Geoscience Reference
In-Depth Information
Figure 10.28.
(a) 'Lithoprobe' seismic-reflection data right across the Trans-Hudson
orogen on an east-west profile located in the south of the box in Fig. 10.27. Data
have been migrated, coherency-filtered and displayed using an automated routine
that displays the main reflections. The section is to true scale assuming a constant
migration velocity of 6 km s
−1
. Note that Line 9 and Line 3 are offset by
30 km
north-south. 'M', reflection Moho; and 'Root', crustal root. (b) A geological
interpretation of (a). Main geological designations: WD, Wollaston domain; WB,
Wathaman-Chipewyan batholith; RD Rottenstone domain; LRD La Ronge belt; GD,
Glennie domain; HLB, Hanson Lake block; FFB, Flin Flon belt; NGC, Namew gneiss
complex KD, Kisseynew domain; TB, Thompson belt; PGB Pikwitonei granulite
domain; and SC Superior craton. Arrows show major shear zones, faults and thrusts.
Reprinted with permission from
Nature
(Lucas
et al
.,
Nature
,
363
, 339-42. Copyright
1993. Macmillan Magazines Ltd.)
∼
western part of the Reindeer zone. Results from a series of seismic experiments
across the orogen in Canada (Lithoprobe) and in the U.S.A. (COCORP) have
delineated the deep-crustal and uppermost-mantle structures beneath this orogen
(Fig. 10.28). Tectonic activity took place over a region
1000 km in width. The
crust is thicker than normal beneath the orogen (40-54 km), with the thickest crust
∼
