Submarine lava flow direction revealed by neutron diffraction analysis in mineral lattice orientation

Abstract

The ocean crust is formed by the rising of magma from mid-ocean ridges and voluminous (1-30 km 3 ) flows of lava away from ridge axes. However, our understanding of the emplacement kinematics of submarine lava is often limited to plan view geometries of near-axis lava. Drilled cores provide in situ access to the intact internal structure of submarine lavas. We used neutron diffraction to study off-axis lava flows drilled into the uppermost crust of ODP/IODP-Site 1256 (Cocos Plate). We provide quantitative insights into submarine lava microstructures and strong evidence for a secondary lava injection into the interior of a solidifying flow of lava along the NW-SE direction parallel to the paleo-ridge axis of the East Pacific Rise. The dynamics of lava inflow are controlled by crystal abundance and the temperature of the lava-crystal mixture rather than by local seafloor topography. We provide a description of an in situ shear within submarine lavas revealed by composite shape and lattice preferred orientations, accounting for a dominant laminar nonuniform-type flow.

Tectonic analysis and paleo-stress determination of the upper lava section at ODP/IODP site 1256 (East Pacific Ocean)

“…Similar to the trends of the principal stress axes in the detected stress states, several local 514 and regional morphologic or tectonic features display NW -SE and/or NE -SW principal Fontana and Tartarotti (2013), and Zucali et al (2014); (4) the paleo-EPR crest orientation, 520 which trends NW -SE (as shown by the magnetic anomalies; see Fig. 1) as well as the MAT, 521 and the NE -SW-trending CNS-2 abandoned at 14.7 Ma (Meschede and Barckhausen, 2000).…”

“…The Lava Pond is likely to flow within a trough oriented NW -SE (similar to the trough 586 detected by Hallenborg et al, 2003) confined at the NE and SW border (hence with a 587 confining pressure along the NE -SW direction) with the possibility of extending only along 588 the NW -SE direction (Fontana and Tartarotti, 2013;Zucali et al, 2014). Thus, the Lava 589…”

“…When the Lava Pond was emplaced off axis at ~15 Ma, it flowed along the NW -SE 604 direction and was likely confined in a trough (Fontana and Tartarotti, 2013;Zucali et al, M A N U S C R I P T…”

The 3D quantitative lattice and shape preferred orientation of a mylonitised metagranite from Monte Rosa (Western Alps): Combining neutron diffraction texture analysis and synchrotron X-ray microtomography

“…Neutron (and X-ray) diffraction can provide structural information and the quantification of LPO (Baker and Wenk, 1972;Chateigner et al, 2000;Wenk et al, 2001Wenk et al, , 2010Zucali et al, 2010Zucali et al, , 2012Zucali et al, , 2014. By using the Rietveld method (Rietveld, 1969), it is generally possible to obtain the crystallographic properties of the different phases (such as lattice parameters, crystallite size, crystal structure, microstrain, etc.…”

Crystallographic and Seismic Anisotropies of Calcite at Different Depths: A Study Using Quantitative Texture Analysis by Neutron Diffraction

“…The samples were cut in cubes of ≈ 1cm edge ( In order to evaluate the Crystallographic Preferred Orientation (CPO) of the samples we used the non-disruptive method of the Quantitative Texture Analysis (QTA) by neutron diffraction, successfully applied on various types of rocks and synthetic materials: in monomineralic quartzites [20], marbles [17], limestones [21], dunite [22] or glaucophanite [23], in poly-phasic rocks, as amphibolite [24,25], quartz-feldspatic mylonitic orthogneisses and gabbros [26,27], subacqueous lavas [28] or sandstones [29].…”