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Reddish Dox Formation is at the west, basalt east. (downstream view, ~west/southwest) (high resolution expandable photo – Note: massive sections of Cardenas on both sides of river) The upper unit of the Cardenas Basalt is a series of cliff-forming basaltic and andesitic lava flows that are interbedded with beds of breccia, sandstone, and ...
Stromatolites have been reported from the Comanche Point Member. The Dox Formation locally interfingers with, and is baked by, basalt lava flows of the overlying Cardenas Basalt. Within the central Grand Canyon, pre-Tapeats Sandstone erosion has removed parts of the Unkar Group above the level of the middle part of the Dox Formation.
The Uinkaret volcanic field is an area of monogenetic volcanoes in northwestern Arizona, United States, located on the north rim of the Grand Canyon. [ 2 ] Lava flows from the Uinkaret volcanic field that have cascaded down into the Grand Canyon, damming the Colorado River , have been used to date the canyon's carving. [ 3 ]
Grand Canyon lies on the southern end of the Intermountain West seismic belt. [84] At least 35 earthquakes larger than 3.0 on the Richter Scale occurred in the Grand Canyon region in the 20th century. [85] Of these, five registered over 5.0 on the Richter Scale and the largest was a 6.2 quake that occurred in January 1906. [85]
The Apache Group was intruded with basalt and diabase between 1.05 and 1.14 billion years ago. The Mescal Limestone metamorphosed, forming asbestos and superheated diabase magma "baked" the limestone to marble. The 1.07 billion year old limestone, shale, quartzite, sandstone and basalt of the Unkar Group is also found in the Grand Canyon.
As in the case of the Grand Canyon asbestos deposits, dolomite and limestone reacted with silica-bearing fluids, heated by the basalt intrusions, forming the serpentine mineral chrysotile. Much like the Grand Canyon asbestos deposits, these basaltic sills and dikes range in age from 1,050 to 1,140 Ma.
Nankoweap Creek is located upstream from the Lipan Point–Basalt Creek section. The creek is west of Marble Canyon, and enters the canyon near Lower Marble Canyon. The Tanner Graben, a downdropped graben of Dox Formation and Cardenas Basalt is topped by a bright, multilayered section of the Nankoweap Formation. It lies opposite Tanner Creek ...
The majority of the Grand Canyon Supergroup geologic members are found in the south and southwest stretch of the Colorado River starting from Marble Canyon, traverses the southeast perimeter of the Kaibab Plateau, and flows northeasterly entering Granite Gorge and regions of the Vishnu Basement Rocks.