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The Smartville Block, also called the Smartville Ophiolite, Smartville Complex, or Smartville Intrusive Complex, is a geologic terrane formed in the ocean from a volcanic island arc that was accreted onto the North American Plate during the late Jurassic (~160–150 million years ago). The collision created sufficient crustal heating to drive mineral-laden water up through numerous fissures along the contact zone. When these cooled, among the precipitating minerals was gold. Associated with the Western Metamorphic Belt of the Sierra Nevada foothills it extends from the central Sierra Nevada mountain range, due west, under a section of the Central Valley and California Coast Ranges, in northern California. The ophiolitic sequence found in this terrane is one of several major ophiolites found in California. Ophiolites are crustal and upper-mantle rocks from the ocean floor that have been moved on land. Ophiolites have been studied extensively regarding the movement of crustal rocks by plate tectonics.

Gold

Gold was discovered in California in the mid 1800s. The Smartville Block is named for the small Gold Rush town of Smartville in Yuba County, California. Gold found in the Smartville Block and within the metamorphic belts of the Sierra Nevada foothills were created through hydrothermal processes. Mineral rich groundwater is heated geothermally and injected towards the surface through fractures in the rock created from faulting. Gold and other minerals are precipitated from this fluid and have accumulated in the Sierra Nevadan metamorphic belt region in features called veins.^[2] ^[1]

The Smartville Block's eastern margin is the Rescue Lineament-Bear Mountains fault zone, and generally defines the range of gold-bearing veins of the Mother Lode region, important in the history of the California Gold Rush.

Geology

The Smartville Ophiolite is divided into sections based on lithology that describe the origin of the rocks it is made up of. In order of increasing depth: the top most unit is called the upper volcanic unit, then the lower volcanic unit, followed by the dike complex, and the plutonic suite at the bottom. The upper volcanic unit consists mainly of pillow lava and massive lavas with turbidites also being common. The turbidites of the upper volcanic unit are made of a siliceous rock type and have sandstones and conglomerate tops. Next is the lower volcanic unit, which is mostly pillow lava, breccia, and intrusive rocks. Metasediments of mostly mafic and intermediate tuffaceous composition are cut by dikes (intrusive rock). Below the lower volcanic unit is the dike complex. The dike complex has dacite and rhyolite dikes that cut into the rocks of the lower volcanic unit. At the base is the plutonic suite that are made up of gabbro, diorite, and other plutonic rocks that are intruded by dikes as well as granitic plutons from the Nevadan Orogeny.

References

^ ^a ^b Irwin, William; Wooden, Joseph (2001). "Map Showing Plutons and Accreted Terranes of the Sierra Nevada, California, With a Tabulation of U/Pb Isotopic Ages" (PDF). USGS. Retrieved 11 October 2021.
^ McPhee, John (1981). Annals of the Former World. New York: Farrar, Straus and Giroux. pp. 480, 484–91, 502, 504, 506, 543–44. ISBN 9780374518738.

Additional Reading

Assembling California, John McPhee, 1993. Farrar, Straus and Giroux, New York. ISBN 0-374-52393-2
Day, Howard W., E. M. Moores, and A. C. Tuminas. "Structure and tectonics of the northern Sierra Nevada." Geological Society of America Bulletin 96.4 (1985): 436–50.
Dilek, Yildirim. “Tectonic Significance of Post-Accretion Rifting of a Mesozoic Island-Arc Terrane in the Northern Sierra Nevada, California.” The Journal of Geology, vol. 97, no. 4, 1989, pp. 503–518.
Dilek, Yildirim. "Structure and tectonics of an Early Mesozoic oceanic basement in the northern Sierra Nevada metamorphic belt, California: Evidence for transform faulting and ensimatic arc evolution." Tectonics 8.5 (1989): 999–1014.
Menzies, Martin, Douglas Blanchard, and Costas Xenophontos. "Genesis of the Smartville arc-ophiolite, Sierra Nevada foothills, California." American Journal of Science 280 (1980): 329–44.
Saleeby, Jason B. "Polygenetic ophiolite belt of the California Sierra Nevada: Geochronological and tectonostratigraphic development." Journal of Geophysical Research: Solid Earth 87.B3 (1982): 1803–24.
Taylor, Ryan D. (2015). Orogenic gold formation and tectonic evolution of the Grass Valley gold district and temporal correlations of gold deposits in California. Diss. Colorado School of Mines. Arthur Lakes Library.
Xenophontos, Costas, and Gerard C. Bond. "Petrology, sedimentation and paleogeography of the Smartville terrane (Jurassic)-bearing on the genesis of the Smartville ophiolite." (1978): 291–302.

[Irwin_&_Wooden-1] Irwin, William; Wooden, Joseph (2001). "Map Showing Plutons and Accreted Terranes of the Sierra Nevada, California, With a Tabulation of U/Pb Isotopic Ages" (PDF). USGS. Retrieved 11 October 2021.

[2] McPhee, John (1981). Annals of the Former World. New York: Farrar, Straus and Giroux. pp. 480, 484–91, 502, 504, 506, 543–44. ISBN 9780374518738.

[1]

[2]

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+{{short description|Volcanic arc accreted onto the North American Plate}}
-The '''Smartville Block''', also called the '''Smartville Complex''' or '''Smartville Intrusive Complex''', is a geologic zone in the foothills of the [[Sierra Nevada (U.S.)|Sierra Nevada]] mountains in [[California]].  Its eastern margin generally defines the gold-bearing veins of the [[Mother Lode]] important in [[California Gold Rush|California's history]].  It is named for the small town of Smartsville in the [[Gold Country]].
+[[File:Geologic map depicting the Smartville Complex and other accreted terranes in California.jpg|thumb|400px|Geologic map depicting the Smartville Complex (in brown) and other accreted terranes in California. <ref name="Irwin & Wooden" />]]
+The '''Smartville Block''', also called the '''Smartville Ophiolite''', '''Smartville Complex''', or '''Smartville Intrusive Complex''', is a geologic [[terrane]] formed in the ocean from a volcanic [[island arc]] that was accreted onto the [[North American Plate]] during the late [[Jurassic]] (~160–150 million years ago). The collision created sufficient crustal heating to drive mineral-laden water up through numerous fissures along the contact zone. When these cooled, among the precipitating minerals was [[gold]]. Associated with the Western Metamorphic Belt of the Sierra Nevada foothills it extends from the central [[Sierra Nevada (U.S.)|Sierra Nevada]] mountain range, due west, under a section of the [[Central Valley (California)|Central Valley]] and [[California Coast Ranges]], in northern California. The ophiolitic sequence found in this terrane is one of several major ophiolites found in California. [[Ophiolites]] are crustal and upper-mantle rocks from the ocean floor that have been moved on land. Ophiolites have been studied extensively regarding the movement of crustal rocks by [[plate tectonics]].
+==Gold==
-The Smartville Block is thought to be a geologic [[terrane]], a piece of crust, probably an island arc, which accreted to the [[North America]]n continent in the [[Jurassic|Jurassic Period]], about  165 million years ago.  The collision created sufficient crustal heating to drive mineral-laden water up through numerous fissures along the contact zone.  When these cooled, among the precipitating minerals was [[gold]].
+Gold was discovered in California in the mid 1800s. The Smartville Block is named for the small Gold Rush town of [[Smartsville, California|Smartville]] in [[Yuba County]], California. Gold found in the Smartville Block and within the metamorphic belts of the Sierra Nevada foothills were created through hydrothermal processes. Mineral rich groundwater is heated geothermally and injected towards the surface through fractures in the rock created from faulting. Gold and other minerals are precipitated from this fluid and have accumulated in the Sierra Nevadan metamorphic belt region in features called [[vein (geology)|veins]].<ref>{{cite book |last1=McPhee |first1=John |title=Annals of the Former World |date=1981 |publisher=Farrar, Straus and Giroux |location=New York |isbn=9780374518738 |pages=480,484-91,502,504,506,543-44}}</ref> <ref name="Irwin & Wooden">{{cite web |last1=Irwin |first1=William |last2=Wooden |first2=Joseph |title=Map Showing Plutons and Accreted Terranes of the Sierra Nevada, California, With a Tabulation of U/Pb Isotopic Ages |url=https://pubs.usgs.gov/of/2001/0229/pdf/of01-229.pdf |publisher=USGS |access-date=11 October 2021 |date=2001}}</ref>
+The Smartville Block's eastern margin is the [[Rescue Lineament-Bear Mountains fault zone]], and generally defines the range of gold-bearing veins of the [[Mother Lode]] region, important in the history of the [[California Gold Rush]].
+==Geology==
+The Smartville Ophiolite is divided into sections based on [[lithology]] that describe the origin of the rocks it is made up of. In order of increasing depth: the top most unit is called the upper volcanic unit, then the lower volcanic unit, followed by the dike complex, and the plutonic suite at the bottom. The upper volcanic unit consists mainly of [[pillow lava]] and massive lavas with [[turbidites]] also being common. The turbidites of the upper volcanic unit are made of a [[siliceous rock]] type and have [[sandstones]] and [[conglomerate (geology)|conglomerate]] tops. Next is the lower volcanic unit, which is mostly pillow lava, [[breccia]], and intrusive rocks. Metasediments of mostly [[mafic]] and intermediate [[tuffaceous]] composition are cut by dikes (intrusive rock). Below the lower volcanic unit is the dike complex. The dike complex has [[dacite]] and [[rhyolite]] dikes that cut into the rocks of the lower volcanic unit. At the base is the plutonic suite that are made up of [[gabbro]], [[diorite]], and other plutonic rocks that are intruded by dikes as well as granitic plutons from the [[Nevadan Orogeny]].
+==See also==
+* {{annotated link|Sierra Nevada-Great Valley Block}}
+* {{annotated link|Rescue Lineament-Bear Mountains fault zone}}
 ==References==
+{{reflist}}
-* ''Assembling California'', by [[John McPhee]], published 1993 by Farrar, Straus and Giroux, New York.
+==Additional Reading==
+* ''Assembling California'', [[John McPhee]], 1993. Farrar, Straus and Giroux, New York. {{ISBN|0-374-52393-2}}
+* Day, Howard W., E. M. Moores, and A. C. Tuminas. "Structure and tectonics of the northern Sierra Nevada." ''Geological Society of America Bulletin'' 96.4 (1985): 436–50.
+* Dilek, Yildirim. “Tectonic Significance of Post-Accretion Rifting of a Mesozoic Island-Arc Terrane in the Northern Sierra Nevada, California.” ''The Journal of Geology'', vol. 97, no. 4, 1989, pp.&nbsp;503–518.
+* Dilek, Yildirim. "Structure and tectonics of an Early Mesozoic oceanic basement in the northern Sierra Nevada metamorphic belt, California: Evidence for transform faulting and ensimatic arc evolution." ''Tectonics'' 8.5 (1989): 999–1014.
+* Menzies, Martin, Douglas Blanchard, and Costas Xenophontos. "Genesis of the Smartville arc-ophiolite, Sierra Nevada foothills, California." ''American Journal of Science'' 280 (1980): 329–44.
+* Saleeby, Jason B. "Polygenetic ophiolite belt of the California Sierra Nevada: Geochronological and tectonostratigraphic development." ''Journal of Geophysical Research: Solid Earth'' 87.B3 (1982): 1803–24.
+* Taylor, Ryan D. (2015). ''Orogenic gold formation and tectonic evolution of the Grass Valley gold district and temporal correlations of gold deposits in California''. Diss. Colorado School of Mines. Arthur Lakes Library.
+* Xenophontos, Costas, and Gerard C. Bond. "Petrology, sedimentation and paleogeography of the Smartville terrane (Jurassic)-bearing on the genesis of the Smartville ophiolite." (1978): 291–302.
+{{-}}
+{{California Faults}}
-[[Category:Sierra Nevada]]
 [[Category:Terranes]]
+[[Category:Geology of California]]
+[[Category:California Gold Rush]]
+[[Category:Sierra Nevada (United States)]]
+[[Category:Geography of Amador County, California]]
+[[Category:Geography of Calaveras County, California]]
+[[Category:Geography of El Dorado County, California]]
+[[Category:Geography of Mariposa County, California]]
+[[Category:Geography of Tuolumne County, California]]
+[[Category:Geography of Yuba County, California]]
+[[Category:Seismic faults of California]]

v t e Seismically active fault zones and tectonic blocks of California
Statewide Faults	San Andreas Fault Salinian Block
Southern California	Brawley Seismic Zone Chino Fault Elsinore Fault Zone Elysian Park Fault Garlock Fault Hollywood fault Hosgri Fault Imperial Fault Zone Laguna Salada Fault Newport–Inglewood Fault Northridge Blind Thrust Fault Peninsular Ranges Puente Hills Fault Raymond Fault Rose Canyon Fault Salton Trough San Cayetano Fault San Diego Trough Fault Zone San Felipe Fault Zone San Gabriel Fault San Jacinto Fault Zone Santa Maria River Fault Santa Ynez Fault Shoreline Fault Sierra Madre Fault Zone Ventura Fault White Wolf Fault Whittier Fault Yorba Linda Fault
Northern California	Bartlett Springs Fault Calaveras Fault Clayton-Marsh Creek-Greenville Fault Concord Fault Hayward Fault Zone Healdsburg Fault Maacama Fault Mendocino Fracture Zone Mendocino Triple Junction Mount Diablo Thrust Fault Monta Vista Fault Nacimiento Fault Pleasanton Fault Rinconada Fault San Gregorio Fault San Pablo Fault Seal Cove Fault Serra Fault Silver Creek Fault Tesla Fault West Napa Fault
Sierra Nevada	Death Valley Fault Zone Furnace Creek Fault Zone Honey Lake Fault Zone Kern Canyon Fault Maria fold and thrust belt Owens Valley Fault Rescue Lineament-Bear Mountains fault zone Sierra Nevada Batholith Sierra Nevada Fault Sierra Nevada-Great Valley Block Smartville Block Walker Lane
Category California Geological Survey Seismic Hazards Mapping Act Mexico (list)