ABSTRACT
Parts of two separate collisional orogens are investigated in this
study. One is the Middle-Late Ordovician Taconic orogen in eastern
New York and western Vermont, and the other is the active
Himalayan orogen of southeastern Tibet. Part I through III deal
with a strain history and associated fluid properties during the
late Taconic event in the western margin of the orogen and
adjacent foreland. Senses of slip along slickensided
quartz-calcite veins in the melange belt and their field
relationships suggest an extension event following the late
Taconic thrusting (Part I). In Part II, oxygen isotope analysis of
veins and host rocks, and fluid inclusion and stable isotope data
from veins/vug-fillings are presented. I propose that
metamorphic waters were expelled from the internal Taconic orogen
and subject to a large-scale westward migration principally within
the detachment zone. In Part III, orogen-parallel normal faults
newly mapped in the Bald Mountain region also show the regional
late extension of the orogen, induced by breakoff of the
eastward-subducted slab. The extension probably started in the New
York promontory and propagated northward. Strike-slip cross
faults/veins were formed by differential motions induced by
northward propagation of the tear point and a coupled marginal
pull from the dangling slab edge. Part IV addresses structures and
uplift/exhumation mechanism of the Namche Barwa massif,
southeastern Tibet. The Namche Barwa massif is a dome-antiformal
active basement uplift, where a part of the Higher Himalaya with
the Tethyan-metasedimentary cover have been structurally uplifted
through a tectonic half window marked by the Indus-Tsangpo suture.
The western-northern massif margin predominantly contains the
Himalayan fabrics locally overprinted by younger fabrics. The
Nam-la Thrust Zone recording intense south- to southwest-directed
thrust motion defines the southern boundary of the recently and
rapidly exhumed massif core region. Anomalous lithospheric
thickening is suggested as the most plausible mechanism causing
the anomalous uplift/exhumation of the Namche Barwa massif.
Lim, C., 2007. Late structures and strain history accompanying
fluid flows in the western Taconic Orogen of the New York-Vermont
Appalachians, and Structural geology and tectonic evolution of the
Namche Barwa region, Tibet. Unpublished PhD dissertation, State
University of New York at Albany. 310 pp., +x; 4 folded maps.
University at Albany Science Library call number: SCIENCE
MIC Film QE 40 Z899 2007 L56
Copies of this PhD dissertation can be ordered
from Proquest UMI
Front matter (title,
table of contents, abstract, acknowledgements) - 0.34MB pdf
file
Figure pages in dissertation
(colour
and greyscale photos and figures, with captions): - 49.6MB
pdf file
Plate 1 - Geology
of the Bald Mountain region, eastern New York
(coloured geological outcrop map;
scale 1:12,000) - 0.24MB pdf file
Plate 2 - Structural
map of foliation and lineation orientation in the region of
Namche Barwa and Gyala Peri, SE Tibet
(coloured map and
stereographic diagrams; map at scale of 1:1million) - 1MB pdf file
Plate 3 - Structural
map of slickenside and slickenline orientation in the region of
Namche Barwa and Gyala Peri, SE Tibet
(coloured map and
stereographic diagrams; map at scale ~1:870,000) - 1.1MB pdf file
Plate 4 - Structural
map of fold hinge orientation in the region of Namche Barwa and
Gyala Peri, SE Tibet
(coloured map and
stereographic diagrams; map at scale ~1:890,000) - 1.1MB pdf file