I 

I 

I 

Biogeochemistry of a Highly Serpentinized, 

Chromite-Rich Ultramafic Area, Tehama 

County, California 

U.S. GEOLOGICAL SURVEY BULLETIN 1901 
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ERRATA SHEET 

This table replaces table 2 in USGS Bulletin 1901. 

Table 2. Summary statistics for element concentrations in leaf and stem material of whiteleaf manzanita and needles of 

digger pine 

[Prior to calculation, data were converted to logarithms; data expressed as ppm, dry weight base, except where noted; site replicated samples (12 

and 9, manzanita and pine, respectively) and duplicate analyses (12 for each species) were averaged prior to calculations; ratio, proportion of the 

number of analyses having values above the lower limit of determination to the total number of analyses; GM and GD, geometric mean and 

deviation, respectively; leaders (--),no data available] 

Element or Manzanita Digger 12ine 

ash yield Ratio GM GO Observed range Ratio GM GD Observed range 

Ash% 112:112 3.6 1.20 2.0 - 5.8 91:91 2.3 1.20 1.5 - 3.5 

Al 112:112 20 1.40 11 - 68 91:91 73 1.56 21 - 170 

As 8:112 <1.2 - 2.6 1:91 <0.85 - 0.88 

Ba 112:112 8.9 1.67 1.2 - 30 91:91 0.84 1.49 0.30 - 1.9 

Ca% 112:112 0.67 1.41 0.18 - 1.6 91:91 0.27 1.60 0.086 - 0.80 

Cd 44:112 <0.03 0.17 11:91 <0.026 - 0.075 

Cr 112:112 1.4 2.13 0.29 7.5 91:91 1.1 1.80 0.42 - 7.5 

Cu 112:112 4.3 1.43 1.4 - 9.0 91:91 4.2 1.34 1.9 - 9.1 

Fe 112:112 28 1.39 13 - 59 91:91 91 1.62 16 - 220 

Mg% 112:112 0.34 1.12 0.10 - 0.6 91:91 0.24 1.31 0.12 - 0.46 

Mn 112:112 29 1.75 8.0 - 130 91:91 73 1.81 7.8 - 210 

Nb 95:112 0.25 1.36 <0.15 - 0.48 41:91 <0.12 - 0.23 

Ni 112:112 2.6 1.94 0.56 13 91:91 4.2 1.82 0.70 - 13 

P% 112:112 0.052 1.52 0.015 0.17 91:91 0.12 1.32 0.057 - 0.25 

Pb 2:112 <0.24 0.41 77:91 0.52 1.80 <0.24 - 2.2 

Sr 112:112 14 1.54 3.4 34 91:91 2.4 1.88 0.59 - 15 

Ti 112:112 1.3 1.49 0.60 3.2 91:91 3.6 1.73 0.73 - 10 

v 7:112 <0.04 - 0.08 91:91 0.14 1.77 0.024 - 0.37 

y 36:112 <0.007 0.036 18:91 <0.006 - 0.01 

Zn 112:112 30 1.25 14 50 91:91 20 1.49 5.3 - 54 

Biogeochemistry of a Highly Serpentinized, 

Chromite-Rich Ultramafic Area, 

Tehama County, California 

By L. P. GOUGH, G. R. MEADOWS, L. L. JACKSON, 

and S. DUDKA 

Biogeochemical processes in a chaparral-zone, serpentinized 

ultramafic area are investigated as they relate to geochemistry 

and element concentration patterns in manzanita and pine tissue 

U.S. GEOLOGICAL SURVEY BULLETIN 1901 
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government. 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1989 

For sale by the 

Books and Open-File Reports Section 

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Library of Congress Cataloging-in-Publication Data 

Biogeochemistry of a highly serpentinized, chromite-rich ultramafic area, 

Tehama County, California I by L.P. Gough ... [et al.]. 

p. em. - (U.S. Geological Survey bulletin ; 1901) 

Includes bibliographical references. 

Supt. of Docs. no.: I 19.3:1901 

1. Chromite-California-Tehama County. 2. Geobotanical prospecting. 

3. Whiteleaf manzanita-California-Tehama County-Composition. 

4. Pinus sabiniana-California-Tehama County-Composition. 

5. Serpentinite-California-Tehama County I. Gough, L.P. II. Series. 

QE75.B9 no. 1901 

[TN490.C4] 

557.3 s-dc20 89--600232 

[553.4'643] CIP 
CONTENTS 

Abstract 1 

Introduction 1 

Purpose of study 1 

Description of the study area 2 

Location 2 

Geology 2 

Country rock 3 

Alteration 3 

Physiography and vegetation 4 

Chromium resource assessments 4 

Sample collection, preparation, and analytical methods 4 

Gridded sampling design for plants 4 

Excavated manzanita shrub 6 

Vertical traverse sampling design for soils 6 

Surface water collections 6 

Statistical analysis of data 7 

Results and discussion 8 

Biogeochemical summaries, gridded study area 8 

Powder X-ray analysis of plant ash 8 

Summary statistics 8 

Results of the analysis of variance 8 

Description of biogeochemical patterns 9 

Interpretation of univariate element associations 9 

Interpretation of multivariate element associations U 

Vertical element trends in the soil profile 16 

Uptake and translocation of elements by manzanita 17 

Biogeochemical exploration for chromium 21 

References cited 23 

FIGURES 

1. Map showing topography, past mining sites, and surface water sampling sites in 

Elder Creek study area 2 

2. Photograph of Elder Creek study area 3 

3. Map showing biogeochemical and geochemical sampling sites in gridded study 

area 5 

4. Three-dimensional diagrams showing areal concentration patterns for six 

selected elements and ash yield in manzanita shrub stem and leaf material and 

digger pine needles 12 

5. Graphs showing soil physical and chemical variables for soil profiles 08I and 

07G 18 

Contents Ill 
6-7. Diagrams showing: 

6. Relative position of sampled materials and concentration of selected 

elements from whiteleaf manzanita shrub 21 

7. Relation between distance from the basal burl of an excavated manzanita shrub and concentrations of Ca, Mg, and ash yield, and Cr, Fe, Mn, 

and Ni in samples of roots, stems, and leaves 22 

TABLES 

1. Methodology for analyses of sampled materials 7 

2. Summary statistics for element concentrations in leaf and stem material of 

whiteleaf manzanita and needles of digger pine 9 

3-4. Distribution of element concentration variation in samples of: 

3. Whiteleaf manzanita leaf and stem material 10 

4. Digger pine needles 10 

5-6. Results of R-mode factor analysis for: 

IV Contents 

5. Manzanita stem and leaves showing relative loadings of element 

concentrations on four factors derived by varimax rotation 16 

6. Digger pine needles showing relative loadings of element concentrations 

on four factors derived by varimax rotation 16 
Biogeochemistry of a Highly Serpentinized, 

Chromite-Rich Ultramafic Area, 

Tehama County, California 

By L.P. Gough, G.R. Meadows, L.L. Jackson, and S. Dudka 

Abstract 

The processes that influence Cr mobility and its uptake 

by plants were studied in a serpentinized, chromite-rich 

ultramafic area of the Coast Range, northern California. Areal 

element concentration trends in the stem and leaf material of 

Arctostaphylos viscida (whiteleaf manzanita) and in the 

needles of Pinus sabiniana (digger pine) are related to 

geological and biological processes that control or influence 

these trends. 

Plants were collected from a gridded rectangular area 

of about 0.25 km2

; 44 m separates the sampling sites. Both 

manzanita and pine were collected, where found, at 116 

accessible sites. Based on the results of element 

concentration patterns in plant materials, soils were collected 

in excavated pits at eight sites; both dry- and wet-season 

collections were made. 

Results of a one-way, three-level analysis of variance 

show that, in general, differences in concentrations of most 

elements in manzanita shrubs and pine trees separated by 

44 m or more are greater than those separated by less than 

about 3 m. Very similar areal patterns between the two plant 

species were found for Ni concentrations and to a lesser 

degree for Cr, AI, Fe, and P. 

Associations for 14 and 15 elements (and ash yield) 

within manzanita and pine, respectively, were examined 

using R-mode factor analysis. A four-factor varimax solution 

explains almost two-thirds of the total variance for manzanita. 

Similarly, four almost identical factors explain almost threefourths of the total variance for pine. Factor 1 (for manzanita) 

and factor 2 (for pine) are mainly associated with the alkalineearth metals and account for 25 and 21 percent of the total 

variance, respectively. All four factors demonstrate the 

importance of intrinsic and possibly extrinsic processes that 

influence the chemistry of these plants. 

The uptake of Cr by manzanita and its translocation 

within the shrub was found to be regulated. Chromium 

concentrations were five times greater in some root tissue 

samples than in stem material. Nevertheless, areal Cr 

Manuscript approved for publication, July 7, 1989. 

patterns were found to vary greatly and, in general, show 

high Cr concentrations on the western side of the study area 

in a highly dissected ridge and gully region near two 

abandoned chromite mines. Additional scattered high Cr 

concentrations throughout the study area are suspected to 

reflect areas where the availability of Cr is greatest due to 

topographical and chemical influences. 

In general, the uptake of Cr by manzanita and pine in 

these serpentinized soils probably involves both the physical 

dissemination of chromite and the oxidation of Cr(lll) to 

Cr(VI). 

The use of biogeochemistry to differentiate the 

occurrence of concealed chromite deposits is not yet clearly 

defined. It would seem, however, that in regions where 

dispersion of chromite aggregates (pods) has occurred 

(resulting in increased chromite-grain surface area) and 

where the potential for Cr oxidation exists, biogeochemistry 

may be a useful tool with which to locate new exploration 

targets. 

INTRODUCTION 

Purpose of Study 

Chromium is considered a strategic "mineral" by 

the U.S. Government, but of the 51 major Cr deposits 

and districts identified worldwide, none are in the U.S. 

(DeYoung and others, 1984). Ninety-five percent of the 

world's known Cr reserves are in South Africa and 

Zimbabwe, and because the U.S. currently imports all of 

the Cr it uses and because world supplies are precarious, 

it is important to assess less conventional methods with 

which to find domestic Cr deposits. 

This study was initiated as part of the U.S. 

Geological Survey's CUSMAP (Contiguous U.S. 

Mineral Assessment Program) project of the Redding, 

Calif., 1° x 2° quadrangle. We report the results of 

investigations designed to define areal element 

concentration trends in plant material, and we suggest 

Introduction 1 
geochemical and biogeochemical processes that may 

control or influence these trends. A better understanding 

of the mechanisms of Cr mobility in serpentinized ultramafic soils and of element uptake by plants growing in 

ultramafic areas containing chromite deposits is 

necessary if biogeochemical methods of chromite 

prospecting are to be effective. 

Although chromite is a refractory mineral, 

vegetation growing in ultramafic areas typically contains 

large and variable Cr concentrations. In order for Cr 

uptake to occur, hexavalent forms of Cr apparently must 

be present; however, the mechanisms by which Cr(VI) is 

formed in soil or absorbed by vegetation is not known. 

The use of Cr concentrations in vegetation as an 

exploration tool has also not been determined. 

An increase in our knowledge of the biogeochemistry of Cr and related elements is applicable not only to 

exploration efforts but also to environmental and 

toxicological concerns because Cr (particularly as 

Cr(VI)) can be both phyto- and zoo-toxic. 

Description of the Study Area 

Location 

The study area is in the southeast corner of the 

Redding 1 o X 2° quadrangle, Tehama County, northern 

California, in the southeast-quarter of sec. 16, T. 25 N., 

R. 7 W. (Raglin Ridge, Calif., 1:24,000 quadrangle) (fig. 

1). It encompasses an area of slightly less than 0.25 km2 

in rugged, highly serpentinized, ultramafic terrain south 

of the North Fork of Elder Creek. 

The elevation of the Elder Creek study area ranges 

from about 450 to 670 m. The topography of the area is 

varied; for purposes of discussion, we divided the region 

into four landscape units (fig. 2): (1) a region of steep 

ridges and gullies, (2) a gently sloping ( < 5 percent) low 

bench region, (3) a moderately sloping ( > 5 percent) 

high bench region, and ( 4) a high, moderately dissected 

ridge. The ridge and gully region is deeply cut by highly 

eroded incised drainages. 

Geology 

The study area is at the northern tip of a northtrending, tabular peridotite body of the Coast Range 

ophiolite suite (Strand, 1962; Irwin, 1964) near the 

junction of three major geologic provinces, the Klamath 

Mountains, the Coast Range, and the Great Valley 

(Irwin, 1966). Although Bayer (1983) mapped the area 

as part of the Franciscan Complex of the Coast Range, 

Blake and others (1982) associated it with the preCenozoic rocks of the Great Valley. 

Blake and others (1982) suggested that the 

peridotite and associated sedimentary rocks were 

0 

® 

0.1 0.2 0.3 

EXPLANATION 

Unimproved road or trail 

Site of mined chromite deposit. 

Symbol size shows relative 

importance of mined areas 

(after Rynearson, 1946) 

G) Stnface water sampling sites, 1986 

Figure 1. Topography, past mining sites, and surface water 

sampling sites in the Elder Creek study area. Contour interval 

50 ft. Grid sample area is in SE/4 sec. 16, T. 25 N., R. 7 W. 

abducted onto a Late Jurassic age volcanic arc, sometime 

between Late Jurassic and Early Cretaceous time. This 

ophiolite sequence and the overlying sedimentary rocks 

have been identified as the Elder Creek terrain (Blake 

and others, 1984). 

The chromite deposits within the peridotite have 

been classified as alpine-type (podiform ), rather than 

stratiform-type deposits (Wells and others, 1946; Thayer, 

1966; Page and Johnson, 1977) based on tectonic origin 

and chemistry. Podiform-type deposits occur within 

island arcs or mobile mountain belts, whereas stratiform 

deposits are associated with stable cratons of Precambrian age (Hutchison, 1983). Cr/Al ratios of 

podiform -type deposits vary greatly with respect to 

relatively constant Mg!Fe ratios (LeBlanc and Violette, 

1983). 

2 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
/ 

Figure 2. View of the Elder Creek study area looking south. The ravine of the North Fork of Elder Creek is in the 

foreground, and four landscape units are identified (see text for discussion). 

Although the formation of podiform-type chromite 

deposits is not completely understood, the geologic 

processes involved are agreed upon by most researchers. 

Partial melting of oceanic, upper mantle rock produces a 

dunitelike residuum in which segregation and crystal 

settling occur to form cumulate layers of chromite within 

the dunite. Later tectonic forces may give the chromite 

layers their tabular, podiform shapes (Dickey, 1975; 

Hutchison, 1983). These deposits are then obducted at 

some later time as part of an ophiolite sequence. 

Shearing and serpentinization were probably the 

dominant geologic forces within the area. The tectonic 

origin of the steep gullies that cut the area is made 

obvious by the associated altered and brecciated rocks. 

Ephemeral streams, active during the wet, rainy season 

from November to March, have deepened and 

emphasized the shear zones. The gullies trend north. 

Two major gullies dominate the topography of the "steep 

ridges and gullies" section of the western half of the study 

area (fig. 1). Shearing and subsequent erosion have 

resulted in the physical transport of large volumes of 

chromite downslope. 

Country Rock 

The peridotite in the Elder Creek study area is 

composed mostly of dunite, with small amounts of saxonite, diorite, and rodingite (Rynearson, 1946). At least 

one diorite dike cuts the study area; it strikes east -west, 

normal to the shear zones. The dike is composed of very 

fresh, unaltered rock to highly altered rock that can be 

identified only by a relict intrusive texture seen in thin 

section. No outcrops of pyroxenite were observed in the 

area, and rodingite was noted at only one locality, in one 

of the shear zones. A small sample of a micaceous, 

lavender rock was tentatively identified as kammerite. 

Chemical analysis shows it contains only 1.2 percent Cr, 

however, and it has subsequently been classified as a 

chromium chlorite. 

Alteration 

Serpentine is omnipresent in the study area and 

serpentinization is by far the most common form of 

alteration. The serpentine usually has a black, glossy 

Introduction 3 
appearance, though it may be present in the soil as a fine . . ' medmm-green, earthy matenal. 

The second most common type of alteration is a 

complex of magnesitelike carbonate minerals. This type 

of alteration is most commonly found in the shear-zone 

gullies and smaller erosion gullies. The magnesite may 

take several forms, from dense white rocklike material to 

pisolitic nodules, to a white powderlike substance tl1at 

forms the matrix of highly altered, breccialike rocks. 

Pisolitic nodules were also found on a vertical wall 

formed downslope of the study area, where mining 

operations have cut the toe from a slope. These nodules 

appear to have formed recently-they are soft and clayey 

during the wet season and more dense and dry during 

hot, dry periods-and some of the carbonate may be 

derived from weathering activity. The dense, white magnesite thus would be derived from the flushing of mobile 

magnesium by the weathering of peridotites (Wildman 

and others, 1968). 

Physiography and Vegetation 

Kruckeberg (1984, p. 9) described the 

?hysiography of the northern Coast Range region, which 

mcludes the area of the Redding quadrangle, as follows: 

From the arid foothills bordering the western edge of 

the Sacramento Valley to the fog belt of the coastal redwood 

region, serpentines outcrop with great frequency. The 

Klamath-Siskiyou mountains to the north have the largest 

ultramafic outcrops in the state, indeed in North America. 

From arid to mesic, from low elevation * * * to the highest 

peaks * * * there is an ultramafic outcrop (either igneous or 

metamorphic) for nearly every kind of terrain and exposure in 

northwestern California. 

The vegetation of the Elder Creek study area has 

been defined as serpentine chaparral (Kruckeberg, 

1984). The ecology of serpentine areas is complex and is 

characterized by: (1) soils imbalanced in macronutrients 

(very high in Fe and very low Ca/Mg ratios) and having 

low levels of Nand P, (2) soils containing unusually high 

(often toxic) levels of Cr, Ni, and sometimes Co, (3) 

sparsely vegetated areas (the term "serpentine barren" 

refers to areas completely lacking vegetative cover), ( 4) 

areas of open-tree and shrub canopies and high surface 

soil temperatures, and (5) unstable soils usually low in 

surface soil moisture (Walker, 1954). Kruckeberg (1984) 

quoted Hanes' (1977) description of California 

serpentine chaparral as follows: 

Serpentine chaparral is an open, low type associated 

with serpentine soils from San Luis Obispo Co. northward 

through the Coast Ranges and foothills of the northern Sierra 

Nevada. The shrubs are characterized by apparent 

"xeromorphism"***and dwarfed stature resulting from 

reduced productivity and growth***The dominant shrubs are 

Adenostoma fasciculatum ***and Heteromeles arbutifolia* * *, 

but noteworthy are several localized endemic shrub species, 

Arctostaphylos viscida and Ceanothus jepsonii. 

Cupressus sargentii, Ganya congdonii, and Quercus 

durata are unmistakable "indicator species" because o1 their 

typical restriction to, and numerical dominance on, serpentine 

soils ***Serpentine chaparral may be associated with foothill 

woodland (Pinus sabiniana * * *) or montane coniferous forest 

(P. jeffreyi***, P. ponderosa***P. attenuata***, and Pseudotsuga menziesii) as an understory** *The thousands of hectares 

of serpentine chaparral in the north Coast Ranges are easily 

distinguished from the oak-grasslands on hills of nonserpentine origin*** 

The dominance of whiteleaf manzanita (Arctostaphylos viscida Parry) is evident in the photograph of the 

area (fig. 2). Manzanita shrubs generally are smaller and 

more crowded in the low bench region (northeast) and 

larger and more widely spaced in the high bench region 

(southwest). Individual digger pine trees (Pinus sabiniana Dougl.) are scattered about but are apparently most 

common on the small ridge crests, particularly in the 

steep ridge and gully region. 

Chromium Resource Assessments 

Only a very few Cr resource assessment studies of 

the Elder Creek area are available (Diller and others, 

1921; Rynearson, 1946; Wells and Hawkes, 1965). 

These studies are quite dated and were made when Cr 

production in the area was near its maximum. Most of 

the mining in the Elder Creek area of Tehama County 

occurred between 1890 and the late 1940's (Rynearson, 

1946). 

Reports on U.S. and world Cr production, the past 

and future development of Cr as an essential industrial 

commodity, and the status of the Cr industry in general 

have been reviewed by Thayer (1966, 1973), Morning 

(1978), Thayer and Lipin (1978), Lipin and Thayer 

(1980), Papp (1983), and DeYoung and others (1984). 

Acknowledgments.-We especially thank Joanne 

Danielson, Shasta College, Redding, Calif., for her field 

observations and for bringing to our attention the 

geological role of the shear zones. Examination of dry 

plant material and ash by powder X-ray diffraction was 

provided by Steve Sutley and Jerry Gaccetta. Chemical 

analyses were performed by the authors and by Paul H. 

Briggs. 

SAMPLE COLLECTION, PREPARATION, 

AND ANALYTICAL METHODS 

Gridded Sampling Design for Plants 

In June 1984, a grid of approximately 440 m by 500 

m was positioned over an area of known chromite 

4 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
0 

2 

3 

4 

5 

6 

7 

8 

9 

10 

A J K L 

e I 

• I 

' 0 I 

I 

.A A .A • ·A' •I A • • A • 

A • I A. I Aj I 

.i AI 

~ A. • • A • 0 • A • A. •' • J 

I 

A I j LOW BENCH I 

t (~ I 

.A .A • • • • • el A \ A A I 

~. I 

STEEP RIDGES AND GULLIES I 

A 

A. !; • • • • .\ f A • • A • A. \ A I 

·' \-·-

• / . ...-, . -""'\ 

f ! A • t .A • ... • / .,.. ..... •' \ A,'// A A \ A 1/ A .I 

A • '\. A Jl ......... ·I • .A • A • • • • • if ... • 

A .......... ...._ ./~., A 

0 A 1r--:::-·-.-·/ I . 

Ai 

I -~ ', ,. _ _,I \ A 

.A 0 • A e • eo ~ /e. .....'".,.. j 

• A ,.,.--........ _,-..... /0/ A'\.. ~ f . • ..... - -·""""" / ............ --- . > / ,... ...-· ·--:::::_,./ ./·-·, ', .,.. .......... _./ . ............ /' / ...-· ......... -·-·-<' ·-......... . \ ' /-- .r· oAI -·-· A \_ ·'\.. M. i \ ~-.,.. • // _.. • i • I 

I 

N 

A. • \ \. / I \ ............. _ ......... 

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• • • • • \ • \ A A A A A 

i HIGH BENCH 

j\ Ae A. A. • I 

eA .. ~ 

0 0.1 0.2 KILOMETERS 

EXPLANATION 

• Manzanita shrub sample site 

A Digger pine sample site 

Landscape unit boundary 

o Soil profile site 

0 Excavated manzanita shrub (07H) 

---- Unimproved mining road 

A 

A 

• • 

HIGH RIDGE 

A A 

• • 

Figure 3. Biogeochemical and geochemical sampling sites in the gridded study area (fig. 1). 

mineralization (figs. 1, 3). The grid design allowed us to 

evaluate areal biogeochemical data for the purpose of 

mapping individual element concentration trends. In the 

less than 0.25-km2 area, there are 120 sampling sites with 

centers separated by 44 m. Because of impassible terrain, 

however, six sites were not sampled (fig. 3); two 

additional sites were added in the northeast corner, 

making a total of 116 accessible sites. 

Sample Collection, Preparation, and Analytical Methods 5 
At each site, plant material collected included 

stems and leaves (current year's growth, usually the 

terminal 5-8 em) of the shrub whiteleaf manzanita (A. 

viscida) and two-year-old needles (needles from the 

second whorl) of the tree digger pine (P. sahiniana). 

Because element concentrations in leaf samples can vary 

depending on where on the plant the sample is taken 

(Brooks, 1984 ), each sample consists of about 20 g of 

material collected from around the perimeter of a single 

individual shrub or tree located as close as possible to the 

measured grid point. All manzanita samples were 

collected at about 1.5 m above the ground using stainless 

steel shears. Pine needles were stripped by hand from the 

lowest accessible branches; these usually were 3-5 m 

above ground and had to be obtained using extension 

pruning shears. 

Manzanita was found at 112 of the 116 sampling 

sites and digger pine at 91 (fig. 3). About 10 percent of 

the sites for each species were chosen randomly for 

replication and another 10 percent for duplicate sample 

analysis. At each replicated site a shrub (or tree) adjacent 

to the original sample was chosen for sampling. The 

analytically duplicated samples were made after the dry 

material was ground in the laboratory. 

Plant samples were stored in Hubco cloth bags. In 

the laboratory the samples were dried in a forced-air 

oven at about 38 °C for 24 hours. Samples were then 

ground in a Wiley mill to pass a 1.3-mm screen. Ten 

percent of each of sample was then split and submitted 

for duplicate chemical analysis. 

Excavated Man zan ita Shrub 

In August 1985, a single manzanita shrub at the 

crest of an old road cut near site 07H (fig. 3) was 

excavated. The purpose of this collection was to evaluate 

the relative concentrations of elements among regions of 

the plant and to assess the possible partitioning of 

absorbed elements between root and shoot tissue. Major 

roots were traced laterally along the road cut for about 7 

m and vertically for about 2m. Samples include: (1) root 

cortex and stele (epidermis peeled and removed) at 

about 1-m intervals away from the basal manzanita burl, 

(2) basal burl wood (composite of cross section, bark 

peeled and removed), (3) main stem wood 1 m above 

burl (composite of cross section, bark peeled and 

removed), (4) primary branches off main stem (outer 

bark was peeled and removed), (5) secondary branches 

off primary branches, and ( 6) small stems with leaves. As 

above, all samples were ground in a Wiley mill after 

being dryed in an oven. Prior to grinding the wood 

samples were first cut into small pieces using a handsaw. 

Vertical Traverse Sampling 

Design for Soils 

In August 1985, eight pits were excavated through 

the highly weathered soil and rock profile (fig. 3) at sites 

judged to be different biogeochemically as determined by 

evaluation of the manzanita and digger pine chemistry. 

The purpose of the soil collections was to examine soil 

chemical and physical properties that might help to 

define trace metal mobility in ultramafic terrains. 

The pits were located adjacent to the manzanita 

shrub (or shrubs) that was sampled as part of the gridded 

biogeochemical study. Pits were excavated to a depth of 

about 100 em and samples were collected at five depths: 

0-5 em (surface litter having been scraped away), 10, 20, 

40, and 80 em. At each depth, paired samples, separated 

by about 20 em, were sieved through a 1-cm screen and 

then placed in 1-L polyethylene acid-washed bottles. The 

bottles were sealed in order to prevent moisture loss. 

Rocks were collected from the bottom of each pit for 

chemical analysis and thin section examination. 

In the laboratory, part of the collected soil was 

allowed to dry at ambient temperature and part was kept 

in plastic bottles. About 50 g of undried material was 

removed, and pH, moisture percentage, and the presence 

of Cr(VI) were measured; mineralogical determinations 

using X-ray diffraction were conducted for selected 

samples. In addition, 25 g of bulk material was placed in 

65-mL screw-cap bottles, the material was rewetted with 

25 mL of distilled water, and the samples were allowed to 

stand for 6 months after which they were again tested for 

the presence of Cr(VI). One hundred grams of soil was 

ground to -100 mesh and used for bulk chemical 

determinations of total and inorganic C (organic C was 

calculated as the difference between the two measured C 

values) and other major and trace elements as described 

in table 1. 

Surface Water Collections 

The study area is cut by several north-trending 

gullies, all of which drain into Elder Creek (fig. 1 ). 

Surface water is present in these gullies for only a 

relatively short time during the wet season each spring. 

In late March 1986, we collected water samples 

from four different gullies, at both the top of the slope 

containing the field area and the bottom of the slope 

before the streams drained into Elder Creek (fig. 1). The 

samples were placed in acid-rinsed 500-mL polyethylene 

bottles. The bottles were capped and refrigerated. 

Measurements were made of pH, conductivity, and the 

colorimetric test for the presence of hexavalent Cr. 

6 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
Table 1. Methodology for analyses of sampled materials 

[Study: A, soil pit geochemical; B, plant grid biogeochemical; C, excavated shrub biogeochemical; D, intermittent stream chemical] 

Variable Method Study Reference or notes 

Total concentrations ofB, Ba, Ca, Co, Cr, 

Cu, Fe, Mg, Mn, Ni, Pb, Sc, Ti, V, Y, Zn, 

and'h 

ICP1 on dry soils sintered with Na202 A Lichte and others, 1988 

Total concentrations of AI, As, B, Ba, Be, 

Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Nb, Ni, P, 

Pb, Sr, Ti, V, Y, and Zn 

ICP1 on acid-digested ash of plant 

material 

B Church and others (1987) 

Total concentrations of Ca, Cu, Cr, Fe, Mg, 

Mn, andNi 

Atomic absorption spectrometry on 

acid-digested ash of manzanita leaves, 

stems, and leaves and stems together 

c Harms (1976) 

Percent total C, organic C, and carbonate C Combustion infrared photometry, 

difference, and coulometric titration, 

respectively, on dry soil 

A Jackson and others (1988) 

Soil moisture Gravimetric 

Ash yield Gravimetric on plant dry material 

A 

B 

Loss of weight after 24 hrs at 

105 °C 

Ashed at 500 °C 

Plant ash and soil mineralogy Powder X-ray diffraction A,B 

A,D 

Starkey and others (1984) 

pH Glass electrode, 1: 1 water: soil ( <2-mm 

fraction) slurry, and stream water 

Peech (1965) 

Cr(VI) presence in water and field soils Qualitative colorimetric test with 

s-diphenyl carbazide 

A, D Modified from Bartlett and 

James (1979) 

1Inductively coupled argon plasma optical emission spectrometry. 

STATISTICAL ANALYSIS OF DATA 

All chemical data summarized and interpreted in 

this report are listed in Meadows and others (1988). Data 

reported by the analyst for plant material on an ashweight basis were converted to dry-weight equivalents 

and then transformed to logarithms prior to statistical 

analysis. Summary statistics are reported as the 

geometric mean (GM) and geometric deviation (GD). 

For those elements having normal frequency 

distributions but for which there were censored values at 

the left or low end of the distribution (values below the 

lower limit of analytical determination, LLD), the 

geometric mean and deviation were estimated using the 

technique of Cohen (1959). For those elements not 

censored, the geometric mean was calculated as the 

antilogarithm of the mean of the logarithmic values, and 

the geometric deviation was calculated as the 

antilogarithm of the square root of the total variation as 

estimated by analysis of variance. The latter calculation 

accounts for the effects on the total variability of the 

nested analysis of variance design. 

Because ash yield varies, the conversion from an 

ash-weight base to a dry-weight base produces variable 

LLD values for elements with censoring. The mean and 

deviation estimation technique of Cohen (1959), 

however, cannot handle variable LLD values. A single 

LLD was created using an algorithm devised by A.T. 

Miesch (oral commun., 1986, U.S. Geological Survey, 

retired) which adjusts the variable LLD values to a 

common value based on a procedure that produces the 

fewest overall changes in the data in order to make that 

adjustment. 

Detailed discussions of the application of the 

unbalanced, nested, analysis of variance design are given 

by Tidball (1976), Tidball and Ebens (1976), and Severson and Tidball (1979) for geochemical studies and by 

Erdman and others (1976) and Erdman and Gough 

(1977) for biogeochemical studies. In the present study 

three analysis of variance levels were employed. The 

design allowed us to estimate how the element content of 

both plant and soil materials varies geographically and 

with sample preparation and analysis. 

The analysis of variance requires completely 

numeric data sets; therefore, all censored data were 

substituted with a real value equal to 0.7 times the LLD 

in ash. This multiplier is an acceptable fraction of the 

LLD as used in these types of studies (see Miesch, 1976). 

We assumed that this substitution would result in valid 

Statistical Analysis of Data 7 
analysis of variance results as long as censoring did not 

exceed about one-third of the total number of values. If 

an element was more than one-third censored, it was 

dropped from the study. 

Fourteen uncensored elements in manzanita and 

fifteen elements (one with censoring) in pine were used 

in R-mode factor analysis. This nonstatistical multivariate technique is used to examine groupings of elements 

and is based on the correlation coefficients between 

elements within a species. A varimax rotation of the 

principal components was performed on the element 

concentration data (variables), and loadings of the 

variables were calculated for each factor (see McNeal 

and others, 1985; Davis, 1986). A loading is equivalent to 

the correlation between the variable and the factor score. 

Statistical analysis of the data was performed using the 

U.S. Geological Survey's STATPAC library (VanTrump 

and Miesch, 1977). 

For three-dimensional surface plots, irregularly 

spaced x, y, and z data were gridded by using an 

interpolation method based on an inverse distancesquared weighted-power algorithm (Golden Software, 

GRID and SURF gridding and plotting programs, 

version 3.0). Cubic-spline smoothing was employed in 

the calculation of the grid lines and x, y, z plots were 

generated that have exaggerated height/width ratios. 

RESULTS AND DISCUSSION 

Biogeochemical Summaries, Gridded 

Study Area 

Powder X-ray Analysis of Plant Ash 

Dry, ground plant material and plant ash were 

analyzed mineralogically using powder X-ray diffraction. 

The ash consists of calcite and fairchildite (a potassium 

calcium carbonate) or natro-fairchildite. These minerals 

are pyrogenically derived from an organic-Ca mineral 

(identified as the calcium oxalate hydrate mineral whewellite) in the dry-ground manzanita leaf material. This 

type of conversion has been reported previously (Milton 

and Axelrod, 1947; Erdman and others, 1977). 

Geometric mean Ca concentrations are 0.67 and 0.27 

percent of the dry material for manzanita and pine, 

respectively (table 2). The X-ray analysis provides no 

information on the possible contribution of any Mgcarbonate minerals (for example, magnesite), even 

though Mg concentrations average 0.34 and 0.24 percent 

of the dry material in manzanita and pine, respectively. 

Summary Statistics 

The concentrations of Cr, Cu, Mg, Nb, Ni, and Zn 

in manzanita and pine are similar (different by less than 

a factor of two )(table 2). Although concentrations of Cr, 

Mg, and Ni are usually high in ultramafic soils, their areal 

patterns are very dissimilar across the study area 

(discussed later). Concentrations of the alkaline-earth 

metals (Ba, Ca, and Sr) are much higher in manzanita 

than in pine (by factors of two to ten). Barium and Sr 

substitute for Cain plant cell walls. Because the manzanita samples consist of some woody material, their higher 

alkaline earth concentrations seems logical. The manzanita and pine samples possess low ash yields typical of 

vegetation samples free of dust; microscopic examination 

of both types of material showed very little surficial 

contamination. 

Data for Ca, Mg, Cr, and Ni in both species 

compare closely with element levels in similar plant 

materials from other serpentine areas in California 

(Koenigs and others, 1982; Wallace and others, 1982). 

TheCa levels in both species are also similar to Ca levels 

in plant materials from nonserpentine areas (Ebens and 

Shacklette, 1982; Kabata-Pendias and Pendias, 1984). In 

general, however, concentrations of Cr, Mg, Ni, and Ti 

are elevated as compared to plant materials from nonserpentine areas, whereas concentrations of AI, Fe, P, 

Pb, and Sr are very much lower (from a factor of about 

two for Fe and P to about eight to ten for AI and Sr). 

Elevated levels of Cr, Mg, and Ni in plant tissue reflect 

the elevated levels of these same elements in the soil, 

which is derived from ultramafic parent material; 

however, soils of the study area are also very high in Fe, 

a trend not reflected in the plants. 

Results of the Analysis of Variance 

The one-way analysis of variance design segregated 

the total variance for each element (in either manzanita 

or pine) between the following sources: (1) among the 

gridded sites, (2) between replicated shrubs or trees at a 

site, and (3) between duplicate analyses of the same 

sample (tables 3, 4). 

Of the elements tested, only Ca concentrations in 

manzanita had an important proportion of their variance 

attributed to the analytical level; 46 percent of the 

variability in these data result from analytical 

imprecision. Except for Ca, therefore, interpretation of 

areal element concentration patterns is possible. Analysis 

of variance was not performed for those elements having 

more than one-third of their values below the lower limit 

of analytical determination. 

Fifteen of sixteen and fifteen of nineteen elements 

in manzanita and pine, respectively, showed a significant 

proportion of their variability among sites; 8 of 16 and 12 

8 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
Table 2. Summary statistics for element concentrations in leaf and stem material of white leaf manzanita and needles of 

digger pine 

[Prior to calculation, data were converted to logarithms; data expressed as ppm, dry-weight base, except where noted; site-replicated samples (12 and 

9, manzanita and pine, respectively) and duplicate analyses (12 for each species) were averaged prior to calculations; ratio, proportion of the number of 

analyses having values above the lower limit of determination to the total number of analyses; GM and GD, geometric mean and deviation, 

respectively; leaders ( --),no data available] 

Element or Manzanita 

ash yield Ratio GM GD Observed range 

Ash% 112:112 30.6 10.20 20.0 - 50.8 

Al 112:112 20 10.40 11 - 68 

As 8:112 <10.2 - 20.6 

Ba 112:112 80.9 10.67 10.2 - 30 

Ca% 112:112 0.67 10.41 0.18 - 10.6 

Cd 44:112 <0.03 - 0.17 

Cr 112:112 10.4 20.13 0.29 - 70.5 

Cu 112:112 40.3 10.43 10.4 - 90.0 

Fe 112:112 28 10.39 13 - 59 

Mg% 112:112 0.34 10.12 0.10 - 0.6 

Mn 112:112 29 10.75 80.0 - 130 

Nb 95:112 0.25 10.36 <0.15 - 0.48 

Ni 112:112 20.6 10.94 0.56 - 13 

P% 112:112 0.052 10.52 0.015 - 0.17 

Pb 2:112 <0.24 - 0.41 

Sr 112:112 14 10.54 30.4 - 34 

Ti 112:112 10.3 10.49 0.60 - 30.2 

v 7:112 <0.04 - 0.08 

y 36:112 <0.007 - 0.036 

Zn 112:112 30 10.25 14 - 50 

of 19, respectively, show significance between replicated 

samples at a site. For most elements, therefore, the 

variability in the data has a strong regional component 

across the study area, as well as a site-specific component. Exceptions include the concentrations of Cu, Nb, 

and Pb in pine, which show significant proportions of 

their variance as between neighboring individuals (table 

4). Regional trends for these elements in pine therefore 

do not occur. The chemistry of manzanita shrubs and 

pine trees separated by 44 m or more should be more 

important, in general, than that of those separated by less 

than about 3 m. 

The strong regional component supports a general 

growth-form characteristic of both species. We observed 

that the lateral root system of an excavated manzanita 

extended 7 m away from the basal burl. At one location, 

where a hillside was truncated by a small stream, the 

roots of a moderately large manzanita were observed to 

extend vertically for more than 5 m through deeply 

weathered serpentinite. Morov (1967) reported that on 

stony soils digger pine characteristically has a welldeveloped, deep-penetrating tap root and extensive, 

spreading root laterals. Our observations support this 

same general trend for pines growing over serpentine. 

The chemistry of the aerial portions of both manzanita 

Digger eine 

Ratio GM GD Observed range 

91:91 20.3 10.20 10.5 - 30.5 

91:91 73 10.56 21 - 170 

1:91 <0.85 - 88 

91:91 0.84 10.49 0.30 - 10.9 

91:91 0.27 10.60 0.086 - 0.80 

11:91 <0.026 - 0.075 

91:91 10.1 10.80 0.42 - 70.5 

91:91 40.2 10.34 10.9 - 90.1 

91:91 91 10.62 16 - 220 

91:91 0.24 10.31 0.12 - 0.46 

91:91 73 10.81 70.8 - 210 

41:91 <0.12 - 0.23 

91:91 40.2 10.82 0.70 - 13 

91:91 0.12 10.32 0.057 - 0.25 

77:91 0.52 10.80 <0.24 - 20.2 

91:91 20.4 10.88 0.59 - 15 

91:91 30.6 10.73 0.73 - 10 

91:91 0.14 10.77 0.024 - 0.37 

18:91 <0.006 - 0.01 

91:91 20 10.49 50.3 - 54 

and pine, therefore, should represent an integration of a 

very large area. By sampling at 44-m intervals, we had 

hoped to minimize root-area overlap, and the results of 

the analysis of variance support this supposition. 

Description of Biogeochemical Patterns 

Interpretation of Univariate Element Associations 

Results of the analysis of variance show that 

regional differences exist in the chemistry of manzanita 

and pine but cannot be used to discern areal patterns. 

Figure 4 graphically depicts the concentration patterns 

for six selected elements and ash yield in manzanita 

shrub stems and leaves and digger pine needles. Except 

for P in pine needles, large proportions of the total 

variance of these six elements occur at a regional scale 

( > 44 m; tables 3, 4). 

The following is a list of the simple correlation 

coefficients (r) between concentrations of the same 

component in manzanita and pine. Correlations were 

calculated between samples taken at 88 sites where both 

species were collected (probability levels and significant 

Results and Discussion 9 
Table 3. Distribution of element concentration variation in 

samples of white leaf manzanita leaf and stem material 

[Unbalanced nested variance analysis based on 137 samples except 

where noted; asterisk (*) indicates variance component tested significant 

at the 0.05 probability level; ratio represents proportion of the number of 

analyses having values above the lower limit of determination to the 

total number of analyses 1 

Anal~sis of variance 

Percentage of total variance 

Between Between 

Total Among shrubs duplicate 

Element or log10 sites at a site analyses 

ash yield Ratio variance (113)1 (12)1 (12)1 

Ash 137:137 0.0064 89* 10* <1 

AI 137:137 0.0217 78* 18* 4 

Ba 137:137 0.0494 78* 16* 6 

Ca 137:137 0.0222 21 33 46 

Cr 137:137 0.1083 91* 8* 1 

Cu 137:137 0.0237 66* 17 17 

Fe 137:137 0.0205 88* 7 5 

Mg 137:137 0.0224 94* 4* 2 

Mn 137:137 0.0592 92* 7* <1 

Nb2 120:137 0.0510 62* 12 26 

Ni 137:137 0.0830 97* 2* 1 

p 137:137 0.0331 84* 12* 4 

Sr 137:137 0.0352 95* 3 2 

Ti 137:137 0.0301 82* <1 18 

Zn 137:137 0.0092 83* 8 9 

1Number of samples representing ANOV level. 

2Data reported as below the lower limit of analytical determination 

were replaced with a value equal to 0.7 times the limit value. 

correlation coefficients follow, P.os ==0.21, indicated by *, 

and P.Dl ==0.27, indicated by **): 

AI 0.332** Cr 0.413** 

Ash yield 0.211 * Cu 0.063 

Ba 0.098 Fe 0.308** 

Ca 0.178 Mg 0.026 

Mn 0.160 Sr 0.247* 

Ni 0.750** Ti 0.207 

p 0.512** Zn -0.131 

These data indicate that the distribution patterns 

for elements having significant positive correlation 

coefficients tend to be similar for both manzanita and 

pine; the larger r, the more similar the pattern. The 

patterns for Ni in manzanita and pine are very similar, 

concentrations are low on the west side of the study area 

and progressively higher toward the east and northeast. 

Aluminum, Cr, Fe, and P have r values between manzanita and pine greater than 0.3 but less than 0.52 and show 

similar areal concentration patterns (fig. 4). Ash yield 

and Sr patterns (r= 0.211 and 0.247, respectively) are 

less similar. These data indicate that manzanita and pine 

Table 4. Distribution of element concentration variation in 

samples of digger pine needles 

[Unbalanced nested variance analysis based on 112 samples except 

where noted; asterisk (*) indicates variance component tested significant 

at the 0.05 probability level; ratio represents proportion of the number of 

analyses having values above the lower limit of determination to the 

total number of analyses 1 

Anal~sis of variance 

Percentage of total variance 

Between Between 

Total Among shrubs duplicate 

Element or log10 sites at a site analyses 

ash yield Ratio variance (91 )

1 (9)1 (12)1 

Ash 112:112 0.0065 90* 9* <1 

Al 112:112 0.0368 87* 12* 1 

Ba 112:112 0.0304 88* 4 8 

Be2 82:112 0.0416 70* 11 19 

Ca 112:112 0.0429 83* 14* 3 

Cr 112:112 0.0651 95* 2 3 

Cu 112:112 0.0164 21 65* 14 

Fe 112:112 0.0435 83* 11* 6 

Mg 112:112 0.0136 79* 11 10 

Mn 112:112 0.0665 89* 8* 3 

Nb2 85:112 0.0294 17 72* 11 

Ni 112:112 0.0676 92* <1 8 

p 112:112 0.0147 51 38* 11 

Pb2 100:112 0.0782 27 56* 17 

Sr 112:112 0.0757 92* 8* <1 

Ti 112:112 0.0567 82* 10 8 

v 112:112 0.0611 84* 8 8 

Zn 112:112 0.0300 73* 24* 3 

1Number of samples representing ANOV level. 

2Data reported as below the lower limit of analytical determination 

were replaced with a value equal to 0. 7 times the limit value. 

may have somewhat similar uptake, translocation, and 

accumulation physiological abilities for AI, Cr, Ni, P, and 

Fe. 

The patterns shown in figure 4 have almost 

opposite surface trends for Cr as compared to Ni and 

possibly Fe. Nickel concentrations, and to a lesser degree 

Fe concentrations, increase from the steep ridges and 

gullies on the west side of the study area to the less 

dissected, more gently sloping low benches of the 

northeast (fig. 3). Chromium, however, shows several 

scattered areas of high concentration; concentrations on 

the west side in the steep ridges and gullies region are 

generally higher. 

The following table of correlation coefficients helps 

quantify these observed relations. The comparisons are 

made between elements within a species, not among 

species, and involve 112 samples of manzanita and 91 

samples of digger pine. Because a large proportion of the 

variability for these elements in each species occurs 

among sites, each sample is considered independently; a 

10 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
value greater than about 0.21 is statistically significant 

but may have only limited importance. 

Manzanita 

Cr Fe Mn Ni 

Cr 0.172 0.009 -0.390 

Digger Fe 0.260 -0.003 -0.174 

pine Mn -0.304 0.076 0.300 

Ni -0.355 0.089 0.713 

These data show that for both species Cr has a 

large, negative correlation with Ni. Strong positive 

correlations occur between Ni and Mn. These data 

support the observed areal trends discussed above and 

shown in figure 4. 

Interpretation of Multivariate 

Element Associations 

In order to better quantify the multivariate nature 

of the relations discussed in the previous section and to 

interpret the mechanism for the element concentration 

patterns, R-mode factor analysis was used to interpret 

the plant chemistry (tables 5, 6). Factor analysis relates 

variables (concentrations of elements) to factors based 

on the correlation coefficients among the variables 

(Davis, 1986). In this study a factor consists of an 

association of elements. The association can often be 

interpreted to indicate a common controlling process 

that may be chemical, physical, or physiological in nature. 

A loading is equivalent to the correlation between the 

variable and the factor score; consequently, the larger the 

loading, the stronger the relation. The composition of 

each factor is shown according to the order of loading on 

that factor. Significance values for loadings do not exist. 

Although the total composition of each factor includes all 

of the variables, we list only the more important onesthat is, those having loadings greater than 0.3 (explains 

more than 9 percent of the total variance of the variable). 

A four-factor model was chosen as optimum; 

factors were extracted until simple structure was 

obtained (Joreskog and others, 1976). For manzanita, the 

four factors explain a total of 62 percent of the total 

variance in the data. The remaining 38 percent of the 

variance is not appreciably explained by increasing the 

number of factors to a maximum of ten. 

For manzanita, factor 1 (table 5) explains 25 

percent of the total variance. In factor 1, ash yield is 

associated with the alkaline-earth metals, Zn, and to a 

lesser degree, Cu, Ni, and Mn. This factor demonstrates 

the physiological correlation between ash yield and Ca. 

Calcium is a major nutrient element and Ba and Sr 

commonly substitute for Ca in plant cell walls. 

A four-factor model was also optimum for pine and 

explains a greater proportion (72 percent) of the total 

variability than for manzanita. Like manzanita, ash yield 

(factor 2, table 6) is identified with the alkaline-earth 

metals; also present are P, Mn, and Mg. Twenty-one 

percent of the variability in the pine data is explained by 

factor 2. 

Both manzanita and pine have an AI, Fe, and Ti 

factor (factor 2, table 5, and factor 1, table 6, 

respectively). As with all peridotite soils, Fe is present in 

great abundance (about 4-14 percent), and because the 

soils are almost neutral (pH from about 6.8 to 7.4), a 

proportion of the Fe would be mobile. Titanium and AI, 

however, are not expected to be readily available for 

uptake. Fe/Ti and Al/Ti ratios for plant analyses versus 

soil analyses are dissimilar and suggest that this factor 

does not reflect the external presence of dust (clay): 

Approximate ratios 

Fe/Ti Al/Ti 

Manzanita 22 15 

Pine 25 20 

A-horizon soil 103 6.8 

B-horizon soil 115 6.6 

Both manzanita and pine possess a factor 

dominated by Cr and Ni (factor 3, tables 5, 6). Although 

this factor makes up only 10 and 12 percent of the total 

variance for manzanita and pine, respectively, the inverse 

association of these two metals is clear. Chromium and 

Ni are not essential elements but are abundant in 

peridotite environments, the former in large 

concentrations in chromite and olivine and the latter in 

olivine and Mg-pyroxene. An important conclusion is 

that both species are responding in a physiologically 

similar manner to the incorporation of Cr and Ni into 

tissue. This conclusion may mean that soils high in Cr do 

not occur in the same location as those high in Ni. 

The composition of factor 4 (tables 5, 6) varies 

greatly and has no readily apparent explanation. This 

factor explains only 10 and 8 percent of the total 

variability in the data. Phosphorus is usually deficient as 

a micronutrient in serpentine soils, not only because of its 

paucity in peridotite minerals, but also because in 

alkaline environments it tends to react with carbonates 

and is rendered unavailable for absorption. Copper is 

found as a substitution element in pyroxene; however, its 

Results and Discussion 11 
Soil pit locations 

Pit OOL 

Pit 08L 

Pit 07H Pit 081 

Pit 07E 

Pit 07C 

Pit 078 

Pit 07G 

Ash Yield, Manzanita Ash Yield, Digger Pine 

Figure 4 (above and folowing pages). Areal concentration patterns for six selected elements and ash yield in manzanita 

shrub stem and leaf material and digger pine needles within the Elder Creek study area. Reference plot shows viewing angle, 

general plot orientation, approximate position of grid lines (tick marks), and position of excavated soil profile sites. 

mobility probably is not great in these soils. Copper, like 

P, is essential for plant growth and if available will be 

absorbed. 

Magnesium loads more strongly on factor 4 for 

manzanita than for pine ( 45 and 10 percent, 

respectively). Once it has weathered free from peridotite, 

it can react with soil carbonate, and we have identified 

hydromagnesite as the dominant carbonate mineral in 

soils of the study area. Hydromagnesite was also 

observed as an evaporite among the serpentine cleavages 

and along headwalls where ground water emerges from 

fractures in the ultramafic bedrock. Although Mg levels 

in these soils are high (typically 10-21 percent) and 

although the presence of evaporites suggests that the 

magnesium is mobile, its uptake by manzanita and pine is 

not great. 

12 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
Iron, Manzanita Iron, Digger Pine 

Manganese, Manzanita 

Manganese, Digger Pine 

Results and Discussion 13 
Aluminum, Digger Pine 

Aluminum, Manzanita 

Chromium, Manzanita Chromium, Digger Pine 

14 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
Nickel, Manzanita Nickel, Digger Pine 

Phosphorus, Manzanita Phosphorus, Digger Pine 

Results and Discussion 15 
Table 5. Results of R-mode factor analysis for manzanita 

stems and leaves showing relative loadings of element 

concentrations on four factors derived by varimax rotation 

[Variables in the multivariate analysis include concentrations of Al, Ba, 

Ca, Cr, Cu, Fe, Mg, Mn, Ni, P, Sr, Ti, Zn, and ash yield] 

Percent 

Factor number and inter12retation variance 

Factor Factor 1 Factor 2 Factor 3 Factor 4 explained 

loading 251 171 101 101 621 

1.0 100 

90 

Ti 

0.9 AI 80 

Ash Fe 

70 

Ca 

0.8 -Cr2 _p2 

Ni 60 

Ba 

0.7 50 

Mg 

40 

0.6 

Zn 

30 

0.5 Sr 

Sr 

20 

0.4 Cu Mn 

Mn 

Cu 

Ni Zn 10 

0.3 

1 Percentage of total variance explained by factor and by all factors. 

2variable with a negative loading. 

Vertical Element Trends in the Soil Profile 

The explanation of the factors discussed above 

helps define the biogeochemical processes that produce 

particular element associations in plants. Additional geochemical information is needed, however, to further 

explain element mobility and uptake processes. 

Based on the areal element concentration patterns 

observed for elements in plant tissue discussed above, in 

1985 soil profiles were exposed at sites (fig. 1) where 

both manzanita and pine showed: (1) high levels of Cr 

and low levels ofNi and Mn (pits 07B, 07C, and 07H), (2) 

high levels of Ni and Mn and low levels of Cr (pits 081 

and OOL), and (3) low levels of all three elements (pits 

07E, 07G, 08L)(fig. 3). These areas were delimited using 

the general patterns shown in figure 4 and element 

concentration percentile maps. 

As discussed in the methods section, paired soil 

samples were collected from the profiles at depths of 0-5, 

10, 20, 40, and 80 em. The consolidation of this material 

varies with depth, from truly loose soils, high in oxidized 

Fe (red), to friable, highly weathered peridotite (gray 

green). Mineralogical identification of parent material in 

Table 6. Results of R-mode factor analysis for digger pine 

needles showing relative loadings of element concentrations 

on four factors derived by varimax rotation 

[Variables in the multivariate analysis include concentrations of AI, Ba, 

Ca, Cr, Cu, Fe, Mg, Mn, Ni, P, Ph, Sr, Ti, Zn, and ash yield~ Ph is the 

only element included in the calculations that possesses censored values 

Percent 

Factor number and interr2retation variance 

Factor Factor 1 Factor 2 Factor 3 Factor 4 explained 

loading 31 1 21 1 121 a1 721 

1.0 100 

AI 90 

Ti Ca 

0.9 Fe 80 

Ni 70 

Ba 

0.8 Ph Ash Mn 

-cu2 60 

Sr 

0.7 -Cr2 50 

p 40 

0.6 

30 

0.5 

-Mg2 20 

0.4 Mg Ash 

Mn Zn 

Cr Ba Ba Mg 10 

0.3 Sr Mg 

1 Percentage of total variance explained by factor and by all factors. 

2variable with a negative loading. 

thin sections from each of the profiles was difficult 

because of extensive weathering and serpentinization; 

however, phenocrysts of unaltered pyroxene grains were 

observed. Parent material having a large number of these 

phenocrysts was classified as saxonite (Rynearson, 1946) 

and parent material having no phenocrysts and remnant 

dunitelike textures was classified as dunite. The 

classification given to the parent material collected at the 

bottom of each soil profile is as follows: 

Soil profile Rock type 

021 Saxonite 

07B Dunite 

07C Dunite 

07E Saxonite 

07G (unknown) 

07H Dunite 

081 Saxonite 

08L Saxonite 

OOL Dunite 

Figure 5 shows the average value for variables 

measured in paired samples from two profiles, 081 and 

07G; element concentrations represent total amounts. 

16 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
Based on both physical setting and on element 

concentrations, these two profiles were selected as 

qualitatively representative end-member examples of the 

spectrum of differences in the nine profiles excavated. 

Profile 08I is typical of the gently sloping ( < 5 percent), 

bench regions within the study area (fig. 3). It seems to 

represent a higher degree of weathering relative to pits 

located in more steeply sloping terrain. The Mg!Fe ratio 

in the top 20 em of profile 08I is considerably lower than 

that for profile 07G. This relative decrease in Mg and 

corresponding increase in Fe is due to Mg removal by 

ground waters and is usually considered to represent a 

high degree of weathering in serpentine-derived soils 

(Wildman and others, 1968). 

Pit 08I is in an area where both manzanita and pine 

show relatively high levels of Ni and Mn and low levels of 

Cr. Pit 07G, typical of the steep ridges and gullies, is 

located where manzanita and pine show low levels of Cr, 

Ni, and Mn. This latter pit is on the side of a 15-percent 

slope that has deep, transported soil. 

In general, profile 081 shows higher total 

concentrations of the elements selected than does profile 

07G; AI is different by almost an order of magnitude, but, 

more commonly, a factor of only 2 or 3 separates the 

values in the two pits. Vertically, the profile in the gully 

having transported soil (07G) shows very uniform 

concentrations with depth; the variability in the profile on 

the nearly level bench (08I) is much greater. This latter 

profile shows decreases in Ca, Cr, and organic C with 

depth and an increase in soil moisture. Profile 07G shows 

only a major decrease in organic C with depth; soil 

moisture increases but, unlike 08I, only within the first 10 

em. The profile in the gully shows considerably higher pH 

values than profile 08I; pH does not appreciably vary 

with depth in either profile. 

As determined through the use of element 

concentration percentile maps (mentioned above), 

profile 08I is in an area where both manzanita and pine 

show generally high levels of Ni and Mn and low levels of 

Cr; profile 07G is in an area where manzanita shows 

generally low levels of all three elements (pine was not 

collected here). Based solely on total soil chemistry, the 

soil samples from these profiles are directly related to 

this general plant -chemistry observation. In addition, 

because pH is lower in the soils from 08I, it follows that 

more mobile forms of the metal cations might be 

available to plants in this region. 

Uptake and Translocation of 

Elements by Manzanita 

A manzanita shrub was excavated near pit 07G (fig. 

1) in an attempt to understand the importance of element 

uptake and translocation. Figure 6 shows the total 

concentration of six elements (ash-weight base) and ash 

yield in manzanita root, basal burl, stem, and stem and 

leaf samples collected at eight locations along the 

excavated shrub. Soil contamination was minimal 

because of the very smooth and easily peeled nature of 

manzanita root epidermis. 

The ratio of Ca to Mg in plant tissue increases from 

root tissue to stems (fig. 7, upper), as expected for a plant 

growing in a soil high in available Mg relative to Ca. This 

ratio then decreases in the terminal leaf tissue, where Mg 

plays a major role in photosynthesis. The Ca!Mg ratio of 

2.8 in terminal leaf tissue is similar to a ratio of 2.2 

reported by Wallace and others (1982) for a different 

species of California serpentine manzanita; the absolute 

concentrations are considerably different (Ca ~0.54 and 

Mg ~0.25 percent), probably because we included stem 

tissue in our samples. The ash yield increases from the 

small secondary roots to the larger primary roots, 

decreases at the basal burl, and then increases toward the 

stems and leaves. This pattern may result both from 

differences in tissue type and because the ground 

samples were not dried at temperatures greater than 40° 

C prior to analysis. By comparing element trends only on 

an ash-weight basis, however, problems due to 

differences in ash yield are avoided. 

Figure 7 (lower) shows trends for Cr, Fe, Ni, and 

Mn with respect to distance from the basal burl. 

Chromium, Fe, and Ni behave similarly in that they 

decrease in concentration from the secondary to the 

primary roots and then greatly increase in the basal burl 

before continuing to decrease toward the stems and 

leaves. Although relatively little Cr, Fe, or Ni are translocated along the roots, the basal burl appears to 

accumulate these elements; at the very least, the burl is a 

central collecting point for root -translocated elements. 

Also, very little Cr, Fe, or Ni are translocated to the 

leaves. 

Iron and Mn are essential elements and both are 

involved in respiration reactions, enzyme activation, and 

electron transport. Unlike Mn and other essential 

cations, however, Fe is relatively immobile within plant 

tissue. Figure 7 (lower) clearly shows that Mn, and not 

Fe, is readily translocated to the secondary stems and 

leaves where it is concentrated by an order of magnitude 

over what is in the burl. 

We sampled only tissue associated with major 

lateral roots, not the mass of smaller, less readily 

traceable feeder rootlets, and our observations of metal 

translocation do not account for the activity of these 

rootlets. The soil pit excavations reveal that a great 

majority of manzanita and pine rootlets occur at depths 

of about 15 em or less. The relative importance of metal 

uptake by the major deep laterals as compared to the 

shallow rootlets is unknown. 

Results and Discussion 17 
..... 

C» 

tD 

o· 

co 

CD 

0 

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CD 

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c;;· 

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-< 

2. t ~ 0 ~ 0 I I I :::T 

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3 t ::+ 

CD I I I 

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0.0 0.5 1.0 1.5 1o-1 1 10 0.0 0.5 1.0 1.5 

CALCIUM, IN PERCENT ALUMINUM, IN PERCENT CHROMIUM, IN PERCENT 

20 

40 

60 

80 

~ \ 

t 

\ 

f 

I 

I 

I 

I 

I 

t 

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I 

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100 I Ill !IIIII Ill! II Ill I Ill I Ill I ''''11''1' II' 

0.1 0.2 0.3 0.4 0.5 

NICKEL, IN PERCENT 

Figure 5 (above and following three pages). Soil physical and chemical variables for soil profiles 081 (circles) and 07G (triangles) plotted as a function of depth in 

excavated soil pits. Profile 081 was in the gently sloping, high bench area, which has moderate to good soil development; profile 07G was in the steep, eroded ridge and 

gully region, which has a moderate to deep layer of transported soil. 
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ORGANIC CARBON, IN PERCENT 

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SOIL MOISTURE, IN PERCENT MAGNESIUM, IN PERCENT 
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20 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 

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<· 

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> :>> Fe(%) 1.2 

Mg(%) > 10 :.::: f ·:; 

Mn (ppm) 900 •:•:> Ni (ppm) 560 

··:•::.::::::::·•.···: .• : ••• /?:·••::··: .... ·••...:•:•····· •·•·•·• 

:::> :>:: 

: ........ ····•· :::;: ::::: 

Figure 6. Relative position and the concentration of selected elements (ash-weight basis) in sampled materials from whiteleaf 

manzanita shrub. 

Biogeochemical Exploration for Chromium 

Our report of the inability of manzanita to readily 

translocate Cr from roots to aerial tissue is apparently a 

common characteristic of serpentine vegetation in 

general (Koenigs and others, 1982; Wallace and others, 

1982). That plant species physiologically block the 

transport of, or selectively accumulate, potentially toxic 

metals is well documented (Gough and others, 1979). 

Nevertheless, it may be possible to use manzanita, and 

possibly pine, as an aid in the exploration of concealed 

chromite deposits. 

Our data show complementary Cr trends across 

the study area for both manzanita and pine. Although 

highly immobile and resistant, detrital chromite is the 

most common form of Cr in these soils; if oxidized to the 

hexavalent state, a large amount of Cr could be made 

available for uptake. We have semiquantitatively 

measured highly variable amounts of mobile Cr(VI) in 

about half of the excavated soil pits, as well as in water 

from ephemeral streams that drain the study area 

(Meadows and others, 1987). The occurrence of Cr(VI) 

in s~ils and waters offers an explanation as to the 

probable Cr form absorbed by plants. Investigations into 

the mechanism for the oxidation of Cr(III) to Cr(VI) and 

of Cr speciation in these ultramafic soils are ongoing. 

The vegetation shows high levels of Cr in samples 

collected in the steep ridge and gully region (fig. 4 ), 

which was, until the early 1950's, the area of chromite 

mining. Two inactive chromite mines are on the western 

edge of this region (fig. 2). This study, however, cannot 

definitively distinguish between the relative importance 

of the old chromite mines and prospects and the possible 

influence of the concomitant highly dissected 

topography. 

Results and Discussion 21 
A 30~------------------------------------~ 

EXPLANATION 

B 

13 

EXPlANATION 

12 oCr (xlOO) ? oFe I 

oMn I 

I 

0 !). Ni(xlO) I 

I 

8~10 I 

I 

x s I 

I 

I 

2 I 

a.. I 

a.. 8 I 

I 

~ I 

I z7 I 

I 

0 I 

I i= 6 I 

<( I 

a: I 

I 1- 5 I z I 

w I 

u 4 I 

z I 

I 0 ~ u 3 / / 

2 o-------- / / 

0----~--------o-----o-~ 

0 

-10 -8 -6 -4 -2 0 2 4 6 

DISTANCE FROM BASAL BURL, IN METERS 

Figure 7. Relation between distance from the basal burl 

(noted as zero) of an excavated manzanita shrub and (A)the 

concentrations of Ca and Mg and ash yield and (B) the 

concentrations of Cr, Fe, Mn, and Ni in samples of roots 

(negative distance) and stems and leaves (positive distance). 

All concentrations are on an ash-weight basis. 

In general, we found that the uptake of Cr by 

manzanita and pine in these serpentinized, chromite-rich 

soils probably involves both the physical dissemination of 

chromite and the active formation of Cr(VI) by the 

oxidation of Cr(III). The north-trending shear zones that 

form the prominent erosional gullies in the western half 

of the study area appear to have accentuated the breakup 

of chromite pods and dissemination of chromite in 

general. Chromium is geochemically immobile as detrital 

chromite (mixed oxides and hydroxides of Cr and Fe); 

however, the dispersed chromite grains offer greater 

surface area for potential oxidation. Preliminary studies 

show that soil Cr is being oxidized to Cr(VI)(Gough and 

others, 1986). Once it is oxidized, it apparently remains in 

the hexavalent state for some time and concentrations of 

Cr(VI) as great as 250 ppb have been found (Meadows 

and others, 1987). These concentrations were observed 

in both the dry season (August) and when ephemeral 

streams were flowing through the area (March). This 

discovery implies either that the residence time of Cr(VI) 

in these soils can be measured in months or years or that 

oxidation actively occurs throughout the year. The 

presence of organic matter can serve to reduce Cr(VI) 

and thus decrease its residence time in the soil; however, 

organic carbon is never greater than 4 percent in the soils 

(fig. 5) and it is concentrated in only a few centimeters 

near the surface. 

A mechanism for the oxidation of Cr(III) is still 

being sought. We have observed Fe- and Mn-oxide 

coatings on pebbles in the shear-zone gullies; oxidized 

Mn has been reported by Bartlett and James (1979) as an 

electron acceptor that affects the oxidation of Cr(III) to 

Cr(VI) in many field soils. Oxidation of Cr may also be 

aided by the occurrence of brush fires (Cary, 1982), 

which are common in the chapparal ecosystem. These 

fires may oxidize both surface-soil Cr and Cr in plant 

material that then becomes part of the soil. Also, soil pH 

and aeration in the study area are certainly favorable for 

oxidation. 

A mechanism for biogeochemically defining the 

occurrence of concealed chromite deposits is far from 

refined. It would appear, however, that in areas where 

chromite surface area is increased (through weathering 

and dissemination) and Cr oxidation can occur, it may be 

possible to use plant chemistry to identify general target 

areas for further exploration. 

Future biogeochemical exploration studies in 

similar terrain should investigate the use of basal burl 

tissue. Because the root system translocates absorbed 

elements to the burl from a volume of surrounding soil, 

the burl both concentrates and integrates the geochemistry of a large area. Because of this integration 

process there is probably less seasonal variability in the 

concentration of elements in burl as compared to stem or 

leaf tissue. Further, we found that the concentration of 

Cr and Ni is about 3.0 and 2.5 times greater, respectively, 

in the burl as compared to stems and leaves, thus 

enhancing the analytical detection of these elements. 

22 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
REFERENCES CITED 

Bartlett, R., and James B., 1979, Behavior of chromium in soils; 

III, Oxidation: Journal of Environmental Quality, v. 8, 

p. 31-35. 

Bayer, K.C., 1983, Structural, lithological, and physiographic 

provinces in the fold and thrust belts of the United 

States: 2 maps, 1:2,500,000 scale, published by author. 

Blake, M.C., Jr., Harwood, D.S., Belley, E.J., Irwin, W.P., 

Jayko, A.S., and Jones, D.L., 1984, Preliminary geologic 

map of the Red Bluff 100,000 quadrangle, California: 

U.S. Geological Survey Open-File Report 84-105. 

Blake, M.C., Jr., Howell, D.C., and Jones, D.L., 1982, 

Preliminary tectono-stratigraphic terrane map of 

California, scale 1:750,000: U.S. Geological Survey 

Open-File Report 82-593. 

Brooks, R.R., 1984, Biological methods of prospecting for 

minerals: New York, John Wiley and Sons, 322 p. 

Cary, E.E., 1982, Chromium in air, soil and natural waters, in 

Langard, S., ed., Biological and environmental aspects of 

chromium: Amsterdam, Elsevier Biomedical Press, 

p. 49-64. 

Church, S.E., Mosier, E.L., and Motooka, J.M., 1987, 

Mineralogical basis for the interpretation of multielement (ICP-AES), oxalic acid, and aqua regia partial 

digestions of stream sediments for reconnaissance 

exploration geochemistry: Journal of Exploration 

Research, v. 29, p. 207-233. 

Cohen, A.C., Jr., 1959, Simplified estimators for the normal 

distribution when samples are singly censored or 

truncated: Technometrics, v. 1, p. 217-237. 

Davis, J.C., 1986, Statistics and data analysis in geology (2nd 

ed.): New York, John Wiley and Sons, 646 p. 

DeYoung, J.H., Lee, M.P., Lipin, B.R., 1984, International 

strategic minerals inventory summary report-chromium: U.S. Geological Survey Circular 930-B, 41 p. 

Dickey, J .S., 1975, A hypothesis of origin for podiform chromite 

deposits: Geochimica et Cosmochimica Acta, v. 39, 

p. 1051-1074. 

Diller, J.S., Westgate, L.G., and Pardee, J.T., 1921, Deposits of 

chromite in California, Oregon, Washington, and 

Montana: U.S. Geological Survey Bulletin 725-A, 

p. 1-67. 

Ebens, R. J ., and Shacklette, H. T., 1982, Geochemistry of some 

rocks, mine spoils, stream sediments, soils, plants, and 

waters in the Western Energy Region of the Conterminous United States: U.S. Geological Survey 

Professional Paper 1237, 173 p. 

Erdman, J.A., and Gough, L.P., 1977, Variation in the element 

content of Pannelia chlorochroa from the Powder River 

Basin of Wyoming and Montana: The Bryologist, v. 80, 

p. 292-303. 

Erdman, J.A., Gough, L.P., and White, R.W., 1977, Calcium 

oxalate as the source of high ash yields in the terricolous 

lichen, Pannelia chlorochroa: The Bryologist, v. 80, 

p. 334-339. 

Erdman, J.A., Shacklette, H.T., and Keith, J.R., 1976, 

Elemental composition of selected native plants and 

associated soils from major vegetation-type areas in 

Missouri: U.S. Geological Survey Professional Paper 

954-C, 87 p. 

Gough, L.P., Meadows, G. R., and Jackson, L. L., 1986, Uptake 

of chromium by vegetation and its mobilization in ultramafic soils, California: Soil Science Society of America, 

Agronomy Abstracts, v. 78, p. 168. 

Gough, L.P., Shacklette, H.T., and Case, A.A., 1979, Element 

concentrations toxic to plants, animals, and man: U.S. 

Geological Survey Bulletin 1466, 80 p. 

Hanes, T.L., 1977, California chaparral, in Barbour, M.G., and 

Major, J., eds., Terrestrial vegetation of California: New 

York, John Wiley, p. 428-440. 

Harms, T.F., 1976, Analysis of plants and plant ashes by 

methods other than emission spectroscopy, in Miesch, 

A.T., Geochemical survey of Missouri, methods of 

sampling, laboratory analysis, and statistical reduction of 

data: U.S. Geological Survey Professional Paper 954-A, 

p. 17-18. 

Hutchison, C.S., 1983, Economic deposits and their tectonic 

setting: New York, Wiley-Interscience, 365 p. 

Irwin, W.P., 1964, Late Mesozoic orogenies in the ultramafic 

belts of northwestern California and southwestern 

Oregon: U.S. Geological Survey Professional Paper 

501-C, p. C1-C9. 

Irwin, W.P., 1966, Geology of the Klamath Mountains 

Province, in Geology of Northern California: California 

Division of Mines and Geology Bulletin 190, p. 19-62. 

Jackson, L.L., Brown, F.W., and Neil, S.T., 1988, Major and 

minor elements requiring individual determinations, 

classical whole rock analysis, and rapid rock analysis, in 

Baedecker, P.A., ed., Geochemical methods of analysis: 

U.S. Geological Survey Bulletin 1770, p. G1-G23. 

Joreskog, K.G., Klovan, J.E., and Reyment, R.A., 1976, 

Methods in geomathematics 1, Geological factor 

analysis: New York, Elsevier, 178 p. 

Kabata-Pendias, A., and Pendias, H., 1984, Trace elements in 

soils and plants: Boca Raton, Florida, CRC Press, 315 p. 

Koenigs, R.L., Williams, W.A., Jones, M.B., and Wallace, A., 

1982, Factors affecting vegetation on a serpentine soil; II, 

Chemical composition of foliage and soil: Hilgardia, v. 

50, p. 15-26. 

Kruckeberg, A.R., 1984, California serpentines, flora, 

vegetation, geology, soils, and management problems: 

Berkeley, University of California Press, 180 p. 

LeBlanc, M., and Violette, J.F., 1983, Distribution of 

aluminum-rich and chromium-rich chromite pods in 

ophiolite peridotites: Economic Geology, v. 78, 

p. 293-301. 

Lichte, F.E., Golightly, D.W., and Lamonthe, P.J., 1988, 

Inductively coupled plasma-atomic emission 

spectrometry, in Baedecker, P.A., ed., Geochemical 

methods of analysis: U.S. Geological Survey Bulletin 

1770, p. B1-B10. 

References Cited 23 
Lipin, B.R., and Thayer, T.P., 1980, The outlook for small 

chromite mines, in Meyer, R.F., and Carman, J.S., eds., 

The future of small scale mining: New York, United 

Nations Institute for Training and Research (UNITAR), 

p. 191-196. 

McNeal, J.M., Severson, R.C., and Gough, L.P., 1985, The 

mode of occurrence of extractable elements in soils from 

the Northern Great Plains: Soil Science Society of 

America Journal, v. 49, p. 873-881. 

Meadows, G.R., Dudka, S., Jackson, L.L., Gough, L.P., and 

Briggs, P.H., 1988, Analytical results and sample locality 

map of whiteleaf manzanita, digger pine, soil and water 

samples, Redding CUSMAP sheet biogeochemical study, 

Tehama County, California: U.S. Geological Survey 

Open-File Report 88-595, 27 p. 

Meadows, G.R., Jackson, L.L., and Gough, L.P., 1987, Pulse 

polarographic determination of naturally occurring 

Cr(VI) in soils and waters [ abs.]: Rock")' Mountain 

Section Society for Applied Spectroscopy, 29th 

Conference, Aug. 2-6, 1987, Program, p. 32. 

Miesch, A.T., 1976, Geochemical survey of Missouri-Methods 

of sampling, laboratory analysis, and statistical reduction 

of data: U.S. Geological SuiVey Professional Paper 

954-A, 39 p. 

Milton, C. and Axelrod, J ., 194 7, Fused wood-ash stones: 

Failchildite (n. sp.) K2C03.CaC03, buetschliite (n. sp.) 

3K2C03.2CaC03.6H20 and calcite, CaC03, their 

essential components: The American Mineralogist, v. 32, 

p. 607-624. 

Morning, J.L., 1978, Chromium, in 1976 Bureau of Mines 

minerals yearbook: U.S. Bureau of Mines, p. 1-12. 

Morov, N.T., 1967, The genus Pinus: New York, Ronald Press, 

602 p. 

Page, N.J., and Johnson, M.G., 1977, Chromite resources ofthe 

podiform chromite deposits and exploration for 

concealed chromite deposits in the Medford-Coos Bay 

quadrangles, southwestern Oregon: U.S. Geological 

SuiVey Open-File Report 77-656, 14 p. 

Papp, J.F., 1983, Chromium: U.S. Bureau of Mines Mineral 

Commodity Profile, 21 p. 

Peech, M., 1965, Hydrogen-ion activity, in Methods of soil 

analysis, Part 2, Agronomy 9: American Society of 

Agronomy, p. 922-923. 

Rynearson, G.A., 1946, Chromite deposits of the North Elder 

Creek area, Tehama County, California: U.S. Geological 

SuiVey Bulletin 945-G, p. 191-210. 

Severson, R.C., and Tidball, R.R., 1979, Spatial variation in 

total element concentration in soil within the northern 

Great Plains coal region: U.S. Geological Survey 

Professional Paper 1134-A, p. A1-A18. 

Starkey, H.C., Blackmon, P.D., and Hauff, P.L., 1984, The 

routine mineralogical analysis of clay-bearing samples: 

U.S. Geological SuiVey Bulletin 1563, 32 p. 

Strand, R.G., 1962 [1976], Geologic map of California, Redding sheet: California Division of Mines and Geology, 

scale 1:250,000, 1 sheet plus index. 

Thayer, T.P., 1966, Chromite, in Mineral resources of 

California: California Division of Mines and Geology 

Bulletin 191, p. 120-126. 

__ 1973, Chromium, in Brobst, D. A., and Pratt, W. P., eds., 

United States mineral resources: U.S. Geological SuiVey 

Professional Paper 820, p. 111-121. 

Thayer, T.P., and Lipin, B.R., 1978, A geological analysis of 

world chromite production to the year 2000 A.D.: 

Council of Economics, American Institute of Mining, 

Metallurgical and Petroleum Engineers, Feb. 26-Mar. 2, 

1978, Denver, Colo., Proceedings, p. 143-152. 

Tidball, R.R., 1976, Chemical variation of soils in Missouri 

associated with selected levels of the soil classification 

system: U.S. Geological SuiVey Professional Paper 

954-B, p. B1-B15. 

Tidball, R.R., and Ebens, R.J., 1976, Regional geochemical 

baselines in soils of the Powder River Basin, MontanaWyoming, in Laudon, R. B., ed., Geology and energy 

resources of the Powder River: Wyoming Geological 

Association, Annual Field Conference, 28th, Guidebook, 

p. 299-310. 

VanTrump, George, Jr., and Miesch, A.T., 1977, The U.S. 

Geological Survey RASS-STATPAC system for 

management and statistical reduction of geochemical 

data: Computers and Geoscience, v. 3, p. 475-488. 

Walker, R.B., 1954, The ecology of serpentine soils; II, Factors 

affecting plant growth on serpentine soils: Ecology, v. 35, 

p. 259-266. 

Wallace, A., Jones, M.B., and Alexander, G.V., 1982, Mineral 

composition of native woody plants growing on a 

serpentine soil in California: Soil Science, v. 134, p. 

42-44. 

Wells, F.G ., and Hawkes, H. E., 1965, Geological investigations 

of chromite in California, Part I, Klamath Mountains: 

California Division of Mines and Geology Bulletin 134, 

chapter 1, p. 130-191. 

Wells, F.G., Cater, F.W., and Rynearson, G.A., 1964, Chromite 

deposits of Del Norte County, California: California 

Division of Mines Bulletin 134, chapter 1, p. 1-47. 

Wildman, W.E., Jackson, M.L., and Whittig, L.D., 1968, Serpentinite rock dissolution as a function of carbon dioxide 

pressure in aqueous solution. American Mineralogist, v. 

53, p. 1252-1263. 

*U.S GPO: 1990 773-047/06025 

24 Biogeochemistry of Chromite-Rich Ultramafic Area, Tehama County, California 
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