Framework and petrogenesis of the northern Peninsular Ranges batholith, southern California

2014 ◽  
Author(s):  
D.M. Morton ◽  
F.K. Miller ◽  
R.W. Kistler ◽  
W.R. Premo ◽  
C-T.A. Lee ◽  
...  
Keyword(s):  
Southern California ◽  
Peninsular Ranges

Regional crustal thickness variations of the Peninsular Ranges, southern California

Geology ◽  
2000 ◽  
Vol 28 (4) ◽  
pp. 303-306
Author(s):  
Jennifer L. Lewis ◽  
Steven M. Day ◽  
Harold Magistrale ◽  
Jennifer Eakins ◽  
Frank Vernon
Keyword(s):  
Southern California ◽  
Crustal Thickness ◽  
Peninsular Ranges ◽  
Thickness Variations

An earthquake-explosion reversed refraction line in the Peninsular Ranges of southern California and Baja California Norte

1982 ◽  
Vol 72 (4) ◽  
pp. 1195-1206
Author(s):  
F. Alejandro Nava ◽  
James N. Brune
Keyword(s):  
Sierra Nevada ◽  
High Velocity ◽  
Southern California ◽  
Baja California ◽  
Crustal Thickness ◽  
Arrival Times ◽  
Narrow Zone ◽  
Peninsular Ranges ◽  
Thick Crust

abstract An approximate reversed refraction profile has been obtained for the center of the Peninsular Ranges of southern California and Baja California Norte using arrival times from Corona blasts to obtain the NW-SE profile, and arrival times from the well-located Pino Solo earthquake of 17 July 1975 to obtain the reversing SE-NW profile. The results indicate a relatively high-velocity crust, with P velocities of 6.57 to 6.95 km/sec, similar to the high velocities found by Hadley and Kanamori (1979). A crustal thickness of about 40 km was found for the axis of the Peninsular Ranges, significantly greater than was found by Hadley and Kanamori (1979) for the average crustal thickness of the northern part of the province. This suggests that the thick crust may be confined to a relatively narrow zone along the axis of the province. The crustal thickness found here is approximately 10 km less than found for the deeper crust of the Sierra Nevada (Bateman and Eaton, 1967; Pakiser and Brune, 1980).

Petrology and emplacement of the Los Pinos pluton, southern California

1976 ◽  
Vol 13 (9) ◽  
pp. 1288-1300 ◽  
Author(s):  
M. J. Walawender
Keyword(s):  
Experimental Data ◽  
Volcanic Eruption ◽  
Southern California ◽  
Major Element ◽  
Parent Magma ◽  
Chemical Analyses ◽  
Eastern Margin ◽  
Peninsular Ranges ◽  
Summit Region ◽  
Pelitic Rocks

The Los Pinos gabbro is located on the eastern margin of the gabbro sub-belt of the Peninsular Ranges batholilh. Two lithologic sequences are recognized in this pluton. The outer group consists of bimodal assemblages of hornblende and plagioclase in several textural varieties, whereas the inner group contains a variety of olivine–plagioclase rocks. Symplectitic intergrowths of spinel, amphibole, and orthopyroxene have developed wherever the olivine and plagioclase were in contact. The outer group is generally the older of the two, although there is evidence suggesting that their emplacement overlapped in time. The contact between the two groups is characterized locally by sequences of comb layers up to 65 m thick. Major-element chemical analyses emphasize the differences between the two groups. The outer group is generally richer in total alkalis, titanium, and silica. Variation diagrams suggest that different differentiation mechanisms operated within each group.Textural and published experimental data suggest that the two groups are derived from a parent magma by clinopyroxene fractionation at PT > 5 kbar. The more silicic differentiates were emplaced at shallower levels into a series of regionally metamorphosed pelitic rocks. Volatile streaming in restricted channels along a conduit zone and periodic degassing of the melt, possibly through volcanic eruption, produced the comb layering in the summit region. The remaining fraction intruded along the old conduit zone. Differentiation at these shallower levels (PT < 5 kbar) produced the olivine–plagioclase cumulates. The symplectic intergrowths in these units formed at this shallower level prior to the solidification of the melt.

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