Data report: permeability of ~1.9 km-deep coal-bearing formation samples off the Shimokita Peninsula, Japan

Ijiri, Akira; Ikegawa, Yojiro; Inagaki, Fumio

doi:10.2204/iodp.proc.337.202.2017

Cited by 4 publications

(4 citation statements)

References 8 publications

(12 reference statements)

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“…Our grain size measurement from the uppermost sample in Unit III (1925.21 mbsf) is consistent with the grain size distribution of one sample from 1925.38 mbsf measured via sieve analysis by Ijiri et al (2017). Overall, these results show systematic changes downhole that may provide insight to paleoenvironmental conditions and the role of the host material for microbial activity.…”

Section: Resultssupporting

confidence: 81%

Data report: grain size distribution of unconsolidated sands offshore Shimokita Peninsula, Japan (IODP Site C0020)

Phillips¹,

Johnson²

2017

Proceedings of the IODP

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We report particle size analyses measured from 28 unconsolidated sand samples recovered during Integrated Ocean Drilling Program Expedition 337 from Hole C0020A. These samples span from 1277 to 2002 meters below seafloor (mbsf) across two lithostratigraphic units that record a transition from a nearshore estuarine/ intertidal to an offshore hemipelagic paleoenvironment. Most recovered lithologies, including coarse-grained lithologies, are semiconsolidated to consolidated; however, some intervals of sand are unconsolidated and suitable for particle size analysis. Bulk sand samples were measured using a laser diffraction particle size analyzer. All samples fall within the range of sand to silty sand, with silty sand more abundant deeper than 1925 mbsf. Samples contain 49%-97% sand, 3%-42% silt, and 0%-13% clay. Median grain diameter ranges from 55 to 405 µm. Clay and silt content in these sands reach a minimum at ~1500 mbsf and then increase below 1925 mbsf in a coal-bearing unit containing shale, siltstone, sandstone, and unconsolidated sand. The recovered sediment sequence revealed a transition from offshore marine to nearshore/terrestrial environments that was described in four lithostratigraphic units (Figure F1) (see the "Site C0020" chapter [Expedition 337 Scientists, 2013b]) that span the late Oligocene to early Pleistocene (Phillips et al., 2016). Unit I (647-1256.5 mbsf; no core recovery) is composed of a hemi-Chapter contents

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Section: Resultssupporting

confidence: 81%

Data report: grain size distribution of unconsolidated sands offshore Shimokita Peninsula, Japan (IODP Site C0020)

Phillips¹,

Johnson²

2017

Proceedings of the IODP

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“…7b) Nevertheless, voids in fractures may form an important pathway for fluid flow through coalbeds, because the in-situ permeability of fractured coal is much higher than that of the intact coal matrix or neighboring siltstone/shale formations (Fig. 5b, Ijiri et al 2017). Therefore, it is considered that nutrients and energy sources were mainly released from the coal layers through the cleats, where large amounts of energy sources are stored, and that these compounds seeped into the overlying permeable sandy sediments.…”

Section: Why Do Coal-bearing Units Have Anomalously High Microbial Bimentioning

confidence: 99%

“…However, a larger microbial biomass was observed in lignite coal layers. Physical and chemical characteristics of the cored sediment samples were determined at onboard and offshore laboratories (Gross et al 2015;Glombitza et al 2016;Tanikawa et al 2016;Ijiri et al 2017;Trembath-Reichert et al 2017), but the key factors responsible for constraining the vertical distribution of the microbial populations in the deep sedimentary biosphere have not yet been well clarified (Hinrichs and Inagaki 2012). While permeability and pore characteristics potentially govern not only microbial biomass but also the reservoir capacity of microbially produced coalbed methane (Gamson et al 1993;Clarkson and Bustin 1996;Strąpoć et al 2011), the transport dynamics associated with these characteristics have not yet been reported.…”

Section: Introductionmentioning

confidence: 99%

Geophysical constraints on microbial biomass in subseafloor sediments and coal seams down to 2.5 km off Shimokita Peninsula, Japan

Tanikawa

Tadai

Morono

et al. 2018

Prog Earth Planet Sci

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To understand the ability of microbial life to inhabit a deep subseafloor coalbed sedimentary basin, the correlation between fluid transport properties and the abundance of microbial cells was investigated based on core samples collected down to about 2.5 km below the seafloor during the Integrated Ocean Drilling Program Expedition 337 off the Shimokita Peninsula, Japan. The overall depth profiles for porosity and permeability exhibited a decreasing trend with increasing depth. However, at depths greater than 1.2 km beneath the seafloor, the transport characteristics of the sediments were highly variable, with the permeability ranging from 10 −16 to 10 −22 m 2 and the pore size ranging from < 0.01 to 100 μm. This is mainly attributed to the diversity of the lithology, which exhibits a range of pore sizes and pore geometries. Fracture channels in coal seams had the highest permeability, while shale deposits had the smallest pore size and lowest permeability. A positive correlation between permeability and pore size was confirmed by the Kozeny-Carman equation. Cell abundance at shallower depths was positively correlated with porosity and permeability, and was less strongly correlated with pore size. These findings suggest that one of the factors affecting the decrease in microbial cell abundance with increasing depth was a reduction in nutrient and water supply to indigenous microbial communities as a result of a decrease in porosity and permeability due to sediment compaction. Anomalous regions with relatively high cell concentrations in coal-bearing units could be explained by the higher permeability and larger pore size for these units compared to the surrounding sediments. Nutrient transport through permeable cleats in coal layers might occur upwards toward the upper permeable sandstone layers, which are well suited for sustaining sizable microbial populations. Conversely, impermeable shale and siltstone with small pores (< 0.2 μm, which is smaller than microbial cell size) may act as barriers to water and energy-yielding substrates for deep microbial life. We propose that the pore size and permeability govern the threshold for microbial habitability in the deep subseafloor sedimentary biosphere.

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“…Gross et al, Glombitza et al, 2016 ;Ijiri et al, 201760 Inagaki et al, 2012Tanikawa et al, 2016 Inagaki et al, Imachi, H., Aoi, K., Tasumi, E., Saito, Y., Yamanaka, Y., Saito, Y., Yamaguchi, T., Tomaru, H., Takeuchi, R., Morono, Y., Inagaki, F. and Takai, K. 2011…”

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Interactions between biogenic gas and microbial activity in the subseafloor

et al. 2018

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Data report: permeability of ~1.9 km-deep coal-bearing formation samples off the Shimokita Peninsula, Japan

Cited by 4 publications

References 8 publications

Data report: grain size distribution of unconsolidated sands offshore Shimokita Peninsula, Japan (IODP Site C0020)

Data report: grain size distribution of unconsolidated sands offshore Shimokita Peninsula, Japan (IODP Site C0020)

Geophysical constraints on microbial biomass in subseafloor sediments and coal seams down to 2.5 km off Shimokita Peninsula, Japan

Interactions between biogenic gas and microbial activity in the subseafloor

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