. ... ··; 

. . ~ ·. . . 

. -~ '. ·: . .,.·} '· ' .... ..:~ . . ····" ··· . 

.. 

OF .. THE AlAE 

Crystallization and Differentiation 

of the Alae Magma, 

Alae Lava Lake, Hawaii 

By THOMAS L. WRIGHT and DALLAS L. PECK 

SOLIDIFICATION OF ALAE LAV"A LAKE, HAWAII 

G E 0 L 0 G I C A L S U R V E Y P R 0 F E S S I 0 N A L P A P E R 9 3 5-C 

An account of the crystallization history 

and chemical differentiation of tholeiitic basalt 

from one of Kilauea's lava lakes 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1978 
UNITED STATES DEPARTMENT OF THE INTERIOR 

CECIL D. ANDRUS, Secretary 

GEOLOGICAL SURVEY 

H. William Menard, Director 

Library of Congress Cataloging in Publication Data 

Wright, Thomas Llewellyn. 

Crystallization and differentiation of the Alae magma, Alae lava lake, Hawaii. 

(Solidific.ation of Alae lava lake, Hawaii) 

(Geological Survey professional paper; 935-C) 

Bibliography: p. 

1. Lava-Hawaii-Alae lava lake. 2. Phase rule and equilibrium. I. Peck, Dallas Lynn, 1929- joint author. 

II. Title. III. Series. IV. Series: United States. Geological Survey. Professional paper; 935-C. 

QE461.W84 552'.2 77-17801 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 

Stock Number 024-001-03093-4 
CONTEN~rs 

Abstract 

Introduction ------------------------------------------------------------------

AcknovvledgT.nents ------------------------------------------------------------

~ethods of study --------------------------------------------------------------

Drilling --------------------------------------------------------------------

Page 

C1 

1 

2 

2 

2 

Temperature measurements 4 ------------------------------------------------

Laboratory studies -------------------------------------------------------- 4 

Petrology of Alae basalt ------------------------------------------------------ 7 

Bulk chemical composition ------------------------------------------------ 7 

Chemical modes ------------------------------------------------------------ 11 

Petrography -------------------------------------------------------------- 13 

Discussion -------------------------------------------------------------------- 16 

~ineral paragenesis --------------------------------------------------------

Rates of crystallization of minerals -----------------------------------------

Variation of liquid composition during crystallization ------------------------

Natural differentiates of Kilauean tholeiite --------------------------------

Summary ----------------------------------------------------------------------

References cited ---------------------------------------------------------------

ILLUSTRATIONS 

16 

17 

18 

18 

19 

19 

Page 

FIGURE 1. Index map shovving topographic contours and location of drill holes __ C3 

2-4. Graphs shovving: 

TABLE 1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

2. ~odal data for Alae lava lake ---------------------------- 14 

3. Weight percent glass plottE~d against temperature --------- 15 

4. Liquid line of descent ------------------------------------ 17 

TABLES 

Record of drill holes in Alae lava la.ke ------------------------------

Drill cores from Alae lava lake ----------------------------·--------

Chemical analyses of undifferentiated and differentiated samples, Alae 

lava lake -------------------------------------------------------- Chemical analyses of mineral and glass separates, Alae lava lake .. 

Composition of residual glass, Alae lava lake------------------------

Computer-calculated chemical modes, Alae lava lake _________________ _ 

Mineral analyses used in mixing cal.culations ------------------------

Comparison of observed and calculated values of relatively incompatible trace elements in Alae lava lake ------------------------

Petrographic modes for selected oozes from Alae lava lake ·-----------

Page 

C2 

5 

8 

10 

10 

11 

12 

13 

16 

III 
IV 

Metric unit 

millimeter (mm) meter (m) 

kilometer (km) 

square meter (m2) 

square kilometer (km2) 

hectare ( ha) 

cubic centimeter (cm3) 

liter (L) 

cubic meter (m3) 

cubic meter cubic hectometer (hm3) 

liter 

liter 

liter 

cubic meter 

cubic meter 

gram (g) 

gram 

tonne (t) tonne 

CONTENTS 

METRIC-ENGLISH EQUIVALENTS 

English equivalent ;\:letric unit English equivalent 

Length Specific combinations-Continued 

0.0:3937 inch (in) 

3.28 feet ( ft) 

.62 mile (mi) 

Area 

10.76 

.386 

2.47 

Volume 

0.061 

61.03 

35.31 

.00081 = 810.7 

2.113 

1.06 

.26 

.00026 

6.290 

Weight 

0.035 

.0022 

1.1 

.98 

square feet (ft2) 

square mile (mi2) acres 

cubic inch (ina) 

cubic inches 

cubic feet (ft3) 

acre-foot ( acre-ft) 

acre-feet 

pints (pt) 

quarts (qt) gallon (gal) 

million gallons (:M:gal or 10s gal) 

barrels (bbl) (1 bbl=42 gal) 

ounce, avoirdupois (oz avdp) 

pound, avoirdupois (lb avdp) 

tons, short (2.000 lb) 

ton, long (2,240 lb) 

cubic meter per rsecond 

(m3/s) 

liter per second (L/s) 

cubic meter per second 

per square kilometer 

[ (m3/s)/km2] 

meter per day (m/ d) meter per kilometer 

(m/km) 

kilometer per hour 

(km/h) 

meter per second (m/s) meter squared per day 

(m2 /d) 

cubic meter per second 

(m3 /s) 

cubic meter per minute 

(m3/min) 

liter per second (L/s) 

liter per second per meter [ (L/s) /m] 

kilometer per hour 

(km/h) meter per second (m/s) 

gram per cubic 

centimeter (g/em3) 

gram per square 

centimeter (g/ cm2) 

gram per square 

centimeter 

35.3 

.0353 

91.47 

3.28 

5.28 

.9113 

3.28 

10.764 

22.826 

= 264.2 

15.85 

4.83 

.62 

2.237 

62.43 

2.048 

.0142 

cubic feet per second (ft3/s) 

cubic foot per second 

cubic feet per second per 

square mile [ (ft3/s) /mi2] 

feet per day (hydraulic 

conductivity) (ft/d) 

feet per mile (ft/mi) 

foot per second (ft/s) 

feet per second 

feet squared per day (ft2/d) 

(transmissivity) 

million gallons per day (Mgal/d) 

gallons per minute (gal/min) gallons per minute 

gallons per minute per foot 

[(gal/min) /ft] 

mile per hour (mi/h) 

miles per hour 

pounds per cubic foot (lb/ft3) 

pounds per square foot (lb/ft2) 

pound per square inch (lb/in2) 

Specific combinations Temperature 

kilogram per square 

centimeter (kg/cm2) kilogram per square 

centimeter 

0.96 

.98 

atmosphere (atm) 

bar (0.9869 atm) 

degree Celsius (°C) 

degrees Celsius 

(temperature) 

1.8 degrees Fahrenheit (°F) 

= [ (1.8X °C) +32] degrees Fahrenheit 
SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA, 

ALAE LAVA LAKE, HAW All 

By THOMAS L. WRIGHT and DALLAS L. PEcK 

ABSTRACT 

The 15-m-thick lake of lava, which erupted into Alae pit 

crater in August 1963, has been sampled by core drilling 

through the crust and by emplacing ceramic probes in the 

melt. Temperature profiles were obtained by inserting 

thermocouples in open drill holes. Petrographic studies of 

pumice and drill cores, combined with chemical analyses of 

crust, melt, filter-pressed liquids (oozes), and mineral and 

glass separates, show the sequence of crystallization in a 

tholeiitic basalt. 

Olivine (Foso) is the first mineral to crystallize at about 

1,190°C, followed closely by augite (Wo!oEn!,.~Fsn.2) at 1,180°-

1,185oC and plagioclase (An7o) at 1,165°-1,170oC. Ilmenite 

(Ilm9oHemlo) first appears at 1,070°C, followed by pigeonite 

(composition unknown) at about 1,050°C, magnetite at about 

1,030oC, and apatite at l,Ol0°C. The solidus is 980°C. 

Plagioclase changes composition during crystallization 

from An1o in the pumice to an average composition of An59 

in the crystallized basalt. Traces of sodic plagioclase and 

alkali feldspar were detected during the separation of the 

residual glass for analysis. Bulk clinopyroxene in the crystallized basalt is calculated to have an "FeO" /MgO ratio of 

1.3. Olivine was zoned to at least Fom before it ceased 

crystallizing at about 1,100°C. 

The Alae basalt is a tholeiite that has a very uniform 

bulk composition as follows: Si02=50.47; Al20a=13.67; Fe20a 

=1.30; Fe0=9.80; Mg0=7.55; CaO=ll.ll; Na20=2.38; K20 

=0.54; Ti02=2.74; P::05 =0.27; Mn0=0.17. During crystallization of silicates, but before the appearance of Fe-Ti 

oxides, the liquid changes composition with, overall, a slight 

decrease in Si02 and decreases in Al20a, MgO, and CaO, and 

increases in "FeO," Na20, K"O, P20.,, and Ti02. Following 

the appearance of opaque phases, Al20:1 shows little change, 

MgO and CaO continue to decrease, Si02, Na20, K20, and 

P20s increase; Ti02 and "FeO" reach a maximum, then decrease. P205, which is progressively enriched in the liquid 

throughout most of the crystallization, eventually goes into 

apatite. Among minor elements, Cr and Ni are depleted and 

Ba, Cu, Li, Nb, Rb, Y, Yb, and Zr are enriched in successively 

lower temperature liquids. Sr remains nearly constant, Ga 

shows a slight increase in late liquids, and V reaches a maximum and then is depleted in lower temperature liquid. The 

residual liquid, represented by a colorless glass making up 

about 6 percent by weight of the crystallized basalt, contains more than 75 percent Si02 and can be calculated to 

consist of more than 95 percent quartz plus feldspar. Its 

composition corresponds to a calc-alkaline rhyolite. 

Liquids (oozes) that flow into open drill holes were found 

to have brought in less than 10 percent crystals from the 

enclosing partly crystalline crust. Within this crystal fraction the plagioclase/pyroxene ratio tends to be higher than 

in the host rock, suggesting that plagioclase and pyroxene 

were separated during flow. 

Extensive use has been made of "chemical modes," the 

computation of mineral and liquid proportions from knowledge of the chemical composition of a rock and its constituent 

phases. It is shown that optical modal data for Alae basalt 

are grossly in error; pyroxene is overestimated by 20 percent and opaque minerals by a factor of two, and plagioclase 

is correspondingly underestimated. Using the chemical modal 

data, the crystallization curve is shown to be S-shaped and 

to have a horizontal discontinuity at the temperature of the 

crust-melt interface. 

INTRODUCTION 

The eruption of Kilauea Volcano in August 1963 

ponded a basaltic flow in the bottom of Alae Crater, 

forming a stagnant lava lake. Six days after the 

eruption we drilled a hole 0.9 m into the crust, an 

estimated 8 em less than the thickness of the crust. 

The following day we measured a temperature profile in that drill hole. During 1963 and 1964 we 

drilled 11 additional holes from which 17 kg of core 

were recovered. Additional samples of molten basalt 

were collected in ceramic combustion tubes and on 

thermocouples. Repeated temperature measurements 

were made in the open drill holes during 1963 and 

1964 while the lake solidified and for another three 

years while the lake continued to cool. The center 

of the lake reached ambient temperature by August 

1967. Petrographic, mineralogical, and chemical 

studies of samples of melt, drill core, and quenched 

samples of pumice provide data that contribute to 

our knowledge of the crystallization and, particularly, differentiation of tholeiitic basalt. 

Cl 
C2 SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

The following preliminary reports describe aspects 

of the cooling history. Peck and others (1964) report temperature measurements in the lake through 

February 1964; Peck and others (1966) describe 

the crystallization of basalt in the lake; and Decker 

and Peck ( 1967) give an account of infrared temperature measurements in the lake. Skinner and 

Peck (1969) report on an immiscible sulfide liquid 

found in one sample of melt. Recently Shaw and 

others (1977) and Peck and others (1977) report 

results of finite-element modeling of the cooling 

history. 

In October 1968 the floor of Alae Crater was overrun by new lava. Subsequently, beginning in May 

1969, the crater was filled by lava from the longlived Mauna Ulu eruption (Swanson and others, 

1971). As of this writing, the spot once marked by 

Alae Crater now stands high as part of the Mauna 

Ulu shield volcano. 

This report is the third of a series of chapters on 

the solidification of Alae lava lake. Chapter A 

(Peck and Kinoshita, 1976) describes the eruption 

and the formation of surface features of the lake. 

Chapter B (Peck, 1978) presents and interprets 

temperature measurements made in the drill holes, 

the density and vesicularity of recovered core, and 

also the results of repeated level surveys of the lava 

surface, all of which provide information on the pattern of solidification of the lake. 

The present report extends the field studies of 

crystallizing basalt in Kilauea lava lakes and benefits 

significantly from earlier study of the two lava lakes, 

one prehistoric and one historic, in Makaopuhi pit 

crater (Wright and Okamura, 1977). A general summary of studies of Kilauea lava lakes, including an 

annotated bibliography, is given by Wright and 

others (1976). 

ACKNOWLEDGMENTS 

This study of Alae lava lake has been a team 

effort by the staff of the U.S. Geological Survey's 

Hawaiian Volcano Observatory. For the gathering 

of temperature data we are particularly indebted to 

the following staff members: George Kojima, who 

constructed the thermocouples ; William Francis, 

John Forbes, Reginald Okamura, Elliot Endo, and 

Willie Kinoshita, who helped in the drilling and in 

the temperature measurements ; and Burton Loucks, 

who made much of the special equipment used in 

the study. The continuous recording of temperature 

in drill holes in the lake was a joint effort with a 

visiting team of scientists and technicians from 

Japan, which included Profs. T. Minakami, D. 

Shimozuru, S. Aramaki, and K. Kamo, and Messrs. 

T. Miyasaki and S. Hiraga. Dr. Aramaki also helped 

in the drilling. During this study, we have received 

much helpful advice from Joel Swartz, Herbert Shaw, 

and Arthur Lachenbruch, all of the Geological Survey. Rosalind T. Helz and Bjorn Mysen reviewed 

the manuscript. 

METHODS OF STUDY 

DRILLING 

Holes were bored in the solidified crust of the 

lava by means of a portable core drill with tungsten 

TABLE 1.-Record of drill holes in Ala.e lava lake 

Drill hole 

Date No. Depth of interval drilled (ft) 

8/29/63 -------------- 1

1 

9/3/63 --------------- 1 

9/6/63 --------------- ~ 

9/17/63 -------------- 10/1/63 and 10/2/63 --

10/24/63 ------------- 11/7/63 -------------- 11/20/63 ------------- 11/27/63 ------------- 12/16/63 -------------

1 

33 

3 

3 

'4 

4 

55 

1/29/64 -------------- 5 4/1/64 and 4/2/64 ____ 66 

4/15/64 -------------- 6 

4/22/64 -------------- 6 4/22/64 -------------- 77 

4/29/64 -------------- 7 6/4/64 --------------- 7 6/10/64 -------------- 7 6/17/64 -------------- 88 

6/18/64 -------------- 8 

7/28/64 -------------- 99 

7/29/64 -------------- 9 

9/11/64 -------------- 9 

9/14/64 -------------- 9 

10/20/64 ------------- 9 

10/22/64 _____________ 1010 

un 

11/17/64 ------------- 11 1212 

11/19/64 ------------- 12 

0 - 2.83 

2.67- 3.75 

3.62- 4.6 

0 - 2.15 

4.20- 5.58 

0 - 9.33 

7.80-11.40 

9.9 -13.40 

0 -15.3 

11.3 -15.3 0 -29.2 

17.5 -21.0 

0 -32.25 

17.75-42.8 

19.4 -35 

0 - 0.83 0 -20 

19.7 -21.8 

21.35-23.4 

0 -20.75 

20.75-28.65 

0 -11.7 

11.7 -12.7 

12.7 -22.7 

22.7 -34.5 

34.5 -52.9 

0 -16 

0 - 9 

9 -16 

0 -15.7 

15.7 -47 

(to base of crust) 

(to base of crust) 

(to base of crust) 

(to base of crust) 

(to base of crust) 

(to base of crust) 

(through 2 ft of melt, 

lower crust and base 

of lake at approximately 28.5 ft) 

{plug of ooze) 

(through 6 ft of melt 

into lower crust) 

(through plug of ooze and lower crust to near base of lake) 

(through plug of ooze) 

(mast hole) 

(through 1 ft of melt 

into lower crust) 

(EX hole to 24.5 ft) 

( SP hole 24.5-34.5 ft) 

(through partly molten center of lake into 

lower crust) 

(through base of lake at approximately 48.0 

ft and into 1840 lava 

(cored from 48-50 

ft)) 

(through base of lake at approximately 44.5 

ft) 

1 Near the major axis of the lava lake on the opposite side from the 

Yents, 165 ft S. 44 E. of the eenter of the lake (fig. 1) ; altitude of 

<·ollar 2,5137.2 ft on Feb. 10, 1964. 

"Hi rt ~'l. 75 E. of drill hole 1; altitude of collar 2,567.3 ft on l!'eb. 

10. 1964. 

3 20 ft S. 15 E. of drill hole 1; altitude of collar 2,567.3 ft on Feb. 

10, 1964. 4 1 ft N. 75 E. of drill hole 3; altitude of collar 2,567.3 ft on Feb. 

10. 1964. 5 30a ft S. 49 E. of drill hole 1 ; altitude of collar 2,565.8 ft on 

Feh. 10, 1964. •• Uo ft .:s. 17 E. of drill hole 1; altitude of collar 2,567.4 ft on 

Sept. 24, 1964. • 3G ft S. 85 W. of drill hole 1 ; altitude of collar 2,566.9 ft on :\Iay 12, 1964. s 1 ft SW. of drill hole 7; altitude of collar 2,566.9 ft on May 12, 

1964. 9 260 ft N. 42 W. of drill hole 1; altitude of collar 2,567.5 ft on 

July 31. 1964. 10 310 ft N. 16 E. of drill hole 1; altitude of collar 2,568.0 ft on 

NoY. ::~. 1964. 11 330 ft S. 87 W. of drill hole 1 ; altitude of collar 2,566.9 ft on 

NoY. 3, 1964. 12 2 ft due east of drill hole 2; altitude of collar 2,567.5 ft on 

Jan. 21, 1965. 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C3 

EXPLANATION 

•1 0 Drill hole 

0 

I 

0 

100 

I 

I I 

200 FEET I I 

50 METERS 

CONTOURS IN METERS ABOVE SEA LEVEL 

FIGURE 1.-Index map of Alae lava lake, showing topographic contours at the base and margin of the lake and 

location of the numbered drill holes. 

carbide bits. The drill was powered by a 9-horsepower gasoline engine. Most of the holes were 2.86 

em in diameter, but the upper part of one hole (drill 

hole 9) was cut to 3.8-cm diameter by means of EX 

bits. During the first 15 months after the eruption 

12 holes were drilled. Dates and depths of drilling 

are listed in table 1, and the locations of the numbered drill holes are plotted on figure 1. 

All except the first two holes were made with a 

drill mounted on a portable mast anchored in the 

crust. The bits were cooled with water pumped 

through the drill pipe by a portable 31;4 -horsepower 

gasoline engine. The water was fed through hoses 

from the rim of the crater and stored in a 50-gallon 

(190-L) steel drum near the drilling site. About 10 

gallons of water were used for each linear foot of 

drilling. The first two holes were drilled by holding 

the drill manually and pouring water into the hole 

by hand. 

A core barrel was used during the drilling, except 
C4 SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

near the base of the crust, where the barrel impeded 

the flow of the cooling water and had to be removed. 

For most of the drilling, the drill stem was pulled 

at 1- or 2-foot (30- or 60-cm) intervals and the core 

was collected. Core samples were numbered eonsecutively in each hole; thus sample A-9-5 is the fifth 

core sample from drill hole 9 in the Alae flow. Core 

recovery averaged between 25 and 50 percent for all 

holes. Typically, recovery was good from that part 

of the crust that was at temperatures of 700°C or 

less before drilling. In several holes, however, recovery was poor from the cavernous and highly 

vesicular zone between depths of 0.3-1.2 m. Core 

recovery was also poor from the interval of crust 

that was at temperatures between 700°C and 950°C 

before drilling, apparently because some cores 

shattered when quenched by the drilling water. Fortunately, abundant core was recovered from the interval of crust that had been at temperatures of 

950°C and 1,070°C, the interval spanning the zone 

of crystallization. No core was recovered from lava 

that was at temperatures of more than 1,070°C, 

before drilling. 

TEMPERATURE MEASUREMENTS 

Temperatures in drill holes were measured on 47 

different days during the four-year study of the 

cooling lake. Most measurements were made with 

thermocouples of chromel-alumel, and, a few with 

thermocouples of platinum-platinum plus 10 percent 

rhodium, using a portable millivolt potentiometer 

and a 0°C reference junction in an ice-filled vacuum 

bottle. Most of the temperature measurements have 

an accuracy of ± half a percent at 500°C and 

± 1 percent at 1,000°C. Details of thermocouple construction and calibration are given in chapter B. 

In several drill holes, temperatures were measured 

both in the crust and in the underlying melt. This 

was done by pushing a ceramic probe into the melt 

through the bottom of a drill hole after boring 

through the base of the crust. Temperatures were 

measured with a thermocouple inserted in the probe. 

Probes as long as 3 m were constructed from 91.5-

cm lengths of 2.54-cm OD mullite tubes (the lower 

tube closed at one end), joined with 10.16-cm sleeves 

cemented with silica cement. The probe was attached 

to the drill steel with a machined fitting. The whole 

probe unit was placed in the completed drill hole 

and the temperature was then measured at the bottom of the hole. After the temperature had reached 

1,065°C to 1,070°C, 1 the unit could be pushed 

slowly on into the melt. Sometimes, but not al.ways, 

it could also be pulled out. Excessive pressure caused 

the ceramic probes to crack, allowing melt to enter. 

An unbroken probe was not emplaced in the melt 

until December 2, 1963. Six attempts were unsuccessful during the preceding three months. Later work 

in the 1965 lava lake in Makaopuhi Crater has shown 

that stainless steel probes can be used successfully 

for long periods in the melt, and can be emplaced 

with less hazard of breakage. 

Several different methods were used to estimate 

the temperature of core samples immediately before 

drilling. Sometimes the temperatures of cores recovered from drill holes adjacent to existing holes 

were determined by measuring the gradient in the 

existing holes immediately before drilling. Other 

times the holes were deepened only a few inches at a 

time, particularly in the zones of crystallization; and 

the core temperatures were estimated by extrapolating the gradient measured in these holes before 

renewed drilling. In other holes, the temperatures 

were estimated from a plot of the depth of isotherms 

versus the square root of time (see fig. 10, chapter 

B), extrapolating the depths of isotherms back to 

the time of drilling from a plot of temperatures 

measured in each hole over a period of time after 

drilling. Temperature intervals assigned to cores 

from the upper crust of the lake in the range 500°C 

to 1,070°C are probably accurate to ± 2 percent, 

estimated from the uncertainty in reconstructing 

isotherms for a single drill hole (see fig. 10, chapter 

B). Temperatures assigned to cores in the range 

below 500°C are less accurate, perhaps ± 10 percent, 

because of greater differences between holes, marked 

effect of rainfall, and slower thermal recovery after 

drilling. Temperatures assigned to cores from the 

lower margins of the lake are highly interpretive 

and may be in error by as much as ±20 percent. 

Table 2 is a complete list of all samples collected 

and an estimate of their temperatures at collection. 

LABORATORY STUDIES 

All drill cores were inspected under a binocular 

microscope, and a thin section from each core interval was examined under the petrographic microscope. Modal counts were made with a point counter. 

Selected pieces of core were analyzed chemically by 

the rock analysis laboratory of the Geological Survey 

in Denver, Colo. A total of 22 standard and 48 partial 

1 This temperature marks the interface between crust and melt in 

all of the lava lakes. The transition from crust to melt takes place 

when the lava is approximately 50 percent crystallized, and is marked 

by an abrupt change in physical properties-particularly shear 

strength-of the basalt. Below the transition temperature, the basaltic 

crust behaves as a rigid solid. Above the transition temperature, the 

melt, either in a liquid or supercooled form, gives little resistance to 

either a drill or a blunt-ended probe pushed by hand. 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C5 

TABLE 2.-Drill cores from Alae lava lake TABLE 2.-Drill cores from Ala.e lava lake-Continued 

Drill hole No. 1 Drill hole No. 6 

Estimated Estimated 

Sample temperature Weight of Sample temperature Weight of ComNo. Depth (ft) Date of collection core (g) Comments No. Depth (ft) Date of collection core (g) ments (oC) (oC) 

A- 1-1 0.8 - 1.2 8/29/63 520- 650 11 A- 6-1 0 - 0.4 4/ 1/64 40- 50 127 

2 2.7 - 3.1 9/ 3/63 880- 950 4 May include 2 .4- .5 do 50 72 ooze from 3 .5- .7 do 50- 60 29 

2.7-2.8 ft 4 .7- .9 do 60 89 

(tempera- 5 0 - 1.0 do 40- 60 89 ture= 6 1.0 - 2.0 do 60- 90 12 

1,040°- 7 2.0 - 3.0 do 90- 140 34 

1,060°C). 8 3.0 - 5.0 do 140- 250 13 

3 3.1 - 3.75 do 950-1,040 27 9 5.0 - 6.0 do 250- 320 66 

4 3.75 do 1,040 5 10-- 6.0 - 7.0 do 320- 410 65 

5 3.8 - 4.0 9/ 6/63 995-1,015 7 11 __ 8.0 -10.0 do 480- 610 144 

6 4.25- 4.6 do 1,040-1,075 7 12 -- 10.0 -11.0 do 610- 670 62 

7 4.8 - 5.0 9/17/63 960- 980 7 13 -- 11.0 -12.0 do 670- 730 100 

8 5.0 - 5.2 do 980-1,000 18 14 -- 13.0 -15.0 do 790- 890 112 

15 -- 15.0 -16.0 do 890- 930 42 

16-- 16.0 -17.0 4/ 2/64 930- 970 21 

Drill hole No. 2 17* - 19.0 -20.0 do 1,030-1,050 75 

18 -- 22.0 -23.0 do 1,060-1,070 17 

19* - 23.0 -24.0 do 1,070? 33 

A- 2-1 0 - 0.5 9/ 6/63 190 33 20 -- 24.0 -25.0 do 1,070? 9 

2 .5 - 1.0 do 350 62 21 * - 25.0 -26.0 do 1,070? 27 

3 1.0 - 1.3 do 490 15 22 -- 27.0 -28.0 do 1,070? <1 

4 1.3 - 1.5 do 580 23 23 -- 28.0 -29.0 do 1,060-1,070 26 

5 2.0 - 2.15 do 720 8 24* - 31.0 -32.0 do 1,030-1,010 30 

25*- 19.0 -19.7 4/15/64 1,010-1,030 23 Ooze. 

26-- 20.0 -27.5 do 1,030-1,060 52 

Drill hole No. 3 27 -- 35.0 -40.0 do 970- 900 61 

28 -- 19.4 -21.0 4/22/64 1,000-1,020? 17 

29* - 25.0 -29.0 do 1,060-1,050 38 Ooze. 

A- 3-1 0 - 0.8 10/ 1/63 50- 280 18 30* - 29.0 -31.0 do 1,050-1,020? 28 Ooze. 

2 .8- 2.8 do 280- 620 63 31 -- 23 -28? 4/ 3/64 1,045-1,060? 19 Ooze on 

3 2.8 - 3.8 do 620- 740 25 thermo4 4.8 - 5.8 do 850- 940 12 couple. 

5 6.8 - 7.8 do 1,020-1,075 16 

6 7.5 - 9.75 10/24/63 950-1,080 <1 Drill hole No. 7 ooze 9.9 11/ 6/63 1,040 <1 Contaminated from old A.- 7-1 0 - 0.4 4/22/64 40- 60 159 drill pipe. 2 .4- .6 do 60- 70 121 

3 .6- .8 do 70- 80 85 

4 0 - .7 4/29/64 50- 75 14 

Drill hole No. 4 5 .7- 2.0 do 75- 120 28 

6 2.0 - 3.0 do 120- 150 89 

7 3.0 - 4.0 do 150- 190 127 

A.- 4-1 0 - 0.25 11/20/63 50- 70 19 8 4.0 - 5.0 do 190- 230 93 

2* .::-.::- .25- .8 do 70- 130 56 9 5.0- 6.0 do 230- 290 88 

3 -- .8- 2.1 do 130- 290 5 10-- 6.0 - 7.0 do 290- 360 95 

4 2.1 - 3.05 do 290- 410 20 11 __ 7.0 - 8.0 do 360- 430 140 

5* == 3.05- 4.45 do 410- 580 38 12-- 8.0 - 9.0 do 430- 500 172 

6* -- 4.45- 5.95 do 580- 715 57 13-- 9.0 -10.0 do 500- 560 47 

7 -- 5.95- 6.95 do 715- 790 7 14 -- 10.0 -10.6 do 560- 600 50 

8* -- 9.9 -10.9 do 970-1,010 33 15 -- 12.0 -13.0 do 640- 700 64 

10* - 10.9 -12.0 do 1,010-1,040 28 16 -- 13.0 -14.0 do 700- 770 46 

11 -- 12.0 -12.85 do 1,040-1,060 3 17 -- 15.0 -16.0 do 820- 870 24 

12*- 14.0 11/21/63 1,067 19 Ooze on 18 -- 17.0 -18.0 do 910- 950 92 

thermo- 19 -- 18.0 -19.0 do 950- 990 140 

couple. 20 -- 19.0 -20.0 do 990-1,020 66 

13* - 14.2 -20.5 12/ 2/63 1,065-1,125 500 Filled 21 -- 19.7 -20.0 6/ 4/64 945- 955 <1 

ceramic 22 -- 20.0 -21.0 do 955- 990 127 

com bus- 23 -- 21.0 -21.8 do 990-1,010 53 

tion tube. 24 -- 21.8 -22.7 6/10/64 995-1,015 3 

25*- 22.7 -23.4 do 1,015-1,030 47 

Drill hole No. 5 Drill hole No. 8 

A- 5-1 - 0.35 12/16/63 A.- 8-1 0 - 2.0 6/18/64 40- 100 56 

0 40- 70 116 2 2.0 - 4.0 do 100- 170 211 

2 .35- .55 do 70- 90 73 3 4.0 - 6.0 do 170- 260 122 

3 .55- .7 do 90- 100 61 4 6.0 - 7.45 do 260- 340 59 4 0 - .2 do 40- 55 17 5 8.0 -10.0 do 370- 470 72 

5 .2 - 1.0 do 55- 130 23 6 -- 10.0 -12.0 do 470- 570 166 

6 1.0 - 2.0 do 130- 220 27 7 -- 13.9 -14.9 do 670- 720 26 

7 2.0 - 3.0 do 220- 320 34 8 -- 14.9 -15.9 do 720- 770 12 

8 3.0 - 5.1 do 320- 510 177 9 -- 20.75-21.85 6/19/64 960- 990 20 

9 6.1 - 7.1 do 590- 660 30 10* - 22.85-23.35 do 1,020-1,030 20 

10 == 10.2 -11.2 do 840- 890 26 11 -- 23.85-24.85 do 1,040-1,050 25 

11 -- 11.2 -12.2 do 890- 940 45 12 -- 24.85-25.85 do 1,050-1,060 8 

12 -- 13.2 -14.2 do 980-1,010 30 13 -- 25.85-26.85 do 1,060-1,070 9 

13 -- 14.2 -16.2 do 1,010-1,060 89 14 -- 26.85-27.85 do 1,060-1,050 24 

14 -- 18.2 -20.2 do 1,070 10 

15 -- 20.2 -22.2 do 1,070-1,040 40 

16 -- 22.2 -23.2 do 1,040-1,020 9 Drill hole No. 9 17 -- 26.2 -28.2 do 940- 870 15 Ooze on 18 -- 28.2 -29.2 do 870- 840 11 thermo- A- 9-1c __ 0 - 0.3 7/28/64 40-

~g l 137 19 -- 17.8 -18.3 12/30/63 1,050±2 23 couple. 1a __ .3- .55 do 60- 102 

1b -- .55- .85 do 70- 90 141 

20* - 19.0 -20.0 do 1,045±5 55 Do. 2 0 - 1.6 do 40- 110 

±50° 

90 

3 1.6 - 2.3 do 110- 130 62 21 -- ca. 18.5 do 1,050± <1 Do. 4 2.3 - 3.55 do 130- 170 16 

5 4.55- 5.55 do 200- 240 172 

See footnote at end of table. 6 5.55- 6.7 do 240- 290 217 
C6 SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

TABLE 2.-Drill cores from Alae lava lake-Continued 

Drill hole No. 9-Continued 

Estimated 

Sample temperature Weight of 

No. Depth (ft) Date of collection core (g) Comments 

(oC) 

A- 9-7 -- 6.7 - 7.7 <lo 290- 360 134 

8 -- 7.7 - 8.6 do 360- 410 88 

9 8.6 - 9.7 do 410- 470 146 

10-- 9.7 -10.7 do 470- 520 249 

11 -- 10.7 -11.7 do 520- 570 150 

12 -- 11.7 -12.7 7/29/64 570- 610 273 

13 -- 12.7 -13.7 9/11/64 560- 600 155 

14 -- 13.7 -14.2 do 600- 620 37 

15 -- 14.2 -15.7 do 620- 670 427 

16 -- 15.7 -16.7 do 670- 710 135 

17*- 16.7 -17.7 do 710- 750 161 

18-- 17.7 -18.7 do 750- 780 130 

19 -- 18.7 -19.1 do 780- 800 32 

20 -- 19.1 -20.1 do 800- 830 44 

21 -- 20.7 -21.7 do 850- 870 35 

22 -- 24.5 -26.0 9/14/64 940- 970 114 

23* - 26.0 -27.0 do 970- 990 47 

24 -- 28.8 -30.0 do 1,000-1,010 13 

25* - 30.0 -31.0 do 1,010± 24 

26 -- 32.0 -33.0 do 1,010- 990 115 

27 -- 42.0 -45.0 10/20/64 900- 860± 144 

28 -- 48.0 -50.0 do 810- 770± 8 1840 lava. 

A-10-1 0 - 0.10 

2 .1- .55 

3 .55- .70 

4 .7- .80 

5 .8- .95 

6 .95- 1.10 

8 0 - 2.0 

9 2.0 - 3.0 

10-- 3.0 - 4.0 

11-- 4.0 - 5.0 

12-- 5.0 - 6.0 

13-- 6.0 - 7.0 

14-- 7.0 - 8.0 

15-- 8.0 -10.0 

16 -- 10.0 -12.0 

17 -- 12.0 -14.0 

18 -- 14.0 -16.0 

A-11-1 0 - 0.5 

2 .5- .7 

3 .7- .8 

4 0 - 2.0 

5 2.0 - 4.0 

6 4.0 - 5.4 

7 5.4 - 7.0 

8 7.0 - 9.0 

9 -- 9.0 -10.0 

10 -- 10.0 -12.0 

11 -- 14.0 -16.0 

A-12-1a __ 0 - 0.1 

1b -- .1 - 0.3 

1c __ .3-0.7 

1d -- .7 - 0.9 

2 0 - 1.0 

3 1.0 - 3.0 

4 3.0 - 5.0 

5 5.0 - 7.0 6 7.0 - 9.0 

7 9.0 -11.0 

8 -- 11.0 -13.0 

9 -- 13.0 -15.0 

10 -- 15.0 -19.0 

11 -- 19.0 -23.0 

12 -- 23.0 -27.0 

13 -- 27.0 _31.0 

14 -- 31.0 -35.0 

15 -- 35.0 -39.0 

16 -- 39.0 -43.0 

Drill hole No. 10 

10/27/64 

do 30- 80 

do do 

do do 

do do 

do do 

do 30- 125 

do 125- 180 

do 180- 230 

do 230- 285 

do 285- 340 

do 340- 395 

do 395- 445 

do 445- 540 

do 540- 620 

do 620- 685 

do 685- 745 

Drill hole No. 11 

10/27/64 

do 

do 

do 

do 

do 

do 

do 

11/17/64 

do 

do 

30- 75 

do 

do 

30- 150 

150- 255 

255- 320 

320-- 390 

390- 460 

455- 485 

485- 550 

610- 675 

Drill hole No. 12 

11/17/64 

do 

do 

do 

do 

do 

do 

do 

do 

do 

do 

do 

11/19/64 

do 

do 

do 

do 

do 

do 

40- 150 

do 

do 

do 

40- 150 

150- 280 

280- 375 

375- 465 

465- 545 

545- 610 

610- 675 

675- 725 

725- 815 

815- 880 

880- 905 

905- 895 

895- 860 

860- 810 

810- 750 

29 

216 

78 

41 

73 

45 

125 

92 

88 

112 

159 

159 

118 

228 

213 

155 

69 

222 

119 

27 

110 

275 

195 

244 

226 

108 

228 

89 

18 

69 

186 

110 

54 

73 

51 

182 

322 

171 

272 

250 

380 

425 

38 

212 

263 

222 

398 

*Samples have complete chemical analyses (table 3). 

analyses were made of core; and four additional 

complete analyses were made of samples of pumice, 

spatter, and crust. 

The constituent minerals and glass in two samples 

of pumice and one core sample were separated after 

grinding to -400 mesh size, using heavy liquids, 

an ultrasonic vibrator, a magnetic separator, and an 

elutriator. The separates were studied under the 

microscope in oil immersion, by X-ray diffraction, 

and by chemical analysis. Glass from the pumice 

samples was separated by repeated centrifuging in 

BR-DMF (Bromoform-Dimethylforamide) mixtures 

of specific gravity 2.74± and 2.78. The specific gravity of the glass was determined as 2.761±0.005. 

The purity of the glass was first tested by studying 

the separates on an X-ray diffractometer and comparing the resulting pattern with previously calibrated mixtures of glass and known amounts of 

plagioclase, pryroxene, and olivine. The calibration 

showed that is little as 2 percent of plagioclase or 

olivine and as little as 3 percent of pyroxene could 

be detected as crystalline contamination of a glass. 

The final separates showed no X-ray diffraction 

peaks for the three silicate phases. Next, a standard 

mixture of 1-percent crystals in crystal-free glass 

was prepared as an optical standard. The crystal 

content of the separated glasses was estimated to 

be less than that of the standard and hence the 

glasses submitted for chemical analysis were considered to be 99 + percent pure. 

Plagioclase from the pumice was concentrated 

(but could not be purified) by flotation in a BR-DMF 

mixture of specific gravity 2.71. 

Separation of olivine and clinopyroxene from glass 

in samples of pumice was achieved by first collecting 

the -270 to +400 mesh fraction which sunk in 

methylene iodide (MI) diluted with DMF to a density of 3.20. This sample was then resieved and put 

on a Frantz magnetic separator. When a side slope 

of 15° and a forward slope of 20° were used, the 

olivine was found to be magnetic at 0.65 amperes, 

and the pyroxene to be nonmagnetic at 0.67 amperes. 

Final purification of the pyroxene was achieved by 

crushing the nonmagnetic fraction to -400 to + 500 

mesh and centrifuging in MI-DMF mixtures, the 

specific gravity of which was increased from 3.20 

in steps of 0.01 until the sink fraction consisted of 

essentially glass-free clinopyroxene as determined 

by inspecting it in oils with a petrographic microscope. Pyroxene separated in this way was submitted 

for chemical analysis. The composition of olivine (not 

more than 90 percent pure) was determined using 

the X-ray diffractometer and the calibration of 

Murata and others (1965). 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C7 

One sample of core collected at subsolidus temperatures was crushed and sieved to -400 to + 500 

mesh for separation of residual glass and plagioclase. 

Pyroxene could not be separated effectively because 

of its included opaque phases. The plagioclase was 

separated by repeated centrifuging in BR-DMF 

liquids of specific gravity 2.725 and 2.671. Because 

of the fine grain size, further magnetic separation 

was not attempted. Plagioclase submitted for chemical analysis was estimated from optical examination 

to be essentially free of glass and pyroxene but to 

contain a small but unknown percentage of opaque 

mineral as inclusions. 

The residual glass was separated after elutriation 

of the -400 to +500 mesh sample that formed the 

float fraction in the liquid of specific gravity 2.671. 

The elutriation produced size fractions estimated to 

be -44 to + 25 microns (p.) and -25p. to +lOp.. 

These were then centrifuged in BR-DMF mixtures 

of specific gravity 2.515, 2.400, 2.345, and 2.285. 

The specific gravity of the glass was found to be between 2.285 and 2.345. The following fractions were 

collected for chemical analysis: 

25-44fL _______ 2.400<sp gr <2.515 

10-25fL ________ 2.400<sp gr <2.515 

10-44,u ________ 2.345 <sp gr <2.400 

1 0-44,u ________ 2.285 < sp gr < 2.345 

All samples showed some admixture of feldspar both 

optically and by X-ray diffraction. No further attempt was made to purify the glass because of the 

small grain size and the small quantity of separate. 

PETROLOGY OF ALAE BASALT 

Solidified crust from the lake at depths below 1.5 

m consists of homogeneous gray basalt containing 

sparse olivine microphenocrysts in a fine-grained 

intergranular groundmass. The surface crust contains as much as 35 percent of augite and plagioclase 

in addition to olivine in a base of brown glass. 

Pumice is brown and has a crystallinity of less than 

15 percent. The average modal composition of solidified crust, calculated as weight percent, is as follows: 

3.3 percent olivine, 41.7 percent clinopyroxene, 42.7 

percent plagioclase, 4.6 percent ilmenite, 1.1 percent 

magnetite, 0.6 percent apatite, and 6.0 percent clear, 

residual glass. 

Clinopyroxene appears as equant subhedral grains 

averaging 0.1 mm in diameter. Most is augite which 

has an estimated 2V of about 50°; however, a small 

fraction of the smaller grains are pigeonite which 

has a 2V <10°. Plagioclase is mainly An60 (a index==1.558) but shows some zoning toward An1o 

in the cores. The plagioclase appears as tabular 

crystals averaging 0.2 mm long and 0.04 mm thick. 

Olivine (Foso to Fo7o) is found mostly as corroded 

wedge-shaped tabular crystals 0.4 mm long and 0.1 

mm thick. However, the drill core also contains a 

trace of olivine in roughly equant microphenocrysts 

0.5 mm in diameter. The opaque minerals consist 

mainly of an ilmenite-rich phase (estimated from 

X-ray method of Lindsley, 1962, as ilmenite9o hematite10) in bladed crystals 0.5 mm long and 0.01 mm 

thick. Subordinate magnetite having the estimated 

composition magnetite6o ulvospinel4o (X-ray method, 

Lindsley, 1962) appears as equant crystals about 

0.01 mm in diameter. Apatite forms as minute 

needles 0.01 mm long and scattered through the 

interstitial glass. 

The refractive index of glass varies from 1.61 in 

samples of pumice to 1.492 in the residual glass (see 

Peck and others 1966, fig. 5.). 

BULK CHEMICAL COMPOSITION 

Major- and trace-element analyses of drill core 

from the lava lake are given in table 3. The chemical 

composition is remarkably uniform even for Kilauea 

lavas. Averages have been computed for the two 

samples of pumice and samples collected above and 

below the solidus temperature. The averages do not 

differ significantly from each other or from the 

overall average published earlier (Peck and others, 

1966, table 1, p. 20) except for the ratio of Fe20a to 

FeO, which is higher in samples collected below the 

solidus and in pumice oxidized by contact with air. 

One reason for the chemical uniformity is the low 

content and small size of olivine in the erupted lava. 

Of the 2 percent olivine present on eruption, less 

than half is found as crystals large enough to settle 

at an appreciable rate through the magma (that is, 

more than 1 mm in diameter). The rest of the olivine 

appears as small skeletal crystals that were growing 

at the time of quenching. 

The chemical uniformity is an advantage in studying the sequence of crystallization in the lava lake, 

as one need not consider the effects of variable 

olivine content so evident in other Kilauea eruptions 

(see Powers, 1955; Murata and Richter, 1966; 

Moore and Evans, 1967; Wright, 1971, 1973; Wright 

and Fiske, 1971). 

Analyses of differentiated samples are given in 

table 3B. These include one natural segregation 

(A-9-23), three "oozes" that flowed into drill holes 

and were later cored (A-6-25, A-6-30, and A-6-29), 

and three samples collected on thermocouples or 
cs SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

TABLE 3.-Chemical analyses of undifferentiated (A) and differe-ntiated (B) sa.mples, Alae lava lake 

Oxides 

(weight 

percent) 

Si02 -----------· AbOa ----------· Fe20a ---------- FeO ------------ MgO ------------ CaO ------------ Na20 ----------- K20 ------------

4H20+ ----------

Ti02 ----------- P20s ------------ MnO ------------

C02 ------------ Cl -------------- F --------------

H-186, 

pumice 2 

(1,165) 

50.41 

13.66 

1.30 

9.68 

7.50 

11.09 

2.41 

.56 

.15 

2.72 

.27 

.17 

.03 

.03 

.06 

A. Undifferentiated samples 

Type of sample and (in parentheses) temperature (°C) 

DPH-77, A-4-2, A-4-5, A-4-6, A-4-8, A-4-10, A-6-1,1 A-6-4,1 A-6-7,1 A-6-10,1 A-6-13,1 A-6-17, 

spatter 2 drill drill drill drill drill drill drill drill drill drill drill 

(1,140) corell corell core2 core2 corell corea corea corea corea core 3 cores (70-130) (70-130) (410- (580- (1,010- (40-50) (60) (90-140) (320- (670- (1,030-

580) 715) 1,040) 410) 730) 1,050) 

50.45 50.45 50.47 50.40 50.40 50.39 50.56 50.48 50.50 50.32 50.63 50.47 

13.60 13.58 13.63 13.71 13.77 13.69 13.87 13.76 13.85 13.80 13.84 13.70 

1.63 2.21 2.70 1.40 1.25 1.14 2.64 1.65 1.92 4.18 1.23 1.36 

9.43 8.93 8.32 9.77 9.76 9.86 8.60 9.45 9.25 7.12 9.75 9.70 

7.48 7.51 7.62 7.44 7.64 7.66 7.49 7.54 7.54 7.51 7.64 7.55 

11.11 11.10 11.18 11.06 11.17 11.11 11.11 11.08 11.11 11.10 11.23 11.14 

2.41 2.33 2.38 2.48 2.43 2.39 2.43 

.54 .55 .54 .57 .55 .54 .53 

.11 .19 .08 .06 .02 .02 .03 

2.11 2.75 2.67 2.79 2.63 2.73 2.73 2.10 2.12 2.73 i.7o 2.11 

.28 .28 .27 .27 .26 .27 .28 

.17 .17 .16 .17 .17 .17 .17 

.01 .03 .02 .01 .00 .00 .00 

.02 .03 .02 .02 .03 .02 .02 

.04 .04 .04 .04 .04 .04 .04 

Subtotal __ 100.04 100.05 100.15 100.10 100.19 100.12 100.03 97.00 96.66 96.89 96.76 97.02 100.13 

Less 0 --------- .03 .02 .02 .02 .02 .02 .02 .0 .0 .0 .0 .0 .02 

Total _____ 100.01 100.03 100.13 100.08 100.17 100.10 100.01 97.00 96.66 96.89 96.76 97.02 100.11 

===================================================================== Trace 

elements 6 

(ppm) 

Ba ------------- Cr ------------- Cu -------------

Ga ------------- Li -------------

Nb ------------- Ni -------------- Rb ------------- Sr -------------- V --------------

y -------------- Yb -------------

Zr --------------

Oxides 

(weight 

percent) 

Si02 ------------

Al20a ----------- Fe20a ----------- FeO ------------

MgO ------------ CaO ------------ Na20 ----------- K20 ------------

4H20+ ----------- Ti02 ------------ P20s ------------ MnO ------------

C02 ------------ Cl -------------- F --------------

270 

370 

130 

21 

4 

16.2 

130 

20 

380 

340 

40 

4 

150 

230 

310 

140 

22 

110 

340 

270 

40 

3 

160 

240 

350 

150 

21 

4 

18.4 

140 

<10 

350 

340 

40 

3 

160 

220 

350 

130 

20 

4 

16.4 

150 

<10 

320 

330 

40 

4 

150 

200 

320 

110 

18 

4 

16.6 

90 

<10 

310 

250 

30 

3 

130 

240 

380 

110 

24 

4 

19.3 

140 

<10 

310 

360 

40 

4 

150 

A. Undifferentiated samples-Continued 

Type of sample and (in parentheses) temperature (°C) 

A-6-19, A-6-21, A-6-24, A-7-25, A-8-6,1 A-8-8,1 A-8-10, A-9-17, A-9-25, A-12-16T, 

drill drill drill drill drill drill drill drill drill drill core 

(1,070 

( ?)) 

50.32 

13.82 

1.27 

9.81 

7.49 

11.11 

2.39 

.53 

.06 

2.73 

.27 

.16 

.00 

.02 

.04 

core 

(1,070 

( ?) ) 

core core (1,030- (1,015-

1,010) 1,030) 

core 

(470-

570) 

core 

(720-

770) 

core 

(1,020-

1,030) 

core 

(710-

750) 

core 

(1,010) core 

(810-

750) 

50.46 50.47 50.44 50.38 50.51 50.51 50.48 50.50 50.39 

13.70 13.69 13.66 13.72 13.80 13.59 13.82 13.59 13.77 

1.27 1.11 1.21 3.69 2.19 1.11 1.27 1.21 1.30 

9.90 9.88 9.90 7.65 8.95 9.90 9.77 9.85 9.72 

7.32 7.58 7.49 7.60 7.56 7.63 7.55 7.59 7.56 

11.00 11.17 11.10 11.11 11.15 11.20 11.05 11.15 11.11 

2.39 2.41 2.39 2.34 2.33 2.33 2.36 

.59 .54 .56 .53 .55 .53 .52 

.03 .00 .01 -- .03 .04 .00 .04 

2.85 2.71 2.78 2.77 2.78 2.79 2.70 2.73 2.78 

.28 .27 .28 .27 .26 .27 .25 

.17 .17 .17 .17 .17 .17 .17 

.03 .00 .01 .03 .02 .03 .01 

.02 .02 .02 .03 .01 .02 .01 

.04 .04 .04 .04 .04 .04 .03 

Subtotal __ 100.02 100.05 100.06 100.06 96.92 96.94 100.17 100.06 100.01 100.02 

Less 0 --------- .02 .02 .02 .02 .0 .0 .02 .02 .02 .01 

(1) 

50.52 

13.65 

1.47 

9.57 

7.50 

11.12 

2.41 

.55 

2~75 .28 

.17 

Averages 6 

(2) (3) 

50.46 

13.69 

1.20 

9.84 

7.57 

11.14 

2.38 

.54 

2.74 

.27 

.17 

50.45 

13.72 

1.69 

9.38 

7.56 

11.11 

2.39 

.55 

2.72 

.26 

.17 

Total 100.00 100.03 100.04 100.04 96.92 96.94 100.15 100.04 99.99 100.01 

Trace ========================================================~=========== 

elements 6 

(ppm) 

Ba ------------· 

Cr ------------· Cu ------------- Ga ------------- Li ------------- Nb ------------- Ni -------------- Rb ------------- Sr -------------- V -------------- y -------------- Yb ------------- Zr -------------

210 

260 

100 

16 

4 

18.3 

85 

<10 

300 

320 

30 

3 

130 

See footnotes at end of table. 

270 

370 

130 

21 

4 

16.2 

130 

20 

380 

340 

40 

4 

150 

210 

260 

100 

16 

5 

18.3 

85 

<10 

300 

320 

30 

3 

130 

226 

342 

128 

21 

4 

17.7 

126 

<10 

326 

310 

38 

3.4 

150 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C9 

TABLE 3.-Chemical analyses of undifferentiated (A) and differentiated (B) samples, Alae lava lake-Continued 

B. Differentiated samples 

Type of sample and (in parentheses) temperature (°C) 

H-186GL, 

Oxides 

(weight 

percent) 

Si02 ------------------------

FeO ~~~~~ ======================== 

~gO ========================= CaO ------------------------- Na20 ------------------------ K20 ------------------------- 9H20+ 

Ti02 --======================= P20s ------------------------ ~nO ------------------------- CO• 

F Cl ~-========================= ---------------------------

Subtotal --------------- Less 0 ----------------------

Total ------------------

Trace 

elementss 

(ppm) 

Ba -------------------------- Cr --------------------------- Cu -------------------------- Ga --------------------------

Li --------------------------- Nb --------------------------

Ni --------------------------

Rb -------------------------- Sr --------------------------- V --------------------------- y --------------------------- Yb -------------------------- Zr --------------------------

glass 1 

(1,165) 

50.92 

14.15 

1.24 

9.81 

6.39 

10.98 

2.49 

.57 

.11 

2.88 

.28 

.17 

.00 

.02 

.05 

100.06 

.03 

100.03 

1 Partial analyses: AbOa value includes P205. 2 Analyses by C. L. Parker. 3 Analyses by E. L. Munson. 

DPH-77GL, 

glass 7 

(1,140) 

50.91 

14.19 

1.64 

9.82 

6.06 

10.69 

2.56 

.60 

.05 

3.04 

.29 

.17 

.00 

.02 

.05 

100.09 

.03 

100.06 

A-4-13, 

ooze 2 

(1,065-

1,125) 

50.25 

12.76 

1.24 

12.56 

5.66 

9.66 

2.62 

.80 

.06 

3.77 

.43 

.20 

.02 

.03 

.06 

100.12 

.03 

100.09 

390 

220 

200 

24 

9 

30.1 

78 

20 

340 

390 

50 

4 

240 

4 H20- analyses: H-186 (0.06), DPH-77 (O.OH), A-4-2 (0.02), 

A-4-5 (0.02), A-4-6 (0.01), A-4-8 (0.02), A-4-10 (0.02), A-6--17 

(0.01), A-6-19 (0.02), A-6-21 (0.04), A-6-24 (0.04), A-6-25 

(0.05), A-7-25 (0.02), A-8-10 (0.02), A-9-17 (0.02), A-9-25 

(0.01), A-12-16T (0.00). 

sampling tubes while still m·olten (A-4-13, A-4-12, 

A-5-20). The oozes collected while still molten are 

affected by reaction with the drilling steel. The iron 

in the samples is reduced relative to the least oxidized drill core (table 3A), and heavy trace-element 

contents (for example, Cr, Ni, Cu) are increased. 

Oozes drilled out at temperatures less than 1,065°C 

are not affected by reaction with drilling steel. 

However, two of the three artificially segregated 

oozes (A-6-30 and A-6-29) show some evidence of 

oxidation. This oxidation probably took place because residual air-contaminated drilling water was 

present when the ooze was segregated. 

Analyses of mineral and glass separates are listed 

in table 4. Composition of the plagioclase and olivine 

in the two pumices (H-186 and DPH-77) was estimated by optical and X-ray methods, respectively, 

to be An1o and Fos2· The olivine in DPH-77 is zoned 

to compositions as fayalitic as Fo62 , as shown by 

A-4-12, 

ooze 2 

(1,067) 

50.62 

12.85 

1.31 

12.24 

5.46 

9.42 

2.65 

.88 

.06 

3.74 

.45 

.20 

.03 

.03 

.06 

100.00 

.03 

99.97 

360 

900 

210 

21 

6 

29.9 

690 

10 

380 

400 

40 

4 

210 

A-6-25, 

ooze 2 

(1,010-

1,030) 

50.72 

12.91 

1.80 

12.19 

4.79 

8.82 

2.77 

.96 

.00 

4.28 

.49 

.21 

.00 

.03 

.06 

100.03 

.03 

100.00 

420 

110 

200 

23 

7 

38.7 

110 

10 

320 

450 

60 

6 

280 

A-6-30 

ooze 2 

(1,050-

1,020) 

51.34 

12.44 

2.00 

12.29 

4.39 

8.44 

2.80 

1.07 

.06 

4.39 

.56 

.20 

.00 

.03 

.07 

100.08 

.04 

100.04 

430 

34 

270 

26 

7 

43.8 

37 

20 

390 

330 

60 

5 

280 

A-6-29, 

ooze 2 

(1,060-

1,050) 

51.73 

12.28 

2.18 

12.31 

4.03 

8.14 

2.83 

1.16 

.06 

4.23 

.62 

.21 

.00 

.04 

.09 

99.91 

.05 

99.96 

480 

37 

290 

30 

8 

44.3 

35 

20 

360 

340 

60 

5 

320 

A-9-23, 

segregation 8 

(970-990) 

51.68 

12.44 

1.94 

12.51 

3.88 

8.08 

3.10 

1.17 

.06 

4.25 

.63 

.20 

.00 

.03 

.09 

100.06 

.04 

100.02 

530 

9 

230 

35 

33 

370 

420 

50 

4 

350 

A-5-20, 

ooze 2 

(1,045) 

53.30 

12.37 

1.37 

13.05 

3.10 

7.28 

3.26 

1.57 

.10 

3.36 

.88 

.20 

.04 

.05 

.12 

100.05 

.06 

99.99 

520 

58 

340 

30 

11 

47.4 

45 

30 

300 

270 

70 

5 

340 

A-5-19,1 

ooze 3 

(1,050) 

53.42 

13.25 

1.13 

13.34 

3.08 

7.25 

94.75 

.0 

94.75 

s All trace elements except Nb analyzed spectrographically by J. C. 

Hamilton. Nb analyses by L. B. Jenkins (D. Gottfried, written com- mun., 1966). a Averages: (1) =pumice, (2) =partially molten core collected 

above 1,000°C, (3) =crystalline core collected below 1,000°C. 7 Analyses by V. C. Smith. s Analyses by G. 0. Riddle. u H20- analyses: A-4-13 (0.01), A-4-12 (0.01), A-6-25 (0.05), 

A-6-30 (0.02), A-6-29 (0.03), A-9-23 (0.01), A-5-20 (0.00). 

broadening of the (310) reflection. 

The two pumice glasses and the plagioclase separate from A-12-10, -11 were submitted to two different laboratories for analysis. The Denver rock 

analysis laboratory analyzed these by conventional 

gravimetric methods devised by Lee C. Peck (Peck, 

1964). These analyses are comparable in precision 

with the rock analyses listed in table 3. A second 

laboratory analyzed the separates by micrometric 

methods. The same methods were used to analyze 

the remaining samples, which were separated in 

quantities too small to be analyzed by conventional 

gravimetric methods. The interlaboratory agreement 

is excellent, in general, although small but consistent 

biases are evident for Al203, CaO, alkalis, and 

P2 05. These biases are sufficiently small, however, 

that the remaining mineral analyses may be applied 

with eonfidence in the calculations using the bulk 

rock analyses. 
ClO SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

TABLE 4.-Chemical analyses, 'lln weight percent, of mineral and glass separates, Alae lava lake 

[Sample data: H-186, pumice from the earliest phase of the eruption collected from trees adjacent to Alae crater. DPH-77, pumice from the 

latest phase of the eruption in back of the main vent on the floor of the Alae crater. A-12-10, -11, drill core from the central part of 

Alae lake, 15-23 ft in drill hole 12. Analysts: Vertie C. Smith (columns 1, 3, and 7), DenYer rock analysis laboratory using methods 

outlined in L. C. Peck (1964). John Marinenko (columns 2, 4, 5, 8, 11, 12), Washington rock analysis laboratory using microchemical 

methods. Hobert Meyrowltz (columns 6, ~. lV), Washington rock analysis laboratory using microchemical methods] 

Oxide 

Si02---------------------

Ab03 --------------------

Feo Fe20a-------------------- ____________________ _ 

MgO --------------------- CaO --------------------- Na20 --------------------· K20---------------------

Ti02---------------------

P205---------------------

Cl Mn0 ______________________ ---------------------_ 

F-----------------------· H20+ ____________________ _ 

H20- --------------------

Subtotal -------------· 

Less Total 0 ------------------ _______________ _ 

H-186 

glass 

50.92 

14.15 

1.24 

9.81 

6.39 

10.98 

2.49 

.57 

2.88 

.28 

.17 

.02 

.05 

.11 

.00 

100.06 

.02 

100.04 

50.9 

14.4 

1.1 

10.1 

6.4 

11.2 

2.45 

.50 

2.92 

.30 

.11 

.08 

3.12 

100.58 

.03 

100.55 

DPH-77 

glass 

50.91 

14.19 

1.64 

9.82 

6.06 

10.69 

2.56 

.60 

3.04 

.29 

.17 

.02 

.05 

.05 

.03 

100.12 

.03 

100.09 

50.8 

14.5 

1.3 

10.2 

6.1 

10.8 

2.44 

.51 

2.95 

.33 

.11 

3 .18 

100.22 

H-186 DPH-77 

Si------------------------------· AliV Total --------------------------- _________________________ _ 

Ti AlVI _____________________________ ---------------------------_ 

Cr Fe~ _____________________________ -----------------------------_ 

Mg ------------------------------ Ni------------------------------· 

Cu Zn _____________________________ ------------------------------_ 

Fe~ ----------------------------· Mn ca _____________________________ -----------------------------· _ 

Na K ______________________________ ------------------------------_ 

Total _________________________ _ 

Total of 

all cations 

ca _____________________________ (to 6 0) --------------------_ 

Mg ------------------------------

Fed -----------------------------

augite 

1.8231 

.1769 

2.0000 

.0628 

.0467 

.0557 

.8764 

.2010 

.7171 

.0430 

.0028 

2.0055 

4.0055 

40.0 

48.8 

11.2 

augite 

1.8419 

.1581 

2.0000 

.0888 

.0454 

.0496 

.0167 

.8405 

.0017 

.0041 

.2014 

.0050 

.6811 

.0402 

.0038 

1.9781 

3.9781 

39.5 

48.8 

11.7 

H-186 DPH-77 

augite augite 

49.3 49.78 

5.5 5.66 

2.0 1.78 

6.5 6.51 

15.9 15.24 

18.1 17.18 

.6 .56 

.06 .08 

1.68 1.63 

.05 .05 

.16 

3 .13 

99.69 198.76 

Mineral formulas 

1 Additional oxides in DPH-77 augite; Cr203=0.57; Zn0=0.15; Cu0=0.06. 2 Total iron as FeO. 

sTotal H20. 

A-12-10, 

A-12-10, -11 

plagioclase GLP-1 GLP-2 

53.67 53.7 67.08 66.52 

28.29 28.7 14.15 14.09 

.65 .73 .55 .49 

.36 .22 1.48 1.11 

.18 .14 .25 .20 

11.76 11.8 4.15 4.15 

4.52 4.33 4.07 4.13 

.36 .34 4.31 4.37 

.17 1.8 .68 .60 

.05 .07 1.59 1.62 

.01 < .01 

.00 

.01 < .02 .18 .18 

.00 

.02 3.09 3 .29 3 .56 

100.05 98.78 98.02 

.01 .08 .08 

100.04 100.30 98.70 97.94 

Si------------------------------· 

Al------------------------------

Fe~ ---------------------------- Ti Total-------------------------· _____________________________ _ 

Mg -----------------------------· 

Na Fe~ _____________________________ ----------------------------_ 

Ca !( ______________________________ ------------------------------_ 

Total _________________________ _ 

Total of 

all cations 

(to 32 0) --------------------

An ----------------------------- Ab ------------------------------ Or------------------------------

-11 glass 

GLP-3 GLP-4 

71.5 79.9 

11.5 8.7 

21:51 21:4 

.18 .25 

1.9 2.2 

3.2 2.5 

5.2 2.3 

.63 .49 

1.02 .29 

< .2 < .2 

a.8 

97.44 9-8.03 

Plagioclase 

A-12-10, -11 

9.7514 

6.0580 

.0889 

15.8983 

.0232 

.0487 

.0547 

1.5923 

2.2893 

.0834 

4.0916 

9.7259 

6.1263 

.0995 

15.9517 

.0245 

.0378 

.0333 

1.5205 

2.2898 

.0786 

3.9845 

19.9899 19.9362 

57.7 58.9 

40.2 39.1 

2.1 2.0 

Analyses of the concentrates of residual glass 

(GLP-1 to GLP-4, table 4) show that plagioclase 

and apatite are removed from the residual glass as 

the specific gravity of the separating liquid is decreased from 2.515 to 2.345. Surprisingly, the composition of the lowest specific gravity fraction indicates that potash-soda feldspar was removed in 

addition to apatite when the specific gravity of the 

separating liquid was reduced to 2.285. 

TABLE 5.-Composition, in weight percent, of residual glass, 

Alae lava lake 

GLP-3 shows very weak reflections for plagioclase 

on its X-ray pattern and is considered to be the most 

nearly representative sample of the residual glass, 

containing 2 percent apatite and an undetermined 

amount of alkali feldspar. This analysis, after removal of all P 20s and an equivalent amount of CaO 

as apatite, is given in table 5 with a single electron 

microprobe analysis of residual glass from the same 

Sample No. 

Si02 ------------ Al20a ---------- Fe203 ---------- FeO ------------ MgO _________ _ 

CaO ------------

NaeO ---------- K20 ------------

Ti02 ---------- P205 ---------- MnO ---------- Total ___ _ 

A-12-10, -11 

(wet chemical 1 ) 

75.8 

12.2 

.43 

1.21 

.19 

.60 

3.4 

5.5 

.67 

100.00 

A-12-9 

(electron-microprobe 2 ) 

75.9 

11.9 

31.1 

.05 

.54 

3.37 

5.99 

.24 

99.2 

1 Glass separate GLP-3 (this paper, table 4) recalculated to 100 

percent after removing P20~ and equivalent CaO as apatite. 

2 Analyst: R. T. Helz. a Total iron as FeO. 

drill hole. The small differences between analyses 

reflect the presence of small amounts of plagioclase 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C11 

and Fe-Ti oxide as impurities in the separated glass. 

The analyses are similar to electron microprobe 

analyses of residual glass from the prehistoric lava 

lake exposed in the East Pit of Makaopuhi Crater 

(Evans and Moore, 1968, table 8). 

CHEMICAL MODES 

The term "chemical mode" is used in this paper 

to describe mineral and glass percentages in a rock 

as they are calculated from the bulk chemical composition of the rock using compositions of glass and 

mineral phases (see Wright and Doherty, 1970). The 

mixing equations, one for each major oxide,Z are 

formulated as follows: 

Parent==Differentiate (glass or ooze) +olivine+ 

augite+ plagioclase + pigeoni te +ilmenite+ 

apatite. (1) 

On the assumption that the various chemical data 

are accurately known, the chemical modes provide 

a close approximation to the true modal composition (in weight percent) of either a holocrystalline 

rock or partly molten lava quenched at liquidus temperatures. Such modes may be used in the same way 

as modal data obtained by conventional petrographic 

methods to estimate order of appearance of phases 

and rates of crystallization as a function of temperature. As pointed out in the next section, we consider 

the chemical modes far more accurate than the 

petrographic modes obtained for fine-grained 

basalt. 

Table 6 summarizes the results of chemical mode 

calculations. Modes for H-186 and DPH-77 were 

made by using the rock analyses (table 3), the 

analyzed glasses (table 4), and the analyzed or optically determined mineral compositions (table 4). 

In order to fix accurately the amount of liquid 

(differentiate), P205 was weighted high to ensure 

an exact rna tch between the observed P 205 in the 

parent and that calculated from the mixture of 

minerals and liquid. This procedure assumes that 

P 205 is partitioned to the liquid 3 with the exception 

of a small amount partitioned to augite (see analysis 

of DPH-77 augite, table 4). Later calculations of 

trace-element abundance (table 8) suggest that 

plagioclase may also contain a small amount of P205 

and thus the liquid percentages given in table 6 

represent a maximum value. The residuals in all calculations are less than 0.1 percent. The rest of the 

calculations were made using the mineral compositions given in table 7, and the analyses of differentiated liquids given in table 3B. All of these calculations have residuals of 0.01 or less in all oxides, 

virtually an exact match to the bulk composition. 

The solution values in the calculation using the 

residual glass (A12-10, -11) represent the modal 

abundance of phases in the basalt collected at sub3 See Anderson and Greenland (1969) for discussion of the useful- ness of Pz05 as a fractionation index and its use in evaluating fractionation in Alae lava lake. 

TABLE 6·-Computer-calcula.ted chemical modes, Alae lava lake 

[All mineral proportions in weight percent] 

Parent (table 3) 

Olivine (Foso) ------------- Augite2 ------------------- (MgO/(MgO+FeO)) ------- Plagioclase3 ---------------· (An content) -------------· Pigeonite4 

(En55.3 FS34.5W0!0.2) -------

Ilmenite5 -----------------· Magnetite5 ----------------· 

Apatite ------------------- Total minerals 

crystallized -------· Liquid --------------------· 

Enrichment factor 6 --------

FezOa/ (FezOa + Fe0)7 

Observed ----------------- Calculated ---------------

H-186, 

glass 

pumice 

2.3 

3.4 

(.66) 

0.3 

(70) 

6.0 

94.0 

1.064 

.112 

1 Average (2) given in table 3A. 

DPH-77, 

g"la,;" 

pumice 

2.2 

8.5 

(.65) 

2.7 

(70) 

13.4 

86.6 

1.155 

.143 

A-4-13, A-4-12. ooze- oozemolten molten 

2.0 

17.8 

(.67) 

16.1 

(61.5) 

2.9 

.30 

39.2 

60.8 

1.645 

.084 

.118 

2.7 

19.4 

(.62) 

17.3 

(61.6) 

1.9 

.58 

41.8 

58.2 

1.718 

.097 

.121 

2 Augite compositions used as input: H-186 (H-186 augite, table 4) ; DPH-77 augite, table 4) ; A-4-12 through A-9-23 (mixtures of 

DPH-77 and Fe Aug R, table 7). 3 Plagioclase assumed as An1o for H-186 and DPH-77, and calculated for the remaining samples as a mixture of An50 and An1o (table 7). 

'Pigeonite 13-13P (table 7) used in all calculations. 5 1lmenite (ILM) and magnetite (TIMAG) from table 7 used in all 

calculations. 

Sample No. and type 

A-6-25, 

oozedrilled 

3.5 

22.5 

(.59) 

19.1 

(61.9) 

1.2 

.33 

46.5 

53.5 

1.869 

.129 

.129 

Alae average 1 

A-6-30, 

oozedrilled 

4.3 

24.4 

(.56) 

22.8 

(61.3) 

.8 

.79 

.06 

53.1 

46.9 

2.132 

.140 

.134 

A-6-29, 

oozedrilled 

4.5 

21.0 

(.56) 

24.8 

(60.4) 

1.1 

1.28 

.10 

57.7 

42.3 

2.364 

.150 

.133 

A-5-20, A-12-10, -11, ooze- residual 

molten glass 

3.1 

29.3 

(.57) 

29.2 

(59.8) 

5.8 

2.72 

.23 

70.4 

29.6 

3.378 

.095 

.132 

3.9 

31.7 

(.45) 

43.2 

(56.1) 

9.3 

4.74 

.42 

.6 

93.9 

6.1 

16.529 

.262 

A-9-23, 

segregation vein 

3.5 

25.6 

(.58) 

24.2 

(61.3) 

3.9 

1.26 

.12 

58.6 

41.4 

2.415 

.134 

.132 

6 Enrichment factor calculated as 100-+-weight percent liquid. This 

factor is fixed by P 20:; in the mode calculations and represents the 

expected maximum enrichment of the least compatible element or oxide during crystallization. 7 Fe20a and FeO of each sample were adjusted for purposes of the 

calculation in order to give realistic ilmenite/magnetite ratios and also to fit the actual ratios of the least oxidized drilled samples. 
C12 SOLIDIFICATION OF ALAE LAVA LAKE, HA WAil 

TABLE 7.-Mineral analyses used in mixing calculations 

[Microprobe analyses made by P. W. We1blen: of augite (Fe Aug R) and pigeonite with F20a assumed; of ilmenite and magnetite with 

Fe20a calculated from stoichiometry] 

A B c 

Olivine, Augite 

Fa20 DPH-77 Fe Aug R 

Si02 ----------------- 38.72 50.48 49.52 

Al20a ----------------- .87 5.74 1.28 

Fe20a ----------------- ---- .88 .89 

FeO ----------------- 17.80 7.55 16.58 

MgO ----------------- 42.06 15.46 13.05 

CaO ----------------- .29 17.42 17.66 

Na20 ----------------- .57 

K20 ----------------- .09 

Ti02 ----------------- .02 1.66 .50 

P20s ----------------- .06 

MnO ----------------- .27 .17 .50 

Nature of samples: 

A. Stoichiometric Fa2o with 1.5 percent Cr-spinel included. 0.3 per- cent CaO included as Ca2SiO~. 

B. Analyzed augite (see table 4). Fe20a and FeO adjusted (see text). 

C. Most iron-rich augite from Makaopuhi lava lake. 

solidus temperatures. The calculation is very sensitive to Fe203/Fe0 ratios used in the pyroxene, glass, 

and bulk rock composition. The Fe203/ (Fez03+Fe0) 

contents in the pyroxenes and the differentiates were 

adjusted to fit the following two assumptions: 

1. The parent was taken as the average composition showing the least oxidation in table 3 (see 

average (s), table 3A; Fez03=1.20, Fe0=9.84). This 

represents the composition of the lava before subsolidus oxidation took place (see Sato and Wright, 

1966, and Wright and Okamura, 1977, for further 

discussion of oxidation). 

2. Magnetite was assumed to appear at a lower 

temperature than ilmenite and the magnetite/ 

ilmenite ratio was assumed to increase slightly during crystallization. 

Two consequences of these assumptions are, first, 

that the Fe203/ (Fe203 + FeO) ratio in the analyzed 

DPH-77 augite is too high to fit the calculations for 

the least oxidized bulk composition. We need values 

of Fe203=0.88 and Fe0=7.55 compared with 

analyzed values of Fe203=1.78, Fe0=6.51. The 

calculated mineral formula (table 4) for DPH-77 

shows a cation deficiency relative to six oxygens 

and this imbalance ·Could be improved by reducing 

the amount of Fe203. Thus we feel this analysis is 

probably in error; an adjusted analysis that fits the 

rock composition is given in table 7. The second 

consequence of the assumptions is that A-6-25 is 

the only ooze that has an analyzed Fe203/ ( Fe203 + 

FeO) ratio consistent with its degree of crystallization if one assumes no subsolidus oxidation. The 

calculated and observed Fe203/ (Fe20 3 + FeO) ratios 

are shown at the bottom of table 6. They show that 

samples A-4-13, A-4-12, and A-5-20 are reduced 

D E F 

Pigeonite, Plagioclase Ilmenite, Magnetite, 

la-13P An7o Anoo ILM TIMAG 

54.64 50.74 55.71 0.05 0.06 

1.66 31.53 28.19 .12 1.65 

1.01 9.66 23.63 

19.55 39.81 50.68 

17.60 1.72 1.00 

4.53 14.19 10.26 .08 .08 

3.37 5.67 

.21 .21 

.52 48.14 22.52 

.51 .44 .37 

D. Pigeonite from Makaopuhi lava lake. 

E. Stoichiometric NaAlSiaOs and CaAbSi04 with 0.5 percent K20 

included as KAlSiaOs. ~'. Ilmenite and magnetite from Makaopuhi lava lake. 

relative to what is predicted from the chemical 

mode calculation. This is consistent, as noted above, 

with the environment of collection where the molten 

ooze was collected in contact with drill steel or 

thermocouple sheathing. A-6-30 and A-6-29 are 

slightly oxidized relative to their predicted value, 

which is also consistent with their appearance in 

thin section. These samples and A-6-25 were drilled 

out when solid. The slight oxidation may have taken 

place because of the presence of air-contaminated 

drilling water when the ooze flowed into the drill 

hole. A-9-23, a natural segregation, is essentially 

unoxidized. 

The mineral percentages calculated in table 6 are 

generally consistent with the inferred paragenesis, 

except for the inclusion of pigeonite and ilmenite in 

samples A-4-13 and A-4-12. TiOz is lower in these 

samples than would be predicted on the basis of 

crystallization of silicates only. If ilmenite is removed from the calculation, a Ti02 residual of 0.15 

results, far too high to ascribe to analytical error in 

the rock, ooze, or pyroxene. Pigeonite is probably 

an artifact of ilmenite being included in the calculation and is taken in order to balance the Si02. 

Calculations made without pigeonite have a SiOz 

residual of about 0.2 if NazO is balanced to give the 

same plagioclase composition. We do not know the 

reason for the anomalous compositions. Two possibilities are (1) reaction with steel resulting in loss 

of Ti02 (and FeO?) or (2) admixture of lower 

temperature ooze during collection. The latter seems 

more likely as samples in Makaopuhi lava lake that 

were collected in stainless steel picked up small 

amounts of iron and showed no Ti02 gain or loss. 

Mineral compositions change in a regular way as 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C13 

crystallization increases. (Note: These represent 

the average composition of each phase crystallized 

before collection of the ooze or glass sample. As the 

minerals are normally zoned, the calculated compositions of feldspar and mafic silicates are more 

calcic and magnesian, respectively, than the actual 

composition of the mineral in contact with the 

liquid represented by the glass or ooze. Electron 

microprobe study would be necessary to specify the 

exact compositions of coexisting mineral-liquid 

pairs.) Olivine and pigeonite are taken as fixed 

compositions so that the changing composition of 

the mafic assemblage is represented by the MgO/ 

(MgO+FeO) ratio calculated for augite and given 

in parentheses in table 6. These range from 0.66 in 

the pumice (H-186) to 0.45 in the subsolidus assemblage (A-12-10, -11). Plagioclase changes composition from An1o in the pumice to An56 in the subsolidus assemblage. 

In summary, the data of table 6 represent a nearly 

quantitative representation of changing mineral 

proportions and compositions during crystallization 

of Alae lava lake. These data are plotted in figures 

2 and 3. 

Trace-element content also varies along the liquid 

line of descent. Unfortunately, the collection of melt 

samples and ooze in proximity to drilling steel eontaminated some samples, especially with regard to 

Cr and Ni. The overall variation in trace-element 

content is less regular than for major elements 

(see table 3), precluding an accurate assessment of 

distribution coefficients between silicates and liquid 

along the liquid line of descent. Table 8 summarizes 

data on relatively incompatible elements. The values 

for an undifferentiated bulk composition are taken 

from average (3), table 3A. Maximum enrichment 

factors, assuming that each element is totally partitioned to the liquid, are calculated from the results 

of mixing calculations given in table 6. For example, 

sample A-6-29 represents 57.7 percent crystallization and a consequent maximum enrichment factor 

of 1-;- (1-0.577) =2.364. The mixing calculations 

of table 6 assume that P205 was the most incompatible minor element. 

The data of table 8 indicate the following: 

1. Nb is the most incompatible of the trace elements during silicate crystallization; in fact, it 

appears to be anomalously enriched in oozes A-6-25 

and A-6-30 beyond what is possible by eomplete 

partitioning to the liquid. One possible explanation 

is that P z05 is partitioned in part to phases other 

than augite or liquid (for example, plagioclase). A 

very small amount of P 2 0 5 in plagioclase would increase the enrichment factors to a point where the 

Nb data would fit. Nb is well determined (D. Gottfried, written commun., 1966), yet it still varies over 

a 10 percent range in the undifferentiated samples 

and even in the pumice. Also, Nb may possibly be 

redistributed by a process as yet unrecognized for 

any other element in the lava lakes. At lower temperatures Nb is concentrated by ilmenite and magnetite, 

and the rest of the samples show depletion of Nb 

relative to the maximum calculated enrichment. 

2. Li and K20 show parallel variation indicative 

of slight partitioning to plagioclase at high temperatures, increasing toward lower temperatures. 

3. Zr is not well determined but shows significant 

partitioning to crystallizing phases (probably pyroxene) in the two lowest temperature samples. 

Other trace elements show significant partitioning 

to crystallizing phases at high temperatures and 

either remain constant or are depleted in lower 

temperature samples. 

PETROGRAPHY 

The modal eomposition of Alae lava lake has been 

summarized in an earlier paper (Peck and others, 

1966, fig. 4, p. 635-641). For the present study, new 

thin sections were cut for several samples of partly 

molten core. Counts of 1,500 points were made on 

these and the older sections, using a 0.3 X 0.3-mm 

grid. All modal data, obtained in volume percent, 

TABLE 8.-Comparison of observed and calculated values of rela.tively incompatible trace elements in Alae lava lake 

[Calculated results are obtained by multiplying the trace-element values for average (3) in table 3A. by the maximum enrichment factor 

given in table 6] 

Sample K20 (weight percent) Li (ppm) Nb (ppm) Zn (ppm) 

No. Obs. Calc. Obs. Calc. Obs. Calc- Obs. Calc. 

A-4-13 ------------------- 0.80 0.90 9 6.6 30.1 26.6-31.7 240 247 

4-12 ------------------- .88 .95 6 6.9 29.9 27.8-33.2 210 258 

6-25 ------------------- .96 1.03 7 7.5 38.7 30.3-36.1 280 280 

6-30 ------------------- 1.07 1.17 7 8.5 43.8 34.5-41.1 280 320 

6-29 ------------------- 1.16 1.30 8 9.5 44.3 38.3-45.6 320 355 

5-20 ------------------- 1.57 1.86 11 13.5 47.4 59.7-65.2 340 507 

1 Range calculated from the maximum variation in Nb in undifferentiated core (table 3A.). 
C14 SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

100 \ 

\ 

90 1 

80 

70 

10 

0 

0 5 0 

OLIVINE, 

IN WEIGHT 

PERCENT 

10 

.t- '.\ + 

\ 

\ "\t- \. +. 

-f4 

i= 

20 30 40 50 0 10 

CLINOPYROXENE, 

IN WEIGHT PERCENT 

. \ 

\ .\ 

l \\ 

+· 

~+ -:4-

20 30 40 

PLAGIOCLASE, 

IN WEIGHT PERCENT 

\ 

. 

\ 

·~ 

~ 

~ 

0 10 * 20 

Fe-Ti OXIDE, 

IN WEIGHT PERCENT 

1190 

1150 

1100 

en 

:::1 

..... 

~ 

'"' f3 

w 

a: 

CD 

w 

Q 

!: 

...... MELT !; 

1065 !;( 

CRUST ffi 

a. 

1050 ! 

1000 

980 

.... 

FIGURE 2.-Graph showing modal data for Alae lava lake. Crosses show modal data obtained in transmitted light converted to weight percent (see text). The length of the bars represents the estimated counting error of the mode according 

to the method of Van Der Plas and Tobi ( 1965). The dots ( •) indicate weight percent modes calculated from analyzed 

glasses and oozes (data of table 6) and represent the modal abundances consistent with the bulk chemistry. Note that 

pyroxene and opaque minerals are overcounted and plagioclase undercounted in the optical modes. 

were converted to weight percent by assuming the 

following specific gravity for minerals: olivine and 

pyroxene (sp gr=3.3) ; ·opaque phases (sp gr=4.5). 

The specific gravity of glass used in the conversion 

from volume to weight percent was estimated from 

the refractive index of the glass, assuming linear 

variations between the refractive index (R.I.) and 

specific gravity (sp gr) for the separated glasses: 

(sp gr=2.3, R.I.=l.488; sp gr=2.76, R.I.=l.602). 

The new modal data are summarized in figure 2 

along with the curves defined by the chemical modes. 

An important finding is that there is significant 

bias in the optical modes relative to the chemical 

modes, marked by high values for pyroxene and 

opaque phases and by low values for plagioclase. 

This is evidently the result of the fine grain size of 

the basalt, in particular the very thin (less than 

0.01 mm) laths of plagioclase. From figure 2, we 

can calculate that the pyroxene is consistently overestimated by approximately 24 percent and the 

opaque minerals by 50 percent. If these percentages 

are subtracted from the optical estimates of pyroxene and opaque mineral, respectively, and are added 

to the plagioclase percentage estimated optically, a 

close approximati'On to the chemical mode is obtained. 

The glass content is estimated satisfactorily by 

optical methods. Figure 3 shows the modal percentage of glass plotted against temperature, using the 

chemical modes and all of the· optical modes of 

partly molten samples for which accurate temperature data were available. A single curve can be 

drawn through most of these data, indicating that 

the optical estimate of glass content is satisfactory. 

Serious discrepancies exist for two samples of 

ooze for which chemical modes were calculated 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C15 

1200 1------------------ LIQUIDUS ----------------"71 

1150 

en 

iii = 

.... 

..... 1100 (,) 

en 

..... 

..... 

a: 

c:l 

• I 

I 

1 A-4-13 

I 

I 

I 

DPH-77 

MELT 

/ / 

..... 

Q 1050 T A-6-29 A-4-12 

• • 

CRUST 

~ ...... 

a:: 

= !ci 

a: 

..... 

a.. 1000 :IE 

..... 

I 

A-6-301 

I 

• 

• 

I A-6-25 I 

• 

.... • ------------SOLIDUS----------------; 

RESIDUAL GLASS 

950 

0 10 20 30 40 50 60 70 80 90 100 

GLASS, IN WEIGHT PERCENT 

FIGURE 3.-Graph showing weight percent glass plotted against temperature. The s-shaped line is a best-fit by eye, drawn 

with the modal data for undifferentiated samples in figure 2. Data for glass content of differentiated samples (for 

example, A-6-25) are taken from table 6 and plotted against temperature of collection. Discrepancies for samples 

A-6-25 and A-6-30 are discussed in the text. 

(A-6-25 and A-6-30). Both samples suggest a 

temperature of formation higher than the temperature at the time of collection. Drill hole 6 was the 

first hole to penetrate the lower crust of the lake 

(tables 1, 2). The samples A-6-25 through A-6-30 

were samples of core that filled the open drill hole 

adjacent to the partly molten crust between the tw'O 

1,000° C is-othermal surfaces. The easiest way to 

rationalize the temperature discrepancy shown on 

figure 3 is to infer that all the ooze came in from 

near the hottest zone ( 1,070oC, see table 2) and 

moved up or down the drill hole as it flowed in. 

Thus A-6-29 was collected at a depth corresponding 

to the maximum temperature in the hole and close 

to where it entered the drill hole; and A-6-25 and 

A-6-30 were collected at depths respectively above 

and below where the ooze entered the drill hole. 

Hence the estimated temperatures at the depth of 

collection are too low. 

The temperatures of the pumices (H-186 and 

DPH-77) were estimated from temperature measurements made during the eruption. The liquidus 

temperature of the whole rock (100 percent liquid) 

is estimated from the Mg/Fe ratio using the method 

of Tilley and others (1964). The shape of the curve 

that relates glass content to temperature is very 

similar to that obtained for Makaopuhi lava lake, 

for which a broader range of temperature data is 

known (Wright and Okamura, 1977; Wright and 

others, 1976, fig. 12). The temperatures obtained 

using figure 3 are also shown on figure 2. Figures 

2 and 3 together give a quantitative description of 

crystallization of the liquid line of descent (fig. 4) 

for Alae lava lake. 

Petrographic modes of selected samples of ooze 

are given in table 9. Some of these (for example, 

A-5-20 and A-4-12) contain less than 10 percent 

crystals, commonly clotted together, placing an upper limit on the amount of previously crystallized 

material brought in with the liquid. Other oozes, 

notably those from drill hole 6 (A-6-25, A-6-29, 

and A-6-30), are highly crystalline because they 
C16 SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

TABLE 9.-Petrographic modes for selected oozes, in volume percent, from Alae lava lake 

[A, crystals brought in with liquid; B, crystals growing in the liquid] 

Mineral A-4-12 A-6-25 

1 2 ---------------------------------

Olivine: 

A ---------------------· 

B ---------------------· 

Total ------------- 0.0 

Pyroxene: 

A --------------------- 3.0 

B ---------------------· 

Total ------------- 3.0 

Plagioclase : 

A --------------------- 4.4 

B ----------------------

Total ------------- 4.4 

Ilmenite: 

A ----------------------

B --------------------- 1.3 

Total ------------- 1.3 Magnetite: 

A ----------------------

0.0 

4.8 

26.9 

31.7 

3.1 

11.2 

14.3 

.7 

13.6 

14.3 

0.1 

.1 

3.6 

28.7 

32.3 

3.0 

12.8 

15.8 

15.8 

15.8 

A-6-30 

1 2 

0.0 

6.4 

26.1 

32.5 

5.8 

14.3 

20.1 

.8 

13.4 

14.2 

0.1 

.1 

4.4 

29.0 

33.4 

4.0 

12.9 

16.9 

14.1 

14.1 

A-6-29 

1 2 

0.0 

.0 

3.0 

18.9 

21.9 

4.0 

8.1 

12.1 

.8 

11.4 

12.2 

0.0 

.0 

2.7 

12.9 

15.6 

2.7 

5.9 

8.6 

6.9 

6.9 

A-5-20 

1 2 

0.0 

.0 

2.7 

.4 

3.1 

1.5 

2.0 

3.5 

.7 

.4 

1.1 

0.0 

.0 

2.7 

.3 

3.0 

1.2 

1.1 

2.3 

1.0 

1.0 

2.0 

B --------------------- .1 .2 .9 2.7 7.4 1.0 1.8 

Total ------------- .1 .2 .9 2.7 7.4 1.0 1.8 .0 .0 

Glass 1 ------------------- 91.2 39.6 34.7 30.3 28.1 52.8 67.1 92.4 92.7 ------------------------------------------------------------------ Total ------------- .100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Total A ----------- 7.4 8.6 6.6 13.0 8.4 7.8 5.4 4.9 4.9 

Number of points (0.3X0.3-mm grid) ____ 1,583 420 900 

1 Includes fresh and devitrified or oxidized glass. 

were collected 2 to 3 weeks after drilling (see table 

2) during which time they cooled and crystallized. 

This is further evidence that these oozes initially 

flowed into the hottest part of drill hole 6 and 

moved to cooler parts of the hole where they crystallized before the collection time. These also have 

glomerophyric clots which we interpreted as having 

been associated with the liquid before its entry into 

the drill hole, whereas we interpret the isolated crystals forming the bulk of the ooze as the products of 

crystallization in the time interval before collection 

and after the ooze entered the drill hole. The best 

evidence that the glomeroporphyriUc clots did not 

form in the drill hole is the presence in them of 

resorbed olivine. It is known from study of all the 

lava lakes that magnesian olivine is no longer stable 

at the temperatures at which the oozes are formed. 

DISCUSSION 

MINERAL PARAGENESIS 

The data presented in table 6 and plotted in 

figures 2, 3, and 4 yield the best estimate of the 

crystallization of Alae lava lake along its liquid line 

of descent. The first appearances of pigeonite and 

magnetite are not closely specified and have not 

been checked by electron probe as they were for 

1,000 1,000 1,000 713 1,000 1,428 

Makaopuhi lava lake (Wright and Weiblen, 1967). 

The chemical modes of oozes shown in table 6 are 

an exact match to the bulk composition of the lava 

lake. The appearance of magnetite in the calculations is controlled by assumptions regarding Fe203/ 

(Fe203 + FeO) ratios in the oozes. Overall, the sequence and temperature of crystallization of all 

phases are consistent with those observed in Makaopuhi lava lake. 

Tilley and others (1967, table 6, p. 265) determined the silicate paragenesis in a sample of 

basalt from Alae lava lake. They obtained temperatures of first appearance for augite (1,190°C), olivine 

(1,180°C), and plagioclase (1,155°C). The range of 

temperatures is in satisfactory agreement with the 

data of figure 2, particularly as the liquidus temperature of Alae has been estimated from the (FeO+ 

Fe203) / (MgO + FeO + Fe203) in the bulk composition 

using the calibration of Tilley and others (1964, 

fig. 23, p. 95). The experimentally observed order of 

appearance of olivine and pyroxene is different 

from that inferred from the presence of large 

olivine phenocrysts in the Alae pumice, assumed to 

be the earliest mineral to crystallize. This discrepancy may be apparent because of the uncertainties in the experimental techniques and in the 

extrapolation of data in figure 2. 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C17 

OAPL 

I' I 

I I 

I 

1070 

I 

PI M 

I I 

1060 1050 

I I I 

AP 

I 

I 

I 

980 

------, P205 I- ..... - \ -

•-----.-o-o--·--·-·-·- \ \ 0~------------------------------------~n 

4-

·-·- ·--·- ·----o-o"'"' 

/ 

/ 

/ 

/ 

I 

/ 

I 

I 

I 

I 

I 

I 

0 

I 

I -

I 

I - I 

-

-

-

0~------------------------------------~ 

·----o-o--·--·-·-·-- -· - - - - - - - - - - 0 

.... ~ -

2~------------------------------------~ 

Coo 

10 ,_ •-- --o-o ........ 

--·-·-·---................ 

5--

-

- ..... ..... .... ..... ..... .... 

0 I I I I I I 'o 

8 7 6 5 4 3 2 0 

MQO 

OAPL 

I' I 

1190 

I I 

I 

1070 

I 

PI M 

I I 

1060 1050 

I I 

- • _ - - - o-o- -·--·-·-·--- · • - - -

•----o-o" -

-

/ ·--·-·-· -·- ...... 

I 

..... 

AP 

' ' ' ' 

I 

' \ 

I 

980 

-o o 

- 10 

\ -5 

\ 

'o 

'FeO' 

~------------------------------------~0 

- •----o-o.._ -15AI 0 

'•--·-·-·---·-----------().. 2 3 

~------------------------------------~10 

.... 

8 

.----0-0--·- -·-·-·- I I I I 

7 6 5 4 

MQO 

/ / /' 

-· 

I 

3 

/ 

/ 

I 

/ 

/ 

l 

2 

I 

I 

I 

I 

I 

I 

0 

,_ 75 

I 

I 

I 

I - 70 I 

-65 

-60 

-55 

-50 

l _l_ 45 

0 

EXPLANATION 

0 Olivine M Magnetite 

A Augite AP Apatite 

PL Plagioclase • Bulk composition 

I Ilmenite o Separated and analyzed glasses 

PI Pigeonite • Naturally filter-pressed oozes 

FIGURE 4.-MgO variation diagram showing liquid line of descent for Alae lava lake. Chemical data from table 3A 

(bulk composition), table 3B ('oozes), and table 4 (glasses). The approximate correlation between liquid temperature and composition is shown at the top of the diagram, along with the approximate temperatures of first appearance of minerals on the liquidus. Liquidus= 1,200oC, solidus= 980°C. Figure modified from Wright and Fiske 

(1971, fig. 3). 

RATES OF CRYSTALLIZATION OF MINERALS 

Figure 3 shows the rate of crystallization of the 

basalt as a function of temperature. The pronounced 

S shape indicates low crystallization rates near the 

liquidus and solidus and a very rapid crystallization 

rate at and below the temperature of the crust-melt 

interface. A similar crystallization curve has been 

obtained for Makaopuhi lava lake, where reliable 

temperature measurements extend to 1,160°C 

(Wright and Okamura, 1977). 
C18 SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

VARIATION OF LIQUID COMPOSITION DURING 

CRYSTALLIZATION 

The analyses of glass and oozes from Alae lava 

lake approximate a liquid line of descent for tholeiitic 

basalt from Kilauea and thus define the chemical 

composition of possible differentiates produced either 

by settling of early formed crystals, or by filter pressing of late liquids. The variation of major element 

chemical data for Alae as temperatures decrease 

may be described in three distinct stages (see fig. 

4): 

1. Crystallization of olivine in magnesian lavas 

(T>1,190°C).-Where olivine is the only mineral 

crystallizing, successive liquid compositions will lie 

along olivine control lines. The best description of an 

eruption in which the changing composition of 

lavas was controlled by olivine is that of 1959 

(Murata and Richter, 1966; Wright, 1973). Removal 

of olivine results in depletion of the liquid in magnesia, Cr, and Ni, and to a small extent in iron; but 

it also results in enrichment of the liquid in every 

other chemical constituent. 

2. Crystallization of pyroxene and plagioclase in 

addition to olivine (1,180°C>T>1,070°C).-0nce 

pyroxene and plagioclase begin to crystallize, the 

liquid is depleted in CaO and Si02 in addition to 

MgO and is further enriched in Ti02 and alkalis 

relative to the olivine control lines of stage 1. 4 Total 

iron begins to increase markedly. The variation of 

Al203 in the liquid depends on the ratio of plagioclase to pyroxene. Generally the Al203 decreases 

once plagioclase begins to crystallize in significant 

amount. 

Among the trace elements, Ba, Sr, and Ga are 

partitioned to plagioclase, and Cu, Y, and Yb are 

partitioned to pyroxene. All of these elements are 

eventually depleted in liquids collected at temperatures below 1,070°C. 

The bulk composition of Alae lies near the lowmagnesia terminus of olivine control. As shown in 

figures 2 and 4, all three silicate phases appear very 

close on the liquidus. Nonetheless, the differences 

between the H-186 and DPH-77 glasses and the 

bulk composition show the effects of olivine control 

particularly in Ab03 and Si02, as well as the lesse; 

effect of removal of pyroxene and plagioclase (mainly lower CaO). 

3. Crystallization of oxides (1,070°C>T>980°C). 

-Once ilmenite begins to crystallize, the rate ~f 

increase of total iron and Ti02 in the liquid dimin4 'I'he analyzed plagio('htHf' an1l JJyroxene from Kilauean basalts, 

including those from Alae lava lake, are always more siliceous than 

the bulk composition of the magma. 

ishes. As crystallization continues, maximum values 

for Ti02 and "FeO" are reached, after which both 

oxides decrease markedly in the liquid throughout 

the rest of the crystallization history; CaO and 

MgO continue to decrease. Si02 and alkalis, particularly K20, continue to increase. P205 is enriched in 

the liquid to slightly beyond the point where apatite 

begins to crystallize. V and Nb, and perhaps Zr, are 

concentrated in the Fe-Ti oxides but are enriched in 

the lowest temperature liquid (A-5-20) over their 

initial value. The residual liquid, formed as the 

end product of tholeiitic differentiation, is of rhyolitic composition; 95 percent of the chemical components are those of feldspar and quartz. The 

analyses of the residual liquid from A-12-10, -11, 

recalculated in table 5, can be calculated to the 

following mineral assemblage: 

Percent 

Fe-rich pyroxene ---------------------------------- 1.2 

~agnetite ---------------------------------------- 1.3 

Ilnaenite ------------------------------------------ 0.7 

Feldspar ( Or5oAb47An3) ----------------------------63.3 

Quartz --------------------------------------------33.5 

This assemblage is like that found in a hedenbergite granophyre or in an anhydrous rhyolitic pitchstone. 

NATURAL DIFFERENTIATES OF KILAUEAN THOLEIITE 

The known natural differentiates of Kilauean 

tholeiite all correspond in their chemistry to those 

low-temperature filter-pressed differentiates that are 

similar to the Alae oozes (Wright and Fiske, 1971, 

appendix 3) . Commonly these appear as fracture fillings (segregation veins). 

The natural differentiates generally correspond to 

liquids produced near the boundary separating 

stages 2 and 3 of the liquid line of descent outlined 

above. Differentiation temperatures range from 

about 1,040° to 1,065°C. Two factors are believed to 

operate in restricting the temperature range of 

formation. First, below 1,065°C the crystal mush 

provides a stable framework through which the 

liquid can move. Secondly, open fractures are restricted to the brittle crust and cannot penetrate 

deeper than the crust-melt interface. Hence, the 

pressure differential necessary to trigger filter pressing of liquid is lacking at temperatures higher than 

that of the crust-melt interface. 

Although the filter-press mechanism is well established, the differentiates produced by this mechanism will vary in composition acC'ording to the efficiency of the filter press in separating liquid from 

crystals. Many natural differentiates show the effects 
CRYSTALLIZATION AND DIFFERENTIATION OF THE ALAE MAGMA C19 

of incomplete separation of liquid and crystals and 

separation of minerals in a ratio differing from 

their abundance in the host rock. 

One example is the natural segregation vein from 

drill hole 9 (A-9-23, table 6). The chemical mode 

for A-9-23 may be compared with the ooze A-6-29 

in which the calculated amount of liquid is approximately the same (41.4 percent, 42.3 percent). 

The calculated An content of plagioclase and the 

Mgj (Mg +Fe) content of augite are greater in 

A-9-23 than in A-6-29. This is interpreted as the 

result of small amounts of sQdic plagioclase and Ferich pyroxene being brought in with the liquid. 

The data of table 9 show that the higher temperature Alae oozes brought in crystal aggregates which 

have a higher ratio of plagioclase to pyroxene than 

was in the liquid before filter pressing. This "plagioclase" effect, and any other differences in the ratios 

of minerals brought in with the liquid to those available in the liquid, produce a differentiate which does 

not, strictly speaking, lie on a "liquid line of descent." 

This must be taken into account in postulating a 

parent magma for any basaltic differentiate. At the 

lowest temperature (1,045°C) and highest crystallinity (70 percent) of any Alae ooze (A-5-20), the 

plagioclase effect apparently did not operate. Perhaps in this case, the crystal mush was sufficiently 

tight that fragments of the crystal framework were 

brought in directly with no opportunity for differential movement of plagioclase and pyroxene. 

SUMMARY 

Study of Alae lava lake provides information on 

changing amounts and composition of liquid and 

crystals during crystallization. Modes computed 

from chemical data are more accurate than modes 

obtained optically in transmitted light. Mineral proportions and compositions vary in a regular and 

predictable manner. Likewise, the composition of 

liquid in terms of both major and trace elements 

also varies smoothly. Among the trace elements, Nb, 

Li, and Zr are partitioned to the liquid at high 

temperatures and are increasingly partitioned to 

crystals at lower temperatures. Cr and Ni are depleted at high temperatures by concentration in 

olivine and spinel. The rest of the trace elements 

(Ba, Sr, V, Y, Yb) are partitioned between crystallizing phases and liquid at all temperatures but all 

tend to become slightly enriched in the low-temperature liquids relative to their value in the bulk composition. 

Differentiation takes place by filtration of liquid 

through a crystal mush with variable but small 

retention of the crystal framework in the separated 

differentiated liquid. 

REFERENCES CITED 

Anderson, A. T., and Greenland, L. P., 1969, Phosphorous 

fractionation diagram as a quantitative indicator of 

crystallization differentiation of basaltic liquids: Geochim. et Cosmochim. Acta, v. 33, no. 4, p. 493-505. 

Decker, R. W., and Peck, D. L., 1967, Infrared radiation from Alae lava lake, Hawaii: U.S. Geol. Survey 

Prof. Paper 575-D, p. D169-D175. 

Evans, B. W., and Moore, J. G., 1968, Mineralogy as a 

function of depth in the prehistoric Makaopuhi tholeiitic 

lava lake, Hawaii: Contr. Mineralogy and Petrology, 

v. 1~no. 2,p.85-115. 

Lindsley, D. H., 1962, Investigations in the system FeOFe20a-Ti02: Carnegie Inst. Washington Yearbook 61, 

1961-1962, p. 100-106. 

Moore, J. G., and Evans, B. W., 1967, The role of olivine in 

the crystallization of the prehistoric Makaopuhi tholeiitic 

lava lake, Hawaii: Contr. Mineralogy and Petrology, 

v. 15,no. 3,p. 202-223. 

Murata, K. J., Bastron, Harry, and Brannock, W. W., 1965, 

X-ray determination curve for Hawaiian olivines of composition Fo76-ss: U.S. Geol. Survey Prof. Paper 525-C, p. 

C35-C37. 

Murata, K. J., and Richter, D. H., 1966, Chemistry of the 

lavas of the 1959-60 eruption of Kilauea Volcano, 

Hawaii: U.S. Geol. Survey Prof. Paper 537-A, p. A1-

A26. 

Peck, D. L., 1978, Cooling and vesiculation of Alae lava lake, 

Hawaii: U.S. Geol. Survey Prof. Paper 935-B, 59 p. 

(In press). 

Peck, D. L., Hamilton, M. S., and Shaw, H. R., 1977, 

Numerical analysis of lava lake cooling models: Part II. 

Application to Alae lava lake, Hawaii: Am. Jour. 

Science, v. 277, p. 415-437. 

Peck, D. L., and Kinoshita, W. T., 1976, The eruption of 

August 1963 and the formation of Alae lava lake, 

Hawaii: U.S. Geol. Survey Prof. Paper 935-A, 33 p. 

Peck, D. L., Moore, J. G., and Kojima, George, 1964, Temperatures in the crust and melt of Alae lava lake, Hawaii, 

after the August 1963 eruption of Kilauea Volcano-A 

preliminary report: U.S. Geol. Survey Prof. Paper 

501-D, p. D1-D7. 

Peck, D. L., Wright, T. L., and Moore, J. G., 1966, Crystallization of tholeiitic basalt in Alae lava lake, Hawaii: 

Bull. Volcanologique, v. 29, p. 629-656. 

Peck, L. C., 1964, Systematic analysis of silicates: U.S. 

Geol. Survey Bull. 1170, 89 p. 

Powers, H. A., 1955, Composition and origin of basaltic 

magma of the Hawaiian Islands: Geochim. et Cosmochim. 

Acta, v. 7, nos. 1-2, p. 77-107. 

Sato, M., and Wright, T. L., 1966, Oxygen fugacities directly 

measured in magmatic gases: Science, v. 153, p. 1103-

1105. 

Shaw, H. R., Hamilton, M. S., and Peck, D. L., 1977, 

Numerical analysis of lava lake cooling models: Part I. 

Description of the method: Am. Jour. Science, v. 277, 

p. 384-414. 
C20 SOLIDIFICATION OF ALAE LAVA LAKE, HAWAII 

Skinner, B. J., and Peck, D. L., 1969, An immiscible sulfide 

melt from Hawaii: Econ. Geology Mon. 4, p. 310-322. 

Swanson, D. A., Jackson, D. B., Duffield, W. A., and Peterson, D. W., 1971, Mauna Ulu eruption, Kilauea Volcano: 

Geotimes, v. 16, no. 5, p. 12-16. 

Tilley, C. E., Yoder, H. S., Jr., and Schairer, J. F., 1964, 

new relations on melting of basalts, Carnegie Inst. 

Washington Yearbook 63, 1963-1964, p. 92-97. 

--- 1967, Melting relations of volcanic rock series: 

Carnegie Inst. Washington Yearbook 65, 1965-1966, 

p. 260-269. 

Van Der Plas, L., and Tobi, A. C., 1965, A chart for judging 

the reliability of point counting results: Am. Jour. Sci., 

v. 263,no. 1,p.87-90. 

Wright, T. L., 1971, Chemistry of Kilauea and Mauna Loa 

lava in space and time: U.S. Geol. Survey Prof. Paper 

735, 40 p. 

Wright, T. L., 1973, Magma mixing as illustrated by the 

1959 eruption, Kilauea Volcano, Hawaii: Geol. Soc. 

America Bull., v. 84, no. 3, p. 849-858. 

Wright, T. L., and Doherty, P. C., 1970, A linear programming and least-squares computer method for solving 

petrologic mixing problems : Geol. Soc. America Bull., 

v. 81,p. 1995-2008. 

Wright, T. L., and Fiske, R. S., 1971, Origin of the differentiated and hybrid lavas of Kilauea Volcano, Hawaii: 

Jour. Petrology, v. 12, no. 1, p. 1-65. 

Wright, T. L., and Okamura, R. T., 1977, Cooling and 

crystallization of tholeiitic basalt, 1965, Makaopuhi lava 

lake, Hawaii: U.S. Geol. Survey Prof. Paper 1004, p. 

1-78. 

Wright, T. L., Peck, D. L., and Shaw, H. R., 1976, Kilauea 

lava lakes: Natural laboratories for study of cooling, 

crystallization, and differentiation of basaltic magma: 

Am. Geophys. Union, Geophys. Mon. no. 19, p. 375-390. 

Wright, T. L., and Weiblen, P. W., 1967, Mineral composition 

and paragenesis in tholeiitic basalt from Makaopuhi 

lava lake, Hawaii ( abs.) : Geol. Soc. America ann. mtg. 

New Orleans.