New Zealand Journal of Geology and Geophysics abstracts
Variations in sandstone diagenesis with depth, time, and space, onshore
Taranaki wells, New Zealand
DAVID SMALE
Institute of Geological & Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand
JEFFREY L. MAUK
Geology Department
The University of Auckland
Private Bag 92 019
Auckland, New Zealand
JULIE PALMER
Department of Soil Science
Massey University
Private Bag 11 222
Palmerston North, New Zealand
RAYMOND SOONG
PETER BLATTNER
Institute of Geological & Nuclear Sciences
Lower Hutt, New Zealand
Abstract Study of diagenesis in cores from Kapuni Field,
Waihapa-2, Kaimiro-2, and New Plymouth-2 shows many expected features--quartz
and feldspar dissolution and precipitation, clay mineral precipitation, and
carbonate dissolution and precipitation. Local variations may overprint broader
trends; early quartz overgrowth in parts of the basin is not recognisable in
Kapuni wells, and feldspars may be etched differentially. In the Kapuni Group,
early siderite precipitated from pore waters similar to those in which the host
sediment was deposited, whereas late calcite was probably deposited from fresh
water. In the Moki Formation, some calcite may be similarly late, but
variations in pH modified deposition. Cathodoluminescence of new growth of
calcite and quartz shows considerable variety, and some luminescent and
non-luminescent quartz have grown contemporaneously. Most stable isotope data
show regular trends. Petroleum has migrated within the Taranaki Basin at least
twice: once during early diagenesis of the Kapuni Group, and later after
diagenetic mineral growth had occurred. Deep sandstones of the Farewell
Formation in the Kapuni Field, though now virtually impermeable, probably
passed through a period of diagenetically modified porosity that allowed
migration of early hydrocarbons.
Keywords diagenesis; Taranaki; Moki Formation; Kapuni Group;
clay minerals; quartz overgrowth; feldspar overgrowth; dissolution; heavy
minerals; carbonates; cathodoluminescence; stable isotopes
New Zealand Journal of Geology and Geophysics, 1999, Vol. 42: 137-154
0028-8306/99/4202-0137 $7.00/0 (c) The Royal Society of New Zealand
1999
PDF file of entire paper: medium quality (4392K); (scanned from paper original: notes about this process)
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