restricted to region of oxide gabbros but can also affect oxide free gabbroic rocks This typically indicates the rock has been affected by the addition of more fractionated melt see text
azimuth as described in Structures in Peridotite and Gabbroic Intrusions in Mantle Upwelling Melt Transport and Igneous Crustal Accretion in the Leg 209 Summary chapter
Extended rare earth element REE spidergram showing chondrite normalized trace element abundances of gabbroic rocks from Unit III Normalization values after Anders and Grevesse 1989
Site 1271 Gabbroic rocks from Leg 153 from Agar et al 1997 and Sites 1268 and 1270 are shown for comparison BAG = brown amphibole gabbro Dashed line = detection limit DL for Cr
gabbroic material and ultramafic host these are often so altered that evaluating the original compositions and proportions of the two components is not possible TD = total depth
F7 cpx = clinopyroxene plag = plagioclase
orientation as described in Structures in Peridotite and Gabbroic Intrusions in Mantle Upwelling Melt Transport and Igneous Crustal Accretion in the Leg 209 Summary chapter
IIA Samples in top plot are from the highest level of the unit and the basal plots show progressively lower levels of the core Normalization values after Anders and Grevesse 1989
are given to the left Black arrows = subsidence of gabbroic matrix yellow arrows = deformation related to faulting fracturing and block rotation in the sheeted dikes and lower lavas
Divergence of a Site 1274 fault gouge mud from the MgO + FeO + CaO to SiO2 mixing line is probably due mechanical mixing of gabbroic and ultramafic material in the fault gouge
E Sample 209 1268A 28R 2 51 cm NRM = natural remanent magnetization Solid circles are projections onto the horizontal plane and open circles are projections onto the vertical plane
Site 895 mantle peridotites dunites and gabbroic segregations from Natland and Dick 1996 with the composition fields for dredge and dive samples from Hess Deep Hekinian et al 1993
F16 Extended rare earth element REE spidergram showing chondrite normalized trace element abundances of gabbroic rocks from Unit I Normalization values after Anders and Grevesse 1989
from Site 1271 Gabbroic rocks from Leg 153 from Agar et al 1997 and Sites 1268 and 1270 are shown for comparison BAG = brown amphibole gabbro plag = plagioclase amph = amphibole
Wehrlitic and gabbroic sills in the upper gabbros of the Josephine ophiolite We interpret these sills to have been emplaced at the ridge axis because hypersolidus foliations in the
F20 Extended rare earth element REE spidergram showing chondrite normalized trace element abundances of gabbroic rocks from Unit IV Normalization values after Anders and Grevesse 1989
Figure F23 Close up photograph of harzburgite with a net of anastomosing gabbroic intrusion archive half cut face and back interval 209 1270D 3R 2 32 65 cm
the plutonic rocks along major contacts and contain amongst other lithologies several alkali gabbroic types which may have been derived from deeper unexposed pans of the complex View south over the southern part of the Kanabeam Complex Tour the Kanabeam Complex
in the strict sense gabbros gabbronorites microgabbros and breccias mixtures of highly altered probably originally gabbroic material and ultramafic host TD = total depth
azimuth as described in Structures in Peridotite and Gabbroic Intrusions in Mantle Upwelling Melt Transport and Igneous Crustal Accretion in the Leg 209 Summary chapter
gabbroic clast jpg
Leg 176 Dick Natland Miller et al 1999 Roman numerals indicate the lithostratigraphic units defined during the cruise The light dashed lines show the locations of unit contacts
expected for a melting residue of peridotite that initially had a Bulk Earth composition Sample 209 1270D 1R 1 70 74 cm is enriched in CaO due to secondary carbonate precipitation
Units U1 and U2 = siliceous hemipelagic sediment section U3 = carbonate rich pelagic section U4 = gabbroic sill of the incoming and subducting oceanic plate Unit P1 = prism sediments
websterite olivine and orthopyroxene troctolites olivine and plagioclase norite clinopyroxene orthopyroxene and plagioclase and gabbro clinopyroxene and plagioclase Classification of ultramafic and gabbroic rocks Minerals crystallize from basalt in the order known as Bowen s Reaction Series according to which the earliest minerals crystallizing
host The preserved thickness of this interval is virtually identical to the thickness imaged in the log indicating that despite the break in recovery effectively no material was lost
gabbroic material originally including plagioclase and or igneous amphibole especially in the impregnated dunite sample Site 1270 dunites also include relatively abundant Cr Al spinel
F13 Hole 1271B lithology and stratigraphy Also shown is the percentage of gabbroic material impregnated into the peridotites averaged for each cored interval TD = total depth
the felsic volcaniclastic sequence and the gabbroic rocks within the Orinda Sill Nickel and Platinum Palladium exploration targets also exist in both the Orinda Sill and Ora Banda Sill Click To Enlarge
Figure F3 Geochemical data in sediments of the oceanic plate Gray areas = sections of igneous rock gabbroic sill recovered during Leg 205
from the Atlantis II Transform generally lies within the range of Mg s representing the window of eruptibility of Stolper and Walker 1980 unlike the majority of cumulate gabbroic rocks
F2 are shown in Mg plots for comparison Symbols are as in Figures F3 and F7 cpx = clinopyroxene plag = plagioclase
ground up ultramafic material and the intrusive material probably originally gabbroic occurs as thin selvages at the margins of the larger clasts interval 209 1268A 13R 2 18 29 cm
hours of dive time But at least we were back on track and finally hit bedrock at 1720 local time We expected from last years dives that gabbroic bedrock would be exposed at this depth One of our aims is to follow a complete vertical crustal section that we believe is exposed as a coherent structure along the fault scarp Oceanic crust formed at spreading centers see
Melt Transport and Igneous Crustal Accretion in the Leg 209 Summary chapter All samples have a normal polarity All points are for protogranular shape fabrics in harzburgite
through troctolite to olivine gabbro and olivine gabbronorite This second trend is very similar to that for spinel at Hess Deep Site 895 Arai and Matsukage 1996 EPR = East Pacific Rise
Figure 2 Plate Tectonics Figure 3 The Basalt Tetrahedron Figure 4 Classification of ultramafic and gabbroic rocks Figure 5 Crystallization of igneous rocks
and olivine changes in Kd of the melts with increasing fractionation and or subsolidus reequilibration Linear best fit lines are provided for nonoxide and oxide bearing gabbroic rocks
from ODP Hole 735B on the Southwest Indian Ridge Natland and Dick 2002 and average composition of gabbroic rocks from ODP Leg 153 on the Mid Atlantic Ridge MAR Agar and Lloyd 1997
infer that the entire area may be underlain by mantle peridotite with ~20 40 gabbroic intrusions and impregnations consistent with results of previous dredging and submersible studies
ScienceIndex_: http://t.co/BblyNoSNR1 Lateral Reactive Infiltration in a Vertical Gabbroic Crystal Mush, Skaergaard Intrusion,... http://t.co/QxCOT0AZDX
MaterialsSci: http://t.co/jEo8R2N8Nz Lateral Reactive Infiltration in a Vertical Gabbroic Crystal Mush, Skaergaard Intrusion,... http://t.co/YxXSaH1xU7