatories","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116230260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}