OE0EOOICAL SURVEY PROFESSIONAL PAFER 1170-

*Z-*£TS>

'€.
Merced Peak Quadrangle, 

Central Sierra Nevada, 

C alifornia Analytic Data

By DALLAS L. PECK and GERALD K. VAN KOOTEN

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1170-D

Chemical, semiquantitative spectrographic, and modal analyses 

and potassium-argon, uranium-lead, and rubidium-strontium age 

determinations on plutonic, metavolcanic, and volcanic rocks 

supplement U. S. Geological Survey Geologic Quadrangle Map 

GQ-1531

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1983
UNITED STATES DEPARTMENT OF THE INTERIOR 

JAMES G. WATT, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

For sale by the Distribution Branch, U.S. Geological Survey, 

604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Page

Abstract ____________________________________________ 1

Introduction __________________________________________ 1

General geology ________________________________________ 1

Analytic data __________________________________________ 5

References cited ________________________________________ 29

ILLUSTRATIONS

Page

FIGURES 1-8. Simplified bedrock geologic maps of the Merced Peak quadrangle, showing:

1. Locations of chemically analyzed and isotopically dated rock samples _________—————————————— 3

2. Steeply inclined regional joints ______________________________________————— 14

3. Locations of modally analyzed plutonic rock samples _________________________—______ 19

4. Quartz in volume percent _________________________________—_————__————— 20

5. Potassium feldspar in volume percent ____________________________———————————— 21

6. Plagioclase in volume percent ______________________________—————————————— 22

7. Mafic minerals in volume percent ________________________________________—_ 23

8. Specific gravity ____________________________________________________ 25

9. Plots of modes of granitic rocks __________________________________—_—————————— 27

10. Plots of norms of plutonic and metavolcanic rocks _________________________————————————— 28

TABLES

Page

TABLE 1. Rubidium and strontium determinations on metavolcanic rocks _________________________________ 4

2. Uranium-lead age determinations on zircon from plutonic and metavolcanic rocks _________————————————— 4

3. Potassium-argon age determinations on minerals from granitic and volcanic rocks _________————————————— 5

4. Chemical and spectrographic analyses, norms, and modes of representative igneous rocks _____————————————— 6

5. Modes, specific gravity, and location of plutonic rocks ______________________________________ 15

HI

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, 

CALIFORNIA-ANALYTIC DATA

By DALLAS L. PECK and GERALD K. VAN KooTEN1

ABSTRACT

A variety of plutonic, metamorphic, and volcanic rocks and glacial 

deposits underlie the Merced Peak quadrangle, which spans the 

southeastern margin of Yosemite National Park. More than 800 rock 

samples were collected during geologic mapping of the area, of which 

258 samples of plutonic rocks were analyzed modally and their specific 

gravities determined. The volume percentages of quartz, potassium 

feldspar, plagioclase, and mafic minerals and the bulk specific gravities 

are plotted on a simplified geologic base map and contoured where the 

data permit. Quartz, potassium feldspar, and plagioclase, calculated to 

100 percent, are plotted on triangular diagrams. The modal analyses 

show that the compositions of individual plutons are predominantly 

granite and granodiorite but range from leucogranite to tonalite and 

quartz diorite. Chemical and spectrographic analyses of 41 plutonic 

rocks, 15 metavolcanic rocks, and 11 Pliocene volcanic rocks are 

tabulated, and normative quartz, orthoclase, and plagioclase of the 

plutonic and metavolcanic rocks are plotted on a triangular diagram. 

The metavolcanic rocks are primarily rhyodacite but range from 

rhyolite to andesite. The Pliocene volcanic rocks are predominantly 

trachybasalt but include several flows and volcanic necks of ultrapotassic mafic phonolite. Data on ages determined by the potassiumargon, uranium-lead, and rubidium-strontium methods on some 

plutonic, metavolcanic, and volcanic rocks are tabulated. A map of conspicuous, steeply dipping regional joints is included.

INTRODUCTION

The Merced Peak quadrangle includes an area of 

about 620 km2 of the Sierra Nevada batholith 10-40 km 

southeast and east of Yosemite Valley. The quadrangle 

is nearly bisected by the southeastern boundary of 

Yosemite National Park, which for the most part coincides in the area with the divide between the drainage 

basins of the Merced and San Joaquin Rivers. Altitudes 

range from 6,100 to 13,100 feet (about 2,000 to 4,000 m), 

and much of the area is at or near local timberline. 

Roads are limited to the southern margin, but a network 

of trails provides access to all parts of the area.

This paper supplements the "Geologic Map of the 

Merced Peak Quadrangle, Central Sierra Nevada, 

California" (Peck, 1980), by providing analytic data on 

the plutonic, metamorphic, and volcanic rocks of the

'Arco (Ml and Gas, Geothermal Projects, P.O. Box 2819, Dallas, TX 75221.

quadrangle. It is part of a continuing study of the bedrock geology of the central Sierra Nevada batholith 

reported earlier by Bateman and others (1963), 

Bateman and Wahrhaftig (1966), and Bateman and 

Eaton (1967). A preliminary version of the geologic map 

of the Merced Peak quadrangle was published in uncolored form in 1964 (Peck, D. L., 1964). The bedrock 

geology of the northwestern part of the quadrangle was 

mapped and described by Calkins (1930), and the glacial 

deposits have been studied by Matthes (1930; 1960) and 

Birman (1964). Nokleberg (1970; 1981) mapped the 

Strawberry Mine area in detail as part of this project, 

and his mapping is incorporated in figure 1. Geologic 

maps of adjacent quadrangles have been published by 

Huber and Rinehart (1965), Kistler (1966a), Huber 

(1968), Bateman and others (1971), and Kistler (1973). 

Supplementary geologic and analytic reports include 

Kistler (1966b), Huber and Rinehart (1967), Bateman 

and Lockwood (1976), and Kistler (1974). Isotopic U-Pb 

ages of zircons from several of the plutonic units of the 

Merced Peak quadrangle, as well as from many other 

plutons of the central Sierra Nevada, have been 

reported recently by Stern and others (1981). Plutonic 

rocks in this report are classified according to the 

recommendations of the International Union of 

Geological Sciences (Streckeisen and others, 1973) as 

shown in figure 9A.

GENERAL GEOLOGY

The quadrangle is underlain chiefly by plutonic and 

metavolcanic rocks, as shown in the simplified bedrock 

geologic map (fig. 1) and described in the text of the 

geologic map of the Merced Peak quadrangle (Peck, 

1980). Metasedimentary rocks are exposed only in a few 

localities. The rocks are predominantly metaquartzite 

but include less abundant quartz-biotite hornfels, quartzplagioclase hornfels, tactite, and marble. A fossil from 

the Strawberry Mine area, identified by R.W. Imlay 

(oral commun., 1977) as Inoceramus pseudomytiloidestf) 

of Early Jurassic age, indicates that the beds are cor-
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

119° 30' 119°15 f

37°45

37°30'

.*•':*:•'•••'•'>:-"»'.'

r . ^mg.X . .-, 

i S • * • . , T\ ,-'..,

15 KILOMETERS
MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA

Mount Givens Granodiorite

Mafic phonolite

Half Dome Granodiorite 

(porphyritic phase, overprinted)

Granodiorite 

of Kuna Crest

Granodiorite 

of Grayling Lake

Granodiorite 

of Breeze Lake

Granodiorite 

of Ostrander Lake

Granodiorite 

of Illilouette Creek

Granodiorite 

of Red Devil Lake

Leucogranite 

of Timber Knob

Leucogranite 

of Norris Creek

Granodiorite of Jackass Lakes 

Kjs Leucogranite phase

near Sadler Peak 

Kja Mafic granodiorite phase 

near Ann Lake

Leucogranite porphyry 

of Red Peak

Leucogranite porphyry 

of Post Peak

Granodiorite porphyry 

of Horsethief Canyon

Granite porphyry 

of Star Lakes

Leucogranite 

in small masses

Quartz diorite 

of Long Creek

X 786 

Chemically analyzed sample

Metasedimentary rocks

846

Sample dated by lead-uranium

or potassium-argon method 

? following rock symbol indicates identification of rock is not firmly established

D 165C

Sample part of set dated by 

rubidium-strontium method

FIGURE 1.-Simplified bedrock geologic map of the Merced Peak quadrangle showing the locations of chemically analyzed and 

isotopically dated rock samples. Numbers refer to sample numbers in tables 1 through 5.
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

relative with the fossil-bearing metasedimentary rocks 

of the Boyden Cave pendant described by Jones and 

Moore (1973). Far more abundant are metavolcanic 

rocks, mostly blastoporphyritic, quartzo-feldspathic 

hornfels, epidote-amphibolite hornfels, and weakly 

foliated schist. They are predominantly derived from 

massive pyroclastic rocks of rhyodacitic composition but 

also include less abundant andesite, dacite, and rhyolite 

and sparse flows and shallow intrusions. The metavolcanic rocks along the eastern boundary of the 

quadrangle form the western margin of the Hitter 

Range pendant, described by Huber and Rinehart 

(1965). The metavolcanic rocks intrude metasedimentary rocks near the Strawberry Mine (Nokleberg, 1970; 

1981) and are in turn intruded by many of the plutonic 

units, including quartz diorite and the intrusive sequence of Merced Peak. The rocks have yielded Early 

Cretaceous ages of 95 and 100 m.y. by rubidiumstrontium and lead-uranium methods, respectively 

(tables 1 and 2), approximately the same ages as those 

obtained from the granodiorite of Jackass Lakes. The 

similarity in age of these units and their close spatial 

association and similar chemical compositions suggest 

that they may well be genetically related. The geographic distribution of the metavolcanic rocks (excluding those in the southwest corner of the quadrangle) 

and the plutonic rocks of the Merced Peak intrusive sequence indicates that they may represent the preserved 

lower part of a caldera.

Plutonic rocks ranging from quartz diorite to 

leucogranite underlie most of the quadrangle. The rocks 

constitute many different plutons (29 units are distinguished in fig. 1) that are in sharp contact with one 

another. Most of the plutonic rocks are medium-grained 

granodiorite and granite, but they range from quartz 

diorite to leucogranite and from very coarsely porphyritic granodiorite to fine-grained aplite and 

leucogranite porphyry. Most of the area is underlain by 

plutonic rocks that are part of areally extensive plutons 

or suites of closely related plutons covering 100 to 1,000 

km2 . The intrusive sequences of Merced Peak and 

Washburn Lake are entirely or mostly confined to the 

quadrangle, but others extend-for many kilometers 

beyond the boundaries, particularly the Shuteye Peak,

TABLE I.-Rubidium and strontium determinations on metavolcanic rocks1 *

[Rb and Sr determinations of MP-165B, MP-314, and MP-320 by isotope dilution, Carl Hedge 

analyst, U.S. Geological Survey, Denver, Colo.; all others by XRF, W. P. Doering analyst, 

U.S. Geological Survey, Denver, Colo. Strontium isotope analyses by R. Hildreth, U.S. 

Geological Survey, Denver, Colo., and R. Kistler, U.S. Geological Survey, Menlo Park, 

Calif. Rb/Sr about ±3.0 percent or ±2.0 percent on those specimens determined by XRF 

or isotope dilution, respectively. Strontium isotope ratios are from ±0.02 percent to 

±0.10 percent, normalized to MSr/MSr=0.1194, and adjusted to E and A SrC03 

"Sr/MSr=0.7080. Isochron is regressed by the method of York (1966). Specimen MP-320 

not used in isochron. X"Rb= 1.42 x 10-"/yr. Determinations GC-10 to -204 from Warren 

Nokelberg, 1981; samples from the Strawberry Mine area]

Sample no.

MP-11A _ 

MP-116 __ 

MP-165B __ 

MP-273A __ 

MP-314 __ 

MP-320 __ 

MP-378 __ 

MP-780 __ 

GC-10 _

GC-41 ___ 

GC-50 _

GC-62

GC-204 __

Rb (ppm)

85.8 

94.3 

274 

137 

44.1 

159 

130 

114 

59.0

122 

115

189

136

Sr (ppm)

551 

459 

39.1 

60.4 

472 

47.3 

233 

388 

504

387 

366

96.9

210

Rb/Sr

0.156 

.205 

7.001 

2.266 

.093 

3.362 

.556 

.294 

.117

.315 

.314

1.947

.646

"Sr/"Sr

0.7082 ±.00014 

.7075 ±.0007 

.7341 ±.0002 

.7161 ±.00014 

.7072 ±.0002 

.7149 ±.0003 

.7088 ±.00014 

.7077 ±.00014 

.7073 ±.00014

.7073 ±.00014 

.7077 ±.00014

.7142 ±.00014

.7096 ±.00014

1 Age=94.7 ±4.6 m.y.

1 Initial "Sr/MSr=0.7068±.0002.

Mount Givens, and El Capitan plutons, the intrusive sequence of Buena Vista Crest, and the Tuolumne Intrusive Suite. Individual plutonic suites and large 

plutons typically range from hornblende granodiorite 

(or quartz diorite) rich in discoid mafic inclusions at the 

margins to fine-grained biotite granite or leucogranite 

porphyry at the core.

The plutonic rocks range in age from Early to Late 

Cretaceous (105 to 85 m.y.) on the basis of radiometric 

ages from the Merced Peak quadrangle (listed in tables 2 

and 3) and radiometric ages from adjacent areas. Most 

of the potassium-argon ages have been reduced by nearby younger intrusions, but the age of 95 m.y. for the 

hornblende from a sample of the granodiorite of Jackass 

Lakes (MP-82, table 3) is in good agreement with the 

age of 98 m.y. determined by lead-uranium methods on 

zircon from another sample of the unit (MP-520, table 2). 

That age and those determined on samples of the 

granodiorite of Red Devil Lake (MP-789, table 3) and of 

the metavolcanic rocks are consistent with the observed 

geologic relations and radiometric ages from adjacent 

areas, but the discordant age of 93 m.y. determined 

from a sample of the leucogranite porphyry of Post Peak 

appears to be too low by 6 m.y.

TABLE 2.-Uranium-lead age determinations on zircon from plutonic and metavolcanic rocks

[Determinations by T. W. Stern, U.S. Geological Survey, Reston, Va. Constants used: MgU/M!U 137.88; 238X=0.155x10-" yr1 . Analytic uncertainties approximately ±3 percent. Age determined

from M«Pb/M8U]

Sample no.

MP-520 __ 

MP-568 __ 

MP-789 __ 

MP-846 __

MP-847 __

Rock unit

Granodiorite of Jackass Lakes 

Granodiorite of Illilouette Creek 

Granodiorite of Red Devil Lake 

Leucogranite porphyry of Post 

Peak 

Metavolcanic rocks

Pb 

(ppm)

20.24 

19.64 

20.15 

16.08

11.12

u

(ppm)

1140.4 

1092.8 

807.5 

974.1

600.8

Th 

(ppm)

951.8 

855.6 

1948.9 

392.4

285.5

(atomic 

percent)

0.03148 

.04319 

.02757 

.2873

.1877

(atomic 

percent)

74.95 

75.78 

53.28 

80.71

76.00

M7Pb

(atomic 

percent)

3.929 

4.081 

2.921 

5.227

6.103

2MPb 

(atomic 

percent)

21.09 

20.10 

43.77 

13.77

17.71

Age

98 

100 

98 

93 '

100
MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA

TABLE 3. -Potassium-argon age determinations on minerals from granitic and volcanic rocks

[Constants used WK: -re+Xe=0.581x 10-'° year'1 , y0=4.962x 10-'° year1 ; isotopic abundance 1.167x10-* moles MK per mole K. Radiogenic argon=r*"Ar; total argon=t40Ar. Analysts for 

MP-82, MP-455, and MP-789, R. W. Kistler and Lois Schlocker, U.S. Geological Survey, Menlo Park, Calif. Analyst for VMP-76-21 and MP-841A, Elliot Sims, under the direction of 

G. Brent Dalrymple, U.S. Geological Survey, Menlo Park, Calif.]

Sample

MP-82

MP-455

Mp-789

VMP-76-21 _ 

MP-841A _

VMP-76-21 _ 

MP-841A __ 

MP-841A

MP-841A

Rock unit

Granodiorite of Jackass Lakes

Granodiorite of Illilouette

Creek 

Granodiorite of Red Devil

Lake 

Mafic phonolite near Grizzly 

Creek 

Mafic phonolite near Merced 

Pass

Mafic phonolite near Grizzly 

Creek 

Mafic phonolite near Merced 

Pass 

do

do

Mineral

Hornblende 

Biotite

Hornblende

Hornblende 

Phlogopite

Phlogopite

Phlogopite 

Phlogopite3

Argon

K20 

(weight 

percent)

9.21

1.17 

9.30

1.00 

9.43

.82 

9.83

8.80

40Ar/39Ar 37Ar/39Ar>

1.949 0.02496 

2.091 .03117 

1.729 .03760

.8876 .1674

"Ar^ 

(moles/g xlO11)

115.83

16.25 

121.50

12.53 

116.83

10.57 

5.105

3.859

36Ar/39Ar

0.00541 

.00573 

.00463

.00180

""Ar^ 

(percent)

81

71 

65

63 

79

38 

25.2

32.6

P

0.005678 17.8 

.005702 18.8 

.005702 20.7

.005702 39.5

Age 

(m.y.)

85.5±2.1

95.2 ±2.8 

88.7 ±2.2

85.1±2.5 

84.2±2.1

87.4±2.6 

3.60 ±0.06

3.04 ±0.04

3.55 ±0.21 

4.05 ±0.22 

3.68±0.18

3.60 ±0.10

1 Corrected for "Ar decay (ty.=35.1 days).

2 J is a function of the age of the monitor mineral and of the integrated fast-neutron flux.

Volcanic rocks of Tertiary age occur near Jackass 

Meadow (near the southeast corner of the quadrangle), 

along Cora Creek (10 km farther north), and at several 

small isolated localities. Most are in flows and sparse 

cinder deposits of trachybasalt and less abundant 

trachyandesite similar to the Tertiary volcanic rocks of 

adjacent areas described by Hamilton and Neuerburg 

(1956). Small flows along Grizzly Creek and near Merced 

Pass and a flow and volcanic neck along the west fork of 

Granite Creek, however, represent a rare composition 

for volcanic rocks; they are phlogopite-bearing, 

ultrapotassic, mafic phonolite similar to the orendite 

and olivine orendite of the Leucite Hills, Wyoming (Carmichael, 1967), and the minette dikes of the Navajo 

region (Williams, 1936). The mineralogy, petrology, and 

geochemistry of these volcanic rocks have recently been 

described by Van Kooten (1980). Trachybasalt flows in 

adjacent quadrangles have yielded Pliocene potassiumargon ages of 2.9 to 3.6 m.y. (Dalrymple 1963, 1964). 

Similar ages of about 3.6 m.y. were determined by 

potassium-argon determination of phlogopite and 

sanidine from the Merced Pass and Grizzly Creek 

localities (as listed in table 3, samples MP-841A and 

VMP-76-21), indicating that the trachybasalt and 

phonolite are at least in part contemporaneous.

The Lower Cretaceous and older plutonic and 

metamorphic rocks, but not the Upper Cretaceous 

plutonic rocks, are cut by northwest-trending shears 

along several zones that cross the quadrangle. These 

shears are not indicated on the simplified geologic map 

(fig. 1) but are shown and discussed on the geologic map 

of the Merced Peak quadrangle (Peck, 1980). All the

3 Screened to 60-100 mesh. 

1 Screened to 100-200 mesh.

plutonic and metamorphic rocks are cut by steeply dipping regional joints, as shown in figure 2. This figure, 

which was prepared from aerial photographs of the 

quadrangle, shows a dominant north- to northnortheast-trending set of joint cracks crossed by a less 

prominent west- to northwest-trending set.

Glacial deposits, primarily of Wisconsinan Age, cover 

broad areas of the quadrangle, particularly along 

Granite, Illilouette, and Chiquito Creeks and the North 

and South Forks of the Merced River. These deposits 

are not shown on the simplified geologic map (fig. 1), but 

they are shown and described in the geologic map of the 

Merced Peak quadrangle (Peck, 1980).

ANALYTIC DATA

During the course of the geologic mapping, 845 rock 

samples were collected, including 520 of plutonic rocks. 

Of these, 258 were analyzed modally, and 41 were also 

analyzed chemically and spectrographically, as were 15 

samples of metavolcanic rocks and 11 samples of Tertiary volcanic rocks. The locations of chemically and 

isotopically analyzed samples are plotted in figure 1 and 

listed in table 4 together with the chemical and spectrographic analyses, norms, and modes. Modes were 

determined by counting 1,000 to 2,000 regularly spaced 

points on rock slabs of not less than 40 cm2 , on which 

potassium feldspar had been selectively stained yellow 

and plagioclase red (Norman, 1974). Four constituents 

were counted-quartz, potassium feldspar, plagioclase, 

and mafic minerals. The locations of the modally analyzed samples are plotted in figure 3 and listed in table 5, 

along with modes and specific gravities. The percent-
TABLE ^.-Chemical and spectrographic analyses, norms, and modes of representative igneous rocks

[Chemical analyses: Standard rock analyses listed in columns 12,15,20,22,28,35,38, and 50 by Ellen S. Daniels, under the direction of L. C. Peck, U.S. Geological Survey, Denver, Colo., 1963; rapid rock 

23,24,25,26, 29,31,32,39, 41,42,44, 45,47, 48, 49, 53, 55,56, 58, 59,61,62, 64, and 66 prepared under the direction of Leonard Shapiro, U.S. Geological Survey, Reston, Va., 1963-64; all other an

Hamlin, U.S. Geological Survey, Reston, Va., using the method described by Shapiro (1975) under "single solution" in U.S. Geological Survey Bulletin 1401. Semiquantitative spectrographic analyses in 

22, 23, 24,25, 26, 28,29, 31,32, 35, 38,39, 41,42, 44,45, 47, 48,49, 50, 53, 55, 56, 58, 59,61, 62,64, and 66 by J. C. Hamilton, U.S. Geological Survey, Denver, Colo., and C. Heropoulos, U.S. Geologi

values reported to the nearest number in the series 1,0.7,0.5,0.3,0.2,0.15,0.1, and so on, which represent midpoints on a geometric scale; the precision of a value is approximately plus or minus one b

brackets at 95 percent. N-not detected; detection limits (in ppm) are Ag, 0.5; B, 20; Ba, 1.5; Be, 1; Co, 3; Cr, 1; Cu, 1; Ga, 5; La, 30; Mo, 3; Mb, 10; Ni, 5; Pb, 10; Sc, 5; Sn, 10; Sr, 5; V, 7; Y, 10; Yb

trographic analyses in other columns prepared in 1977 under the direction of C. S. Annell, U.S. Geological Survey, Reston, Va., using automated techniques; the relative standard deviation for each re

and minus 33 percent; detection limits (in ppm) are Ag, 0.1; B, 4.6; Ba, 2.2; Be, 1.0; Ce, 43; Co, 1.0; Cr, 1.0; Cu, 1.5; Ga, 1.5; La, 10; Mo, 1.0; Nb, 3.2; Ni, 1.5; Pb, 6.8; Sc, 1.0; Sn, 1.5; Sr, 1.0; V, 1.0; Y, 

fluorescent analyses by G. Sellers, B. McCall, and J. Lindsay, U.S. Geological Survey, Reston, Va., 1978. Instrumental neutron activation analyses prepared by P. A. Baedecker and L. Schwartz, U.S. G

and 1979; samples were irradiated for 2 hours in RT-3 at the National Bureau of Standards Reactor and counted after 1 week and 2 months decay on a low energy photon detector and on Ge (Li) sp

processing. Modal analyses by Meade B. Norman II, U.S. Geological Survey, Menlo Park, Calif., Gerald K. Van Kooten, Arco Oil and Gas, Dallas, Tex., Dallas L. Peck, and Oleg Polovtzoff, U.S. Geolo

to 2,000-point counts on a slab of at least 40 cm2 . Plagioclase compositions determined by Gerald K. Van Kooten by measuring extinction angles of albite twins on a universal stage. Biotite/hornb

volcanic rocks determined by Gerald K. Van Kooten and Jeffrey W. Hedenquist (formerly U.S. Geological Survey) by counts of 1,000 to 2,000 points on standard thin sections]

1 2

Quartz diorite 

and tonalite

quartz diorite

MP-811 MP-514

3

Tonalite 

of 

Long 

Creek

MP-284

4

Leucogranite 

of Mount 

Clark

MP-766

5

LeucoGranite 

of 

Shuteye 

Peak

MP-629

6 7 8 9 10 11

GranoGrano- diorite MicroGranite diorite porphyry gabbro 

of of of of the Leucogranite 

Gray Grizzly Horsethief Clark porphyry of 

Peak Creek Canyon Range Post Peak

12 13 14 15 1

Granodiorite of 

Leucogranite 

porphyry of 

Red Peak

MP-773 MP-402 MP-395 MP-786 MP-368 MP-192 MP-608A MP-845

Granodiorite

MP-578 MP-520

Ap

MP-

Chemical analyses (weight percent)

SiO, _ _

A1203

Fe203 _ _ _ _ 

FeO

MgO 

CaO _ _ _ 

Na,0

K30 _ _ _

H20+

H,0-

TiO, _

PaOs

MnO 

C02

Cl

F

Less 0 ____________

Sum _ _ _

Powder density

50.8 60.1 

17.1 17.3 

4.5 1.7 

6.9 4.0 

3.9 2.8 

6.4 6.9 

2.4 3.5 

3.2 1.2 

1.6 .61 

.03 .04 

1.0 .59 

.69 .36 

.11 .00 

.06 .03

99 99

61.7 

17.9 

2.2 

2.4 

1.3 

6.1 

4.7 

1.8 

.52 

.01 

.59 

.47 

.00 

.01

100

75.6 

13.0 

.66 

.67 

.16 

.58 

3.8 

4.7 

.40 

.09 

.09 

.02 

.07 

<.05

100 

2.64

74.6 

13.4 

.16 

.56 

.00 

.67 

4.3 

4.6 

.26 

.03 

.00 

.09 

.00 

.02

99

70.1 65.1 67.6 54.4 73.0 77.2 

14.6 16.3 15.9 17.1 13.8 11.9 

1.7 1.3 1.3 1.9 .87 .88 

2.2 3.2 2.3 6.2 1.3 .72 

.51 2.0 .95 4.8 .44 .05 

2.3 4.3 3.1 7.9 1.7 .77 

3.9 3.8 4.4 3.7 3.8 3.2 

3.8 2.4 3.0 1.5 3.9 4.8 

.25 .74 .51 .95 .50 .25 

.06 .03 .06 .13 .14 .01 

.36 .59 .55 .20 .32 .02 

.10 .16 .16 .23 .09 .12 

.08 .11 .13 .16 .16 .00 

<.05 <.05 <.05 <.05 <.05 .01

100 100 100 99 100 100 

2.74 2.73 2.70 2.86 2.62

74.05 77.9 

13.57 12.8 

.75 .32 

1.06 .16 

.32 .10 

1.45 .54 

3.51 3.8 

4.64 4.3 

.19 .42 

.08 .19 

.20 .14 

.04 .06 

.04 .00 

.01 .00 

.02 

.04 

.02 

99.92 101 

2.69 2.65

64.9 68.57 

16.2 15.60 

2.1 1.15 

2.5 1.89 

1.7 .99 

4.1 3.02 

3.8 4.02 

2.9 3.43 

.69 .41 

.14 .05 

.83 .47 

.23 .13 

.07 .08 

.01 .01 

.01 

.05 

.02 

100 99.86 

2.69 2.69

76

13

4

4

100 

2

Semiquantitative spectrographic analyses (parts per million)

Ag___ __ __

B 

Ba

Be

Ce __ _ _____ 

Co

Cr

Cu _ _ _____

Ga

La ______________

Mo

Ni ____________

Pb

Sc

Sn

Sr

V

Y

Yb

Zn _ _..,,.,..,.-.,_.,.

~~ ~~

-

N 

5 

1,000 

1.5 

N 

N 

50 

5 

20 

N 

N 

15 

30 

5 

N 

100 

5 

30 

3 

N

-

N N N N N - 

3 7 10 N 10 

2,000 7,000 1,000 700 700 

1.5 1 1 N 1.5 

N N N N N - 

3 7 5 30 2 

7 15 30 70 50 

3 10 7 15 3 

30 20 20 20 15 

50 30 N N 30 

N N N N N - 

1 7 20 30 15 

30 20 20 N 30 

5 15 15 30 7 

N N N N N - 

100 700 700 1000 300

5 100 70 300 30 

30 20 30 20 20 

33322

N N N N N -

N .1 

N N 

700 520 

2 1.6 

N 32 

N 1.9 

2 2.0 

5 4.5 

20 18 

50 11 

N N 

N N 

15 120 

N 2.4 

N 29 

200 60 

20 N 

20 5.7 

3 .58 

N N

N N 

8.9 N 

830 1,500 

1.9 1.5 

N N 

69 5 

5.6 2 

9.9 5 

23 20 

26 50 

N N 

2.5 N 

26 15 

14 10 

N N 

390 700 

92 50 

25 20 

3.7 2 

6.7 N

11 

4

36 

1

2

3

28 

15 

34 

16 

9

6

3

81 

11 
X-ray fluorescence analyses (parts in million)

Ba __ _ _

Sr ______________

_

733 

693

- - - - - 556 

541

721 

204

564 

86

650 

144

557 

94

909 

430

935 

358

Instrumental neutron activation analyses (parts per million)

Ba

Co __

Cr

Cs

Hf ___ 

Rb

Sb _ _ _ _ -

Ta _ -

Th

u

Zn _ __ _____ 

Zr

Sc _ _

La

Ce

Nd _ _ _

Sm

Eu

Gd _ -

Tb __ ___ _____ 

Tm _

Yb

Lu _ _

-

838 

6.5 

7.2 

2.2 

14.3 

38 

1.8 

.73 

12.7 

4.2 

87 

675 

11.37 

33 

66 

33 

7.2 

1.92 

5.5 

1.03 

.50 

3.2 

.49

-

-

-

-

_

-

|

536 

25.2 

46.2 

8.9 

2.6 

84 

1.2 

.38 

3.3 

1.0 

124

20.54 

16 

32 

19 

4.6 

1.08 

3.8 

.60 

.25 

1.8 

.26

830 

2.1 

1.2 

5.6 

5.9 

163 

3.2 

1.28 

19.9 

7.2 

64 

303 

4.78 

36 

65 

32 

5.9 

.75 

4.6 

.77 

.47 

2.8 

.41

664 

1.5 

1.8 

3.7 

6.2 

184 

.7 

1.24 

29.0 

7.2 

34 

218 

2.50 

46 

84 

33 

6.2 

.46 

4.2 

.67 

.36 

2.4 

.38

800 

2.0 

2.4 

4.6 

6.0 

176 

.2 

1.20 

26.4 

7.0 

50 

192 

3.61 

54 

80 

36 

6.7 

.70 

5.3 

.91 

.56 

3.3 

.47

641 . 1,010 1,013 

.2 9.6 5.4 

2.4 4.2 2.0 

2.6 3.2 7.9 

5.0 5.4 4.7 

162 106 130 

19.4 2.6 .6 

1.36 .86 .86 

19.3 11.8 18.6 

6.9 4.6 5.3 

20 89 65 

175 341 284 

2.47 11.16 6.23 

14 31 34 

30 55 59 

11 26 23 

1.4 5.4 4.3 

.36 1.18 .98 

1.4 5.0 3.4 

.22 .78 .56 

.15 .36 .32 

.9 2.0 1.8 

.16 .34 .28

CIPW norms (weight percent)

Q ______________ 3.903

Or _ 19.161

Ab_ _ _ 20.578

An 26.786

Ne _ _ _

Wo _ .181

En _ 9.842

Fs _ _ _ 7.606

Fo

Fa

Mt _ _ _ 6.611

Hm

D 1.924

Ap _ 1.656

Other .138 

Total ____________ 98.386

15.973

7.153 

29.876 

28.195

1.575 

7.035 

5.010

2.486

1.130 

.860 

.069 

99.363

14.140

10.669 

39.890 

22.496

1.968 

3.247 

1.620

3.199

1.124 

1.117 

.023 

99.493

33.836 

.656 

27.813 

32.206 

2.751

.399 

.668

.958

.171 

.047

99.511

30.854 

.396 

27.543 

36.868 

2.644

.908

.235

.216 

.046 

99.711

26.480 

.129 

22.464 

33.014 

10.761

1.271 

2.191

2.466

.684 

.237

99.696

20.226 

.016 

14.178 

32.145 

20.281

4.980 

4.031

1.884

1.120 

.379

99.240

21.788 

.161 

17.728 

37.232 

14.334

2.366 

2.483

1.835

1.045 

.379

99.400

1.871

8.938 

31.570 

25.835

5.081 

12.055 

9.865

2.773

.383 

.549

98.925

31.266 

.452 

23.042 

32.148 

7.844

1.096 

1.437

1.261

.608 

.213

99.367

38.630 

.351 

28.384 

27.096 

2.975

.125 

.562

1.277

.038 

.284 

.023 

99.746

32.172 

.383 

27.427 

29.562 

6.604

.791 

1.071

1.088

.380 

.095 

.131 

99.709

37.927 

1.049 

25.226 

31.922 

2.270

.247

.109 

.242 

.264 

.141

99.397

20.327

17.108 

32.100 

18.550

.080 

4.227 

1.613

3.040

1.574 

.544 

.023 

99.184

23.847 

.236 

20.293 

33.983 

13.805

2.469 

1.895

1.669

.894 

.308 

.119 

99.517

3

25

38

9

Modes (volume percent)

Quartz _ _ 5.4

K-feldspar ________ .1 

Plagioclase _________ 57.2 

Mafic minerals 37.3

Plagioclase composition 

An range _________ 90-22 

An average 45

Biotite/biotite 

+ hornblende ______ .9 

Bulk specific gravity ___ 2.86

10.8 

.2 

55.3 

33.7

73-21 

40

.6 

2.812

11.4 

4.5 

68.0 

16.1

43-26 

35

.6 

2.751

37.2 

31.0 

29.8 

2.0

35-21 

30

.3 

nd

32.5 

35.5 

30.8 

1.2

32-17 

20

1.0 

2.616

27.9 

25.0 

38.4 

8.7

49-17 

25

.7 

2.66

25.8 

6.1 

53.6 

14.5

41-21 

30

.7 

2.73

19.6 

153 

54.4 

10.7

56-15 

30

.3 

2.71

5.3 

0 

47.0 

47.7

75-33 

60

.4

30.0 

32.3 

32.8 

4.9

37-5 

20

1.0 

2.637

34.1 

37.1 

25.5 

3.3

46-5 

20

1.0 

2.64

28.6 

32.7 

34.3 

4.4

56-13 

20

1.0 

2.65

24.1 

38.6 

37.1 

.2

1.0 

2.565

19.7 

12.2 

52.9 

15.2

56-12 

30

.8 

2.717

23.5 

19.2 

47.3 

10.0

45-12 

25

.9 

2.70

1

1

Location

Latitude __________ 37°44' 

Longitude __ _ 119°16'

37°34' 

119°28'

37°41' 37°42' 

119°24'

37°32' 

119°28'

37°41' 

119°25'

37°31' 

119°29'

37°36'

ii9°23'

37°40' 

119°24'

37°37' 

119°23'

37°38' 37°38' 

119°25'

37°39' 

119°25'

37°38' 

119°25'

37°35' 

119°24'

3

ii9
TABLE 4. -Chemical and spectrographic analyses, norms, and modes of representative igneom rock- Continued

20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 

Granodiorite of 

Ostrander Lake GranoGranodiorite of 

Illilouette Creek

MP-568 MP-478

Granite

MP-617 MP-574

Quartz diorite 

Moun- of 

tain Breeze 

body Lake

MP-351 MP-541 MP-728

Granodiorite of Red Devil Lake

Granodiorite Granite

MP-836 MP-789 MP-798 MP-730 MP-794 MP-682

Granite of Turner Lake

Granite

MP-818 MP-795B MP-328

Aplite

MP-296

Granite por

of 

Cony Cra

MP-821 M

Chemical analyses (weight percent)

Si02

A1303 

Fe,03 __ 

FeO 

MgO 

CaO __ 

Na20 

K,0 

H,0+ __ 

H,0- 

Ti02

Pi05

MnO

C02

Cl

F

Less 0 _

Sum _____ 

Powder 

density _

64.71 69.1 

15.86 14.8 

1.46 1.2 

3.28 2.4 

2.17 1.6 

4.84 4.7 

3.24 3.1 

2.71 2.4 

.55 .46 

.06 .03 

.72 .33 

.15 .25 

.08 .00 

.01 .02 

.03 

.05 

.03 

99.89 100

2.76

70.32 72.2 

14.69 14.7 

.87 .37 

1.76 1.3 

1.03 .52 

2.83 2.0 

3.28 3.3 

4.01 4.0 

.48 .90 

.05 .07 

.40 .30 

.09 .08 

.05 .08 

.02 .08 

.01 

.05 

.02 

99.92 100

2.69 2.67

73.2 70.6 

13.9 14.8 

.24 .90 

1.6 1.8 

.50 .65 

1.8 2.4 

3.1 3.9 

4.5 3.2 

.66 .85 

.05 .12 

.22 .43 

.06 .16 

.04 .08 

< .05 .10

100 100 

2.65 2.64

66.7 

15.3 

1.6 

2.5 

2.3 

3.2 

3.8 

3.0 

.56 

.06 

.62 

.16 

.12 

<.05

100 

2.78

67.9 68.09 69.3 70.5 72.5 72.4 

15.3 15.15 14.9 14.9 14.3 14.6 

2.0 1.50 1.1 1.4 .70 .70 

1.8 2.15 2.2 1.1 1.2 1.1 

1.3 1.33 1.1 .75 .57 .29 

3.3 3.27 2.8 2.4 1.9 1.8 

3.8 3.92 3.8 3.7 3.5 3.6 

3.2 3.12 3.3 3.9 4.2 4.7 

.56 .36 .60 .35 .45 .35 

.06 .06 .08 .07 .04 .02 

.58 .60 .48 .36 .25 .25 

.14 .15 .13 .08 .09 .06 

.11 .09 .11 .05 .07 .08 

.02 .02 <.05 .02 .09 <.05 

.01 

.06 

.03 

100 99.85 100 100 100 100

2.62 2.71 2.74 2.62 2.68 2.63

72.4 

14.1 

1.4 

.92 

.40 

2.2 

3.6 

3.8 

.38 

.22 

.32 

.11 

.05 

.05

100 

2.51

73.2 73.58 

13.8 13.64 

1.4 .73 

.88 1.19 

.40 .65 

2.1 2.21 

3.4 3.53 

4.0 3.57 

.27 .31 

.13 .08 

.34 .30 

.10 .08 

.04 .05 

.02 .06 

.01 

.04 

.02 

100 100.01

2.65 2.65

77.8 

13.2 

.15 

.40 

.00 

.86 

3.6 

5.0 

.21 

.04 

.00 

.08 

.00 

.02

101

70.6 

14.7 

1.2 

.96 

.52 

1.7 

3.2 

4.9 

.56 

.17 

.32 

.10 

.04 

.03 

99 

2.54 

Semiquantitative spectrographic analyses (parts per million)

Ag ____

B 

Ba ______

Be 

Ce

Co _____ 

Cr

Cu 

Ga ___ 

La 

Mo

Ni

Pb

Sc

Sn 

Sr 

V

Y 

Yb ______

Zn _____

N 

N 

700 

2 

N 

10 

20 

10 

20 

30 

N 

7 

10 

15 

N 

700 

100 

15 

2 

N

N N 

N 15 

1,000 1,000 

1.5 1 

N N 

5 N 

7 30 

3 7 

20 20 

50 N 

N N 

5 10 

20 20 

7 N 

N N 

500 700 

70 30 

15 7 

1.5 .7 

N N

5 N 

7 15 

700 1,000 

2 1.5 

N N 

2 3 

30 50 

.7 1.5 

20 20 

50 30 

N N 

10 15 

30 20 

N 5 

N N 

300 700 

30 70 

20 20 

2 2 

N N

N 

N 

1,000

1

N 

10 

15 

7 

20 

30 

N 

7 

10 

10 

N 

700 

150 

50 

5 

N

N N N N N N 

6.1 N 10 15 3 N 

720 1,500 1,000 630 1,000 1,000 

2.2 N 1 2.3 1.5 1.5 

110 N N 55 N N 

10 7 7 5.4 N N 

6.3 5 70 4.0 7 15 

4.1 5 5 3.6 3 5 

21 20 20 21 20 20 

54 30 N 27 30 N 

N N 3 N N 20 

7.6 5 30 4.9 2 7 

22 15 15 24 20 30 

11 10 10 6.9 N N 

N N N N N N 

330 700 700 240 500 500 

74 70 100 36 50 30 

22 20 30 16 15 7 

2.7 2 3 27 1.5 1 

72 N N N N N

N 

N 

420 

1.9 

69 

3.5 

6.9 

3.7 

15 

26 

N 

N 

27 

1.6 

N 

180 

26 

25 

3.7 

N

N N 

N N 

540 700 

1.6 2 

48 

3.1 N 

4.5 3 

4.1 7 

15 15 

28 30 

N N 

N N 

21 15 

4.0 N 

N N 

180 500 

23 30 

15 10 

2.1 1.5 

N N

-

N 

N 

1,100 1,5

2.0 

110 

5.0 

11 

4.2 

21 

55 

N 

9.0 

42 

4.6 

N 

290 7

28 

9.8 

1.4 

N 

X-ray fluorescence analyses (parts per million)

Ba 

Sr

570 481 

406 367

632 798 

319 371

- 941 

395

802 - 787 741 726 843 

370 - 351 292 278 295

525 

275

626 617 

272 286

- 1132 10

342 4
Instrumental neutron activation analyses (parts per million)

Ba

Co

Cr 

Cs __ __ 

Hf 

Rb 

Sb 

Ta 

Th ______ 

U 

Zn

Zr 

Sc __ __ 

La 

Ce

Nd _____ 

Sm _____ 

Eu ____ 

Gd 

Tb 

Tm ____ 

Yb 

Lu _____

678

11.6

17.0 

3.7 

4.2 

88 

.3 

1.43 

31.9 

6.8 

72

301 

12.50 

22 

46 

26 

4.8 

1.05 

4.9 

.69 

.31 

2.1 

.34

573

8.1

15.4 

2.2 

6.2 

72 

2.0 

.99 

8.4 

6.7 

73

268 

11.08 

19 

39 

20 

4.2 

.94 

3.6 

.60 

.26 

2.0 

.31

743

5.5

7.3 

8.3 

4.9 

162 

1.1 

1.22 

29.8 

9.1 

48

255 

5.62 

35 

61 

23 

3.1 

.66 

3.1 

.40 

.19 

1.4 

.25

976

2.6

2.0 

6.2 

4.2 

144 

.4 

1.32 

14.2 

5.2 

48

167 

2.79 

21 

37 

16 

2.4 

.73 

2.4 

.33 

.16 

.9 

.15

- 1.020

_

-

_

-

-

8.5

6.1 

6.1 

5.9 

113 

1.6 

1.06 

13.8 

4.7 

75

311 

9.23 

36 

70 

33 

6.7 

1.29 

5.3 

.95 

.45 

2.8 

.38

846

8.0

5.4 

8.6 

5.6 

132 

1.7 

.98 

18.0 

3.8 

103

230 

8.61 

50 

90 

33 

6.0 

1.19 

4.2 

.80 

.43 

2.5 

.36

_

_

-

-

886 807

6.2 4.0

5.8 3.1 

5.8 11.8 

5.2 4.2 

130 165 

1.6 3.0 

1.08 1.23 

14.0 22.4 

5.3 6.8 

68 55

314 196 

8.27 4.89 

30 36 

62 66 

30 23 

6.3 4.0 

1.10 .83 

5.0 3.5 

.95 .54 

.40 .35 

2.5 2.1 

.38 .32

841 1.000

2.4

2.4 

8.2 

5.1 

184 

2.0 

1.24 

18.6 

10.8 

38

211 

3.16 

37 

58 

24 

4.4 

.72 

2.9 

.48 

.29 

1.7 

.29

2.2

3.0 

4.6 

3.4 

214 

.6 

1.03 

23.3 

5.0 

46

163 

2.71 

27 

46 

18 

3.4 

.65 

2.8 

.34 

.24 

1.3 

.20

720

2.7

5.3 

5.6 

7.3 

163 

.6 

1.99 

60.6 

13.4 

34

302 

2.95 

41 

73 

26 

4.1 

.83 

5.6 

.67 

.38 

2.6 

.43

855

2.6

5.1 

7.4 

7.4 

166 

1.0 

2.13 

48.3 

25.3 

36

389 

3.70 

60 

108 

38 

5.0 

.94 

5.0 

.83 

.51 

2.9 

.50

749

3.9

3.8 

6.0 

4.2 

152 

.5 

1.23 

17.5 

8.5 

48

196 

3.32 

32 

52 

18 

3.8 

.62 

2.8 

.44 

.24 

1.5 

.27

- 1.204

-

-

3.1

8.0 

6.0 

6.1 

239 

1.4 

1.15 

31.3 

7.8 

36

297 

311 

57 

100 

33 

5.2 

.84 

1.4 

.48 

.18 

1.0 

.20

CIPW norms (weight percent)

Q _____

c

Or

Ab

An

Ne

Wo

En

Fs ___

Fo

Fa

Mt _____

Hm ____

n

Ap ___ _

Other __

Total ___

21.304

_

16.027

27.216

20.863

-

.775

5.409

3.780

_

_

2.119

_

1.369

.356

.147

99.363

29.236

_

14.127

26.129

19.305

_

.905

3.969

2.860

_

_

1.733

_

.624

.590

.045

99.525

27.919

.197

23.710

27.697

13.026

-

_

2.567

1.947

_

_

1.262

_

.760

.213

.148

99.447

32.323

1.684

23.661

27.952

8.903

-

_

1.296

1.737

_

_

.537

_

.570

.190

.182

99.034

32.440

.802

26.626

26.265

8.549

_

_

1.247

2.454

_

_

.348

_

.418

.142

99.293

29.374

1.172

18.912

33.004

10.230

-

_

1.619

2.001

_

_

1.305

_

.817

.379

.227

99.039

22.176

.367

17.742

32.180

14.842

-

_

5.733

2.470

_

_

2.322

_

1.178

.379

99.389

24.584

—

18.896

32.132

15.229

-

.038

3.235

.899

_

_

2.898

_

1.101

.331

.045

99.389

24.251

—

18.459

33.136

14.585

-

.087

3.316

1.888

_

_

2.177

_

1.141

.356

.159

99.553

26.163 28.026

.298 0.468

19.520 23.143

32.187 31.440

13.055 11.305

- -

_ _

2.742 1.876

2.546 .363

_ _

_ _

1.596 2.038

_ _

.913 .687

.308 .190

.046

99.327 99.583

31.079

.967

24.854

29.658

8.281

-

_

1.422

1.345

_

_

1.016

_

.475

.213

.205

99.515

28.832

.462

27.787

30.477

8.542

-

_

.723

1.178

_

_

1.015

_

.475

.142

99.634

32.026

.444

22.466

30.477

9.884

-

_

.997

.097

_

_

2.031

_

.608

.261

.114

99.406

33.330

.345

23.618

28.747

9.631

-

_

.995

-

_

_

1.980

.034

.645

.237

.045

99.606

33.678

.384

21.090

29.787

9.818

-

_

1.618

1.179

_

_

1.058

_

.57

.189

.220

99.592

35.403

.533

29.150

30.053

3.569

-

_

_

.602

_

_

.215

_

_

.187

.045

99.757

29.330

1.364

29.248

27.351

7.667

_

_

1.308

.321

_

_

1.757

_

.614

.239

.069

99.268

Modes (volume percent)

Quartz _

K-feldspar

Plagioclase

Mafic

mineral _

Plagioclase

composition

An range

An average _

Biotite/

biotite

+ hornblende

Bulk

specific

gravity

23.4

11.2

48.4

17.0

56-20

45

.6

2.735

26.5

12.4

42.6

18.5

50-30

40

.6

2.74

29.1

23.6

39.2

8.1

47-18

30

.8

2.67

30.5

25.4

38.9

5.2

48-17

30

1.0

2.653

30.6

29.5

34.8

5.1

47-15

30

1.0

2.65

28.7

17.2

48.4

5.7

53-10

30

1.0

2.675

23.0

16.7

48.4

11.9

41-13

25

.6

2.69

26.3

16.2

45.1

12.4

-

-

-

2.68

21.0

13.1

51.5

14.4

33-14

25

.8

2.69

26.5 29.6

19.2 25.1

43.6 39.3

10.7 6.0

33-17

25

.7

2.68 2.66

30.0

28.0

34.4

7.6

30-14

25

.9

2.65

31.3

28.9

35.2

4.6

-

-

1.0

2.644

27.5

25.2

41.8

5.5

-

-

1.0

2.645

27.9

22.7

43.9

5.5

-

-

_

2.644

30.0

21.3

42.7

6.0

34-10

25

1.0

2.66

-

-

-

-

29-15

25

1.0

2.606

32.0

29.9

33.0

5.1

-

-

1.0

2.65

Location

Latitude _

Longitude

37°38'

119°25'

37°33'

119°29'

37°37'

119°27'

37°36'

119°29'

37°31'

119°27'

37°34'

119°24'

37°43'

119°17'

37°44'

119° 16'

37°40'

119°23'

37042' 37043'

119°18' 119°18'

37°43'

1190191

37042'

1190201

37°42'

119°20( '

37°43'

119°19'

37°38'

119°21'

37°39'

1190 21'

37°44'

119°21'
10 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

o O

I

"to

'sl'rtC-c- 00 1C 00 TO l> IO CO

OSOOSU5r-Hl31rHt>NOi-<OOO| ooi-i''"'cdco'''''w I I ocj1>

l^« *—I V fs

\a a* a* tx> l CQCooiMOiN-^iao «oco''''coio

C-NC31O OOCOCOrHCOCO t>eoo->»u5oO"HO'HooO '''' - '''''

> tr- 10 

V

OOCO <N CO iH O CO IO CO

O L£) C3 *H ^< CO \/ O CO

t- *H V o

^ 3; 10 CM 10 oo

fH IO *H »H O I I I CO

O OS -M" iH -M" IO O 

OSOONNNOSr-JOOC^pCONiHpl | | t>

'«»c<ii-!'eJioeJ

N «D

O -«^-^t»t»C<I^»lO

j-t to ' to co 06 c4 ' ' ' ' ' »/

CO »H "

III I

I co co 1-1 10 10 i

I I I I I I

kJ I

iOOfe J<

COC- iH OOCO

1OOCO 1C 1C O Q Q O O IO I OOOCO

>35 CO

"2 ^ "J "•! 1515 °^ 15 "^ '-i 15 i-icoi-iciNc-io <* t- gicoooco

t£> iH CO <N CO N

IH 10 10 o

ocoocoo

iHNN^1

22"? 22 2 2

I r-HCOOO 10O OOOCO

<N 10 r* iH O CO <N

2 2 222 2 laoca 10 10 i> o o o 10 o o o TO

OCO 1C TO O O O <? O OOOCO 

O *HC<ICO CO»H OOCO

222 2 2 2

°2 »HO 2°^S2 »H»H CN1CO ^2S »HCNI 22S^ OOLO

15°.

2222 22 2 2 

2 S^SS ^^S SSS 10

2 2 22 2

i i i i i i i i i i i i i i i i i i i i

22 2
MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA 11

I I I I I I I I I I I I I I I I I I I I I I I

cococooq ^tcofr-io 

TO 'i-icocoeoi-ti-iooTOi-i

r-t •& i-H IO <

locoioe; ^COOST!; o

i 'i-iTC'lOOi-ii-ioiOOOOOlO 

I ^J* CO CO I-H

fr- co co 10

O IO CO 00 •»* O •

eo^ooq oqcooco o i-;osi>e5'^;'^;i 

i 'co^coooc<ii-ios'iooocofr-'osi-i3|i> 'ioi-i 'eo i ^* I-H co os co oo TO

i-JCOOfr; OOi-JCOO CO "P.® ^J"? 1"!

TfTOCo'Tiico'o 'i-iodioi-ioofr-'oTOiocoi-Joo ' 'TO

00 TO i-IOOTO^ffr-TO IO

S

io TJ< 10 co < _osco os ooi-jcoes^os' 

!Co'coTi<cofr-i-!'HcpTfioTOfr-'TOi-ioscoi-iiOi-i 'co

TO r-t ' 00 < ^* fr- TO

CO CO 00 CO Tl<OSCOCO O TOCOlOCOCO^tTO 

fr- ^* CO fr- CO 00 i—t TOLOOCOfr-TOOSlOlOi—ITO CO

^ooooosos coooo< 

i-icoioTOiofr-i-* 'coTOio^eii

. t> co o» co ^ ^

I iH US i-i •J ' ' CO

i-l OS CO i-H TO CO TO

fr- CO CO I-H 00

oo o oa oo coiooqcocoi 

> 'OTOTCCOOI-HOOCOOOCO'T!! ' 'co

I I-H TO IO CO IO

I I I I I I I I I I I I I I I I I I I I I I I

(SassagjggiS: !S^i

1 eo oo i-i ^ co os co i-i co

lOOlOCO CO lOOTffr- frj 00 CO CO i i |^*| l^^^^l^

10 oq TO i> co i i co i-; |

M

I •= I

<N 0> CO <N U3 i-H 00 t*- O ^ CO 00 

t*^ IN t"- U3 O | | ^"j | | [ tTM N C*) O O tTM

o> t- teg o -* m t- m eg co op <£> oo _____ .. t>ooo^Tj«t> 

OO W <N t> CO I |^| I I eg co ^ o o m

O CO CO <N 

CO (N CO

i^sgp ' ' ^ ' ' s ' ^"^si

>ioocoi-i ^S ^ ofr-<

lococooo i jcoco j [CO |t>coi

i ' TO CO 00 i-i i-! i-i

1O1OOOI>| |COTO| |1O|I>C4|1O

^J*OG3CO^ I j^ 1^ I 1^! l^^3 1^ "-i'ooco^ coco i-i i-!' os

i-t^lOfr-0»| |0»5?| |rt|CO-*|CO

escort- coi-i TOI-I gs

CO i-H TO i—t OS

oo cp 10 co o

li-l TO 10

r-t i-l TO CO

O i—I OS CO i—t TO CO O TO 00

50|«£>COOi|lOTjJO) l^lOO^I

W COOOi—' COfr-OS i—) i—t

00 OS i—t 00 TO^OO CO f—t OS

li-ITO^ COT)<OSfr-io i-ICO TO

>OI>CO| |COTOO>fr;CO|l>lO|C>

iTOio-^; w oi " " ^" i-i ' os

I I I

SMB^i

I I I I I I I

I I I I I I I

1 1 1 1 1 1 <p.

I I I I I I I

I I I I I I I I fr".

1 1 1 1 1 1 1 1 °°,

•§ 'fitS 'as g » <v JT.3 Jf^« •"« 2 

«&, S3 E m

I? S3

OQTO

co co 

fr- os
TABLE ^.-Chemical and spectrographic analyses, norms, and modes of representative igneous rock- Continued

57 58 59 60 61 62 63 64 65 

Tertiary volcanic rocks

Trachybasalt

MP-164B MP-37B MP-275 MP-277

Trachyandesite 

MP-265C

Mafic phonolite

MP-164A MP-71 MP-410 MP-840A 

Chemical analyses (weight percent)

SiO,

AUOa

Fe,0, _ _

FeO

MgO

CaO

Na,0

K,0

H20 +

H,0-

TiO, _

P20S

MnO

CO, ______

Cl

F

Less 0 __________________

Sum

Powder density

50.8 

14.2 

2.4 

4.9 

11.4 

8.0 

2.9 

2.5 

.72 

.38 

.89 

.66 

.10 

.01

100 

2.90

50.6 

15.6 

4.2 

3.4 

8.9 

7.2 

3.5 

2.6 

.90 

.26 

1.7 

.09 

.15 

<.05

99 

2.92

51.6 

14.4 

3.7 

4.0 

10.1 

6.8 

3.3 

3.0 

.60 

.11 

1.2 

.69 

.16 

<.05

100 

2.86

51.2 

14.9 

2.8 

5.0 

10.1 

7.5 

3.0 

2.8 

.43 

.17 

1.3 

.60 

.10 

.00

100 

3.06

61.0 

16.5 

3.4 

.98 

4.0 

3.5 

4.2 

3.0 

1.4 

.44 

.57 

.30 

.12 

<.05

99 

2.66

43.7 

10.8 

4.3 

5.3 

15.0 

10.2 

2.8 

3.0 

.82 

.45 

1.4 

1.6 

.21 

<.05

100 

3.06

47.3 

12.2 

3.6 

5.7 

12.0 

9.3 

2.8 

1.9 

2.5 

.80 

1.9 

.67 

.12 

.08

101 

2.74

51.7 

12.7 

3.7 

2.8 

5.7 

6.4 

2.0 

8.4 

1.8 

.89 

1.8 

1.5 

.13 

<.05

100 

2.88

53.1 

13.0 

3.7 

2.8 

5.6 

5.8 

1.7 

7.7 

1.4 

.82 

1.9 

1.5 

.08 

.02

99 

2.79

Semiquantitative spectrographic analyses (parts per million)

Ag

B

Ba

Be

Ce 

Co _ _

Cr

Cu

Ga _ _

La

Mo

Ni

Pb

Sc

Sn

Sr

V _ _ _ _

Y

Yb 

Zn

N 

N 

1,700 

2.3 

N 

39 

800 

77 

25 

38 

N 

310 

110 

20 

7.4 

700 

180 

11 

1.4 

84

N 

N 

1,000

1

N 

30 

150 

30 

10 

30 

N 

150 

N 

15 

N 

1,500 

150 

15 

1.5 

N

N 

N 

1,000

1

N 

30 

200 

30 

10 

N 

N 

200 

10 

15 

N 

1,000 

150 

15 

1.5 

N

N 

7.3 

1,800 

2.0 

69 

40 

510 

27 

29 

N 

N 

300 

40 

18 

N 

760 

130 

13 

1.8 

70

N 

N 

1,000

1

N 

15 

100 

20 

10 

20 

N 

100 

15 

7 

N 

1,000 

50 

7 

.7 

N

N 

N 

2,000 

1 

N 

30 

500 

50 

10 

50 

N 

150 

15 

20 

N 

1,500 

200 

20 

2 

N

N 

6.0 

960 

1.6 

140 

47 

700 

75 

27 

52 

3.4 

320 

110 

20 

7.4 

700 

180 

11 

1.4 

84

N 

N 

3,000 

5 

N 

20 

100 

50 

15 

20 

N 

70 

15 

10 

N 

2,000 

150 

10 

1 

N

N 

N 

3,200 

8.2 

74 

22 

190 

77 

30 

55 

N 

120 

42 

17 

N 

1,900 

160 

15 

1.6 

110
CIPW norms (weight percent)

Qc

Or

Ab

An

Ne

Wo

En _

Fs

Fo

Fa

Mt

Hm _ _

n

Ap

Other

Total

14.794 

24.573 

18.371

7.095 

8.630 

1.742 

13.876 

3.087 

3.485

1.693 

1.565 

.023 

98.934

15.504 

29.885 

19.351

6.722 

6.268 

.069 

11.282 

.138 

6.145

3.258 

.215

98.836

17.788 

28.019 

15.672

5.701 

9.695 

1.004 

10.894 

1.243 

5.383

2.287 

1.640

99.325

16.563 

25.411 

18.939

6.005 

9.072 

1.770 

11.287 

2.427 

4.064

2.471 

1.423

99.432

12.548 

.702 

17.833 

35.750 

15.495

10.021

1.909 

2.103 

1.089 

.715

98.166

17.803 

1.681 

8.074 

11.979 

13.463 

10.707 

1.221 

18.786 

2.360 

6.261

2.670 

3.806

98.810

11.131 

20.807 

14.979 

1.453 

10.823 

8.377 

1.783 

14.892 

2.514 

5.175

3.577 

1.573 

.180 

96.764

49.877 

9.261 

.872 

4.195 

8.845 

7.645

4.639

4.252 

.785 

3.435 

3.570

97.376

.228

45.915 

14.516 

5.147

5.792 

14.074

3.813 

1.104 

3.641 

3.585 

.046 

97.859

Modes (volume percent)

Plenocrysts 

Olivine __________________________ 

Orthopyroxene

Clinopyroxene

Biotite _

Apatite

Ilmenite

Xenocrysts _ _ _ _

Groundmass

-

12.0 

88.0

11.3

88.7

12.0

88.0

6.2 

.9 

.2

.2 

92.5

15.8 

.4

83.8

0.7

1.4 

.6

3.4 

93.9

9.4 

.5

90.1

nd 

nd

Location

Latitude

Longitude

37°35' 

119°20'

37°32' 

119° 16'

37°36' 37°35' 

119° 15'

37°36' 37°35' 

119°20'

37°34' 37° 32' 

119°28'

37°31

119°28
14

119° 30'

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

25' 20' 119° 15'

37°30

10 15 KILOMETERS

FIGURE 2.-Simplified bedrock geologic map of the Merced Peak quadrangle, showing steeply inclined regional joints (heavy lines) observed on 

aerial photographs and the attitude of joints as observed on the ground. See figure 1 for explanation. Figure prepared by J. W. Hedenquist.
MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA 

TABLE 5. —Modes, specific gravity, and location ofplutonic rocks

15

Map symbol 

for rock 

Sample no. unit

MP-1 _______ 

MP-4A

MP-19

MP-39B _____ 

MP-56

MP-61

MP-65

MP-68E

MP-77

MP-82

MP-89B

MP-93

MP-97 ________ 

MP-99B

MP-124B ____ 

MP-133

MP-134B ____ 

MP-135B

MP-138B

MP-143

MP-154A _

MP-155

MP-158

MP-169C ______ 

MP-175 ______ 

MP-180

MP-182

MP-183

MP-185A ______ 

MP-187 _______ 

MP-188

MP-192

MP-195

MP-197 ______ 

MP-198 _____ 

MP-217

MP-221

MP-253

MP-254

MP-257A _____ 

MP-262 _

MP-263 ______ 

MP-271 ______ 

MP-274B ______ 

MP-284 ______ 

MP-285

MP-289 ______ 

MP-290

MP-293B _____ 

MP-298

MP-304

MP-305 _______ 

MP-306 _______ 

MP-307A _

MP-308 ______ 

MP-309

MP-311 _ _

MP-322 __ _ __ 

MP-328

MP-332B _

MP-333

MP-334

MP-335

MP-337 ______ 

MP-338 _______ 

MP-340

MP-341 ______

Kmg 

Kmg 

Kj 

Kj 

Kj 

Kj 

Kj 

Kmg 

Kj 

Kj 

Kj 

Kj 

Ktk 

Kj 

Kqd 

Kpp 

Ktl 

Ktl 

Kpp? 

Kj 

Kj 

Kj 

Kj 

Kj 

Kj 

Kja 

Kja 

Kja 

Kja 

Kmg 

Kj 

Kpp 

Kj 

Kj 

Klg 

Kpp 

Kr 

Kjs 

Kjs 

Kj 

Ktk 

Ktk 

Kj 

Kpp 

Klc 

Kj 

Kr? 

Kr? 

Kr? 

Ktl 

Kr 

Kr 

Kr 

Ktl 

Khd 

Kpp 

Kpp 

Kr 

Ktl 

Khd 

Kj 

Khd 

Kr 

Kj 

Kr 

Ktl 

Ktl

Latitude 37°30'-45'

37°32' 

37°32' 

37°31' 

37°33' 

37°34' 

37°33' 

37°32' 

37°30' 

37°40' 

37°40'

zrw37°38' 

37°34' 

37°35' 

37°33' 

37°38' 

37°38' 

37°38' 

37°37' 

37°38 37°34' 

37°33' 

37°34' 

37°36' 

37°37' 

37°36' 

37°36' 

37°36' 

37°36' 

37°30' 

37°39' 

37°38' 

37°37' 

37°39' 

37°39' 

37°38' 

37°4(y 37°39' 

37°39' 

37°38' 

37°36' 

37°37' 

37°35' 

37°36' 

37°41' 

37°41' 

37°42' 

37°42' 

37°41' 

37°38' 

37°39' 

37°39' 

37°40' 

37°41' 

37°41' 

37°38' 

37°38' 

37°39' 

37°38' 

37°4(y 37°40' 

37°41' 

37°41' 

37°41' 

37°41' 

37°39' 

37°41'

Longitude 

119°15'-30'

119° 16'

119°16' 

119° 19 119° 17' 

119° 16' 

119°19' 

119°21' 

119°21' 

119° 16' 

119°17' 

119° 16' 

119° 16' 

119° 18' 

119° 18' 

119°21' 

119°20' 

119°21' 

119°22' 

119°23' 

119°20' 

119°22' 

119°22' 

119°22' 

119°18' 

119°21' 

1190 21' 

119°22' 

119°22' 

119°20' 

119°25' 

119°18' 

119° 19' 

119° 19' 

119° 18' 

119° 18' 

119°22' 

119°22' 

119° 17' 

119°17' 

119°17' 

119° 18' 

119° 18' 

119°17' 

119° 18' 

119° 16' 

119° 17' 

119° 16' 

119°15' 

119° 16' 

119°21' 

119°22' 

119°21' 

119°21' 

119°21' 

119°20' 

119°22' 

119°22' 

119°20' 

119°21' 

119°19' 

119° 18'

iig0 !^ 119°18' 

119° 18' 

119° 18' 

119°21' 

119°21'

Plagioclase 

(volume percent)

48.8 

51.5 

43.2 

55.9 

61.8 

49.4 

50.1 

52.4 

44.9 

58.1 

43.1 

51.7 

40.5 

43.2 

54.0 

21.7 

40.3 

38.7 

36.1

50.6 

31.7 

46.8 

52.0 

48.8 

51.7 

48.0 

47.1 

54.9 

44.3 

61.6 

25.5 

45.4 

43.1 

31.0 

36.4 

45.9 

36.5 

41.7 

47.9 

40.0 

29.3 

52.2 

30.4 

68.0 

44.6 

62.4 

48.6 

54.7 

34.9 

49.4 

45.8 

41.3 

38.5 

49.7 

37.3 

23.1 

44.4 

42.7 

47.9 

39.2 

35.5 

49.7 

47.0 

39.2 

36.9 

37.3

Alkali 

feldspar 

(volume percent)

9.9 

16.4 

18.6 

3.9 

4.6 

16.2 

20.4 

15.1 

20.7 

11.2 

23.9 

19.4 

23.0 

24.8 

2.3 

44.1 

22.5 

21.7 

31.5

14.8 

33.6 

17.4 

17.9 

19.8 

14.6 

17.9 

13.8 

13.9 

23.5 

7.2 

37.1 

22.0 

25.2 

30.3 

27.9 

19.9 

33.3 

24.3 

16.4 

24.0 

32.2 

15.3 

30.8 

4.5 

21.5 

7.5 

23.7 

15.4 

24.5 

17.1 

20.0 

24.3 

24.1 

20.5 

30.3 

38.7 

16.4 

21.3 

22.2 

27.2 

27.1 

15.9 

20.2 

19.2 

28.2 

27.1

Quartz 

(volume percent)

13.0 

20.4 

29.6 

29.4 

18.6 

25.7 

21.9 

23.3 

24.3 

19.4 

24.0 

19.5 

31.3 

22.5 

18.8 

28.7 

29.6 

31.2 

26.8

21.4 

31.5 

25.5 

22.6 

23.0 

22.2 

23.9 

31.9 

19.3 

20.6 

16.0 

34.1 

23.8 

26.2 

34.6 

28.2 

24.1 

26.7 

25.7 

25.1 

31.4 

33.9 

15.8 

35.4 

11.4 

26.2 

15.8 

19.7 

22.4 

33.0 

22.9 

25.8 

26.6 

31.7 

19.8 

26.9 

33.8 

29.0 

30.0 

19.8 

25.1 

28.1 

23.2 

22.7 

28.3 

29.4 

28.8

Mafic 

minerals 

(volume percent)

23.3 

11.7 

8.7 

10.8 

14.9 

8.7 

7.6 

9.2 

10.1 

11.3 

9.0 

9.4 

5.2 

9.5 

24.8 

5.5 

7.6 

8.4 

5.6

13.1 

3.2 

10.2 

7.5 

8.4 

11.5 

10.2 

7.2 

11.9 

11.6 

15.2 

3.3 

8.8 

5.5 

4.1 

7.5 

10.1 

3.5 

8.3 

10.5 

4.6 

4.6 

16.7 

3.4 

16.1 

7.7 

14.3 

7.9 

7.5 

7.6 

10.6 

8.4 

7.8 

5.7 

10.0 

5.5 

4.4 

10.2 

6.0 

10.1 

8.6 

9.2 

11.2 

10.1 

13.3 

5.5 

6.8

Specific 

gravity 

(g/cm3)

2.751 

2.688 

2.675 

2.71 

2.715 

2.675 

2.64 

2.702 

2.68 

2.69 

2.64 

2.68 

2.63 

2.67 

2.785 

2.623 

2.66 

2.65 

2.625

2.71 

2.635 

2.682 

2.662 

2.663 

2.70 

2.687 

2.67 

2.712 

2.677 

2.73 

2.64 

2.665 

2.65 

2.626 

2.655 

2.68 

2.64 

2.659 

2.66 

2.67 

2.62 

2.73 

2.64 

2.751 

2.677 

2.72 

2.665 

2.69 

2.65 

2.68 

2.665 

2.66 

2.67 

2.694 

2.651 

2.632 

2.68 

2.66 

nd. 

2.67 

2.662

2.675 

2.68 

2.65 

2.66
16 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 5. -Modes, specific gravity, and location ofplutonic rocks- Continued

Map symbol 

for rock 

Sample no. unit

MP-342

MP-348

MP-351

MP-353A

MP-354A

MP-361

MP-364

MP-365 _ ___ 

MP-366

MP-368 _____

MP-371 _____ 

MP-381 ______ 

MP-385 ______ 

MP-386 ______ 

MP-387

MP-388

MP-389B _____ 

MP-391

MP-392

MP-395

MP-398

MP-402

MP-420A _____ 

MP-429

MP-430A

MP-434A ____ 

MP-437A ______ 

MP-439A

MP-440A _

MP-441

MP-443 _______ 

MP-447A

MP-448

MP-450

MP-453

MP-455

MP-460A

MP-465 ______ 

MP-470A

MP-472

MP-473

MP-475

MP-478

MP-484

MP-486

MP-497

MP-498

MP-499A

MP-502

MP-505

MP-506

MP-510

MP-511B

MP-512 _____ 

MP-514 _______ 

MP-520

MP-521

MP-525

MP-529

MP-531

MP-532 ______ 

MP-533

MP-534 _

MP-536 _______ 

MP-539

MP-540

MP-541 ______

Khd 

Kqd 

Ko? 

Ko 

Ki 

Ksp 

Ki 

Ko 

Ko 

Kpp? 

Kj 

Kj 

Klg 

Kj 

Khc 

Kj 

Kqd 

Ko 

Ko 

Khc 

Kj 

Kgc 

Kqd 

Kj 

Ki 

Krp 

Ko 

Kb 

Kb 

Ki 

Ko 

Ko 

Ko 

Ko 

Ko 

Ki 

Kj 

Kb 

Ko 

Ki 

Ko 

Ko 

Ki 

Kj 

Krp 

Krp 

Kgr 

Kgr 

Ko 

Ko 

Ko 

Kqd 

Ko 

Ko 

Kqd 

Kj 

Ki 

Ki 

Ki 

Ko 

Ko 

Ko 

Ko 

Ki 

Ko 

Ki 

Kb

Latitude 

370 3(y-45'

37°41'

37°30' 

37°31' 

37°31' 

37°32' 

37°32' 

37°32 37°32' 

37°32' 

37°37' 

37°37' 

37°37' 

37°36' 

37°36' 

37°36' 

37°36' 

37°37' 

37°37' 

37°37' 

37°36' 

37°35' 

37°31' 

37°38' 

37°37' 

37°37' 

37°37' 

37°38' 

37°35' 

37°35' 

37°35' 

37°35' 

37°36' 

37°36' 

37°35' 

37°35' 

37°35' 

37°34' 

37°34' 

37°34' 

37°33' 

37°33' 

37°33' 

37°33' 

37°33' 

37°32' 

37°40' 

37°40' 

37°40' 

37°35' 

37°36' 

37°37' 

37°36' 

37°35' 

37°35' 

37°34' 

37°35' 

37°34' 

37°34' 

37°34' 

37°34' 

37°34' 

37°33' 

37°34' 

37°34' 

37°34' 

37°33' 

37°34'

Longitude Plagioclase 

119°15'-30' (volume percent)

1190 21'

119°26' 

119°27' 

119°25' 

119°25' 

119°28' 

119°26' 

119°26' 

119°25' 

119°23' 

119°22' 

119°23' 

119°23' 

119°23' 

119°23' 

119°24' 

119°25' 

119°26' 

119°26' 

119°23' 

119°23' 

119°28' 

119°22' 

119°24' 

119°25' 

119°24' 

119°25' 

119°24' 

119°24' 

119°25' 

119°27' 

U9°2& 

U9°3ff 

U9°2& 119°26' 

119°26' 

119°23' 

119°24' 

119°25' 

119°24' 

119°25' 

119°27' 

U9°2ff 119°24' 

119°24' 

119°25' 

119°26' 

119°26' 

119°28' 

119°27' 

119°27' 

1190 2y 119°29' 

119°29' 

119°28' 

119°24' 

119°24' 

119°24' 

119°25' 

119°26' 

119°27' 

119°27' 

119°27' 

119°25' 

119°28' 

119°29' 

119°24'

47.8 

44.6 

34.8 

39.2 

42.7 

28.4 

42.9 

43.1 

43.8 

32.8 

28.8 

43.4 

26.5 

49.4 

50.5 

51.4 

59.2 

39.5 

40.8 

54.4 

45.6 

53.6 

58.0 

49.0 

49.1 

43.6 

52.0 

49.6 

44.7 

45.0 

42.7 

40.3 

40.5 

41.7 

42.1 

41.7 

50.5 

45.7 

41.9 

35.0 

39.2 

37.0 

42.6 

54.3 

35.8 

34.7 

50.6 

58.2 

40.2 

38.0 

36.4 

50.3 

39.3 

42.9 

55.3 

47.3 

45.9 

40.6 

44.8 

40.8 

40.1 

39.0 

41.6 

45.9 

37.3 

49.8 

48.4

Alkali 

feldspar 

(volume percent)

15.1 

14.2 

29.5 

18.9 

11.0 

35.0 

10.9 

18.9 

17.5 

32.3 

33.0 

21.5 

47.9 

16.4 

18.9 

17.3 

0.1 

17.4 

21.0 

15.3 

15.9 

6.1 

4.3 

19.1 

3.8 

23.2 

10.4 

15.6 

21.3 

14.4 

19.8 

23.1 

21.9 

22.4 

21.9 

16.7 

17.9 

18.4 

23.0 

27.0 

23.9 

27.1 

12.4 

13.9 

27.2 

31.7 

7.9 

4.6 

20.2 

23.6 

25.9 

2.4 

23.9 

21.1 

0.2 

19.2 

12.2 

8.6 

10.2 

21.0 

23.6 

24.5 

25.0 

9.3 

24.4 

8.5 

17.2

Quartz 

(volume percent)

26.5 

18.0 

30.6 

33.4 

26.7 

35.0 

25.1 

31.0 

33.4 

30.0 

36.2 

25.7 

23.1 

24.5 

20.7 

22.6 

8.1 

27.3 

26.3 

19.6 

26.2 

25.8 

19.0 

27.4 

19.5 

28.9 

21.5 

28.0 

31.2 

24.8 

30.3 

31.6 

33.8 

29.8 

28.0 

27.0 

21.3 

31.3 

27.7 

27.2 

31.6 

30.3 

26.5 

16.4 

33.2 

30.2 

18.9 

14.8 

27.5 

30.0 

30.5 

24.0 

31.0 

30.2 

10.8 

23.5 

25.6 

30.8 

28.2 

30.6 

30.0 

30.4 

28.3 

29.3 

32.0 

23.1 

28.7

Mafic 

minerals 

(volume percent)

10.6 

23.2 

5.1 

8.5 

19.6 

1.6 

21.1 

7.0 

5.3 

4.9 

2.0 

9.4 

2.5 

9.7 

9.9 

8.7 

32.6 

15.8 

11.9 

10.7 

12.3 

14.5 

18.7 

4.5 

27.6 

4.3 

16.1 

6.8 

2.8 

15.8 

7.2 

5.0 

3.8 

6.1 

8.0 

14.6 

10.3 

4.6 

7.4 

10.8 

5.2 

5.6 

18.5 

15.4 

3.8 

3.4 

22.6 

22.4 

12.1 

8.4 

7.2 

23.4 

5.8 

5.8 

33.7 

10.0 

16.3 

20.0 

16.8 

7.5 

6.3 

6.1 

5.1 

15.4 

6.3 

18.6 

5.7

Specific 

gravity 

(g/cm3)

2.707 

2.726 

2.651 

2.683 

2.731 

2.615 

2.73 

2.67 

2.655 

2.637 

2.627 

2.675 

2.625 

2.675 

2.70 

2.675 

2.835 

2.717 

2.68 

2.71 

2.675 

2.73 

2.76 

2.69 

2.78 

2.656 

2.723 

2.68 

2.657 

2.72 

2.654 

2.645 

2.659 

2.662 

2.636 

2.707 

2.68 

2.667 

2.655 

2.673 

2.64 

2.64 

2.74 

2.70 

2.637 

2.64 

2.77 

2.787 

2.683 

2.677 

2.64 

2.172 

2.64 

2.67 

2.812 

2.68 

2.717 

2.727 

2.714 

2.638 

2.631 

2.658 

2.658 

2.71 

2.66 

2.75 

2.675
MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA 17

TABLE 5. -Modes, specific gravity, and location ofplutonic rocks-Continued

Map symbol 

for rock 

Sample no. unit

MP-543 

MP-546

MP-547

MP-549

MP-557A 

MP-559 

MP-560 _

MP-562A 

MP-563 

MP-565 

MP-567

MP-568 

MP-569A

MP-572

MP-573 

MP-574

MP-575

MP-576 

MP-577 

MP-578

MP-585

MP-586A

MP-591

MP-602A

MP-603B

MP-605A ____ 

MP-608A 

MP-615A _

MP-617

MP-619

MP-622

MP-623

MP-629 

MP-632

MP-640

MP-643A ____ 

MP-644

MP-675

MP-676 

MP-677

MP-678

MP-680

MP-682 

MP-684

MP-685

MP-688

MP-690 ______ 

MP-691

MP-692 ______ 

MP-693

MP-694

MP-695

MP-698

MP-702 _

MP-703 _

MP-708 ___ __

MP-712 __ __

MP-713

MP-714 _______ 

MP-715 __ __

MP-716

MP-717

MP-718

MP-723

MP-724 _________ 

MP-728

MP-729

MP-730

Ki 

Ki 

Ko 

Krp 

Krp 

Kj 

Ki 

Ki 

Ki 

Ki 

Ko 

Ki 

Kmc 

Ko 

Ko 

Ko 

Ko 

Ko 

Krp 

Kj 

Ki 

Ko 

Ki 

Kgp 

Kgp 

Kgr 

Krp 

Krp 

Ko 

Ko? 

Ksp 

Ke 

Ksp 

Kj 

Ktk 

Kn 

Kn 

Khd 

Khd 

Khd 

Khd 

Khd 

Ktl 

Khd 

Khd 

Khd 

Khd 

Kcc 

Kcc 

Ktl 

Kr 

Kr 

Khd 

Khd 

Khd 

Khd 

Kmc 

Kr 

Kr 

Kr 

Kr 

Kr 

Kr 

Kr 

Kr 

Kr 

Kr 

Kr

Latitude 

370 3(C-45'

37°32' 

37°31' 

37°32' 

37°39' 

37°39' 

37°40' 

37°38' 

37°39' 

37°38' 

37°38' 

37°38' 

37°38' 

37°41' 

37°36' 

37°36' 

37°36' 

37°36' 

37°37' 

37°38' 

37°38'

srsv 37°38' 

37°34' 

37°4(y 37°41' 

37°40' 

37°38' 

37°39' 

37°37' 

37°31' 

37°33' 

37°33' 

37°32' 

37°31' 

37°35' 

37°31' 

37°32' 

37°41' 

37°42' 

37°42' 

37°44' 

37°43' 

37°42' 

37°45' 

37°45' 

37°45' 

37°45' 

37°45' 

37°45' 

37°45' 

37°45' 

37°45' 

37°43' 

37°44' 

37°44' 

37°42' 

37°42' 

37°42' 

37°4(y 37°41' 

37°41' 

37°41' 

37°44' 

37°43' 

37°43' 

37°43' 

37°43' 

37°43'

Longitude 119°15'-30'

119°25'

119°24' 

119°26' 

119°25' 

119°24' 

119°24' 

119°26' 

119°28' 

119°26' 

119°28' 

119°27' 

119°25' 

119°25' 

119°28' 

119°28' 

119°29' 

119°29' 

119°28' 

119°25' 

119°25' 

119°29' 

119°29' 

119°29' 

119°25' 

119°26' 

119°26' 

119°25' 

119°25' 

119°27' 

119°26' 

119°30' 

119°30' 

119°28' 

119°23' 

119° 19' 

119°20' 

119°19' 

119°28' 

119°28' 

119°29' 

119°23' 

119°22' 

119°20' 

119°23' 

119°22' 

119°23' 

119°29' 

119°22' 

119°22' 

119°21' 

119°20' 

119°20' 

119°24' 

119°25' 

119°27' 

119°24' 

119°25' 

119°24' 

119°23' 

119°22' 

119°23' 

119°23' 

119° 19' 

119° 16' 

119° 16' 

119°17' 

119°17' 

119°18'

Plagioclase 

(volume percent)

39.8 

36.1 

39.5 

34.8 

28.7 

44.6 

44.4 

46.6 

43.7 

43.9 

40.6 

48.4 

29.0 

39.6 

37.0 

38.9 

37.5 

36.0 

32.9 

52.9 

49.9 

44.8 

49.1 

35.4 

45.0 

53.9 

34.3 

30.9 

39.2 

30.0 

30.0 

37.3 

30.8 

42.2 

35.0 

30.5 

24.7 

43.8 

36.0 

43.9 

47.7 

49.1 

35.2 

46.4 

45.0 

47.4 

44.4 

37.5 

41.7 

40.0 

35.8 

32.9 

37.4 

48.7 

49.2 

49.4 

28.7 

49.1 

47.8 

40.0 

39.1 

48.8 

33.4 

50.6 

49.3 

48.4 

51.4 

39.3

Alkali 

feldspar 

(volume percent)

15.9 

23.5 

21.7 

29.1 

32.3 

19.8 

6.8 

4.9 

9.9 

12.6 

22.7 

11.2 

34.0 

26.3 

27.0 

25.4 

25.1 

24.5 

35.6 

12.2 

3.9 

11.7 

8.2 

30.0 

14.6 

6.9 

32.7 

35.1 

23.6 

30.0 

30.1 

24.6 

35.5 

26.6 

33.4 

36.7 

43.9 

14.2 

26.2 

25.7 

20.1 

19.9 

28.9 

20.4 

20.3 

19.6 

25.8 

28.1 

26.1 

19.3 

28.1 

26.2 

27.5 

20.0 

13.2 

19.0 

32.9 

16.4 

11.0 

23.6 

24.5 

16.8 

30.2 

15.7 

14.6 

16.7 

10.9 

25.1

Quartz 

(volume percent)

25.9 

22.1 

32.0 

30.7 

36.3 

25.3 

25.4 

26.5 

26.6 

25.8 

27.2 

23.4 

35.2 

24.6 

28.8 

30.5 

31.6 

30.9 

28.6 

19.7 

27.0 

29.7 

26.3 

29.9 

26.5 

13.4 

28.6 

29.8 

29.1 

34.6 

31.4 

30.3 

32.5 

23.7 

29.3 

32.5 

29.1 

25.4 

30.9 

20.8 

24.7 

24.7 

31.3 

26.5 

25.7 

26.2 

21.5 

29.7 

26.4 

35.5 

29.8 

34.7 

25.1 

22.1 

25.3 

21.9 

36.6 

23.3 

29.0 

28.9 

28.8 

24.6 

31.2 

21.8 

26.2 

23.0 

26.4 

29.6

Mafic 

minerals 

(volume percent)

18.3 

18.2 

6.8 

5.4 

2.7 

10.3 

23.4 

21.9 

19.8 

17.6 

9.5 

17.0 

1.8 

8.5 

7.2 

5.2 

5.8 

8.6 

2.9 

15.2 

19.2 

13.7 

16.4 

4.7 

13.9 

25.8 

4.4 

4.2 

8.1 

5.4 

8.6 

7.8 

1.2 

7.5 

2.3 

0.3 

2.2 

16.6 

6.8 

9.6 

7.5 

6.3 

4.6 

6.7 

9.0 

6.8 

8.2 

4.7 

5.8 

5.2 

6.3 

6.2 

10.0 

9.2 

12.4 

9.7 

1.8 

11.2 

12.2 

7.5 

7.6 

9.8 

5.2 

11.9 

9.9 

11.9 

11.3 

60

Specific 

gravity 

(g/cm3)

2.715 

2.715 

2.64 

2.651 

2.636 

2.70 

2.75 

2.74 

2.74 

2.715 

2.65 

2.735 

2.63 

2.66 

2.653 

2.653 

2.66 

2.65 

2.645 

2.717 

2.75 

2.71 

2.73 

2.647 

2.70 

2.80 

2.65 

2.625 

nd 

2.635 

2.66 

2.658 

2.616 

2.67 

2.613 

2.62 

2.604 

2.71 

2.66 

2.675 

2.66 

2.68 

2.64 

2.67 

2.67 

2.675 

2.67 

2.65 

2.66 + 

2.65 

o cc

2.64 

2.675 

2.68 

2.69 

2.70 + 

2.61 

2.67- 

2.69 + 

2.66 

2.65-2.66 

2.67 

2.64 

2.68 + 

2.69- 

2.69 

2.69 

2fi6
18 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 5. -Modes, specific gravity, and location ofplidonic rocks-Continued

Map symbol Alkali Mafic Specific 

for rock Latitude Longitude Plagioclase feldspar Quartz minerals gravity 

Sample no. unit 37°30'-45' 119°15'-30' (volume percent) (volume percent) (volume percent) (volume percent) (g/cm*)

MP-732 Kr 37°44' 119° 18' 42.5

MP-735 Kr 37°45' 119° 18' 41.0

MP-737 Kr 37°44' 119°19' 35.6

MP-738 Kr 37°43' 119° 19' 36.1

MP-739 Ktl 37°44' 119°20' 38.7

MP-741 Kk 37°45' 119°15' 51.4

MP-753 Kmc 37°42' 119°26' 22.9

MP-755 Kmc 37°42' 119°26' 23.3

MP-759 Khd 37°43' 119°27' 49.6

MP-760 Khd 37°43' 119°26' 46.5

MP-761 Kgp 37°43' 119°25' 37.9

MP-762 Kr 37°40' 119°23' 45.7

MP-763 Kr 37°40' 119°23' 47.5

MP-764 Kr 37°41' 119°23' 43.8

MP-765 Kr 37°41' 119°24' 47.2

MP-766 Kmc 37°41' 119°25' 29.8

MP-770 Kgp 37°42' 119°25' 38.9

MP-772 Kgp 37°41' 119°24' 28.2

MP-773 Kgp 37°41' 119°25' 38.4

MP-775 Kr 37°41' 119°24' 42.8

MP-776 ______ Kgp 37°40' 119°24' 37.2 

MP-779 Kgp 37°41' 119°25' 33.9

MP-786 ______ Kcr 37°40' 119°24' 47.0 

MP-788 Kr 37°40' 119°23' 49.1

MP-789 Kr 37°40' 119°23' 51.5

MP-790A ____ Ktl 37°42' 119°23' 37.6 

MP-792 Khd 37°45' 119°28' 46.2

MP-793 Khd 37°44' 119°29' 46.9

MP-794 Kr 37°43' 119°19' 34.4

MP-795B Ktl 37°43' 119°19' 43.9

MP-796 Ktl 37°42' 119°19' 38.2

MP-797 Kr 37°42' 119°19' 41.1

MP-798 Kr 37°42' 119°18' 43.6

MP-799 Kr 37°42' 119°18' 47.2

MP-801 ______ Kj 37°42' 119°17' 66.6 

MP-806 Kr 37°43' 119° 16' 52.7

MP-808 Kr 37°43' 119° 17' 50.2

MP-811 Kqd 37°44' 119°16' 57.2

MP-814 Kr 37°44' 119° 18' 40.4

MP-815 Kr 37°44' 119°17' 43.0

MP-816 Kk 37°45' 119° 17' 63.4

MP-817 Kr 37°44' 119° 17' 41.2

MP-818 Ktl 37°42' 119°20' 41.8

MP-819 Khd 37°44' 119°22' 43.7

MP-820 Ktl 37°43' 119° 19' 37.2

MP-821 Kcc 37°44' 119°21' 33.0

MP-822 Ktl 37°44' 119°21' 41.6

MP-823 ______ Ko 37°36' 119°30' 39.2 

MP-825 Kk 37°45' 119°15' 52.6

MP-825-2 Ko 37°35' 119°30' 39.5

MP-831 Kk 37°44' 119° 15' 62.8

MP-833 Kk 37°45' 119° 15' 46.6

MP-835 Kk 37°44' 119° 16' 65.0

MP-836 Kr 37°44' 119° 16' 45.1

MP-843 ______ Krp 37°39' 119°25' 30.7 

MP-844 Krp 37°39' 119°25' 29.6

MP-845 Krp 37°39' 119°25' 37.1

MP-846 Kpp 37°39' 119°22' 40.1

ages of the modal constituents are plotted on the 

simplified geologic maps of figures 4 through 7. 

Isopleths have been drawn where the data permit, but 

no attempt was made to contour all the data 

systematically. Several of the intrusive sequences, 

notably those of Washburn Lake and Buena Vista Crest

23.2 27.0 7.3 2.67- 

25.3 26.3 7.4 2.66 

27.5 30.5 6.4 2.65 

29.1 29.1 5.7 2.65- 

25.7 29.7 5.9 2.634 

15.7 13.1 19.8 2.73 

33.1 40.6 3.4 2.62 

35.1 39.1 2.5 2.62 

17.0 22.6 10.8 2.69 

16.3 22.0 15.2 2.72 

27.4 28.8 5.9 2.64 

15.8 25.0 13.5 2.67 + 

17.1 24.8 10.6 2.68-2.67 

19.2 27.6 9.4 2.66 

19.5 23.0 10.3 2.69 

31.0 37.2 2.0 nd. 

23.2 30,2 7.8 2.66 

25.8 38.3 7.7 2.65 

25.0 27.9 8.7 2.66 

19.0 28.4 9.8 2.69 

22.5 32.0 8.3 2.65 

26.2 33.3 6.6 2.66 

0 5.3 47.7 

17.3 25.0 8.6 2.67 

13.1 21.0 14.4 2.69 

21.4 33.0 8.0 2.67 

25.6 20.6 7.6 2.69 

19.2 22.8 11.1 2.693 

28.0 30.0 7.6 2.65 

22.7 27.9 5.5 2.644 

22.8 32.1 6.9 2.64 

22.1 29.8 7.0 2.65- 

19.2 26.5 10.7 2.68- 

15.4 27.2 10.2 2.67 

7.4 12.4 13.6 2.70 

17.4 18.2 11.7 2.68-2.69 

15.4 22.1 12.3 2.68 

0.1 5.4 37.3 2.86 

20.6 31.1 7.9 2.65 + 

22.4 25.5 9.1 2.67 

9.6 12.0 15.0 2.77 

20.9 26.8 11.1 2.70- 

25.2 27.5 5.5 2.645 

24.0 25.2 7.1 2.66 + 

23.9 33.1 5.8 2.65 

29.9 32.0 5.1 2.65- 

18.0 33.5 6.9 2.66 

24.1 28.9 7.8 2.65 

10.7 11.3 25.4 2.76 

27.2 25.8 7.5 2.648 

9.3 11.5 16.4 2.73 

14.7 13.4 25.3 2.765 

1.3 5.9 27.8 2.79 

16.2 26.3 12.4 2.68 + 

35.6 31.3 2.4 2.625 

38.3 30.5 1.6 2.63 

38.6 24.1 0.2 2.565 

29.3 26.8 5.2 2.66

and Tuolumne Intrusive Suite, show systematic variations inward from the margin. The observed trends are 

an inward decrease in plagioclase and mafic minerals 

and an inward increase in quartz and potassium 

feldspar. Similar variations were noted during mapping 

of the granodiorites of Mount Givens and Jackass Lakes,
119°30'

MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA 19

25' 20' 119°15'

37°45

37<30

35

10 15 KILOMETERS

FIGURE 3.-Simplified bedrock geologic map of the Merced Peak quadrangle, showing locations of modaJly analyzed plutonic rock samples.

Explanation in figure 1.
20

119°30 37°45'

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

25' 20'

37° 30'

10 15 KILOMETERS

FIGURE 4. - Simplified bedrock geologic map of the Merced Peak quadrangle, showing localities of samples analyzed for quartz in volume percent. 

Generalized isopleths show equal volume percent. Contour interval 5 percent. Explanation in figure 1.
119° 30' 

37°45'

MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA

25' 20'

21

37°30'

15 KILOMETERS

FIGURE 5. - Simplified bedrock geologic map of the Merced Peak quadrangle, showing localities of samples analyzed for potassium feldspar in 

volume percent. Generalized isopleths show equal volume percent. Contour interval 5 percent. Explanation in figure 1.
22

119° 30' 

37°45'

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

25' 20'

37°30'

10 15 KILOMETERS

FIGURE 6. - Simplified bedrock geologic map of the Merced Peak quadrangle, showing localities of samples analyzed for plagioclase in volume percent. Generalized isopleths show equal volume percent. Contour interval 5 percent. Explanation in figure 1.
119° 30' 

37°45'

MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA

25' 20'

23

40'

35'

37°30'

10 MILES

0 10 15 KILOMETERS

FIGURE 7. - Simplified bedrock geologic map of the Merced Peak quadrangle, showing localities of samples analyzed for mafic minerals in volume 

percent. Generalized isopleths show equal volume percent. Contour interval 5 percent. Explanation in figure 1.
24 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

but too few samples were collected to document the 

variations. Several of the plutons, however, do not show 

systematic modal variations with respect to their 

margins; this applies particularly to the bodies of quartz 

diorite and tonalite and to those of leucogranite and 

leucogranite porphyry.

Biotite, hornblende, and accessory minerals cannot be 

distinguished consistently on stained slabs, so their 

separate amounts were not determined with the modes. 

The relative abundance of biotite and hornblende was 

determined for many of the chemically analyzed samples 

by counts of 1,000 to 2,000 points in thin sections, and 

the results are given in table 4. In general, biotite and 

hornblende are in nearly equal abundance in quartz 

diorite and tonalite, biotite predominates in granodiorite, and biotite occurs to the near exclusion of hornblende in granite.

The composition of plagioclase in most of the 

chemically analyzed samples was determined by measuring extinction angles of albite twins on the universal 

stage. The ranges and average compositions so determined are listed in table 4. In general, the average 

plagioclase composition of quartz diorite and tonalite 

ranges from An36 to AiUs, that of granodiorite from 

An25 to An36 , and that of granite from An2o to An30.

The bulk specific gravities of 412 samples of plutonic 

and metavolcanic rocks were measured on a directreading balance and are plotted in figure 8. Those of 

modally analyzed plutonic rocks are listed in table 5. 

Table 4 gives the powder densities of chemically analyzed plutonic and metavolcanic rocks. The intrusive sequences of Washburn Lake and Buena Vista Crest show 

a systematic decrease in specific gravity inward from 

the margins, ranging from 2.68 g/cc at the margins to 

2.64 g/cc or less in the cores. In general, quartz diorite 

and tonalite have a specific gravity of 2.83 to 2.73 g/cc, 

granodiorite ranges from 2.73 to 2.66 g/cc, and granite 

ranges from 2.66 to 2.63 g/cc. Plotted specific-gravity 

values of metavolcanic rocks range from 2.56 to 2.95 

g/cc. The values for metavolcanic rocks along the 

eastern border of the quadrangle show the largest variation and a high average value of 2.76 g/cc, reflecting the 

varied composition of the metavolcanic rocks along the 

western margin of the Ritter Range pendant and their

andesitic average composition. The specific-gravity 

values of the metavolcanic rocks farther west in the 

quadrangle (excluding those in the southwest corner) 

show a more limited range; almost all are between 2.60 

and 2.72 and average 2.66, reflecting the rhyodacitic 

composition of these metatuffs.

The percentage contents of quartz, potassium feldspar, and plagioclase were recalculated to 100 and plotted on ternary diagrams (figs. 95 through 9G.). Ternary 

compositions mostly lie within the granodiorite and 

granite fields (fig. 9A) along a band extending from 20 

percent quartz, 70 percent plagioclase, and 10 percent 

orthoclase to 35 percent quartz, 30 percent plagioclase, 

and 35 percent orthoclase. The intrusive sequence of 

Buena Vista Crest, however, as well as the granite of 

Gray Peak, the granodiorite of Grizzly Creek, and El 

Capitan Granite (as shown by modal analysis of samples 

from the adjacent Yosemite quadrangle) range along a 

band of more constant quartz content, from approximately 30 percent quartz, 65 percent plagioclase, and 5 

percent orthoclase to 35 percent quartz, 30 percent 

plagioclase, and 35 percent orthoclase.

The 67, chemical analyses listed in table 4 include 55 

prepared by the rapid method of Shapiro and Brannock 

(1962) and 8 prepared in the U.S. Geological Survey 

laboratories in Denver using standard methods described by L. C. Peck (1964). The percentage contents of 

the computer-calculated normative quartz, orthoclase, 

and plagioclase (ab + an) of the plutonic and 

metavolcanic rocks are plotted in figure 10. Faint lines 

on the triangular plot connect the normative composition of some of the analyzed samples to the modal composition of the same samples in terms of quartz, alkali 

feldspar, and plagioclase. Modal compositions of most 

quartz diorite, tonalite, and granodiorite lie closer to the 

quartz-plagioclase side of the diagram than does the normative plot because the K20 content of modal hornblende and biotite is calculated as orthoclase in the 

norm. Modal compositions of most granites, in contrast, 

lie farther from the quartz-plagioclase side because 

albite in the modal perthitic feldspars is counted with 

potassium feldspar as the alkali feldspar component. 

Compositions near the granite-granodiorite boundary 

differ little between normative and modal plots because 

of the compensating effect of the two factors.
119°30' 

37=45'

MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA 25

25' 20' 11915'

40'

35'

37°30'

2.67

.2.69

.2.69

.2.69 2.69 2.68

2.69

.2.68

10 MILES

J____I I____I

15 KILOMETERS

FIGURE 8.-Simplified bedrock geologic map of the Merced Peak quadrangle, showing localities of samples analyzed for specific gravity. 

Generalized isopleths show equal specific gravity. Contour interval 0.02 percent. Explanation in figure 1.
26 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

Q

EXPLANATION

Quartz

Alkali-feldspar 

including plagioclase 

(Ano_5 average 

composition)

P Plagioclase (

Diorite

and 

gabbro

90

65 

EXPLANATION

Tuolumne Intrusive Suite 

• Half Dome Granodiorite 

+ Granodiorite of Kuna Crest 

x Granodiorite of Grayling Lake 

© Granodiorite of Kuna Crest 

O Mount Givens Granodiorite

90 35 65 

EXPLANATION

Intrusive sequence of

Washburn Lake

® Granite porphyry of

Cony Crags

+ Granite of Turner Lake 

• Granodiorite of Red

Devil Lake
D

MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA 

Q f Q

27

35 65

EXPLANATION

Intrusive sequence of

Buena Vista Crest 

D Granodiorite of Breeze Lake 

 Granodiorite of Ostrander Lake 

x Granodiorite of Illilouette Creek

90

EXPLANATION

Intrusive sequence

of Merced Peak

® Leucogranite of Timber Knob 

A Leucogranite of Morris Creek 

 Granodiorite of Jackass Lakes 

x Leucogranite phase near

Sadler Peak 

+ Granodiorite phase near

Ann Lake

O Leucogranite porphyry of Red Peak 

D Leucogranite porphyry of Post Peak 

o Granodiorite porphyry of 

Horsethief Canyon

90 35 65

EXPLANATION 

 Quartz diorite and

tonalite 

x Microgabbro of the

Clark Range

65

	EXPLANATION 

v Leucogranite in small masses 

D Quartz diorite of Long Creek 

x Leucogranite of Shuteye Peak 

+ El Capitan Granite 

 Granite of Gray Peak 

A Leucogranite of Mount Clark 

O Granodiorite of Grizzly Creek

FIGURE 9.-Plots of modes of granitic rocks. Classification plan by Streckeisen and others (1973). A, Ternary compositions; B, Tuolumne 

Intrusive Suite; C, intrusive sequence of Washburn Lake; D, intrusive sequence of Buena Vista Crest; E, intrusive sequence of Merced Peak; 

F, other granitic rocks; G, quartz diorite, tonalite, and microgabbro.
EXPLANATION

A Toulumne Intrusive Suite

Half Dome Granodiorite

Granodiorite of Grayling Lake

Granodiorite of Kuna Crest 

+ Intrusive sequence of Washburn Lake

Granite porphyry of Cony Crags

Granite of Turner Lake

Granodiorite of Red Devil Lake 

n Intrusive sequence of Buena Vista Crest

Granodiorite of Breeze Lake

Granodiorite of Ostrander Lake

Granodiorite of Illilouette Creek 

• Intrusive sequence of Merced Peak

Leucogranite of Timber Knob

Leucograntie of Norris Creek

Granodiorite of Jackass Lakes

Leucogranite porphyry of Red Peak

Leucogranite porphyry of Post Peak

Granodiorite porphyry of Horsethief Canyon 

x Other plutonic units

Microgabbro of the Clark Range

Granodiorite of Grizzly Creek

Granite of Gray Peak

Leucogranite of Shuteye Peak

Leucogranite of Mount Clark

Tonalite of Long Creek

Quartz diorite and tonalite 

O Metavolcanic rocks

Quartz

Orthoclase

FIGURE 10.-Plots of norms of plutonic and metavolcanic rocks. Lines extend from several normative plots to the modal compo

analyzed sample in a quartz-alkali feldspar-plagioclase plot.
MERCED PEAK QUADRANGLE, CENTRAL SIERRA NEVADA, CALIFORNIA-ANALYTIC DATA 29

REFERENCES CITED

Bateman, P. C., Clark, L. D., Huber, N. K., Moore, J. G., and 

Rinehart, C. D., 1963, The Sierra Nevada batholith-A synthesis 

of recent work across the central part: U.S. Geological Survey Professional Paper 414-D, 46 p.

Bateman, P. C., and Eaton, J. P., 1967, Sierra Nevada batholith: 

Science, v. 158, no. 3807, p. 1407-1417.

Bateman, P. C., and Lockwood, J. P., 1976, Shaver Lake quadrangle, 

central Sierra Nevada, California-Analytical data: U.S. Geological Survey Professional Paper 774-D, 20 p.

Bateman, P. C., Lockwood, J. P., and Lydon, P. A., 1971, Geologic 

map of the Kaiser Peak quadrangle, central Sierra Nevada, 

California: U.S. Geological Survey Geologic Quadrangle Map 

GQ-894, scale 1:62,500.

Bateman, P. C., and Wahrhaftig, Clyde, 1966, Geology of the Sierra 

Nevada, in Bailey, E. H., ed., Geology of northern California: 

California Division of Mines and Geology Bulletin 190, p. 107-172.

Birman, J. H., 1964, Glacial geology across the crest of the Sierra 

Nevada, California: Geological Society of America Special Paper 

75, 80 p.

Calkins, F. C., 1930, The granitic rocks of the Yosemite region, in 

Matthes, F. E., ed., Geologic history of the Yosemite Valley: U.S. 

Geological Survey Professional Paper 160, p. 120-129.

Carmichael, I. S. E., 1967, The mineralogy and petrology of the volcanic rocks from the Leucite Hills, Wyoming: Contributions to 

Mineralogy and Petrology, v. 15, no. 1, p. 24-66.

Dalrymple, G. B., 1963, Potassium-argon dates of some Cenozoic volcanic rocks of the Sierra Nevada, California: Geological Society of 

America Bulletin, v. 74, no. 4, p. 379-390.

———1964, Cenozoic chronology of the Sierra Nevada, California:

California University Publications in Geological Sciences, v. 47,

41 p. 

Hamilton, W. B., and Neuerburg, G. J., 1956, Olivine-sanidine trachybasalt from the Sierra Nevada, California: American Mineralogist,

v. 41, nos. 11-12, p. 851-873. 

Huber, N. K., 1968, Geologic map of the Shuteye Peak quadrangle,

Sierra Nevada, California: U.S. Geological Survey Geologic

Quadrangle Map GQ-728, scale 1:62,500. 

Huber, N. K., and Rinehart, C. D., 1965, Geologic map of the Devils

Postpile quadrangle, Sierra Nevada, California: U.S. Geological

Survey Geologic Quadrangle Map GQ-437, scale 1:62,500.

———1967, Cenozoic volcanic rocks of the Devils Postpile quadrangle, 

eastern Sierra Nevada, California: U.S. Geological Survey Professional Paper 554-D, 21 p.

Jones, D. L., and Moore, J. G., 1973, Lower Jurassic ammonite from 

the south-central Sierra Nevada, California: U.S. Geological 

Survey Journal of Research, v. 1, no. 4, p. 453-458.

Kistler, R. W., 1966a, Geologic map of the Mono Craters quadrangle, 

Mono and Tuolumne counties, California: U.S. Geological Survey 

Geologic Quadrangle Map GQ-462.

———1966b, Structure and metamorphism in the Mono Craters quadrangle, Sierra Nevada, California: U.S. Geological Survey Bulletin 

1221-E, 53 p.

——1973, Geologic map of the Hetch Hetchy Reservoir quadrangle, 

Yosemite National Park, California: U.S. Geological Survey 

Geologic Quadrangle Map GQ-1112, scale 1:62,500. 

-1974, Hetch Hetchy Reservoir quadrangle, Yosemite National

Park, California-Analytic data: U.S. Geological Survey Professional paper 774-B, 15 p.

Matthes, F. E., 1930, Geologic history of the Yosemite Valley: U.S. 

Geological Survey Professional Paper 160, 137 p.

———1960, Reconnaissance of the geomorphology and glacial geology 

of the San Joaquin basin, Sierra Nevada, California: U.S. 

Geological Survey Professional Paper 329, 62 p.

Nokleberg, W. J., 1970, Geology of the Strawberry Mine roof pendant, 

central Sierra Nevada, California: Santa Barbara, University of 

California at Santa Barbara, Ph.D. dissertation, 157 p.

———1981, Stratigraphy and structure of the Strawberry Mine roof 

pendant, central Sierra Nevada, California: U.S. Geological 

Survey Professional Paper 1154, 18 p.

Norman, M. B., 1974, Improved techniques for selective staining of 

feldspar and other minerals using amaranth: U.S. Geological 

Survey Journal of Research, v. 2, no. 1 p. 73-79.

Peck, D. L., 1964, Preliminary geologic map of the Merced Peak quadrangle, California: U.S. Geological Survey Mineral Investigations 

Field Studies Map MF-281, scale 1:48,000.

———1980, Geologic map of the Merced Peak quadrangle, central 

Sierra Nevada, California: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1531, scale 1:62,500.

Peck, L. C., 1964, Systematic analysis of silicates: U.S. Geological Survey Bulletin 1170, 89 p.

Shapiro, L., 1975, Rapid analysis of silicate, carbonate, and phosphate 

rocks-Revised edition: U.S. Geological Survey Bulletin 1401, 

76 p.

Shapiro, Leonard, and Brannock, W. W., 1962, Rapid analyses of 

silicate, carbonate, and phosphate rocks: U.S. Geological Survey 

Bulletin 1144-A, 56 p.

Streckeisen, A. L., and others, 1973, Plutonic rocks-classification 

and nomenclature recommended by the IUGS Subcommission on 

the Systematics of Igneous Rocks: Geotimes, v. 18, no. 10, p. 

26-30.

Stern, T. W., Bateman, P. C., Morgan, B. A., Newell, M. F., and Peck, 

D. L., 1981, Isotopic U-Pb ages of zircon from the granitoids of the 

central Sierra Nevada, California: U.S. Geological Survey Professional Paper 1185, 17 p.

Van Kooten, G. K., 1980, Mineralogy, petrology, and geochemistry of 

an ultrapotassic basaltic suite, central Sierra Nevada, California, 

U.S.A.: Journal of Petrology, v. 21, no. 4, p. 651-684.

Williams, Howel, 1936, Pliocene volcanoes of the Navajo-Hopi County 

[Arizona]: Geological Society of America Bulletin, v. 47, no. 1, p. 

111-172.

York, Derek, 1966, Least-squares fitting of a straight line: Canadian 

Journal of Physics, v. 44, p. 1079-1086.