ABSTRACT
Mount Merino Chert and Shale, Middle Ordovician, is one of the
most
siliceous units of the Taconic sequence (eastern New York and
western Vermont);
it is composed of interbedded shale, siliceous hale, argillite and
chert.
Non-clastic quartz — aggregates of quartz having a.mosaic or
felted texture
— predominates in all beds, except `shale. All siliceous beds are
finely
laminated; most laminae are distinguished from adjacent laminae by
the
texture of the quartz groundmass, and the amount of clastics,
carbonates,
chlorite and sulphides. Statistical comparison of the textures of
the quartz
aggregates which occur with the other mineral components suggests
that
the components of each lamina represent a stable mineralogic
assemblage;
the assemblages probably formed during silica precipitation and
early diagenesis.
These assemblages are compositionally-consistent with experimental
data
regarding the formation of authigenic minerals in the presence of
colloidal
silica.
Mount Merino rocks comprise a minor.part of the Giddings Brook
slice
of the Taconic allochthon; the Mount Merino fauna is the youngest
of the
Giddings Brook slice rock sequence. Mount Merino rocks also occur
as boulders
and blocks in Forbes Hill Conglomerate, an autochthonous
wildflysch-like
terrain underlying the Giddings Brook slice.
Petrographic aspects of Mount Merino rocks indicate a "starved"
depositional
environment distant from an extensive land area. The predominant
source
of silica for the rocks was probably vulcanism (the Ammonoosuc
volcanics)
which became relatively intense during Mount Merino time, just
preceding
emplacement of the Taconic allochthon.
Lang, D.M., 1969. Origin of the Mount Merino Chert and Shale,
Middle
Ordovician, Eastern New York State.
Unpublished MSc. thesis, State University of New York at
Albany.
64pp., +v, +26p. tables.
University at Albany Science Library call number: SCIENCE
Oversize
(*) QE 471 L325X
thesis scanned
text with greyscale pictures) - 12.9MB pdf file
Map 1 - sample
location map - 0.4MB pdf file
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