Ca Geology Powerpoint L #17

Front 1

The Coast Ranges have confused scientists since the ___.

Back 1

1970s

Front 2

30 million years ago the __ plate was being subducted under the North American Plate. When the Pacific Plate came into direct contact with North America, the __ boundary was created. As more of the Pacific plate hit the North American Plate, the ___ lengthened and the ___ and __ Triple Junctions moved north and south. This created two plates from the original one.

Back 2

Farallon plate;

San Andreas transform boundary;

San Andreas transform;

Mendocino (North of SF) and Rivera Triple Junctions (Just means between 3 different plates;

Juan de fuca plate and Cocos plate;

Front 3

The Franciscan Rocks represent pieces of oceanic lithosphere that have accreted onto North Americaby subduction (and obduction) and collision. What are the different types of rocks you can find in them.

Back 3

Sandstone and shales (clay) making Greywacke,

Chert, Limestone, Volcanic rocks, Basalt pillows, Blueschist (Glaucophane & Jadeite), Greenstone, Serpentine, eclogite

Front 4

Sandstones and shales accumulated as marine sediments in relatively deep water. __ is sandstone with more then 15% clay that is dirty grey color. Common here. ___ are sedimentary rocks characterized by fining-upward sequences of sand and mud. It's like an underwater landslide. Like an alluvial fan. Slow. Monterey Canyon is an example.

Back 4

Greywacke;

Turbidities;

Front 5

Siliceous ooze accumulates at the bottom of the sea as fine-grained radiolarian skeletons. These skeletons are full of silica. The type of radiolaria present in it provides evidence about the water ___, __, and __. Good for evidence of marine because it is hard so doesn't weather down easily.

Back 5

Chert;

water depth, temperature, & chemistry;

Front 6

Submarine volcanic plateau. Forms because these are higher in elevation. It is found with volcanic rock.

Back 6

Limestone

Front 7

Turbidites have ___ which means that the bigger coarser sediments are on the bottom and the finer ones are at the top.

Back 7

Graded bedding;

Front 8

Chert is a hard fine-grained sedimentary rock composed of silica, usually the skeletons of ___.

Back 8

Radiolaria;

Front 9

Volcanic rocks make up __% of Franciscan rocks. But they have light ___ due to interaction with sea-water.

Back 9

10%;

metamorphism;

Front 10

___ form when hot lava enters the ocean and cools into rounded blobs. Those found in the Franciscan formed in various submarine environments. Ex. Mid-ocean ridges, sea mounts, and oceanic islands. One type is called because they are metamorphoses green.

Back 10

Basalt Pillows; Greenstone

Front 11

Blueschist. Mineral Glaucophane commonly metamorphoses into Blueschist here. Jadeite is also found (also formed in metamorphic rock). These rocks form at __ pressure and __ temperature. Where is the ideal place for this environment?

Back 11

high pressure; low pressure;

Subduction of oceanic and continental plate.

(significant because metamorphic rocks usually found in places of high pressure and high temperatures)

Front 12

Serpentinite (State rock hooray!). Originates from peridotite (ultramafic mantle rock). Extremely soft and weak. Notorious for creating ___.

Back 12

landslides;

Front 13

Rare metamorphic rock associated with the Franciscan. Contains garnet. Metamorphic rocks tend to last longer.

Back 13

Eclogite;

Front 14

The Franciscan rocks represent the remains of the ancient ___ plate, accreted to North America during the ____. There are at least nine different blocks or terranes have beenidentified.

Back 14

Mesozoic; Farallon plate;

Front 15

The Franciscan Rocks can be divided into three broad areas. What are they?

Back 15

Coastal Belt, Central Belt, Eastern Belt,

Front 16

Franciscan Belt. Northwest-trending zone between Eureka and the Russian River. Greywacke and shale. The youngest rock.

Back 16

Coastal Belt

Front 17

This Franciscan Belt includes the Bay Area. East of the Coastal Belt. It is __ which is “A mixture of rock types jumbled together by tectonicactivity”. Small blocks of greenstone, Blueschist, eclogite, chert, or greywacke“float” in a matrix of highly sheared mudstone. The matrix is the same age as the Eastern Belt

Back 17

Central Belt;

Melange;

Front 18

What is the matrix of the Melange in the Central Belt?

Back 18

sheared Mudstone

Front 19

This Franciscan Belt extends east to the Coast Range Fault. Blueschist. Oldest of the three BUT the matrix (sheared mudstone) in the Central Belt is just as old.

Back 19

Eastern Belt

Front 20

The entire Franciscan encompasses 150Ma of accretion. Middle Mesozoic (late Jurassic) to early Tertiary (Eocene) time.

Back 20

eeeek

Front 21

Similar to the granitic rocks in the Sierra Nevada. Suggests that this was once part of Sierran batholith and wasmoved along the San Andreas fault (transform motion) to itspresent position. Named after Salinas Valley in Monterey County.

Back 21

Salinian Block;

Front 22

___ refers to a point where three plate boundariesmeet. When the Farallon Plate was entirely destroyed beneaththe North American Plate by subduction two [previous answer] were produced. What were they?

Back 22

Triple Junction;

The Mendocino Triple Junction

and the Rivera Triple Junction

Front 23

The ___ is a 6,000’ tall mountainSitting on a 14,000’ ocean floor. BIG DEAL.

Back 23

Mendocino Fracture zone or Mendocino ridge;

Front 24

The San Andreas is separated by other faults. It is not just one long line.

Back 24

YOUR FACE IS ONE LONG LINE

Front 25

Examples of Cenozoic volcanic rocks are what?

Back 25

Morro Bay and Pinnacles National Monument;

Front 26

Morro Bay named after a rounded hill or "___”. There are 14 other similar dome shaped rocks along Hwy 101. Northwest trending between San Luis Obispo and Morro Bay. Remains of domes, plugs, and volcanic necks of an old chain ofvolcanoes dating between 20-27Ma. Dacite (intermediate lava). Why are they still here?

Back 26

Morro;

Differential erosion;

Front 27

____ was similarly formed. Also from ___. Pyroclastic flows and banded flows of rhyolite (felsic lava).

Back 27

Pinnacles National Monument;

Differential erosion;

Front 28

On the east side of the San Andreas fault, North volcanoes are the ____. Northward migration of the Mendocino Triple Junction.

Back 28

younger;