Klamath Mountains

Similar history as E. Blue mts

Rocks are Pz, Mz and Cz in age

Accreted in similar fashion and time line

Part of the same system

Sierra Nevada, Klamath, Blues, Cache Creek (BC) all related

1000 mile long ancient mountain chain

Rotation and faulting moved them around

Most of the Klamaths are located in N. California.

Ranges include: Trinity, Salmon, Scott, Marble

Elevations: 9000’

OR ranges: Siskiyou (OR-CA border)

Elevations: 5000’-7500’

Thick sequences of rocks in East

25,000’ Pz and 15,000’ Mz

Very faulted with high angle thrust faults

Represents high angle subduction slab

What are thrust Faults?

Fault types

Faults represent regions of fractured rock

Occur when stress is placed on rocks tensional (pull apart) or compressional

Fault morphology

Head Wall

Foot Wall

Normal fault

Created by tensional forces

Head wall moves down relative to foot wall

Reverse Fault

Created by compressional forces

Head wall moves up relative to foot wall

Thrust Fault

Similar to reverse fault but angle of fault is low

Klamath Mt. Review:

Similar history as Blue mts

Same system of volcanic island arcs

Rocks are Paleozoic/Mesozoic in age

Many collisions of volcanic terranes/ocean terranes

Each terrane was emplaced “below” previous one by thrust faulting

Review 3 faults types

Normal

Reverse

Thrust

Klamath Mts are comprised of 4 major terranes

Each terrane separated by thrust faults

Most are subdivided into minor terranes

Younger terranes are to the west

Link to OR Geo Map

From east to west (oldest to youngest)

Eastern Klamath Belt (Ordovician to Devonian)

Trinity ophiolite

Central Metamorphic Belt

Metamorphism of ocean sediments

Western Paleozoic and Triassic Belt

Applegate Group (Oregon rocks)

Rattlesnake terraneà Ophiolite

Hayforkà Island arc

May creekà Ophiolite

Tropical fossils similar to Cache Creek terrane in BC and Baker terrane in Blues

Western Klamath Terrane

Condrey Mtn. Schist

Preston Peak ophiolite

Smith River

Josephine Ophiolite

One of the most complete ophiolite sequences in the world

163 mybp

Backarc basin setting

Massive sulfide deposits

Gold, copper, zinc, silver and colbolt

Jurassic through Cretaceous

Emplacement of batholiths due to pressure and melting of continental crust

Core of many mountains in these areas

SW Oregon Terranes…Part of W. Jurassic belt

Cretaceous

Sealevel rises and basins develop in OR and CA

Sediments deposit over 3000-4000 ft thick

Depostion of Hornbrook formation

Stream and estuary environment on edge of continent at the time

Many Seastacks in southern Oregon made of this formation

Cenozoic

Seaway retreats (Tertiary)

Tyee Deltic Complex

Major component of Coast range

Continued uplift with shoreline

Establishment of modern rivers

Pleistocene

Glacial period

Sea terraces exposed

Continued uplift of Klamaths

Klamath-Blue Mountain Lineation

What is it?

A structure/line that is visible from space

400 miles long

Runs under the Cascades

Possible Ideas of what this represents

Represents rotation line of Klamath mountain from Eastern Oregon to Western Oregon

Old shoreline of NW

Evidence for Continuity between Sierras, Klamaths, Blues & Coast range of BC?

Age of rocks: Pz and Mz

Composition of rocks

Sea floor structure

Age of Mountain Building and granites

Some say they represent a 1000 mile long belt of Jurassic Mt. building

Rotation of Klamath & Blue Mt. region

Clockwise rotation by early cretaceous