Site 1256

,

doi:10.2204/iodp.proc.309312.103.2006

Cited by 15 publications

(12 citation statements)

References 103 publications

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“…For example, compared with first-order mid-ocean-ridge segments along the EPR, basalts from Site 1256 have low Zr/TiO 2 and Zr/Y. Although there is overlap among the segments and a large scatter in the data for each segment, Zr/TiO 2 and Zr/ Y appear to decrease with increasing spreading rate (Teagle, Alt, Umino, Miyashita, Banerjee, Wilson, et al, 2006). The origin of this relationship remains unclear.…”

Section: Summary Of Whole-rock Igneous Geochemistry From Site 1256mentioning

confidence: 98%

“…Consequently, the often difficult-to-drill upper ocean crust should be relatively thin. Teagle, Acton, et al, 2003;Teagle, Alt, Umino, Miyashita, Banerjee, Wilson, et al, 2006), which prepared the first scientific borehole for deep drilling by installing a large reentry cone secured with almost 270 m of 16 inch casing through the 250 m thick sedimentary overburden and cemented into the uppermost basement (Fig. F2).…”

Section: Background and Geological Settingmentioning

confidence: 99%

“…With width and temperature contrast not varying, the extra heat supplied by more magma at faster spreading rates must be conducted through a thinner lid (dike layer) to maintain steady state (see Phipps Morgan and Chen [1993] for a more complete discussion). This analysis leads to the prediction that to reach cumulate gabbros in normal oceanic crust with minimal drilling, it is therefore best to target crust formed at the fastest possible spreading rates (Wilson et al, 2006).…”

Section: Rationale For the Superfast Spreading Crust Campaign And Locmentioning

confidence: 99%

“…F2) (Teagle, Alt, Umino, Miyashita, Banerjee, Wilson, et al, 2006), and such lava morphologies have been shown to dominate crust formed at fast spreading rates, away from segment tips (e.g., White et al, 2000White et al, , 2002. Subordinate pillow lavas are present in Hole 1256D (e.g., Tominaga et al, 2009), and because of the large number of fractures and pillow interstices, seismic velocities in these units are generally lower than more massive lava flows.…”

Section: Geological Setting Of Site 1256mentioning

confidence: 99%

“…The predicted composition of the cumulate gabbros generated during this fractional crystallization is very different from that of the gabbros drilled so far. Simple mass balance calculations indicate that the average basalt has lost >30% of its original liquid mass as solid gabbro, implying the presence of at least 300 m of cu-mulate gabbro in the crust below the present base of the hole (Teagle, Alt, Umino, Miyashita, Banerjee, Wilson, et al, 2006).…”

Section: Summary Of Whole-rock Igneous Geochemistry From Site 1256mentioning

confidence: 99%

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Scientists

Teagle

Ildefonse

et al. 2011

IODP Preliminary Report

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Section: Summary Of Whole-rock Igneous Geochemistry From Site 1256mentioning

confidence: 98%

Section: Background and Geological Settingmentioning

confidence: 99%

Section: Rationale For the Superfast Spreading Crust Campaign And Locmentioning

confidence: 99%

Section: Geological Setting Of Site 1256mentioning

confidence: 99%

Section: Summary Of Whole-rock Igneous Geochemistry From Site 1256mentioning

confidence: 99%

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Teagle

Ildefonse

et al. 2011

IODP Preliminary Report

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The influence of porosity and crack morphology on seismic velocity and permeability in the upper oceanic crust

Carlson

2014

Geochem Geophys Geosyst

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[1] The purpose of this study is to explore the relationships between porosity, crack morphology, seismic velocity, and permeability in the upper oceanic crust. In a theoretical model, velocity is a quadratic function of porosity U, and the coefficients are functions of the fractional area of asperity contact A f across the cracks, a measure of crack morphology; thus, v 5 v(A f , U). Fits to data sets from the lava and dike sections in Holes 504B and 1256D yield A f 5 0.096(8) and 0.045(3), with rms errors of 1.7 and 0.3%, respectively. Lower values of A f account for the high porosities and low velocities observed in Layer 2A. After 0.2 Ma, the porosities of both Layer 2A and the deeper part of the lava pile remain in the range 8 6 4%. The observed increase of Layer 2A velocities after 0.2 Ma is caused largely by changing crack morphology as opposed to decreasing porosity; at 8% porosity, an increase of A f from 0.003 to 0.1 accounts for an increase of velocity from 3 to >5 km/s. An empirical log-linear relationship between permeability j and v suggests a relationship between j and A f as well. This relationship between j and v can be explained if the permeability coefficient j o is a closely constrained quadratic function of the area of asperity contact A f . A f is thus the primary variable affecting both seismic velocities and the permeability of the uppermost oceanic crust.

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Structural and petrophysical characterization of the upper basement crustal section at ODP/IODP Site 1256 (East Pacific Ocean)

Fontana

Tartarotti

2013

Geochem Geophys Geosyst

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[1] New ocean crust is constantly being formed from mid-ocean ridge axis. Voluminous flows of lava are emplaced also away from the ridge axis, adding off-axis crustal layers to the crustal pile. Research on deep sea is of great importance to better understand the mechanisms and the nature of the crust forming and evolution. In this work, we decipher the first stages of the postmagmatic evolution of an intact volcanic section from the upper oceanic crust at ocean drilling program/integrated ocean drilling program (ODP/IODP) Site 1256 (Eastern Pacific Ocean). Using for the first time an innovative core-log integration technique to match direct (core-related) and indirect (borehole-related) data by depth shifting and reorienting individual core pieces recovered by drilling, we are able to identify the clusterization of structures and physical properties within distinct downdeep ''strong'' and ''weak'' lava zones, reflecting the cooling and tectonic evolution of lavas rather than lithological variations. We define the evolution of the structural zones that typically affect lava flows: colonnades and entablature zones, studying an offaxis lava flow encountered in present-day upper ocean crust. For the same off-axis flow, we are also able to suggest the lava flow direction (NW-SE) and its relationships with the paleoridge axis. Despite the environmental difficulties in the study of the subseafloor under deep water and using only onedimensional data deriving from ocean drilling, this work shows how an array of diverse data can be integrated into a coherent interpretation of lava flow history obtaining detailed information on the mechanism of submarine lava emplacement and flow.

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Site 1256

Cited by 15 publications

References 103 publications

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The influence of porosity and crack morphology on seismic velocity and permeability in the upper oceanic crust

Structural and petrophysical characterization of the upper basement crustal section at ODP/IODP Site 1256 (East Pacific Ocean)

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