- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
- Abstract
- Affiliation
- All
- Authors
- Book Series
- DOI
- EISBN
- EISSN
- Full Text
- GeoRef ID
- ISBN
- ISSN
- Issue
- Keyword (GeoRef Descriptor)
- Meeting Information
- Report #
- Title
- Volume
NARROW
GeoRef Subject
-
all geography including DSDP/ODP Sites and Legs
-
Africa
-
East Africa
-
Kenya (1)
-
-
Sahel (1)
-
Southern Africa
-
Namibia (1)
-
South Africa (2)
-
-
West Africa
-
Niger (1)
-
-
-
Antarctica
-
Antarctic Peninsula (1)
-
-
Asia
-
Far East
-
China (2)
-
Japan
-
Hokkaido (1)
-
-
-
Middle East
-
Iran (1)
-
-
-
Atlantic Ocean
-
North Atlantic (1)
-
-
Australasia
-
Australia
-
South Australia (1)
-
-
New Zealand (2)
-
-
Black Mountain (1)
-
Central America
-
Nicaragua (1)
-
-
Central Valley (2)
-
Clark Fork (1)
-
Coast Ranges (21)
-
Coyote Lake (1)
-
Diablo Range (4)
-
Europe
-
Western Europe
-
France
-
Paris Basin (1)
-
-
Netherlands (1)
-
United Kingdom
-
Great Britain
-
Scotland
-
Great Glen Fault (1)
-
-
-
-
-
-
Imperial Valley (1)
-
Mexico
-
Baja California (1)
-
Chihuahua Mexico (1)
-
Guanajuato Mexico (1)
-
Jalisco Mexico (1)
-
Oaxaca Mexico (1)
-
-
North America
-
Basin and Range Province (2)
-
-
North Island (2)
-
Northern Highlands (1)
-
Pacific Coast (2)
-
Pacific Ocean
-
East Pacific
-
Northeast Pacific
-
Escanaba Trough (1)
-
Gorda Rise (1)
-
Gulf of California
-
Guaymas Basin (1)
-
-
Mendocino fracture zone (2)
-
-
-
North Pacific
-
Northeast Pacific
-
Escanaba Trough (1)
-
Gorda Rise (1)
-
Gulf of California
-
Guaymas Basin (1)
-
-
Mendocino fracture zone (2)
-
-
-
-
Salinas Valley (2)
-
San Andreas Fault (107)
-
San Joaquin Basin (4)
-
Santa Barbara Basin (1)
-
Santa Clara Valley (1)
-
Santa Cruz Mountains (2)
-
Santa Lucia Range (3)
-
Santa Maria Basin (6)
-
Sierra Nevada (3)
-
South America
-
Argentina (1)
-
Peru (1)
-
-
Southern Ocean
-
Palmer Deep (1)
-
-
United States
-
California
-
Borrego Mountain (1)
-
Calaveras Fault (2)
-
Central California (52)
-
Fresno County California
-
Coalinga California (11)
-
-
Gabilan Range (1)
-
Garlock Fault (2)
-
Hayward Fault (2)
-
Hosgri Fault (6)
-
Imperial County California (1)
-
Kern County California (2)
-
Kettleman Hills (2)
-
Kings County California (3)
-
Los Angeles County California
-
Long Beach California (1)
-
Los Angeles California
-
Northridge California (1)
-
-
San Fernando California (1)
-
-
Monterey County California
-
Parkfield California (139)
-
-
Northern California (1)
-
Orange County California (1)
-
Salinian Block (7)
-
Salton Sea (1)
-
San Benito County California
-
Hollister California (2)
-
San Juan Bautista California (1)
-
-
San Bernardino County California
-
Cajon Pass (1)
-
-
San Diego County California
-
San Diego California (1)
-
-
San Francisco Bay region (2)
-
San Francisco County California
-
San Francisco California (2)
-
-
San Gregorio Fault (3)
-
San Joaquin Valley (7)
-
San Luis Obispo County California
-
Carrizo Plain (5)
-
Cholame California (11)
-
Pismo Basin (3)
-
San Luis Obispo California (8)
-
-
San Mateo County California (2)
-
Santa Barbara County California
-
Santa Maria California (1)
-
-
Santa Clara County California (1)
-
Santa Cruz County California (2)
-
Santa Ynez Mountains (1)
-
Sierra Nevada Batholith (1)
-
Sonoma County California (2)
-
Southern California (18)
-
Sur fault zone (1)
-
Temblor Range (1)
-
Transverse Ranges (3)
-
Ventura County California (1)
-
-
Idaho
-
Valley County Idaho (1)
-
-
Montana (1)
-
Nevada (1)
-
North Carolina
-
Pamlico Sound (1)
-
-
Oregon (1)
-
Utah (1)
-
Virginia (1)
-
Washington (1)
-
Western U.S. (2)
-
-
-
commodities
-
asbestos deposits (1)
-
bitumens (1)
-
metal ores
-
mercury ores (1)
-
-
mineral deposits, genesis (1)
-
oil and gas fields (3)
-
petroleum
-
natural gas (1)
-
-
-
elements, isotopes
-
boron
-
B-11/B-10 (1)
-
-
carbon
-
C-13/C-12 (4)
-
C-14 (6)
-
-
hydrogen
-
D/H (1)
-
deuterium (1)
-
-
isotope ratios (4)
-
isotopes
-
radioactive isotopes
-
C-14 (6)
-
-
stable isotopes
-
B-11/B-10 (1)
-
C-13/C-12 (4)
-
D/H (1)
-
deuterium (1)
-
Li-7/Li-6 (1)
-
O-18/O-16 (3)
-
Sr-87/Sr-86 (2)
-
-
-
metals
-
actinides
-
uranium (1)
-
-
alkali metals
-
lithium
-
Li-7/Li-6 (1)
-
-
-
alkaline earth metals
-
strontium
-
Sr-87/Sr-86 (2)
-
-
-
iron
-
ferric iron (1)
-
ferrous iron (1)
-
-
manganese (1)
-
mercury (2)
-
rare earths
-
ytterbium (1)
-
-
-
noble gases
-
argon (1)
-
-
oxygen
-
O-18/O-16 (3)
-
-
phosphorus (1)
-
-
fossils
-
burrows (1)
-
Chordata
-
Vertebrata
-
Tetrapoda
-
Mammalia
-
Theria
-
Eutheria
-
Carnivora
-
Fissipeda
-
Canidae (1)
-
-
-
Desmostylia (1)
-
Perissodactyla
-
Hippomorpha
-
Equidae (1)
-
-
-
-
-
-
-
-
-
Invertebrata
-
Arthropoda
-
Mandibulata
-
Crustacea
-
Ostracoda (1)
-
-
-
-
Mollusca
-
Bivalvia
-
Ostreoidea
-
Ostreidae
-
Crassostrea
-
Crassostrea virginica (1)
-
-
-
-
-
-
Protista
-
Foraminifera (5)
-
Radiolaria (3)
-
Silicoflagellata (1)
-
-
-
microfossils
-
Conodonta (1)
-
-
palynomorphs
-
Dinoflagellata (1)
-
-
Plantae
-
algae
-
diatoms (3)
-
nannofossils (4)
-
-
-
thallophytes (3)
-
-
geochronology methods
-
Ar/Ar (1)
-
fission-track dating (1)
-
K/Ar (1)
-
optically stimulated luminescence (1)
-
paleomagnetism (5)
-
racemization (1)
-
thermoluminescence (1)
-
U/Pb (3)
-
-
geologic age
-
Cenozoic
-
Quaternary
-
Holocene
-
upper Holocene (3)
-
-
Pleistocene
-
upper Pleistocene (1)
-
-
upper Quaternary (1)
-
-
Tertiary
-
Neogene
-
Miocene
-
lower Miocene (1)
-
middle Miocene (1)
-
Temblor Formation (2)
-
upper Miocene
-
Santa Margarita Formation (4)
-
-
-
Pliocene
-
lower Pliocene (1)
-
upper Pliocene (1)
-
-
-
Paleogene
-
Eocene
-
middle Eocene (1)
-
upper Eocene
-
Tejon Formation (1)
-
-
-
Oligocene (5)
-
Sespe Formation (1)
-
-
Vaqueros Formation (2)
-
-
upper Cenozoic (1)
-
-
Mesozoic
-
Cretaceous
-
Upper Cretaceous
-
Holz Shale (1)
-
Moreno Formation (1)
-
-
-
Franciscan Complex (6)
-
Great Valley Sequence (3)
-
Jurassic
-
Coast Range Ophiolite (4)
-
Middle Jurassic (1)
-
Upper Jurassic
-
Kimmeridge Clay (1)
-
-
-
upper Mesozoic (1)
-
-
Paleozoic
-
upper Paleozoic
-
Calaveras Formation (1)
-
-
-
-
igneous rocks
-
igneous rocks
-
granophyre (1)
-
plutonic rocks
-
anorthosite (1)
-
diorites (1)
-
gabbros (2)
-
granites
-
felsite (1)
-
-
ultramafics
-
peridotites
-
dunite (1)
-
harzburgite (1)
-
lherzolite (1)
-
-
pyroxenite (1)
-
-
-
volcanic rocks
-
andesites
-
boninite (1)
-
-
basalts
-
mid-ocean ridge basalts (1)
-
tholeiite (1)
-
-
pyroclastics
-
tuff (1)
-
-
-
-
ophiolite (3)
-
wehrlite (1)
-
-
metamorphic rocks
-
metamorphic rocks
-
cataclasites (2)
-
metaigneous rocks
-
serpentinite (2)
-
-
metasedimentary rocks (1)
-
metasomatic rocks
-
serpentinite (2)
-
-
schists
-
blueschist (1)
-
-
-
ophiolite (3)
-
turbidite (1)
-
-
minerals
-
carbonates
-
artinite (1)
-
calcite (1)
-
dolomite (1)
-
huntite (1)
-
-
chromates (1)
-
minerals (6)
-
native elements (1)
-
oxides
-
hydroxides (1)
-
-
silicates
-
chain silicates
-
deerite (1)
-
pyroxene group
-
clinopyroxene
-
jadeite (1)
-
-
-
-
framework silicates
-
feldspar group
-
alkali feldspar
-
K-feldspar (1)
-
-
plagioclase (1)
-
-
silica minerals
-
quartz (1)
-
-
-
orthosilicates
-
nesosilicates
-
zircon group
-
zircon (3)
-
-
-
-
sheet silicates
-
chlorite group
-
chlorite (2)
-
-
clay minerals
-
kaolinite (1)
-
smectite (3)
-
-
corrensite (1)
-
illite (4)
-
serpentine group
-
chrysotile (2)
-
serpentine (1)
-
-
-
-
sulfides
-
cinnabar (1)
-
pyrite (1)
-
-
wehrlite (1)
-
-
Primary terms
-
absolute age (9)
-
Africa
-
East Africa
-
Kenya (1)
-
-
Sahel (1)
-
Southern Africa
-
Namibia (1)
-
South Africa (2)
-
-
West Africa
-
Niger (1)
-
-
-
Antarctica
-
Antarctic Peninsula (1)
-
-
asbestos deposits (1)
-
Asia
-
Far East
-
China (2)
-
Japan
-
Hokkaido (1)
-
-
-
Middle East
-
Iran (1)
-
-
-
Atlantic Ocean
-
North Atlantic (1)
-
-
Australasia
-
Australia
-
South Australia (1)
-
-
New Zealand (2)
-
-
biogeography (3)
-
bitumens (1)
-
boron
-
B-11/B-10 (1)
-
-
carbon
-
C-13/C-12 (4)
-
C-14 (6)
-
-
catalogs (1)
-
Cenozoic
-
Quaternary
-
Holocene
-
upper Holocene (3)
-
-
Pleistocene
-
upper Pleistocene (1)
-
-
upper Quaternary (1)
-
-
Tertiary
-
Neogene
-
Miocene
-
lower Miocene (1)
-
middle Miocene (1)
-
Temblor Formation (2)
-
upper Miocene
-
Santa Margarita Formation (4)
-
-
-
Pliocene
-
lower Pliocene (1)
-
upper Pliocene (1)
-
-
-
Paleogene
-
Eocene
-
middle Eocene (1)
-
upper Eocene
-
Tejon Formation (1)
-
-
-
Oligocene (5)
-
Sespe Formation (1)
-
-
Vaqueros Formation (2)
-
-
upper Cenozoic (1)
-
-
Central America
-
Nicaragua (1)
-
-
chemical analysis (1)
-
Chordata
-
Vertebrata
-
Tetrapoda
-
Mammalia
-
Theria
-
Eutheria
-
Carnivora
-
Fissipeda
-
Canidae (1)
-
-
-
Desmostylia (1)
-
Perissodactyla
-
Hippomorpha
-
Equidae (1)
-
-
-
-
-
-
-
-
-
clay mineralogy (4)
-
climate change (2)
-
crust (16)
-
crystal chemistry (2)
-
crystal growth (2)
-
crystal structure (3)
-
data processing (11)
-
deformation (32)
-
diagenesis (11)
-
Earth (1)
-
earthquakes (165)
-
ecology (1)
-
economic geology (4)
-
engineering geology (6)
-
Europe
-
Western Europe
-
France
-
Paris Basin (1)
-
-
Netherlands (1)
-
United Kingdom
-
Great Britain
-
Scotland
-
Great Glen Fault (1)
-
-
-
-
-
-
explosions (7)
-
faults (120)
-
folds (13)
-
foundations (1)
-
fractures (1)
-
geochemistry (6)
-
geochronology (1)
-
geodesy (11)
-
geomorphology (4)
-
geophysical methods (26)
-
glacial geology (1)
-
government agencies
-
survey organizations (1)
-
-
ground water (3)
-
heat flow (2)
-
hydrogen
-
D/H (1)
-
deuterium (1)
-
-
hydrology (3)
-
igneous rocks
-
granophyre (1)
-
plutonic rocks
-
anorthosite (1)
-
diorites (1)
-
gabbros (2)
-
granites
-
felsite (1)
-
-
ultramafics
-
peridotites
-
dunite (1)
-
harzburgite (1)
-
lherzolite (1)
-
-
pyroxenite (1)
-
-
-
volcanic rocks
-
andesites
-
boninite (1)
-
-
basalts
-
mid-ocean ridge basalts (1)
-
tholeiite (1)
-
-
pyroclastics
-
tuff (1)
-
-
-
-
intrusions (4)
-
Invertebrata
-
Arthropoda
-
Mandibulata
-
Crustacea
-
Ostracoda (1)
-
-
-
-
Mollusca
-
Bivalvia
-
Ostreoidea
-
Ostreidae
-
Crassostrea
-
Crassostrea virginica (1)
-
-
-
-
-
-
Protista
-
Foraminifera (5)
-
Radiolaria (3)
-
Silicoflagellata (1)
-
-
-
isotopes
-
radioactive isotopes
-
C-14 (6)
-
-
stable isotopes
-
B-11/B-10 (1)
-
C-13/C-12 (4)
-
D/H (1)
-
deuterium (1)
-
Li-7/Li-6 (1)
-
O-18/O-16 (3)
-
Sr-87/Sr-86 (2)
-
-
-
lava (1)
-
lineation (1)
-
magmas (1)
-
mantle (3)
-
maps (1)
-
Mesozoic
-
Cretaceous
-
Upper Cretaceous
-
Holz Shale (1)
-
Moreno Formation (1)
-
-
-
Franciscan Complex (6)
-
Great Valley Sequence (3)
-
Jurassic
-
Coast Range Ophiolite (4)
-
Middle Jurassic (1)
-
Upper Jurassic
-
Kimmeridge Clay (1)
-
-
-
upper Mesozoic (1)
-
-
metal ores
-
mercury ores (1)
-
-
metals
-
actinides
-
uranium (1)
-
-
alkali metals
-
lithium
-
Li-7/Li-6 (1)
-
-
-
alkaline earth metals
-
strontium
-
Sr-87/Sr-86 (2)
-
-
-
iron
-
ferric iron (1)
-
ferrous iron (1)
-
-
manganese (1)
-
mercury (2)
-
rare earths
-
ytterbium (1)
-
-
-
metamorphic rocks
-
cataclasites (2)
-
metaigneous rocks
-
serpentinite (2)
-
-
metasedimentary rocks (1)
-
metasomatic rocks
-
serpentinite (2)
-
-
schists
-
blueschist (1)
-
-
-
metamorphism (4)
-
metasomatism (3)
-
Mexico
-
Baja California (1)
-
Chihuahua Mexico (1)
-
Guanajuato Mexico (1)
-
Jalisco Mexico (1)
-
Oaxaca Mexico (1)
-
-
mineral deposits, genesis (1)
-
mineralogy (3)
-
minerals (6)
-
Mohorovicic discontinuity (3)
-
noble gases
-
argon (1)
-
-
North America
-
Basin and Range Province (2)
-
-
ocean waves (1)
-
oil and gas fields (3)
-
oxygen
-
O-18/O-16 (3)
-
-
Pacific Coast (2)
-
Pacific Ocean
-
East Pacific
-
Northeast Pacific
-
Escanaba Trough (1)
-
Gorda Rise (1)
-
Gulf of California
-
Guaymas Basin (1)
-
-
Mendocino fracture zone (2)
-
-
-
North Pacific
-
Northeast Pacific
-
Escanaba Trough (1)
-
Gorda Rise (1)
-
Gulf of California
-
Guaymas Basin (1)
-
-
Mendocino fracture zone (2)
-
-
-
-
paleoclimatology (5)
-
paleoecology (4)
-
paleogeography (10)
-
paleomagnetism (5)
-
paleontology (1)
-
Paleozoic
-
upper Paleozoic
-
Calaveras Formation (1)
-
-
-
palynomorphs
-
Dinoflagellata (1)
-
-
paragenesis (1)
-
petroleum
-
natural gas (1)
-
-
petrology (3)
-
phase equilibria (1)
-
phosphorus (1)
-
Plantae
-
algae
-
diatoms (3)
-
nannofossils (4)
-
-
-
plate tectonics (21)
-
pollution (2)
-
reclamation (1)
-
remote sensing (4)
-
rock mechanics (5)
-
sea-level changes (4)
-
sedimentary petrology (5)
-
sedimentary rocks
-
carbonate rocks (1)
-
chemically precipitated rocks
-
chert (3)
-
phosphate rocks (1)
-
-
clastic rocks
-
arkose (1)
-
conglomerate (7)
-
mudstone (5)
-
sandstone (9)
-
shale (6)
-
siltstone (1)
-
-
-
sedimentary structures
-
bedding plane irregularities
-
megaripples (1)
-
scour marks (1)
-
-
biogenic structures
-
bioturbation (2)
-
-
current markings (2)
-
graded bedding (1)
-
planar bedding structures
-
laminations (5)
-
-
secondary structures
-
concretions (1)
-
geodes (1)
-
-
seismites (1)
-
soft sediment deformation
-
slump structures (2)
-
-
turbidity current structures (1)
-
-
sedimentation (9)
-
sediments
-
clastic sediments
-
alluvium (2)
-
clay (3)
-
ooze (2)
-
sand (1)
-
-
marine sediments (1)
-
-
seismology (43)
-
shorelines (2)
-
slope stability (1)
-
soil mechanics (4)
-
soils
-
Aridisols (1)
-
-
South America
-
Argentina (1)
-
Peru (1)
-
-
Southern Ocean
-
Palmer Deep (1)
-
-
stratigraphy (7)
-
structural analysis (3)
-
structural geology (14)
-
tectonics
-
neotectonics (12)
-
-
tectonophysics (9)
-
thallophytes (3)
-
United States
-
California
-
Borrego Mountain (1)
-
Calaveras Fault (2)
-
Central California (52)
-
Fresno County California
-
Coalinga California (11)
-
-
Gabilan Range (1)
-
Garlock Fault (2)
-
Hayward Fault (2)
-
Hosgri Fault (6)
-
Imperial County California (1)
-
Kern County California (2)
-
Kettleman Hills (2)
-
Kings County California (3)
-
Los Angeles County California
-
Long Beach California (1)
-
Los Angeles California
-
Northridge California (1)
-
-
San Fernando California (1)
-
-
Monterey County California
-
Parkfield California (139)
-
-
Northern California (1)
-
Orange County California (1)
-
Salinian Block (7)
-
Salton Sea (1)
-
San Benito County California
-
Hollister California (2)
-
San Juan Bautista California (1)
-
-
San Bernardino County California
-
Cajon Pass (1)
-
-
San Diego County California
-
San Diego California (1)
-
-
San Francisco Bay region (2)
-
San Francisco County California
-
San Francisco California (2)
-
-
San Gregorio Fault (3)
-
San Joaquin Valley (7)
-
San Luis Obispo County California
-
Carrizo Plain (5)
-
Cholame California (11)
-
Pismo Basin (3)
-
San Luis Obispo California (8)
-
-
San Mateo County California (2)
-
Santa Barbara County California
-
Santa Maria California (1)
-
-
Santa Clara County California (1)
-
Santa Cruz County California (2)
-
Santa Ynez Mountains (1)
-
Sierra Nevada Batholith (1)
-
Sonoma County California (2)
-
Southern California (18)
-
Sur fault zone (1)
-
Temblor Range (1)
-
Transverse Ranges (3)
-
Ventura County California (1)
-
-
Idaho
-
Valley County Idaho (1)
-
-
Montana (1)
-
Nevada (1)
-
North Carolina
-
Pamlico Sound (1)
-
-
Oregon (1)
-
Utah (1)
-
Virginia (1)
-
Washington (1)
-
Western U.S. (2)
-
-
waste disposal (2)
-
well-logging (2)
-
-
rock formations
-
Monterey Formation (14)
-
Toro Formation (1)
-
-
sedimentary rocks
-
sedimentary rocks
-
carbonate rocks (1)
-
chemically precipitated rocks
-
chert (3)
-
phosphate rocks (1)
-
-
clastic rocks
-
arkose (1)
-
conglomerate (7)
-
mudstone (5)
-
sandstone (9)
-
shale (6)
-
siltstone (1)
-
-
-
siliciclastics (1)
-
turbidite (1)
-
volcaniclastics (2)
-
-
sedimentary structures
-
burrows (1)
-
channels (2)
-
sedimentary structures
-
bedding plane irregularities
-
megaripples (1)
-
scour marks (1)
-
-
biogenic structures
-
bioturbation (2)
-
-
current markings (2)
-
graded bedding (1)
-
planar bedding structures
-
laminations (5)
-
-
secondary structures
-
concretions (1)
-
geodes (1)
-
-
seismites (1)
-
soft sediment deformation
-
slump structures (2)
-
-
turbidity current structures (1)
-
-
-
sediments
-
sediments
-
clastic sediments
-
alluvium (2)
-
clay (3)
-
ooze (2)
-
sand (1)
-
-
marine sediments (1)
-
-
siliciclastics (1)
-
turbidite (1)
-
volcaniclastics (2)
-
-
soils
-
paleosols (1)
-
soils
-
Aridisols (1)
-
-
Using a landscape fingerprint to identify changes in fault-slip behavior
Complex multiscale reservoir heterogeneity in a tidal depositional environment, Temblor Formation, West Coalinga field, California
Storm-driven sedimentation and dynamics of a sediment slug in an ephemeral stream: Influence on sediment-routing systems within source areas
Hosgri Fault Transpressional Slip Rates Reproduce Observed Central California Coast Uplift Rates
“Aftershock Faults” and What They Could Mean for Seismic Hazard Assessment
A High‐Resolution Earthquake Catalog for the 2004 M w 6 Parkfield Earthquake Sequence Using a Matched Filter Technique
Depositional and diagenetic controls on the mechanical properties of rocks in the Monterey Formation of the Santa Maria Basin, California
ABSTRACT The Monterey Formation of Central and Southern California has produced billions of barrels of oil since the early 1900s. The Monterey Formation in the Santa Maria Basin is a tectonically fractured reservoir, meaning that the fractures formed through natural geologic processes; they are not human-generated artifacts. Open natural fractures provide the effective porosity for oil storage and the permeability pathways through which oil flows from rocks to wells. Monterey strata are notable for a diverse range of lithologies characterized by contrasts in texture and composition. Not all Monterey rock types contain natural fractures. Structural geologists applied the concepts of mechanical stratigraphy to the Monterey Formation to explain fracture variability. Hard rocks, including chert, porcelanite, and dolostone, contain extensive open-fracture systems, while softer lithologies like siliceous mudstone and organic-rich mudstone have few or no open fractures. However, the words “hard and soft” or “strong and weak” are inexact and subject to interpretation. This report constrains these qualitative descriptions by using engineering-geology data to associate rock properties with quantitative measurements of rock mechanical strength.
An observational approach to mudstone sequence stratigraphy: The Monterey Formation of California
ABSTRACT Sequence stratigraphy has proven to be an invaluable tool for the analysis of coarse-clastic depositional systems and the integration of observations across scales from reflection seismic to scanning electron microscope. Applications to mudstone-dominated depositional sequences have been more limited, despite the fact that mudstones make up more than 60% of the global sedimentary volume and generally provide the most complete record of sedimentation in a basin. During the late 1970s and through the 1980s, Bob Garrison and his students at the University of California–Santa Cruz conducted numerous studies that revealed the basic sedimentary and stratigraphic framework of the Monterey Formation in California, advancing our understanding of the sedimentary processes at work in these deep-margin basins. We expanded on that framework using direct observations from outcrops and cores that have been integrated with other subsurface data, as well as a wide variety of information derived from paleontologic, chronostratigraphic, geochemical, and compositional analyses to illustrate a sequence-stratigraphic approach to interpreting fine-grained rocks and their associated depositional systems in these settings. These were some of the earliest investigations of mudstone sequence stratigraphy focused on slope and basinal environments. In this study, observations from outcrops in the Pismo Basin, California, provided the basis for developing a detailed sequence-stratigraphic framework for the Monterey Formation, expanding on the broad-scale characterization of Garrison and his colleagues. These outcrops represent deposition during different phases of basin evolution and in different borderland-type basin settings (slope and basin depocenters). Comparison of coeval strata from different depositional settings and locations documented variation at both the sequence and parasequence scale. Variation of parasequence character, in particular, provided a valuable tool for enhanced understanding of deposition and diagenesis in these margin basins. Extrapolation to the subsurface using gamma-ray logs greatly enhanced basinwide application compared to limited, partial-stratigraphic-section outcrops, and it facilitated the lateral characterization of mudstone depositional sequences. These elements served as the building blocks for improved models of deposition in margin-basin settings.
Refined assessment of the paleoceanographic and tectonic influences on the deposition of the Monterey Formation in California
ABSTRACT Application of updated diatom biochronology to the Monterey Formation and related biosiliceous rocks reveals the imprint of both global paleoclimatic/paleoceanographic and regional tectonic events. A rise in global sea level combined with regional tectonic deepening associated with the development of the transform California margin resulted in the abrupt onset of deposition of fine-grained Monterey sediments that were relatively free from clastic debris between 18 and 16 Ma. The base of the Monterey Formation does not mark a silica shift in diatom deposition from the North Atlantic to the North Pacific Ocean. Rather, a North Atlantic Ocean decline of diatoms after ca. 13 Ma and increasing divergence in nutrient levels between the North Atlantic and North Pacific Oceans between ca. 13 and 11 Ma coincided with a major enhancement of diatom deposition in the Monterey Formation. A stratigraphically condensed interval of phosphate-rich sediments between 13 and 10 Ma in coastal southern California appears to have resulted from sediment starvation in offshore basins during a period of higher sea level, as inland sections such as those in the San Joaquin Valley commonly contain thick sequences of diatomaceous sediment. Increasing latitudinal thermal gradients in the latest Miocene, which triggered a biogenic bloom in the equatorial Pacific Ocean at 8 Ma, also led to enhanced diatom deposition in the uppermost Monterey Formation and overlying biosiliceous rocks. Uplift of the California coastal ranges after ca. 5.2 Ma resulted in an increasing detrital contribution that obscured the presence of diatoms in onshore sediments. Major reduction in coastal upwelling in the early Pliocene ca. 4.6 Ma then caused a drastic reduction of diatoms in sediments offshore southern California.
ABSTRACT The Eocene Kreyenhagen Formation is a widespread siliceous, organic-rich mudstone within the San Joaquin Basin, but it is less studied than the Monterey Formation. This study characterizes the Kreyenhagen Formation in the Kettleman area to define its vertical and lateral variability on the basis redox conditions (Mo, U, Cr), paleoproductivity (biogenic SiO 2 , P, Ba), and detrital input (Al 2 O 3 , TiO 2 ) to determine the dominant environmental conditions during deposition. The Kreyenhagen Formation was correlated across 72 wells over a 4600 km 2 (1776 mi 2 ) area, which revealed an eastward thinning from 335 m (1100 ft) to less than 183 m (600 ft). We identified three informal members on the basis of log response and bulk/trace geochemistry: a lower calcareous silty mudstone, a middle organic-rich clayey mudstone, and an upper siliceous silty mudstone. Spatially, the greatest enrichment of total organic carbon, redox proxies, and biogenic silica occurs along Kettleman North Dome. These properties decrease eastward as clay volume, titanium, and aluminum increase. We interpret the Kreyenhagen Formation to record one transgressive-regressive cycle with contemporaneous climatic cooling: a transgression with initial suboxia and calcareous plankton productivity, a highstand with anoxic-euxinic benthic conditions and clastic starvation, and regression with elevated biogenic silica input. The upward transition from a calcareous to siliceous composition may reflect known cooling and upwelling intensification on the middle Eocene California margin. Mo/U and Th/U patterns suggest variable redox conditions across space and time. Lateral compositional trends indicate that eastern areas were proximal to a Sierran clastic sediment source, while western areas were distal and more anoxic.