VOLCANO 

H.AWAII

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PETROLOGY OF THE 

KILAUEA IKI 

LAVA LAKE

GEOLOGICAL SURVEY 

RFESSIONAL PAPER 537-6
Petrology of the 

Kilauea Iki Lava Lake 

Hawaii 

By DONALD H. RICHTER .and. JAMES G. MOORE 

THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 537-B 

A petrologic and thermometric study of a 

semienclosed body of slowly cooling basalt 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1966 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

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

Washington, D.C. 20402 - Price 30 cents {paper cover) 
CONTENTS 

Abstract __________________________________________ _ 

Introduction ______________________________________ _ 

Acknowledgments _________________________________ _ 

Geologic and petrol~gic setting ______________________ _ 

The 1959 eruption and formation of the Kilauea Iki lava lake ____________________________________________ _ 

Methods of study __________________________________ _ 

Drilling and sampling __________________________ _ 

Thermometry _________________________________ _ 

Physical properties and petrochemistry ___________ _ 

Growth of lava lake crust ___________________________ _ 

Page 

B1 

1 

2 

2 

3 

6 

6 

7 

7 

8 

The crust _________________________________________ _ 

Vesicularity, density, and grain size ______________ _ 

Petrochemistry ________________________________ _ 

Olivine basalt _____________________________ _ 

Transient zone of crystallization _____________ _ 

Diabase segregations _______________________ _ Melt _____________________________________ _ 

Alteration ____ -----------------------------

Differentiation ____________________________________ _ 

Fractional crystallization _______________________ _ 

Alkali transfer _______________________ ---_- ___ ---

References-------------------------~---------------

ILLUSTRATIONS 

FIGURE 1. Map of the Island of Hawaii_ _______________________________________________________________________ _ 

2. Map and section of Kilauea Iki crater _____________________________________________________ ------------

3. Graph showing volume of lava erupted into Kilauea Iki_ _______________________________________________ _ 

4. Core barrel and bit after 1~ hours of immersion in melt ________________________________________________ _ 

5. Growth of crust on Kilauea Iki lava lake _____________________________________________________________ _ 

6. Isotherms in crust of Kilauea Iki lava lake ____________________________________________________________ _ 

7. Composite section through drill hole!_ ___________________________________________________ . ____________ _ 

8. Composite section through drill hole 2 _________________________________________________________ -- _____ -

9. Section through drill hole 3 ________________________________________________ -- _-----------------------

10. Silica-variation diagram _______________________________________________ -- __ --_-----------------------

11. Photomicrographs of crustal rocks from depth of 29 to 31 feet at two different periods during growth of crust__-_--

12. Graph showing relation between volume percentage, index of refraction, and temperature of interstitial glass in 

the transient zone of crystallization __________________________________________ -----------------------

13. Photomicrograph of diabase segregation ________________________________________________________ - __ -- __ 

14. Plot of KzO: Na20 as a function of Si02 for Kilauea Iki lava lake rocks-----------------.,-------------------

15. Graph showing Fe20a : FeO + Fe20 3 as a function of depth _______________________________ - __ -------------

16. Alkali-magnesia-iron oxide diagram of differentiation trend in Kilauea Iki lava lake ________________________ _ 

17. Hypothetical sections through Kilauea Iki lava lake showing mechanism of alkali enrichment_ ______________ _ 

TABLES 

Page 

B10 

10 

11 

13 

18 

20 

21 

22 

23 

23 

24 

26 

Page 

B2 

4 

5 

7 

8 

9 

11 

12 

13 

16 

19 _-

19 

20 

22 

22 

24 

25 

Page 

TARLE 1. Kilauea Iki lava lake temperature profiles________________________________________________________________ B9 

2. Chemical analyses, norms, and modes of rocks from hole!_________________________________________________ 14 

3. Chemical analyses, norms, and modes of rocks from hole 2--------~---------------------------------------- 15 

4. Modes of rocks from hole 3 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 16 

5. Chemical analyses, norms, and modes of tholeiitic differentiates _________________________________ ------------ 20 

6. Composition of clinopyroxene from diabase segregation, hole 3 ____________________________________ ---------- 21 

III 
.THE 1959-60 ERUPTION· OF KILAUEA VOLCANO, HAWAII 

PETROLOGY OF THE KILAUEA IKI LAVA LAKE, HAWAII 

By DoNALD H. RrcHTER and JAl\:t:Es G. MoonE 

ABSTRACT 

The 1959 summit eruption of Kilauea Volcano filled the crater 

of Kilauea lki to a depth of 365 feet with 50 million cubic yards 

of tholeiitic basalt. In the 3-year period since the formation 

of this lava lake, the U.S. Geological Survey core drilled four 

holes through the crust for petrologic and thermometric studies 

of a semienclosed body of slowly cooling basalt. 

Between the end of the eruption in December ~959 and 

December 1962, the crust over the lake of molten lava had 

attained a thickness of more than 43 feet. Growth of the crust 

is attributable to the radiation and conduction of heat which is 

controlled primarily by the amount of rain falling on the lake's 

surface. Rate of crustal growth has decreased from about 4 

feet per month during .the first four months of the lake's history 

to an average rate of 0.34 foot per month between .June and 

December 1962. 

The rocks in the crust of the lava lake are porphyritic olivine 

basalts that have a wide range in phenocrystic olivine content. 

The olivine phenocrysts are set in. a fine-grained, generally bolocrystalline, intergranular groundmass of clinopyroxene and 

plagioclase with minor opaque minerals, apatite, hypersthene 

and glass. The base of the crust is characterized by a 5- to 

6-foot-thick transient zone of crystallization that contains as 

much as 30 percent interstitial liquid at the crust-melt contact. 

Olivine-poor diabase segregations have been found at depths 

below 32 feet and constitute less·than 1 percent of the total core 

examined. 

The bulk density of the crust is almost entirely a function of 

the degree of vesiculation and increases from about 2.0 g per 

cc at the surface to 2.8 g per cc below a depth of 34 feet. 

Densities of nonvesicular glasses that contain a few olivine 

phenocrysts range from 2.6 to 2.9 g per cc. The grain size of 

the groundmass reaches a maximum within 15 feet of the 

surface, regardless of the thickness of the crust. 

A total of 20 new chemical analyses together with 45 modal 

analyses of the rocks and melt in the upper part of the lake 

are presented. These data portray the chemical and mineralogical properties of the crust at five different times during the 

early history of the lake. The changes in composition in most 

of the rocks are due to two processes of fractional crystallization: gravity settling and filter pressing. ·Settling of olivine 

phenocrysts has influenced the composition of the entire crust, 

l'ffecting changes in silica content between 45.61 and 49.61 

percent. 

The olivine-poor diabase segregations and the bo.ttom-hol~ ooze 

found at depth in the crust are filter-pressed residual pore 

liquids and contain as much as 54.08 percent Si02. The low 

refractive index of the glass in the transient zone of crystallization indicates that differentiates with more than 60 percent 

Si02 are capable of being formed by filter pressing. The overall differentiation trend is toward pronounced enrichment in 

K20, Na20, and Ti02, and moderate enrichment in total iron 

oxides with increasing Si02. 

Chemical analyses of the melt indicate that a zone of transient 

alkali enrichment exists immediately below the crust. Enrichment of ~0 in this zone is upwards of 100 percent over that 

in the crust rocks and original lavas that filled the lake. The 

alkalis apparently moved from deep within the lake and concentrated in the melt below the crust. Upon crystallization of 

this zone, the excess alkalis were driven off and deposited as 

crystalline alkali sulfate sublimates in the cooler parts of the 

crust. It is postulated that, if analogous conditions exist in 

the magma reservoirs of the Hawaiian volcanoes, this process 

of alkali enrichment. coupled with removal of clinopyroxene 

by settling, could well explain the formation of alkalic basalt 

from a tholeiite parent. 

INTRODUCTION 

The origin of the two prineipal basalt magma typestholeiitic and alkalic-has been one of the most difficult 

problems in igneous petrology. In 1950, C. E. Tilley 

adv·anced our concepts of basalt petrogenesis by calling 

attention to the presence of tholeiitic magma in an 

oceanic environment and by demonstrating that a consistent chronologieal change in magma type, from tholeiitic to alkalic, occurred during the evolution of 

Hawaiian volcanoes. 

Since 1950, the interest in the Hawaiian Islands has 

been attested to by the increased number of petrologic 

papers referring to Hawaiian basalts. As would be 

expected, however, the various investigators are not 

unanimous in their theories regarding the origin and 

relationship of the two principal basalt magma types. 

Unfortunately, deep-seated igneous processes cannot be 

B1 
B2 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

examined directly, but must be inferred from laboratory investigations of less complex systems and from 

field relationships. The inability to duplicate fully 

the physical-chemical conditions which control the 

natural systems leaves considerable room for speculation and argument. 

The 1959 summit eruption of Kilauea Volcano has 

provided an unexcelled opportunity to study a slowly 

cooling body of tholeiitic basalt. At the end of the 

eruption in late December 1959, approximately 50 million cubic yards of molten lava filled the crater of 

Kilauea Iki to a depth of 365 feet. . This exposed 

magma chamber, where processes of crystallization 

and magmatic differentiation are perhaps analogous to 

those within the Kilauea magma reservoir, presents an 

unparalleled, opportunity for petrologic investigations. 

This ideal natural laboratory has already prompted 

a number of inv~stigations. Shortly after the end of 

the 1959 summit eruption the staff of the U.S. Geological Survey's Hawaiian Volcano Observatory initiated a program of drilling and thermal measurement. 

Temperatures measured in the crust and melt of the 

lava lake during the early stages of this program have 

been the subject of two preliminary reports (Ault and 

others, 1961; Ault and others, 1962). The first hole to 

completely penetrate the crust of the lake was drilled 

in July 1960, by the Lawrence Radiation Laboratory 

(LRL) of the University of California, in an attempt 

to test drilling techniques in hot and molten rock 

masses (Rawson, 1960). Core and melt samples ~rom 

the LRL hole have been studied and analysed by 

Macdonald and Katsura ( 1961). Ground magTietic 

surveys on the lava lake have been conducted by Decker 

(1962), and. F. C. Frischknecht and L. A. Anderson 

(unpub. data) have measured the electrical conductivity of the melt by field electromagnetic techniques. 

This paper (1) summarizes the physical, petrographic, and chemical data obtained from studies of 

core and melt, collected at known temperatures, from 

three successive U.S. Geological Survey holes drilled 

between April 1960 and June 1962, and (2) discusses 

the petrologic implications of these data. Although 

the crust of the lava lake was only a little more than 

41 feet thick in June 1962, magmatic differentiation had 

already affected the composition of the rocks. In fact, 

the range in chemical composition in this relatively 

thin crustal layer is greater than any previously known 

:f.or the exposed volcano of Kilauea. 

ACKNOWLEDGEMENTS 

without whose interest this investigation would not 

have been possible. George Kojima, Robert Koyanagi, 

John C. Forbes, William Francis, Burton C. Loucks, 

and Reginald Okamura gave much of their time during 

the drilling operations and the thermal-profile measurements. Jerry P. Eaton, Wayne U. Ault, and Harold 

T. Krivoy not only aided. in the field but gave advice 

and encouragement throughout the course of the study. 

Special credit is also due Wayne U. Ault who fabricated most of the temperature probes and who was 

responsible for obtain ;ng much of the thermal data. 

The excellent analytical work of Dorothy F. Powers, 

U.S. Geological Survey, Denver, Colo., whose chemical 

analyses are a valuable part of this paper is acknowledged with gratitude. Thanks are also due Howard 

A. Powers, David B. Stewart, and William N. Sharp 

of the Geological Survey for their discussions and aid. 

Appreciation is here given to Superintendent Fred 

A. Johnston of Hawaii National Park and his staff for 

their continued interest in and support of the studies 

of Kilauea Iki lava lake. 

GEOLOGIC AND PETROLOGIC SETTING 

Kilauea is one of five volcanoes that compose the 

Island of Hawaii, largest and southeasternmost island 

in the 1,500-mile-long chain of volcanic islands that 

form the mid-PaCific Hawaiian Archipelago (fig. 1). 

Kilauea, 4,090 feet above sea level, and its lofty companion Mauna Loa, 13,680 feet above sea level, are the 

youngest and most active of the Hawaiian volcanoes. 

N 

r 

CONTOUR INTERVAL 

2000 FEET 

The authors wish to express their appreciation to FIGURE 1.-Map of the island of Hawaii showing location of 

the entire staff of the Hawaiian Volcano Observatory. Kilauea Iki crater on Kilauea Volcano. 

... 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B3 

Both are typical shield volcanoes built by the outpour- I 

ings of many thousands of relatively fluid flows of 

tholeiite basalt; neither volcano is known to l1ave yet 

produced lavas of the alkali basalt suite, which -are 

characteristically erupted intermittently and in minor 

volume during the dying stages of Hawaiian volcanoes. 

The broad summit of Kilauea is indented by a large,. 

relatively flat-floored caldera, approximately 3 miles 

long and 2 miles wide. In the southwest part o:f the 

caldera is Halem:uunau, a precipitously walled 500-

:foot-deep crater with a diameter o:f about 3,200 :feet. 

Two rift zones-a southwest and an east-extend down 

the flanks o:f the volcano, :from the summit area to :far 

below sea level. Summit eruptions, as the name implies, are restricted to the caldera region with most 

o:f them occurring in Halemaumau; fl-ank eruptions, 

which generally :follow a summit outbreak, occur along 

the rift zones. 

IGlauea Iki, site o:f the 1959 summit eruption, is a 

deep and relatively large pit crater immediately ea.st o:f 

the summit caldera. This crater is approximately 1 

mile long and one-half mile wide, and its rim ranges 

:from about 3,900 :feet a·bove sea level along the northwest and west sectors -to about 3,600 feet above sea level 

along the low, narrow ridge that separates Kilauea Iki 

:from the summit caldera (see fig. 2). The preeruption 

fl·oor o:f Kilauea Iki was a small fla;t plain, 37 acres in 

area, averaging 3,130 :feet above sea level. This plain 

was the surface o:f a shallow lava pond :formed during 

the brief eruption o:f 1868, the last eruptive activity in 

the crater prior to 1959. 

The bulk o:f the tholeiitic lava flows o:f Kilauea is remarkably similar in composition, and any changes that 

do occur, both within the lavas o:f a single eruption and 

:from eruption to eruption, are, in general, ·aUributahle 

to the addition or removal o:f olivine (Powers, 1955). 

The average silica content o:f Kilauea basalt, determined 

by 24 chemical analyses o:f prehistoric ( pre-1790) and 

historic flows, is about ·50 percent, the norm containing 

a :few tenths of a percent olivine (Macdonald, 1949b, p. 

7 4). The minor intrusive rocks and some o:f the massive flow rocks o:f Kilauea, on the other hand, show the 

effects o:f more advanced differentiation. Rocks :from 

the Uwekahuna laccolith in the IGlauea caldera wall 

range :from 45.7 to 52.04 percent in silica content, a 

range in composition as great as tha;t found :for all the 

analyzed IGlauea flows (Murata and Richter, 1961). 

Likewise, l{uno and others (1957) have :found that 

:segregation veins in a thick augite-olivine basalt flow 

exposed in the caldera wall contain 52.36 percent Si02 

which, until the present study, represented the most 

siliceous tholeiitic differentiate found on Kilauea. 

Recently, evidence has also been found suggesting 

that an increase in K 2 0 in the Kilauea magma has occurred during late prehistoric-ea.rly historic time 

(Moore and Richter, unpub. dU~ta). This change is in 

the direction of part of the shift from tholeiitic to alkalic basalt. 

THE 1959 ERUPTION AND FORMATION OF THE KILAUEA 

IKI LAVA LAKE 

The 1959 summit eruption of Kilauea Volcano began 

at 8:08p.m. on November 14, 1959, when several discontinuous fissures halfway up the 600-foot south wa.Il of 

IGlauea Iki began discharging liquid lava (Richter and 

Eaton, 1960). In 2 hours the line of eruptive fissures 

was approximately one-half mile long, with the indi~ 

vidual lava fountains rea.ching heights of 100 feet. 

Through the night, however, activity gradually ceased, 

first along the outermost vents. By ·the next day only 

one vent, in the west end of the crater (vent, fig. 2), 

remained active. As the eruption continued both the 

rate of lava extruded from the single vent and the size 

of the lava fountain increased, with the fountain reach-

. ing heights of 1;200 feet by November 20. On November 21, after almost 7 days of continuous eruption, the 

level of the lava in the crater reached the level ·of the 

vent and the founta.ining ceased. 

In the next 4 weeks, 16 additional eruptive phases, 

ranging in duration from 321;2 hours (4th phase) to 

1%, hours (14th phase), occurred in IGlauea Iki. · The 

17th and last of the eruptive phases, stopped at approximately 8 :00 a.m., December 20, 1959, marking the end 

of the summit eruption. All these lruter and shorter 

phases of the eruption were apparently fed by the same 

conduit-vent system which fed the week-long first 

phase,.. and, moreover, all erupting stopped soon after 

lake lava reached the level of the vent. 

This phenomenon of lake lava drowning the active 

lava fountain and stopping the extrusion of lava was 

exceptionally well displayed during the eruption. As 

lake lava encroa·ched upon the 'Orifice of the vent, just 

prior to the end of an eruptive phase, the fountain ac-· 

tivity became very erratic, suggesting that the relatively 

heavier, degassed lake lava was impeding the natural 

flow of new gas-charged lava from the vent. As the 

lake level conti_nued to rise, it was apparent that grea:t 

quantities of lake lava were actually pouring into the 

vent between bursts of fountaining, until finally, enough 

material filled the conduit to effectively prevent vesiculation and thereby pressurecapped the system. After 

the cessation of fountaining, the entire lake surface 

would immediately subside as more and more lake lava 

flowed back down the vent. This backflowiri.g lava evidently returned to the magma reservoir from which it 
B4 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

3000 

FEET ·ABOVE 

SEA LEVEL 

CINDER-PUMICE 

CONE 

N 

\ 

0 200 400 600 800 FEET 

CONTOUR INTERVAL 100 FEET 

Dashed contours represent pre-eruption 

crater topography 

FIGURE 2.-Map and section of Kilauea Iki crater before and after the 1959 summit eruption showing location of U.S. 

Geological Surve~ drill holes. Small open circles show location of permanent reference stations on the surface of the 

lava lake. 

had risen, there to mix with new magma and again rise 

. to the surface in ·a subsequent eruptive phase. Backflow 

often continued for as long as 2 days after the end of a 

phase, causing the lake level to subside as much as 50 

feet. In the first hour of hackflow the volume rate 

frequently exceeded 2 million cubic yards per hour, or 

more than twice the average rate of eruption. 

The volume of lava erupted into Kilauea Iki during 

the 17 eruptive phases, and the volume withdrawn following each phase is shown graphically, as a function 

of time, in figure 3. A quantitative measure of the 

rate of extrusion and withdrawal is expressed by the 

slope o~ the lines in the graph. During the week -long 

first phase, the rate of extrusion increased from 40,000 

cubic yards per hour for the first 2 days of eruption to 

a maximum of 500,000 cubic yards per hour on the 

sixth day and then decreased slightly to 300,000 cubic 

yards per hour on the last day. During the laker 

phases, rates of extrusion (and withdrawal) were generally much higher. The maximum rate 1neasured was 

1,600,000 cubic yards per hour during the 31j2 -hourlong 16th phase. 

A total of 40 million cubic yards of lava filled the 

crater at the end of the first phase; backflow was relatively minor and resulted in a loss of only 1,500,000 

cubic yards. The very obvious change in the average 

net capacity of the lava lake (fig. 3) from 40 million 

to 50 million cubic yards between the third and fourth 

phases was due to a change in the elevation of the vent. 

The fourth phase activity started on the steep, inner 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B5 

side of the new cinder-pumice cone approximately 40 

feet higher but over the same area as the vent of the 

earlier phases. In all subsequent phases the vent remained at this higher but somewhat variable level allowing the lake to fill to a much greater depth before 

flowing hack into the vent. Following five of the eruptive phases (Nos. 2, 7, 9, 12, m:t-d 15), more lava was 

withdrawn than had been erupted during each phase. 

Apparently some form of breakdown around the orifice 

of the vent, probably caused by the backflowing lava, 

allowed some of the lake lava from the earlier phases 

to escape. The lake attained ·its greatest depth ( 414 

ft) and volume (58 million cu yd) at the end of the 

eighth phase on December 11, 1959. After the end of 

the last backflow on December 23, 1959, the lava lake 

contained slightly less than. 50 million cubic yards and 

had a maximum depth of approximately 365 feet. 

vVith the exeeption of the pyroclastic debris, ··most 

of which built the cinder-pumice cone lee,vard of the 

vent (fig. 2), all the lava extruded during the eruption 

was eontained in IGlauea Ild. Because of the extreme 

fluidity of the lav:a and rapidity of filling, it is assumed 

that most of the lava was thoroughly mixed, and any 

possible correlation between specific layers of lake lava 

and lava from an individual eruptive phase is unlikely. 

Furthermore, since filling, convection currents have no 

doubt contributed to a certain amount of mixing within 

the still fluid part of the lake. 

The filling of the crater was neither orderly nor systematic. In the first phase, most of the early lavas 

poured into the trough leading from the shallow west 

end to the deep east end of the crater and spread 

rapidly across the crater's flat floor (fig. 2). By the 

time lava in the bottom of the erater reached a depth 

of 25 feet, new lava flowing down the trough from the 

vent had begun to plunge under the crust of the lake, 

floating it upward and filling the young lake from 

below. Although this process continued throughout 

most of the first phase, the original crust on the lake 

did not persist more than a few days and, in fact, a 

60r-----------------------~------------------------------------------------------------~ 

50 

"' 40 

8 

X 

en 

Cl 

a::: 

<( 

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(.) 30 

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(.) 

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:::> 

...J 20 0 

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14 16 

~-_}}J'.,,,}',,,_}\)\hJ!J.,,,.]\_. __ 

, ___ . ______ )\ _)'-----.------ ---- . 

ERUPTIVE PHASES 

18 20 22 24 

NOVEMBER 1959 

1.. 

26 28 

3 

30 2 

_4_ 1 6 7 

4 6 8 

8 

10 12 14 16 

DECEMBER 1959 

18 20 

l!_,IGURE 3.-Graph showing volume of lava erupted into Kilauea Iki during the 1959 summit eruption. Dashed line after 

the end of an eruptive phase represents backflow of lava down the vent. Each dot is a volume measurement. Note 

that the volume of totallava actually decreased during the fourth eruptive phase. 

796'-503 0~66-2 
B6 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

new crust. formed over most of the lake -at least once 

or twice every 24 hours. As the crust floated upward, 

a zone of very thin and unstable crust was left between 

the thick, older crust · and the sloping crater walls. 

From this peripheral weak zone, liquid lava continually 

welled up from below and spread out over the old surf.ace, eventually cooling to form a new crust. In the 

later phases, most of the new lava contributed to the 

lake spread from the vent area as thick surface flows, 

covering and probably assimilating the old crust. In 

at least two phases, however, subcrust:al injection 

played an important role in filling the lake. 

The process of backflow following an eruptive phase 

further compli_cated the lake's history. Crustal foundering, somewhat similar to that which occurred at the 

periphery of the lake during filling, continually 

reworked the lake surfa.ce during backflow. This reworking appeared to be a direct consequence of the 

liquid lake lava attempting to reach a common level 

in the concave bow 1 formed by the continual subsidence 

of the lake's crust. In this manner, an entirely new 

surface crust was generally formed every few hours 

on the lake. The end result on December 23, 1959, 

was an extremely level lake surface, with m·aximum 

relief of less than 5 feet over an area of approximately 

135 acres (see section, fig. 2). 

METHODS OF STUDY 

In March 1960, less than 3 months after the end of 

the 1959 eruption, engineering surveys by the staff of 

the U.S. Geological Survey's Volcano Observatory 

were conducted in and around Kilauea Iki to set up 

controls for the various investigations planned on the 

lava lake. A 4,000-foot base line trending a pproximately N. 80° W. and a 2,000-foot crossline, both with 

permanent stations spaced every 100 feet, were laid out 

by transit and tape (fig. 2). Case-hardened 2-inch 

concrete nails driven into the crust through stamped 

aluminum tags were used to designate the permanent 

stations. Temperatures of more than 100° C within 

2 inches of the surface were indicated by the f.act that, 

after the nails were emplaced, water dropped on the 

nailheads would immediately boil. 

After the control lines were installed, a level line 

was carried into the crater and the elevations of all 

permanent stations were determined. Releveling, repeated every 3 to .8 months since the original survey, 

has shown that the lake surface subsided an average 

of 0.7 foot per year during the 2-year period ending 

March 1962. 

Access to the surface of the lava lake is by means of 

a 1-mile-long foot trail which switchbacks down the 

400-foot-high east wall of the crater (fig. 2). 

DRILLING AND SAMPLING 

A total of four holes (fig. 2) has been drilled by 

the U.S. Geological Survey into the crust of the lava 

lake between April 1960 and December 1962. As mentioned previously, however, only data from the first 

three hole-s are fully presented in this paper. All holes 

were core drilled their entire length, but core recovery 

seldom averaged more than 20 percent, principally because of the extreme temperatures and the consequent 

unorthodox drilling methods used. Melt was collected 

below the crust in holes 1 and 3, and during the first 

penetration of hole 2; no attempt was made to sample 

the melt in the second penetration of hole 2. 

On April 9, 1960, hole 1 was drilled to a depth of 

71h feet using an ordinary lh-inch electric hand drill 

powered by a 300-watt portable generator. The bit 

employed was a hollow, tungsten-carbide masonry 

drill, 1~$ inch in diameter and capable of holding 3 

inches of core, welded to a section of %-inch solid steel 

rod. On April 25 the hole was deepened to 11.8 feet 

and on May 6 to 12.7 feet. Drilling was done dry .to 

7 feet; below that, water was sparingly poured into 

the hole during drilling in an attempt to cool the 

bottom. Despite the cooling, however, temperatures 

at depths of more than 12 feet often reached 900° C, 

and at 12.7 feet both the drill and bits failed to function 

properly and drilling was temporarily halted. Although the equipment used in this first drilling on the 

lava lake was primitive, it demonstrated that core drilling in extremely hot rock is feasible. 

Hole 1 finally penetrated the crust on August 24, 

1960, using a 1~) -inch core drill powered by 2~~-hp 

gasoline engine with a maximum speed of 400 rpm. 

The drill bits, specially . :fabricated by Sprague and 

Henwood, Inc., consisted of tungsten-carbide cutters set 

in a high-temperature matrix with nickel shims. Core 

was collected in. a conventional thin-wall, 2-foot doubletube core barrel. During drilling, water was manually 

pumped into the drill rods through a water swivel designed and built by Chester K. Wentworth of the U.S. 

Geological Survey. · 

Using the same drilling equipment, hole 2 was dri1led 

through the crust (29.7 ft thick) on April13, 1961, and 

again on October 4, 1961 (35 ft thick).· Immediately 

after the second penetration in October, a stainless 

steel-ceramic probe containing a thermocouple was 

forced 4 feet into the melt below the crust ( Ault and 

others, 1962). . 

Hole 3 was drilled through the crust ( 41.6 ft thick) 

between May 31, and June 11, 1962, again using the 

same equipment as that used for hole 2. An attempt to 

force a 10-foot probe into the melt proved unsuccessful, 

and the hole, still containing the probe and approxi-

. mately 15 feet of drill rod, was abandoned. 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B7 

With more elaborate and powerful drilling equipment 

(a conventional 9-hp portable drill and a 3%-hp water 

pump), hole 4 penetrated the melt at 43.6 feet on December 6, 1962. On January 10, 1963, after extreme 

cooling with water, hole 4 was deepened to 48 feet, or 

about 4 feet below the normal crust-melt boundary. 

Drilling rates through the vesicular basalt of the 

crust could be maintained, under ideal conditions, as 

high as 1 foot per minute. In the denser rocks, below 

about 30 feet, drilling was generally slower; and within a few feet of the melt drilling was always very slow, 

with mtes rarely exceeding 0.1 foot per minute. Moreover, extreme care had to be exercised when approaching the melt owing to liquid oozing from the wall of the 

hole and freezing onto the drill bit. On more · than 

one occasion the bit stuck fast in the hol"e and the drill 

stalled. When this occurred, the rods and bi·t were 

left without benefit of coolant water until thermal 

equilibrium returned (generally 15 to 20 min) after 

which the string of rods could, with considerable difficulty, be withdrawn. 

The drill bit, however, could not survive being submerged too long in the highly corrosive melt. ·when 

the melt was penetrated at 22.5 feet in hole 1, the bi.t 

became stuck and the rods snapped 15 feet below the 

collar of the hole. The rods 'vere finally extracted after 

1Vz hours, during which time the entire bit plus 5 

inches of the double-tube core barrel had been completely dissolved by the melt (fig. 4). 

Drill rods were pulled after every 3 inches during the 

drilling ·of hole 1 when the masonry bit was used, and 

at least after every 2 feet when the convent.ional core 

barrel was used. Care was taken to reduce grinding up 

of the core to a minimum, but even with precaution 

many drilling runs produced no core whatsoever. Mel~ was collected with either the drill bit or a specially 

designed 5-inch-long, hollow steel spoon. Samples of 

c~re from the three hol~s are numbered consecutively, 

w1th respect to depth, as follows: Hole 1, IU-100 to 

KI-115; hole 2, KI-150 to KI-186; hole 3, KI-200 to 

KI -236. (See figs. 6, 7, and 8.) 

EA • t. IL J ¥II J 1,1 IJII::OII.III.~Ii,JH .. ,If .• 4 .J ,. PFOiit~l.liiJiihii'Cf .. 

·~· .. "V'-

FIGURE 4.- Core barrel and bit after i% hours of immersion in 

melt at a depth of 22.5 feet. Compare with new core barrel 

and bit. 

THERMOMETRY 

It is not the intent of this paper to discuss fully the 

temperature investigations that have been undertaken 

on the lava lake. Hmvever, the temperature profiles 

measured in the holes as soon as possible after drilling 

and hence, indicative of the sample temperature a:t time 

of collection, are important in understanding the 

crystallization history of the lava lake. Not all the 

many temperature profiles measured through the crust 

of the lava lake since April1960 are used in this paper. 

These valuable source data are the basis for studies 

presently underway on the physical properties of the 

crustal rocks and for calculations of physical constants, 

such as thermal diffusivity and latent heat of 

crystallization. 

Most of the temperatures obtained in the drill holes 

were measured with sheathed chromel-alumel thermocouples and a slide-wire potentiometer with a rea;din()' " accuracy of 0.005 millivolt. The sheathed thermocouples consisted of matched chromel-alumel pairs, 

swaged with powdered MgO filler, in a thin-wall 310-

stainless-steel case. Unsheathed thermocouples were 

used successfully for the first measurements in hole 1, 

but after melt. penetration, a few seconds exposure to 

the extremely hot S02 -rich bottom-hole vapors would 

disintegrate the alumel element. In hole 3 a compound 

5-pair chromel-alumel thermocouple, with junctions 

spaced 3 feet apart, was used. Laboratory cali-brations, 

using the melting-point technique and latterly a comparison with aN ational Bureau of Standards calibrated 

platinum-platinum-90, rhodium-10 thermocouple, indicate an accuracy of about one-half of 1 percent at 500° 

C and about 1 percent at 1000° C for the thermocouple 

tern peratures. 

Bottom-hole temperatures were also measured, whenever conditions permitted, with incandescent ,filamenttype optical pyrometers. In the shallower holes (hole 

1 and first penetration of hole 2), optical-pyrometer 

temperatmes were within 5° C of those obtained by 

chromel-alumel thermocouples. In the deeper holes, 

however, a greater divergence was observed, with the 

optical-pyrometer values consistently higher by as 

much as 10° C. Surface and near-surface (less than 

1 ft) drill-hole temperatures were measured with mercury thermometers. 

PHYSICAL PROPERTIES AND PETROCHEMISTRY 

Rock-density determinations were made on most uniform pieces of core greater than one-half inch long. 

The ends of the selected core sa.mples were ground flat 

to form a nea-r-perfect cylinder, and the dimensions 

(length and diameter) were measured with vernier 
B8 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

calipers. The weight of the individual cylinders was 

determined on a laboratory balance. 

A total of 21 samples, including rock, melt, and one 

clinopyroxene separate, were chemically analyzed in the 

Denver Rock Analysis Labora·tory of the U.S. Geological Survey. The clinopyroxene from a diabase segregation in hole 3 was separated by means of heavy liquids 

and an isodynamic separator. Norms of the analyses 

were calculated by computer. Modes were determined 

for 45 samples, and with only a few exceptions, more 

than 500 points were counted per thin section. The 

composition of the olivines was deterrnined by the 

X-ray method of Yoder and Sahama (1957), and the 

composition of the feldspars, where practical, by the 

method of Tsuboi. 

GROWTH OF LAVA LAKE CRUST 

In the 3-period between the end of eruption in December 1959 and the last drilling in December 1962, the 

crust of the Kilauea Iki lava lake ruttained a thickness 

of 43.6 feet. Although the growth of the crust has been 

studied only in a very restricted area over the deepest 

part of the lake (fig. 2), the level surface indicates a 

comparable growth rate-hence uniform thicknessover a much larger area. A·t the periphery of the lake 

and in the relatively shallow west end, however, the 

crust is presumably thicker. 

The criterion used to identify the base of the crust 

when drilling was the depth at which drill rods noticeably sank into the melt. Even though this depth is a 

complex relation of several physical and mechanical 

factors (see Ault and others, 1962, p. 2811), temperatures measured in all the drill holes at this depth were 

consistently between 1057° and 1065° C. The base of 

the crust was also identified. independently during the 

empla.cement of the melt probe in hole 2 as the 1065° C 

isotherm (Ault and others, 1962), corroborating the 

temperatures measured at the base of crust determined 

by drilling. As would be expected, there is no sharp 

demarcation between solid and 1iquid; instead, the 

contact is a zone only a few inches thick of rapid change 

in the proportion of crystals ·and in viscosity. Thin 

sections of crust and melt across this narrow zone reveal a glass (liquid) content of 24 to 26 percent in the 

lowermost crust and 30 to 73 percent in the upper part. 

of the melt. The relatively rapid change in degree of 

crystallinity over an exceedingly limited temperature 

interval (<5° C) is due to the onset of plagioclase 

crystallization at or slightly above the 1065 ° C isC\therm. 

It should also be noted that the thermal profiles (table 

1 and figs. 6, 7, 8) show that the base of the. crust is 

marked by only a subtle change in the slope of the 

thermal gradient. 

The growth of the crust is shown graphically in 

figure 5 as a function of time. The rate of growth 

de.creased from an average of 2.8 feet per month, during 

the first 8.1 months, to an average of 0.34 feet per 

month during the 5.6 months ending December 6, 1962. 

In the 22-month period between August 1960 and June 

1962, however, the rate of growth decreased only 

slightly from 0.95 to 0.80 feet per month. Five selected 

temperature profiles, based on measurements made 

when equilibrium returned after drilling and therefore 

representative of the core-sample temperature at time 

of collection, are listed in table 1. These same data are 

plotted graphically in figures 6, 7, and 8. A contoured 

temperature diagram of depth versus time for the crust 

of the lava lake is shown in figure 6. The descent of 

all isotherms below 600° C has been virtually linear~ the 

rates ranging from 0.12 feet per month for 100° C to 

0.6 feet per month for 600° C during the period between 

April 1960 and tT une 1962. Isotherms above 600° C 

were relatively steep during the early period of crust 

formation and since about January 1962 have shown a 

marked tendency to flatten. 

The transfer and loss of hea;t from the upper part 

of the lava lake, which directly affects the growth of 

the crust, are controlled principally by (1) the interrelated effects of radiation and conduction and (2) the 

vaporization of water (rain). Although all these 

processes will be effective until thermal equilibrium 

between the lake and its environment is attained, each 

plays a dominant role at various periods in the lake's 

development. During eruption and in the first few 

hours of stable crust formation, loss of heat was almost 

entirely due to radiation. However, as the crust 

0~~~~~~~~~~~~~~~~~~~~ 

4 \ 2·

4 April 9 

3 _9 \ . HOLE 1 8 ft per\ I April. 2. 5 

12 month \,~Mall .. ? 

._16 ~16.0 

~ 20 1.8 \,, Aug 24 

ft per month' 

~24 22.5 

0.95 

HOLE 2 

April 13 

CRUST 

HOLE 3 HOL 

4 

Dec 3 

June 1 

::i 

t28 

LIJ 

0 32 

ft per month 9.? ............ . 

0.93 !october 4 Dec 6 

36 

40 

44 

MELT ft per month 5 0 Prob~l · lJI-80 

ft per month June 1 41.6 

June _25 0_

34 ~_3.6 

ft per month 

JFMAMJJASONDJFMAMJJASONDJFM 

1961 1962 

FIGURE 5.-Growth of crust on Kilauea Iki lava lake as of 

December 1962, showing calculated average rate of crustal 

growth between drilling. 
PETROLOGY OF THE KILAUEA IKI LAVA L,AKE B9 

TABLE 1.-Kilauea Iki lava lake temperature profiles, holes 1 to 3 

1 2 3 

--

Depth (feet) Temperature ("C) Depth (feet) Temperature ("C) 

Depth (feet) Temperature ("C) 

May 16,1960 Sept. 8, 1960 Oct. 2 and 5, 1961 June 21, 1962 

Surface ----------- 152 Surface 148 3. 0 87 

0. 5 1 105 ------------ 2. 0 147 6. 0 99 

1.0 . 87 98 4.0 302 9. 0 200 

2. 0 196 182 8. 0 511 11. 9 314 

3. 0 342 278 12. 0 640 13. 0 346 

4. 0 447 364 16.0 728 16. 0· 442 

6.0 589 481 20.0 794 19. 0 530 

8. 0 708 585 24.0 861 21. 9 615 

10.0 806 679 27.6 929 25. 0 695 

12.0 ----------- 760 32.2 1000 29. 5 818 

12.8 915 ------------ 33.2 1024 32. 5 899 

14. 0 838 34.2 1046 35. 5 966 

16. 0 907 35.2 1063 38.4 1021 

18.0 972 36.2 1081 41.5 1060 

18.5 986 37.2 1092 

22.4 2 1065 38.2 1101 

39.2' 1106 

t Mercury thermometer. 2. Drilled 0 to 30.4 ft on Apr. 13, 1961; drilled 27.4 to 35.2 ft on Oct. 4, 1961. 2 Optical pyrometer. All other temperatures by chromel-alumel thermocouple. 3. Drilled 0 to 42ft between May 31 and June 11, 1962. 

1. Drilled 0 to 12.8 ft between Apr. 9 and May 6, 1960; drilled 12.8 to 22.7 ft on Aug. 

24, 1960. 

1960 1961 

TIME---~ 

1962 

FIGURE 6.-Isotherms in crust of Kilauea Iki la:va lake. plotted 

as a function of time. Diagram compiled from thermal data 

from drill holes 1, 3, and 4. 

(a poor heat conduotor) became thicker, radiation 

became less and less efficient and heat loss became 

dependent. on the amount of heat transferred to the 

surface by conduction·. A third cooling process, 

vaporization of water, is a function of the amount of 

rain falling on the lake and being changed to vapor 

upon contact with hot rocks in the crust. Because an 

average of approximately 100 inches of rain per year 

falls on the Kilauea Iki area, the vaporization of water 

is now by far the most important. single process contributing to the cooling of the lava lake. 

The amount of heat (heat of vaporization) required 

to change 1 gram of water at 100° C from a liquid to 

a vapor is 540 calories. Assuming that the basalt has 

a specific heat of 0.20 and a density of 2.7 g per cc, 

1 cc of basalt will have a thermal capaci·ty (mass X specific heat) of 0.54 cal per deg C, or 0.54 cal will be 

released for every degree cooled. Hence, the amount 

of heat necessary to vaporize 1 cc ( 1 g) ·of water is 

equivalent. to the heat released in cooling 1 cc of basalt 

from 1100° to 100° C. 

However, these calculations can only be used as a 

rough qualitative measure of crustal growth because 

they fail to consider processes that add heat to the 

crust. For example, if all the rain falling on the lake 

was utilized in cooling and no heat was added, approximately 8 feet per year of lake lava would be transformed into crust having a temperature of 100° C. 

This is a rate of 0.67 foot per month, virtually double 

the observed rate ( 0.36 ft per month) . between June 
BlO THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

and December .1962, and yet this r.ate does not include 

the contribution due to heat loss by conduction and 

radiation. The physical-chemical processes that add 

heat to the crust in significant quantities are ( l) heat 

o£ crystallization; (2) solar radiation, and (3) convection. Heat of crystalliza;tion is by far the most 

important of these processes, especially in the lower 

5 feet of crust where upwards of 70 percent ·Of the total 

volume is still liquid. The heat contributed by solar 

radiation to the surface of the lake and by convective 

overturn in the melt ·aTe of secondary importance but 

need to be considered in any attempt to understand the 

heat budget of the lake. 

Furthermore, the questionable validity of the basic 

assumptions (density and specific heat of the basalt) 

could also affect the calculation o£ the rate of heat 

loss due to cooling by water. If either the density or 

specific heat are more than assumed, then by definition 

the thermal capacity of the basalt would be correspondingly larger and hence more water would be 

required to cool an equivalent amount of basalt. On 

the other hand, recycling of the water in the crust could 

substantia1ly add to the effectiveness of cooling by the 

vaporization of rainfall. In fact, it is entirely possibl~ 

that much of the 100 inches of rain per year is used 

over and over again, especially as the crust thickens 

leaving a relatively cool top ·to condense the vapors 

rising from the hotter zones at depth. 

Though the above considerations are somewhat speculative, the rate of heat· flow through the crust of the 

lake may be compared with the rate of heat loss due 

to the vaporization of rainfall. On the basis of a miiform heat conductivity of 5.1 X 10-3 cal per em per 

deg C for the crustal basalt, the rate of heat flow in 

cal?ries per second can be expressed by the equation : 

. T -T 

Rate of heat flow=k 1 2 XA, t 

where k is the thermal conductivity of basalt, T 1 - T 2 

the difference in temperature between the top and base 

of crust ( 1000° C), t the thickness in centimeters, and 

A the area (1 cm2 ). As all parameters are fixed, with 

the exception of t, it is apparent that the rate of heat 

flow varies inversely with .thickness. Solving the equation for thicknesses of 10, 20, 30, and 40 feet (305, 610, 

914, and 1,219 em), the corresponding heat flow rates 

are 16.4, 8.1, 5.5, and 4.1 X 10-3 cal per sec. Hence, for 

a crust thickness of about 40 feet, the heat loss due to 

vaporization of rainfall begins to exceed the heat loss 

by conduction. 

THE CRUST 

Megascopically, the bulk of the rocks in the 42-foot 

thick crust of. the ICilauea Iki lava lake is porphyritic 

olivine basalts that have a wide range of content of 

phenocrystic olivine. The base of the crust is characterized by a 5- to 6-foot-thick zone of fluid-rich basalt, 

referred to as the transient zone of crystallization, 

which moves downward at a rate equal to the crustal 

growth rate. Olivine-poor diabase segregations found 

only at depths below 32 feet constitute less than 1 percent of the total crust thickness examined. 

The basalts exposed on the surface of the lake and 

in cracks penetrating a few feet below the surface are 

highly vesicular, the voids constituting up to 40 percent 

by volume of the rock. The groundmass matrix is generally dense, breaks with a rough hackly fracture, and, 

depending on the degree of crystallinity, ranges 1n 

color froin gray to nearly black. 

VESICULARITY, DENSITY, AND GRAIN SIZE 

The size, shape, and relative abundance of the vesicles 

in the crust of the lava lake are shown diagrammatically in the drill-hole sections in figures 7, 8, and 

9. The extreme top of the crust, too thin to portray in 

the sections, is characterized by a chilled glassy skin 

not more than 1 inch thick, containing abundant vesicles 

and covering, in many places, large flat gas blisters 

(macrovesicles) as much as 3 feet in diameter. Immediately below the glassy skin the vesicles are generally more uniform in habit and, as would be expected, 

decrease in size and abundance with depth. With the 

exception of a number of anomalous dense layers in 

the upper part of the crust, the spherical vesicles decrease from 8 to 10 mm in diameter near the surface to 

1 mm or less in diameter below about 34 feet. In addition to the spherical vesicles, relatively large flattened 

voids and irregular tubes, probably formed under conditions of subtle shearing within the crust, are locally 

common at depths below 26 feet. Vesicles in the diabase segregations are even more irregular and form 

intricate branching tubes as much as three-fourths inch 

long. 

The thin dense layers restricted to the upper 14 feet 

of crust are apparently partially remelted re.mnants of 

old crust that were engulfed hy liquid lava during the 

last period 'Of crustal foundering ·on the lake's surface. 

Although probably limited in areal extent and erratically distributed, these dense 7-ones have locally affected 

the composition of the overlying strata. In every case 

where a dense zone has been recognized it formed an 

impermeable barrier to sinking ·olivine crystals and 'was 

overla.in by layers ·of crystal mush with a.s much as 37 

percent modal olivine. 

The bulk density of the crust is almost entirely a 

function of t.he degree of vesicularity ; the effect of 

changes in the olivine content on the density is possibly 

only apparent, at depth, in hole 3 (figs. 8 and 9). Bulk 

densities range from a .low of 1.8 to 2.1 g per cc near the 
'PETROLOGY OF THE KILAUEA IKI LAVA LAKE Bll 

MODAl COMPOSITION, IN 

PERCENTAGE BY VOlUME 

0 20 40 60 80 0 20 40 

NO CORE 

MELT 

(5-6-60) 

NO CORE 

Glass, mode 

' / ' / dI I I 

0 0.05 0.10 0.15 0.20 

GRAIN SIZE, IN MilliMETERS 

~,--r-,--r-,-~~~,_-r-,--r-,-~--r-~--, 

I 

I 

d 

I I 

o· 

I I I I I I 

2oo· 4oo· 6oo· soo· 1ooo· 12oo· 

TEMPERATURE, IN DEGREES C 

I!.,IGURE 7.-Camposite section through drill hole 1 with pertinent mineralogical and physical data. Relative size, shape, 

and abundance of the vesicles in drill core are portrayed diagrammatically by pattern. Dashed lines denote obvious 

textural and chemical discontinuities. 

sui-face to a maximum of 2.7 to 2.8 g per cc below a 

depth of 34 feet. The increase -frmn 1.8 to 2.5 g per cc 

occurs fa·irly rapidly and consistently in about the first 

6 feet of crust; below that the increase from 2.5 to 2.8 

g per cc is erra:tic and gradual. The anomalously lowdensity zone bebveen 26 and 32 feet in hole 3 may be due 

to· n. corresponding low olivine content in this same 

general interval (·fig. 9). 

Bulk densities were determined for a number of nonvesicular glasses that were collected while still liquid. 

Melt samples, containing a few olivine phenocrysts, had 

densities of 2.66 g per cc (sample l(I-186, 35.0 to 35.2 

ft, hole 2) and 2.78 g per cc (sample l(I-235, 42.05 to 

42.3 fit, hole 3). The silica-rich liquid that oozed into 

the bottom of hole 1 (sample I\I-113, 22.3 to 22.5 ft) 

from the base of the crust had a. density of 2.65 g per cc. 

l\1oreover, the specific gravity :of vesicle-free fragments 

of tachylite from the surface of the lake ranges between 

2.6 and 2.9. li. A. Powers (written co~mun.) luis observed that vesicle-free glass shards from the Kilauea 

Iki lavas had specific gravities very close to 2.9 or perhaps even more. 

The groundmass grain size (figs. 7, 8, and 9) does not 

s~Tow a consistent increase with depth as might be expected. There is an increase in size directly helow the 

surface and directly above the base of the crust, but the 

maximum grain size appears to be a:t:btined within 15 

feet of the surface, regardless of the thickness of crust. 

PETROCHEMISTRY 

A total of 20 new chemical analyses together with 45 

modal analyses of the rocks and melt in the crust of the 

lake are presented in tables 2, 3, 4, and 5. These data 

portray the chemical and mineralogical properties of 

the crust a.t five different times (Apr. 9 to May 6, 1960; 

Aug. 24, 1960; Apr. 13, 1961; Oct. 4, 1961; and May 31 

to June 11, 1962) during the early history of the lake. 

Although melt penetration occurred on the four latter 
B12 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

SAMPLE DENSITY, IN GRAMS PER 

CUBIC CENTIMETER 

MODEL COMPOSITION, IN 

PERCENTAGE BY VOLUME 

2.0 2.5 3."0 0 

I 

20 40 60 80 0 20 40 

1-

UJ 

UJ 

LL. 

2 

8 

Kl-1571 

10 ~::l~~l Kl-160 

Kl-161 

Kl-162 

NO CORE 

NO CORE 0: , 00 

• 0 0 ,. 

• ~ •• 0 

1""1 1111 1 

T 

r~~ 

1 

I 

I 

I 

I 

I 

\ 

I 

I 

\ 

I I ~, ~.-r~~--~~--.-r-.'1-.-.-.~.-~ 

Temperature 

I I 

~---- ' I 

'~ 

I 

\ I I I I I I I I I I I I I 

0 0.05 0.10 0.15 0.20 0° 200° 400° 600° 800° 1000° 1200° 

GRAIN SIZE, TEMPERATURE, IN DEGREES C IN 

MILLIMETERS 

FIGURE 8.-Composite section through drill hole 2 (see fig.7). 

dates, only the samples collected on April13, 1961, and 

May 31 t.o June 11, 1962, represent isochronal surface to 

melt profiles. The dates of sampling and the locations 

of the sam pies are shown on the diagrammatic drillhole sections in figures 7, 8, and 9. 

The chemical analyses were done by standard gravimetric methods in the Denver laboratories of the U.S. 

Geological Survey by the analysts credited in tables 2, 3, 

4; and 5. All these analyses appear consistent; that is, 

they plot on smooth linea.r control lines in variation 

diagrams when compared with one another, with analyses of Kilauea lavas earlier than those of the 1959 

eruption, and with Kilauea Iki analyses made hy other 

labon-.,tories (Tilley, 1960). Only the 10 Kilauea Iki 

analyses of Katsura (in Macdonald and Katsura, 1961, 

table 1, p. 362) show a marked divergence from the 

analyses presented here; Katsura's analyses when 

plotted on a silica-variation diagram, similar to that 

used in this paper (fig. 10), are erratic and define, only 

within broad limits, the linear control lines tightly controlled by ·analyses from other laboratories. Also, 

l{atsura's analyses show a bias (again comparing with 

analyses from other laboratories) toward low silica by 

as much as 2 percent. The low silica values are partly 

compensated for by anomalously high alumina values, 

and it is the writers' opinion that the apparent discrepancies lie largely in the values reported for these 

two constituents. 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B13 

OLIVINE BASALT 

In thin section the predominant •tholeiitic olivine basalt samples consist of large olivine phenocrysts s~t in 

a groundmass of fine-grained clinopyroxene, plagioclase, and ·opaque minerals with varying amounts of 

glass (see fig. 11). Minute needlelike crystals of 

apatite ( ~) are common in the glass of the more vi'tric 

rocks, and minor hypersthene was observed In a few 

thin sections. The groundmass texture grades from 

completely glassy rut the surface, through interstitial in 

a zone a few feet below the surface, to intergranular below about 5 feet. Beginning in the transient zone of 

crystallization at the base of the crust and going upwards, this textural sequence is reversed with the glass 

representing a true interstitial liquid phase at the temperature and time of collection. 

0 

2 

4 

6 

8 

10 

12 

14 

16 

18 

Iw 

w 

u.. 20 

~ 

:i 

I- 22 a. 

w 

0 

24 

en 

w 

I-

<: 26 0 

t!' 

z 28 ::i 

..J 

0:: 

0 30 N 

1.0 

01 

.... 

...; 32 

z 

::::> 

-, 34 I 

.... 

('Y) 

> 

<: 36 

:E 

l38 

40 

42 

SAMPLE 

DENSITY, IN GRAMS PER 

CUBIC CENTIMETER 

2.0 2.5 3.0 

1""1""1 

0 

I 

KI-200I b• o 0 o 

Kl-201! oOo 0 OPF"N SPArE 

K1-2o2 o~ogoo 

Kl-203 OPFN St-'AI E 

Kl-2041 .o.ooo•o 

Kl-205 0 • oOo Oo oO• o 

Kl-206 <?·o~c?. 0 Kl-207 °Q~0·· 0 · 0 0 0 

NO CORE 

~1?-~~~p __ .,_,2_0_..!.9. 

·o.o:o~o 

O•OoOo 

NO CORE 

NO CORE 

I 

MODEL COMPOSITION, IN 

PERCENTAGE BY VOLUME 

20 40 60 80 0 20 40 '---~ L ____ L I lr--r-'T"I :..........---.~.---r-~~--r--r-~--,.---,-.--.,.----, 

I 

I 

I 

I 

I 

I 

I 

Glass, mode 

Temperature June 21. 1%2 

I I 

SEGREGA~riON + I_ :~~~J '----- t=' ,----- I 

NO CORE . . . 

NO CORE 

.· · ... : 

I 

0.05 0.10 0.15 

GRAIN SIZE, IN 

MILLIMETERS 

I 

oo · 200° 400° 600° 8oo· 1 ooo· 12ooo 

TEMPERATURE, IN DEGREES C 

FIGURE 9.-Section through drill hole 3 (see fig. 7). 
B14 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

TABLE 2.-0hemical analyses, norms, and modes of rocks from hole 1, Kilauea Iki lava lake 

[Results in percent. D. F. Powers, analyst] 

Si 02 _____ - _________ -__________________________________ _ 

Ah03- ------------------------------------------------ _ Fe203. ___ -- ___________________________________________ _ 

FeO __ ------- ___ ------------ ____ --------- ________ ------ MgO ___ -------------- ______ --~---------- ______ -------- CaO __________________________________________________ _ 

Na20 ____ ------~----------- ------------------- ________ _ 

K20 ___ ------------------------------------------------ H 20+ __ ------------------------------------------------ H20-_ -------------------------- ___ ------------- ______ _ Ti 02. _________________________________________________ _ 

P20s.-------------------------------------------------- MnO _ ------------------------------------------------- C 02-------- _------- __________________________________ _ Cl ____________________________________________________ _ 

F------------------------------------------------------

KI-115 

0-.1 

48.29 

11.48 

1. 59 10.03 

13.58 

9.85 

1. 90 

.44 

.05 

.05 

2.33 

.23 

.18 

. 01 

.02 

.03 

KI-100 KI-102 KI-104 

0.1-.5 2-2.5 4--4.5 

Chemical analyses 

48.83 

12.38 

2.15 

9. 41 11.08 

10.64 

2.02 

.47 

. 03 ---------- ---------- 2.47. ---------- ---------- .24 ---------- ---------- .17 ---------- ----------

. 02 ----~----- ---------- .03 ---------- ----------

Sample and depth (feet) 

KI-105 KI-106 

5-5.5 6-7 

46.67 ---------- 9.65 ---------- 1 13.01 ----------

19.05 ---------- 8.19 ---------- 1.58 ---------- .38 ----------

. 03 ---------- 2.09 ---------- .18 ---------- .17 ----------

. 01 ---------- .02 ----------

KI-107 

7.5-8 

45.61 

8.33 

2.12 

10.02 

23.06 

6. 98 

1.33 

.32 

KI-108 KI-109 

9-9.5 10.5-11 

. 04 ---------- ---------- 1.70 ---------- ---------- .16 ---------- ---------- .17 ---------- ----------

. 02 ---------- ---------- .02 ---------- ·----------

KI-110 

11-11.5 

45.50 

8.17 

1. 60 10.44 

23.87 

6. 79 1. 28 

. 31 

.04 

1. 54 

.15 

.17 

.01 

.02 

SubtotaL __________________ -------- ___ ------------ 100. 06 99.94 ---------- ---------- (2) ---------- 99.88 ---------- ---------- 100.39 

Less o __________ --------------------------------------- . 01 .01 ---------- ---------- ---------- ---------- . 01 ---------- ---------- . 01 

TotaL ____________________________________________ _ 100.05 99.93 99.87 99.88 

Norms 

KI-112 

(melt) 

22.5 

49.27 

12.10 

1. 77 9.89 

10.46 

9.65 

2.25 

. 65 

.03 

3.30 

.30 

.17 

.02 

.04 

99.90 .02 

99.88 

Q ______________________________________________________ ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---·------ ---------- or______________________________________________________ 2. 60 2. 78 __________ __________ 2. 25 1. 89 ---------- ---------- !. 83 3. 84 

ab_ ---------------------------------------------------- 15.80 16.94 ---------- __________ 13.29 11.10 ---------- ---------- 10.75 18.88 an_---------------------------------------------------- 21.64 23.41 ---------- __________ 18.16 15.89 ---------- ---------- 15.67 21.08 di: wo __________________________________________________ _ 10.68 11.55 ---------- ---------- 8.85 7.34 ---------- ---------- 7.07 10.28 en ______ --- __________________________________________ _ 7.07 7. 54 ---------- ---------- 6. 21 5.34 ---------- ---------- 5.C9 6.64 fs ______ -- ___________________________________________ _ 2.84 3. 21 ---------- ---------- 1. 89 1. 32 ---------- ---------- 1. 34 2. 95 

hy: en __________________________________________________ _ 12.57 13.64 ---------- ---------- 10.61 10.69 ---------- ---------- 9. 30 15.75 fs ___________________________________________________ _ 5.05 5. 80 ---------- ---------- 3.22 2. 64 ---------- ---------- 2.44 6. 99 ol: fo ___________________________________________________ _ 9.93 4.49 ---------- ---------- 21.45 29.00 ---------- ---------- 31.56 2.56 fa ___________________________________________________ _ mt 4.40 2.11 ---------- ---------- 7.18 7.88 ---------- ---------- 9.14 1. 25 ____________________________________________________ _ 2. 31 3.12 ---------- ---------- 2.32 3.07 ---------- ---------- 2.32 2. 57 iL ___ --- ______________________________________________ _ 4.43 4.69 ---------- ---------- 3.97 3.23 ---------- ---------- 2. 92 6. 27 

ap------ hL ____________________________________________________ -----------------------------------------------_ .54 . 57 ---------- ---------- .43 .38 ---------- ---------- .36 . 71 

.03 .03 ---------- ---------- .02 .03 ---------- ---------- .02 .03 fr _____________________________________________________ _ .04 . 04 ---------- ---------- .02 .03 ---------- ---------- .03 .05 

Total ________ ------- ______ ----------- ___ ----------- ·99. 93 99.92 99.87 ---------- 99.83 ---------- ---------- 99.84 99.85 

Modes 

Phenocrysts: Olivine __________________________________ ---------- 4 

Groundmass: . Pyroxene __ --------------------------------------- ___ ---------- 54 Plagtoclase ________________ ---------- ___ -------------- ---------- 19 

Opaques ____ ----------------------------------------- ---------- 3 Glass________________________________________________ _ _ _ _ _ _ _ _ __ . 20 

I Total iron calculated as Fe203. For norm, 10.27 percent allocated to FeO. 2 Partial analysis, total omitted. 

The extreme variation in chemical composition of 

the olivine basalts is controlled principally by the physical addition or removal of olivine phenocrysts. The 

content of modal olivine ranges from 2 percent (sample 

KI-184) to 37 percent (sample l{l-109), effecting 

changes of more than 4 percent in silica and more than 

15 percent in magnesia. This pronounced olivine control (Powers, 1955) on the composition of the basalts 

is best demonstrated by the silica-variation diagram in 

figure 10. Each of the major constituent oxides, when 

plotted against Si02 , defines a_ unique straight line between about 50 percent Si02 and the plot for the com17 

51 

24 

5 

3 

14 32 10 33 37 35 4 

55 38 55 37 39 38 18 

21 24 27 25 17 21 5 

8 4 6 4 6 5 0 

2 2 1 1 1 <1 3 74 

3 Very dark glass, probably includes some opaques. 

position of hypothetical olivine (Fat 5 ) at 40 percent. 

Si02 • Rocks containing more than about 50 percent. 

Si02 and less than 7 to 8 percent MgO are, in general, 

olivine poor and hence are unaffected by olivine control. 

Although the modes of the groundmass minerals in 

the olivine basalts vary widely depending on the concentration of phenocrystic olivine, the relative proportions of these minerals in the glass-poor basalts are 

fairly constant. The most striking constancy of volume ratios is between clinopyroxene ( 37 to 65 mode 

percent) and plagioclase (19 to 33 mode percent), 

which, with only a few exceptions, is remarkably close 
TABLE 3.-0hemical analyses, norms and modes of rocks from hole 2, Kilauea Iki lava lake 

[Results in percent. Analyses by D. F. Powers, except samples KI-184 and Kl-186 by C. T. Parker] 

Sample and depth (feet) 

KI-150 Kl-151 Kl-152 Kl-153 KI-154 Kl-155 Kl-156 Kl-157 KI-158 Kl-159 Kl-160 Kl-161 KI-163 KI-164 Kl-165 Kl-167 KI-168 KI-169 Kl-184 Kl-185 Kl-186 1

---- -~---1 I I I I I ~--- -I - I I I I I I I I I 

o-1. 2512. 2H ~- 25 5. 2&-5. 76. 4-6. 75 e. 7>-7 7-7. 5 8.5-ll. 5 9. s-10. 1 10. 1-10. 510. o-u. •ln. 9-12. 8 26.52-27 ~ 21. &-27. • 27.!>-29. 1 29.>-29. 1 29. 7-29. • 20. 9-ilO. 4 31. 8-32. 8 32. 8-33. 5 34. 3-35 

Chemical analyses 

8102-------------------- -------- -------- -------- 46.53 -------- 48.12 47.93 46.96 49.16 48.41 47.90 --------- --------- 48.45 48.98 --------- 48 .. 74 .--------- 49.61 --------- 49.20 

Al20s-- ---------------- -------- -------- -------- 9.49 -------- 11.43 11.18 9. 90 12.54 11.80 11. 17 --------- --------- 11.64 12.05 --------- 11.60 --------- 12.91 --------- 12.32 

Fe20a- _ --------------- _ -------- -------- -------- 2.16 -------- 2.26 2.46 2.13 1.83 2.81 2. 41 --------- --------- 1.04 1.39 --------- 1. 38 --------- 1. 60 --------- 1. 26 FeO ______ --- _ -------- __ -------- -------- -------- 9. 79 -------- 9.46 9.36 9. 72 10.02 8.91 9.36 --------- --------- 10.37 10.17 --------- 10.18 --------- 9. 68 MgO --------- 10.13 ___________________ -------- -------- -------- 19.28 -------- 13.65 14.33 18.31 10.05 12.52 14.64 --------- -------...... 13.23 11.18 --------- 12.35 --------- 8.84 --------- 10.51 CaO ___ --------------- _ -------- -------- -------- 8.18 -------- 9.87 9.64 8.58 10.55 10.18 9.58 --------- --------- 10.13 10.83 --------- 10.45 --------- . 10.96 --------- 11.05 

Na20- _ ---------------- -------- -------- -------- 1.54 -------- 1. 89 1.86 1. 58 2. 09 1. 93 1. 82 --------- --------- 1. 89 1. 73 --------- 1. 67 --------- 2.24 --------- 2. 02 K20 ______ -------------- -------- -------- -------- .38 -------- . 46 .45 .37 . 56 .48 . 41 --------- --------- .45 .80 --------- . 79 --------- .55 --------- .48 

H20+ ---~- -------------- -------- -------- -------- . 08 -------- . 03 . 01 . 00 . 06 .08 . 00 --------- --------- . 09 . 02 --------- . 04 --------- . 02 --------- .04 H2o-___________________ -------- -------- -------- .04 -------- . 05 . 04 . 00 . 02 .02 . 02· --------- --------- . 00 . 00 --------- .01 --------- .01 --------- . 02 Ti02- _: ________________ -------- -------- -------- 1.99 -------- 2.34 2.32 2.01 2. 73 2.47 2.24 --------- --------- 2.35 2. 48 --------- 2.44 --------- 3. 03 --------- 2. 50 

P206-----.- --~ --------- -------- -------- -------- .18 -------- .22 .21 .19 . 26 .23 . 21 --------- --------- .23 .24 --------- .23 --------- .27 Mn --------- .23 0 __________________ -------- -------- -------- .18 -------- .18 .18 .18 .18 .18 .18 --------- --------- .18 .18 --------- .18 --------- .17 --------- .18 

002-------------------- -------- -------- -------- .11 -------- . 04 . 02 .00 . 00 . 00 . 01 --------- --------- . 00 .01 --------- .01 --------- . 01 --------- . 01 CL-------- ___ .. ________ -------- -------- -------- . 01 -------- .03 . 02 . 01 .02 .01 . 01 --------- --------- . 01 .01 --------- . 02 --------- . 01 --------- . 02 

F--- ------------------- -------- -------- -------- . 03 -------- .04 . 03 . 03 . 04 . 03 . 03 --------- --------- . 03 . 03 --------- . 03 --------- .04 --------- .04 s _______________________ -------- -------- -------- . 00 -------- .00 . 02 . 01 . 01 . 01 . 00 --------- --------- . 01 .01 --------- . 00 --------- --------- --------- --------

SubtotaL----------J--------j--------j--------J 99.97j--------jl00.07jl00.06j 99.98,100.121 100.07 Less 0----------------- -------- -------- -------- . 01 -------- . 03 . 02 . 02 . 03 . 02 99.99 J---------J---------I 100.10 I 100.11 I---------I 100.12 I---------I 99.95 J---------l 100.01 . 01 --------- --------- . 02 . 02 --------- . 01 --------- . 02 --------- . 02 

TotaL-------------'--------1--------'--------1 99.96 1--------1100.04 1100.04 I 99.96 1100.09 I 100.05 99.98 1---------'---------1 100. os I 100.09 1---------' 100.11 1---------' 99.93 1---------' 99.99 

Norms 

an. ~-~~=== _____________________________________________ ==== = === = ==== ===1 ==== ==== 1 ====== = = 1 ======== 1--~r~r 18.60 1 ==________ ==== ==1·-~r 21.72 ~r~--~r~r 21.04 ~--~r 18.87 ~r~--23.26 ~ r~-~---~r .. 22.16 rs -~---~r~rl 21.20 ------------------

==== ===== 1===== ====!---~~:gr 21.99 22.86 ~---~r~-1 ---------==== =====~---~r~rl 21.97 ==== 

--------- ===== ~---~r 23.65 ~r 1 ---------

===== ====~---~rrz 23.28 m: . wo ___________ -----. __ -------- -------- -------- 8.62 -------- 10.68 10.54 9. 31 11.34 11.14 10.35 --------- --------- 11.11 12.17 --------- 11.78 --------- 12.00 --------- 12.45 en _________________ . __ -------- -------- -------- 6.16 -------- 7.28 7.30 6.60 7. 07 7. 70 7.17 --------- --------- 7.18 7.65 --------- 7.58 --------- 7.37 --------- 7.68 fs ____________________ -------- -------- -------- 1. 70 -------- 2. 56 2.38 1. 89 3. 59 2. 54 2.33 --------- --------- 3.18 3. 78 --------- 3.42 --------- 3. 94 --------- 4. 04 by: en ________ . _____ ----._ -------- -------- -------- 13.78 -------- 13.97 13.61 12.13 13.88 14.78 13.68 --------- --------- 11.24 12.70 --------- 12.98 --------- 13.86 --------- 12.26 fs _____________ . ____ . _ -------- -------- -------- 3.80 -------- 4. 92 4.43 3. 48 7. 04 4.87 4.44 --------- --------- 4.99 6.27 --------- 5.85 --------- 7. 41 --------- 6.45 

ol: fo ____________________ -------- -------- -------- 19.67 --- ............. 8. 93 10.35 18.84 2.85 6.09 10.93 --------- --------- 10.18 5.24 --------- 7.14 --------- .54 --------- 4.36 fa ____ . _________ . ____ . -------- -------- -------- 5.98 -------- 3. 47 3. 71 5. 95 1. 60 2.21 3. 91 --------- --------- 4. 98 2.85 --------- 3.54 --------- .32 --------- 2.53 

mt_ -------------------- -------- -------- -------- 3.13 -------- 3.28 3.57 3. 09 2.65 4.07 3.49 --------- --------- 1. 51 2. 02 --------- 2.00 --------- 2.32 --------- 1. 83 

il_ __ -------------------- -------- -------- -------- 3. 78 -------- 4.44 4.41 3.82 5.18 4.69 4.25 --------- --------- 4.46 4. 71 --------- 4.63 --------- 5. 75 --------- 4. 75 

~t:~~==== ==== ==== ~==== = 

-------- -------- -------- .43 -------- . 52 .50 . 45 . 62 .54 .50 --------- --------- .54 . 57 --------- .54 --------- .64 --------- .54 

.02 -------- . 05 . 03 . 02 . 03 . 02 . 02 --------- --------- . 02 . 02 --------- .03 --------- . 02 --------- . 03 fr _____________________ . -------- -------- -------- . 05 -------- . 06 .04 .04 .06 .04 .04 --------- --------- .04 .04 --------- . 04 --------- . 06 --------- . 06 nc ______________________ -------- -------- -------- .26 -------- .10 . 05 -------- -------- --------- .02 --------- --------- --------- . 02 --------- .02 --------- . 02 --------- .02 pr ______________________ -------- -------- -------- -------- -------- -------- .04 . 02 . 02 . 02 --------- --------- --------- . 02 . 02 --------- --------- --------- --------- --------- --------

TotaL _____________ I _______ .I _______ J _______ _I 99.87 1--------1 99.99 1100.00 I 99.99 1100.03 99.96 99.95 1---------1---------' 100.01 I 100.09 1---------' 100.05 1---------' 99.90 1---------' 99.94 

Modes 

Phenocrysts: Olivine___ 15 5 29 19 25 7 23 32 5 8 --------- 14 7 11 7 6 8 20 2 6 Groundmass: 

Pyroxene_____________ 47 53 41 49 44 59 46 40 65 56 --------- 55 55 50 50 45 42 27 50 43 43 Plagioclase___________ 21 26 24 20 22 25 24 20 20 24 --------- 23 24 24 21 21 17 11 28 24 21 

&f:S~~~~~============ 1~ ~ ~ 8 7 9 5 6 11 12 --------- 8 7 5 5 4 3 1 7 5 3 4 2 0 2 . 1 1 Tr. 0 8 10 17 24 30 I 41 13 22 26 Apatite ______________ ------------------------ Tr. Tr. -------- ________ Tr. Tr. Tr. _.,. _______ --------- --------- --------- · Tr. Tr. Tr. --------- Tr. Tr. Tr. 

1 Probably includes some opaques. 

t-c:l 

1::<.1 

8 

~ 

0 

t-4 

0 

0 

~ 

0 

~ 

~ 1::<.1 

p:j 

~ 

t:-4 

~ 1::<.1 

> 

8 

t:-4 

~ t:-4 

> p:j 

1::<.1 

t:d 

1-' 

~ 
B16 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

TABLE 4.-Modes of rocks from hole 3, Kilauea Iki lava lake 

[KI-228: Diabase segregation] 

Sample and depth (feet) 

KI-200 KI-203 KI-207 KI-209 KI-210 KI-213 KI-216 KI-217 KI-220 KI-223 KI-225 KI-228 KI-231 KI-233 KI-234 KI-236 

(melt) 

0.1-0.4 2-2.5 5-6 8-9 11-12 14-15 17-18 21-22 24-25 27-28 29-31 33-34 36.7-37.4 37.7-39 40.8-41.6 41.6-41.7 

-----------·1------------------------------------------------ .Phenocrysts: Olivine_________ 12 23 

Groundmass: 

Pyroxene_________________ 41 42 Plagioclase_______________ 22 21 Opaques__________________ 10 11 Glass_____________________ 15 3 

Apatite ___________________ -------- --------

(j') 

UJ 

Cl 

x 

0 

a::: 

UJ 

:I: 

f0 

u.. 

0 

UJ 

~ 

<{ 

fz 

UJ 

(.) 

a::: 

UJ 

a... 

24 

23 

22 

21 

20 

19 

18 

17 

16 

15 

14 

13 

12 

11 

10 

9 

8 

7 

6 

5 

4 

3 

2 

0 

44 

12 

11 

G1,.0 

45 46 

w 

_j 

0 

J: 

rtl u.i w N 

_j 0 

0 0 

J: 

z 

0 

f= 

<( 

(.!) (\j w 

0:: 

(.!) 

w 

(/)0 

w 

_j 

0 

J: 

...: 

_j 

w 

<> 

• 

47 48 49 50 51 52 53 54 55 

PERCENTAGE OF SiO 2 

FIGURE 10.-Silica-variation diagram of all analyzed crust rocks and melt samples from Kilauea Iki lava lake. 

Calculated average composition of Kilauea Iki lava (K. J. Murata, unpub. data) is shown by + at 48.21 

percent Si02. Lines drawn through the oxide plots below 49.61 percent Si02 represent olivine (Fa15) control 

lines. Note change in scale for total iron. 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B17 

to 2: 1. In the olivine basalts with more than about 

20 to 30 mode percent interstitial glass, on the other 

hanrl, there is a marked increase in the volume ratio of 

clinopyroxene to plagioclase. Melts collected at the 

base of the crust contain, after quenching, bet-ween 30 

and 74 mode· percent glass, and the volume ratio of 

clinopyroxene to plagioclase is consistently greater 

than 2.5: 1 and is as high as 4.5: 1 (sample KI-236). 

These relations suggest that clinopyroxene begins to 

crystallize at somewhat higher temperatures than 

plagioclase in the melt. 

The olivine phenocrysts in the crust range in size 

from 0.08 to over 4 mm in diameter. In the upper 2 

to 3 feet of crust, olivine is euhedral to slightly 

rounded; below 3 feet, however, and throughout the 

remainder of the crust, it is highly rounded and embayed due to resorption by the melt. Evidence of reaction between the olivine phenocrysts and melt is 

spotty and inconsistent. Abnormal concentrations of 

clinopyroxene around the margins of the olivine were 

observed below a depth of 27 feet in hole 2 and below 

a depth of 5 feet in hole 3. Yet in hole 1 no apparent 

coronas were evident. Small crystals of hypersthene(~) were present on resorbed olivine crystals at 

a depth of 2 to 2.5 feet in hole 3 (sample I\:I_:_203) but 

were not observed to bear this relation elsewhere in the 

crust. The composition of five olivine separates from 

depths of 2 to 2.5, 8 to 9, 17 to 18, 29 to 31, and 37.7 to 

39 feet in hole 3 ranged from Fa14 to Fa17 • No consistent relation between composition and depth is apparent, and the olivine crystals show no evidence of 

zoning. 

Clinopyroxene, the most abundant groundmass mineral in the olivine basalts, occurs as small, stubby hypidiomorphic prisms and irregular grains averaging 

0.05 mm in diameter. Sparse microphenocrysts as 

much as 0.6 mm in diameter and with ragged crystal 

outlines were observed scattered through the groundmass in a few sections at a depth of more than 14 feet 

in holes 2 and 3. A tendency toward a subophitic intergrowth is discer_nible in some of the sections, but in 

general the clinopyroxene crystals are smaller than the 

plagioclase laths. This is a rather curious feature inasmuch as the clinopyroxene begins to crystallize at 

slightly higher temperatures and has a higher ratio to 

plagioclase in the glassy rocks than in the holocrystalline rocks. Glomerocrystic clots of clinopyroxene and 

plagioclase are common in the vitric basalts at the surface of the crust but are absent in the glass-rich basal 

zone. In this basal zone and the underlying melt· the 

clinopyroxene is present as minute perfect euhedra dispersed through the glass. Zoning is not apparent in 

either the microphenocrysts or groundmass clinopyroxenes, but the latter do exhibit simple twinning. 

The groundmass clinopyroxenes are augitic with an approximate composition of W 04oEn5oFS1o (large 2V, 

y= 1.710) ; no optical properties indicative of pigeonite 

were observed. Clinopyroxene with Fs: En approximately 17: 83 is apparently in equilibrium with olivine 

Fa14 to Fa11. 

The plagioclase occurs as hypidiomorphic laths, 

plates,. and needles as much as 1 mm in length. In the 

clinopyroxene-plagioclase glomerocrysts typical of the 

vitric basalts at the top of the crust, the plagioclase 

commonly occurs as radiating star-burst clusters of 

laths, each lath mantled by a concentration of small 

clinopyroxene crystals. Slight zoning was observed in 

some of the larger crystals. The composition of the 

plagioclase at a depth of 34.3 to 35 feet in hole 2 

(sample KI-186) is Ans4· 

Hypersthene is rare in the basalts and was neYer 

observed to exceed more than 1 percent by volume of 

the rock. Small crystals, probably of hypersthene, 

were observed on resorbed olivine phenocrysts near the 

surface in hole 3 (sample KI-203), but elsewhere 

hypersthene forms relatively large (as much as 0.1 mm) 

irregular to blocky prisms scattered through the 

groundmass. In the m-odal analyses (tables 2, 3, and 4) 

the minor amount of hypersthene· is included in modal 

pyroxene. 

Opaque minerals occur in a variety of forms in the 

groundmass and constitute between 3 and 12 percent 

of the total volume of the rock. Within 10 feet of the 

surf·ace the opaque minerals generally form irregular 

masses with abnormally high concentrations around 

the periphery of the vesicles. · At depths greater than 

about 10 feet they tend to be more regular in outline, 

forming rods, equant crystals, a.nd chainlike groups of 

equant crystals· as much as 1 mm in length. Although 

no large crystals of opaque minerals were observed in 

the melt, the general opacity of the melt glass is 

probably due in part to included opaque microlites. 

AU of the opaques appear to be strongly ferromagnetic 

and hence rich in magnetite. The high titania content 

of the basalts, however, strongly indicates the presence 

of ulvospinel (FeTi04) molecule in the magnetite and 

probably primary ilmenite as well. 

Minute needlelike crystals of apatite( n occur in 

trace amounts throughout much of the glass and are 

especially common in the glass-rich basalt in the transient zone of crystallization. The needles occur singly 

and in tufted groups. 

Cristobalite was first identified in cores from hole 4 

drilled December 3 to 6, 1962. It was not observed 
'\, 

Bl8 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

In any core from the earlier drill holes. The cristohalite occurs as well-formed white pseudoisometric 

crystals as much as one-half mm in size lining vesicles. 

It occurs in much of the core in the interval11.9 to 15.9 

feet and also near the bottom of the interval15.9 to 19.9 

feet. Some of the rock probably contains up to 1 

percent cristobalite, and all the rock containing the 

mineral is otherwise rather normal-appearing olivine 

basalt with 10 to 20 percent olivine. The temperature 

range of the cores containing the cristobalite was 400° 

to 615° C ~t the time of collection, and hence the cristohalite crystallized at a higher temperature range. 

Because it occurs only in vesicles in olivine-rich rocks, 

the cristobalite must have crystallized from hot gases 

streaming through the crust from the melt below. 

Such gas transfer indicates depletion of Si02 in the 

melt and enrichment of Si02 in the crust. 

The glass content decreases from about 80 mode percent in the rapidly chilled upper inch of crust to 0 to 3 

mode percent below a depth of 5 feet (figs. 7, 8, and 9). 

About 6 feet above the base of the crust, at the top of 

the transient zone of crystallization, the glass content 

again increases and reaches approximately 30 mode 

percent (sample l{l-168) at the crust-melt contact. 

Most of the glass in the upper part of the crust is 

dark brown to nearly opaque, typical basaltic glass 

( n= 1.61 to 1.63) probably corresponding to compositions of 49.02 to 49.85 percent Si02 and 7.44 to 10.20 

percent MgO (K. J. Murata, unpub. analyses of glass 

from 1959 eruption). The low-silica and high-magnesia content of some of these glasses indicates that 

they would have crystallized significant -amounts of 

magnesian olivine if they had not been quenched. The 

glass in the lower part of the crust and melt is discussed 

in more detail in the following sections. 

TRANSIENT ZONE OF CRYSTALLIZATION 

Although the rocks in the zone of crystallization are 

virtually all olivine basalts, similar mineralogically 

and chemically to the overlying holocrystalline basalts, 

the unique ·character of the zone and significance 

of the included magmatic fluids warrants a separate 

description. 

The base of the transient zone of crysta-llization is the 

ernst-melt contact. Here, as previously described, the 

transition between crust ( <30 percent liquid) and melt 

(>30 percent liquid) is relwtively abrupt and occurs 

within a thin zone not more than a few inches thick at 

about the 1065° C isotherm. The less well defined top 

of the zone, where pore liquid ceases to exist, lies 5 to 6 

feet above the base of the crust at a pproximwtely the 

970° C isotherm. As the crust of the lake grows, the 

zone of crystallization will not only advance downward 

but will also increase in thickness owing to a decrease in 

the lake's thermal gradient. 

The transient nature of the zone of crystallization is 

well illustrated in the two photomicrographs in figure 

11. Figure 11A depicts the state of crystallization 

within the crust-melt contact (sample KI-168) at a 

depth of 29.7 to 29.9 feet and a;t a temperature of 1065° 

C (fig. 8) in hole 2 on April 13, 1961. The abundant 

glass, which constitutes 30 percent of the rook (table 3), 

pervades the entire groundmass and surrounds the crystals and crystal groups of clinopyroxene, plagioclase, 

and opaques. Figure 11B shows a thin section of core 

(sample KI -225) from the same depth ( 29 to 31 ft) , 

but collected about 14 mon~hs later (June 1, 1962) in 

hole 3 at a temperature of approximately 825° C (fig. 9). 

Crystallization is virtually complete, and only a trace 

of glass (table 4) remains in the groundmass. Moreover, the amount of opaque minerals has wbout doubled 

(from 3 percent in sample KI-168 to 7 percent in sample 

Kl-225) during the course of crystallization. 

Unlike the glass in the upper part of the crust, which 

was quenched, the glass in the transient zone of crystallization represents a sample of residual pore liquid 

in equilibrium with the groundmass minerals at the 

temperature of sampling. Hence, the composition of 

these glasses is strongly dependent on temperature and 

exhibits marked changes through the relatively narrow 

. zone of crystallization. The relationship between volume, temperature, and index of refraction of the glass 

in the base of the crust on October 1961 and June 1962 is 

shown graphically in figure 12. Upward from the base 

of the crust the index of refraction of the glass decreases, 

concomitant with a decrease in amount and temperature, 

from 1.61 (melt, sample KI-236) to 1.508 (sample, 

KI-231), 41j2 feet above the base. The color of the 

glass also changes through this interval from dark 

brown at the base to very pale brown. A very crude 

estimation of the composition of these glasses can he 

made by reference to the work of Stewart (1962) on the 

indices of refraction of fused Hawaiian rocks. Analyses showed that the melt glass with n= 1.61 corresponds 

to a composition of about 49 percent Si02, ·in good 

agreement with the assumed compositions for glass of 

similar index at the surface of the crust. Using 

Stewart's least-squares curve showing the relation between index of refra-ction and Si02 content for all rocks 

studied (both alkalic and· tholeiitic), we found that the 

lowest index of refraction (1.508) observed corresponds 

on the same curve to 59 percent Si02. However, because of ·a pnssible pronounced divergence between the 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B19 

FIGURE H.-Photomicrographs of crustal rocks from depths of 

29 to 31 feet at two different periods during growth of crust. 

A. (upper), Resorbed olivine phenocryst in glass-rich groundmass from depth of 29.7 to 29.9 feet (temp 1065° C) on April 

13, 1961. Groundmass minerals are clinopyroxene, plagioclase, and opaques. B (lower), Resorbed olivine phenocryst 

in holocrystalline groundmass from depth of 29 to 31 feet 

(temp 825° C) on June 1,1962. 

alkalic and tholeiitic index of refraction curves with 

increasing silica content, the lo"~> index glass may contain somewha:t more than 59 percent Si02 • 

Two pore fluids from the base of the crust have boon 

analyzed ( taoble 5) . One is the diabase segregation 

(sample KI-228) described in the following section, 

and the other is a glass (sample KI-113) collected from 

AMOUNT, IN PERCENTAGE BY VOLUME 

0 10 20 30 40 50 60 70 80 90 100 

31-

32-

33-

34-

' ', ' ' 

Hole 2 

Drdled Oct. 3-4, 1961 

Temperature profile Oct. 5, 1961_ 

35-------

c~\, ~------- ==,.---' Melt 

36-

37-

32-

tw ~SEGREGATION i ::~_::SJ f Cl.. I u.J I 0 35-1 I 

I 

I 

36-\ 

Hole 3 

On/led June I-ll, /962 

Temperature profile June 21, 1962 

1.56 1.58 1.60 1.62 1.64 1.66 

INDEX OF REFRACTION (n) 

lPIGURE 12.-Gra ph showing relation between volume percentage 

index of refraction, and temperature O'f interstitial glass in the 

transient zone of crystallization at two different periods 

during growth of crust. 

the bottom of hole 1 (22.3 to 22.5 ft). The glass 

(n=l.569, Ste·wart, 1962) represents a low-viscosity 

liquid that oozed from the base of the e1·ust into hole 1 

after the August 24, 1960, drilling and chanced to adhere to the end of a thermocouple used during a temperature-profile measurement. The glass contains 

54.08 percent Si02 and 5.02 percent total alkalis-the 

most silica- and alkali-rich tholeiitic material ever 

analyzed from Kilauea. Neither the diabase segregation nor the glass ooze, however, are appreciably 

enriched in iron. The relative silica content of ·the two 

differentiates indicates that the ooze \Yas derived from 

a higher level in the transient zone of crystallization 

and at lower temperatures than the segregation. 
B20 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

TABLE 5.-Chemical analyses, norms, and modes of tholeiitic 

differentiates Kilauea Ilci lava lalce 

[Results in percent. D. F. Powers, analyst] 

Sample and depth (feet) 

KI-ll3 

(ooze, hole 1) 

22.3-22.5 

Chemical analyses 

Si02---------------------------- 54. 08 

AhOa--------------------------- 1 13. 62 

F0.10a--------------------------- 213. 03 FeO ____________________________ ------------ MgO_ ___ _ _ _ ___ _ _ _ _ __ _ _ _ _ _ _ _ _ __ _ 4. 26 

CaO____________________________ 7. 03 

~a20--------------------------- 3. 32 

H20+ K20---------------------------- 1. 70 ______________________________________ _ 

H2o-________________ ___________ . 04 

Ti02--------------------------- 3. 37 

P205-------------- Mn 0 ___ ____________------ _________________ -------- ------------ ___ ___ _ C02- ___ --- ________________________________ _ CL _______________________________________ _ 

F_____________________ ____ ___ __ .13 

SubtotaL_ __ ____ __________ __ (3) Less 0 _____________________________________ _ 

TotaL ____ ________________ _____________ _ 

Norms 

or Q--------------- _____________________________ ---------------_ 

ab ____________________________ _ 

an ____________________________ _ 

di: wo __________________________ _ 

en __________________________ _ 

fs __________________ ________ _ _ 

hy : 

6.27 

10. 04 

28. 08 

15. 88 

6. 23 

2. 87 

3.31 

KI-228 (diabase segre- gation, hole 3) 

33--34 

50. 32 

13. 35 

1. 79 

10.39 

5.69 

9. 89 

2. 72 

. 84 

. 04 

. 00 

4. 40 

. 41 

. 19 

. 00 

. 02 

. 06 

100. 11 

. 03 

100. 08 

3. 36 

5.00 

23. 06 

21. 13 

10.44 

5. 60 

4.49 

en___________________________ 7. 74 8. 60 

fs _- __ - - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 8. 94 6. 2 0 

cl: . fo _____________________________ ______________________ _ 

fa ___________________________________________________ _ 

mt_____________________________ 2. 17 2. 55 

iL_____________________________ 6. 40 8. 36 

ap _____________________________ 1.18 1. 01 

fr__---- ------ ------------------ . 22 . 07 

TotaL _______________ ______ _ 99. 33 

Modes 

Olivine ____________________________________ _ 

Pyroxene ___ _____ ____________ __ ____________ _ 

Plagioclase _________________________________ _ 

0 paques _ ________________________ - ___ ------ _ Glass _________________________ ___ __________ _ 

Apatite ____________________________________ _ 

99. 87 

Tr. 34 

41 

8 

16 

1 

1 AJ,O,+P,o,. On basis of spectrographic analysis (P. Barnett, written commun.), 

0.50 percent allocated for P20, for norm. 2 Total iron calculated as Fe,Oa. For norm, 10.38 percent allocated to FeO. • Partial analysis, total omitted. 

DIABASE SEGREGATIONS 

Segregations consisting principally of mediumgrained clinopyroxene and plagioclase have been found 

in hole 3, at depths below 32 feet (fig. 9) . Two have 

been observed. The uppermost and largest segregation 

occurs between 32.8 and 34.1 feet (sample KI-228) and 

the smaller one, which is less than 0.1 foot thick, occurs 

at 38 feet. In thin sections of the largest segregation 

the equigranular clinopyroxene and plagioclase crystals form a hypidiomorphic to subophitic intergrowth 

with minor opaque minerals, olivine, apatite(?), and as 

much as 16 percent interstitial glass (fig. 13). No hyFIGURE 13.-Photomicrograph of diabase segregation with plain 

light (.A, upper) and crossed nicols (B, lower) showing hypicliomorphic-granular to subophitic clinopyroxene-plagioclase intergrowth. Large dark areas in upper middle and 

right middle parts are vesicles. Interstitial gla s with needlelike apatite(?) crystals occurs around the long opaque crystal aggregate and in the left middle part. 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B21 

persthene was observed. The crystals commonly project into and also grow within the abundant irregular 

vesicles and form a local diktytaxiticlike texture. 

Plagioclase, the most abundant mineral of the segregations ( 41 mode percent), occurs as subhedral laths 

and plates averaging 1 mm in length and 0.2 mm in 

width. The crystals are zoned ranging from An55 to 

An4s, noticeably more sodic than the plagioclase in the 

olivine basalts. Subhedral to subophitic clinopyroxene, in subordinate amount ( 34 mode percent), 

occurs as unzoned and optically homogeneous crystals 

(2V=45°, y=l.72) averaging 1 mm in diameter. The 

clinopyroxene has a composition of W o35.5 Eri4G.5 Fs1s.o 

(table 6), containing a somewhat greater proportion of 

ferrosilite tha.n the groundmass augites of the olivine 

basalts. Olivine was not observed in thin section but 

was present in trace amounts in the heavy-mineral 

separates from the segregation. The olivine has an 

average composition of Fa26 ; slight zoning is apparent 

in some of the crystals. Although the segregation 

olivine is considerably richer in iron than the olivine in 

the basalt, the average magnesia content of the segregation olivine is still greater than that of the coexisting 

clinopyroxene .. This relation supposedly indicates nonequilibrium (l\tfuir and Tilley, 1957), a condition which 

appears untenable in view of the observed physical and 

mineralogical features in the segregation and enclosing 

rock. The opaque minerals are all strongly ferromagnetic and occur as elongate and equant crystals and as 

chains of equant crystals. 

TABLE 6.-Com1J08ition of clinopyroxene from diabase segregation, sample IU-228A, hole 3 

[Results in percent. J?. F. Powers, analyst] 

Chemical analyses Composition 

Si02--- ---------------------------------- 51.04 Wo ___________ ------------ 35. 5 Al20a------------------------------------ '3. 52 En ________________________ 46.5 

Fe20a------------ ------------------------ 1. 67 Fs ____ -------------------- 18.0 FoO __ ----------------------------------- 9. 45 MgO ____ -------------------------------- 15.66 Cao _____________ ------------------------ 16.66 

Na20- __ --------------------------------- . 44 

K20- _ ----------------------------------- . 04 I-I20--- __ --- __________ -------------- __ _ _ _ . 00 

'l'i02------------------------------------- 1.44 

99.92 

The interstitial glass ( n= 1.503) in the segregations 

represents an extreme tholeiitic differentiate. Unlike 

t.he glass in the transient zone of crystallization, however, it was app.arently solid when collected (fig. 12) 

and hence not in equilibrium with the crystal phases of 

the segregation at the collection temperature. In thin 

section the glass is colorless to very pale brown and 

contains fairly abundant needlelike growths of apatite( n. The work of Stewart (1962) indicates that 

the glass probably contains more than 60 percent Si02. 

A chemical and modal analysis of the diabase segregation is presented in table 5. The relatively low-bulksilica content ( 50.32 percent), despite the predominance 

of silica-rich constituents (plagioclase, 55 percent Si02; 

clinopyroxene, 51.04 percent Si02; glass, 60 to 68 percent 

Si02), is apparently due to the 8 percent of opaque minerals. An interesting, but inexplicable feature of the 

segregation not observed in other siliceous tholeiitic differentiates from Hawaii, is the extremely rich TiOz content of 4.40 percent, which results in a high ilmenite 

norm of 8.36 percent. Moreover, in the ooze from hole 

1, which is even richer in silica, the titania content is 

relatively low and comparable to titania values in other 

rocks of similar silica content. No abnormal changes in 

the remaining oxides, other than those attributable to 

fractional crystallization, are apparent. 

MELT 

The melt is that part of the iava lake with temperatures above 1065° C and is a viscous liquid containing 

variable amounts of crystalline olivine, minor clinopyroxene, and a trace or no plagioclase. Although the 

mineralogy and bulk chemistry of the melt (where 

sampled), crust, and original lavas are grossly similar, 

there is a marked enrichment in alkali content of the 

melt which appears to have significant petrologic implications. The melt in hole 1 (sample KI-112) is also 

abnormally high in titania, probably indicating some 

contribution of titania-rich interstitial liquid from the 

transient zone of crystallization. 

In figure 14 are plotted the K 20: N a20 ratios, as a 

function of weight percent Si02, for all the analyzed 

samples from the Kilauea Iki lava lake. Also plotted 

is ,the average composition of the 1959 lavas (K. J. 

Murata, unpub. data) that filled the lake. The outstanding features shown by this plot are : ( 1) the uniform 1(20 : N a2 0 ratios for most of the crust rocks, 

including those of the average 1959 lava, and (2) the 

anomalously high ratios for the two analyzed melt 

samples (KI-112, table 1; J(I-168, table 2). Alkali 

ratios for the holocrystalline olivine basalts, most of 

the vitric-rich basalt in the transient zone of crystallization, and the average 1959 lava, consistently fall 

between 0.22 and 0.25, regardless of bulk-silica content. 

The melt in hole 1 (sample KI-112, depth 22.5 ft) and 

hole 2 (I\:I-168, depth 29.8 ft), on the other hand, have 

alkali ratios of 0.29 and 0.47 respectively. One sample, 

from the transient zone of crystallization (KI-165, 

depth 27.9 to 29.1 ft) about 1 foot above the melt in 

hole 2, also shows a marked increase in the alkali ratio. 

I-Iowever1 other samples from this zone (KI-164, depth 

27.5 to 27.9 ft; I\:I-184, depth 31.8 to 32.8 ft; and 

KI-186, depth 34.3 to 35 ft) have a normal alkali con-
B22 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

SEGREGATION 

Melt 033.5 

e22.5 

0 10.0 

05.5 6.80 ~0.3 e5.4 7.2o o27.7o 032.3 0 .. • 34.5 9.0 11.~ 0.1 0.3 

e Hole 1 

o Hole 2 

0 Hole 3 

Ooze 

.22.4 

55 

FIGURE 14.-Plot of K20: Na20 as a function of Si02 for all 

analyzed Kilauea Iki lava lake rocks. Average composition 

of 1959 Kilauea lki lavas (after K. J. Murata) is shown by+· 

Numbers refer to average depth, in feet, of the samples. Line 

and arrow indicate possible trend of "normal" alkali ratio 

above 50 percent Si02. 

tent. This increase in KzO : N a 20 ratio shown by the 

melt is principally due to an increase in K 20 (fig. 10); 

the N azO content appears to be anomalously low in 

one melt sample· (KI-168) but slightly high in the 

other (KI-112). 

The high alkali ratio of the diabase segregations and 

bottom-hole ooze containing more than 50 per~ent SiOz 

may not be entirely anomalous, but in part a normal 

consequence of enrichment through fraction.al crystallization. Moreover, these rock types are noticeably 

enriched in both K 2 0 and N a2 0. The line in figure 14 

portrays this possible trend above 50 percent SiOz, 

based on a number of analyzed tholeiitic differentiates 

from Hawaii (l(uno and others, 1957, Murata and 

Richter, 1961). 

Thus, the evidence indicates that a zone of unknown 

thickness in the melt., directly below the crust-melt contact, is signific~ntly enriched in total alkalis, particularly K20. Moreover, on the basis of the two melt 

analyses available, there is a suggestion tha;t enrichment is enhanced as the depth of the zone increases. 

lTpon crystallization of the melt in this enriched zone, 

the excess alkalis are apparently driven off, together 

with water and probably 802 , into the highly fractured 

and cool rocks of the crust. In some respects, this zone 

is similar to the transient zone of crystallization, for. 

it advances downward as the crust grows, leaving no 

evidence of its former presence in the overlying holocrystalline rocks. 

ALTERATION 

The rocks of the crust show only minor affects from 

alteration. The most obvious alteration phenomenon 

is along the many cracks and under the small tumuli 

on the lake where the lava has acquired a reddish-brown 

hue due to a surficial oxidation of the iron by ascending 

hot vapors. Around the hotter and hence deeper 

cracks, the lavas are partially digested, leaving a rime 

of gelatinous silica, often in association with crystalline sublimates of sulfur and the anhydrous alkali sulfates, thenardite, and aphthitalite. 

Within the crust some of the olivines undergo an incipient alteration consisting of an orange-brown stain 

around the margins of the crystais and along fractures 

penetrating the crystals. This staining first becomes 

apparent at a depth of about 2 feet below the surface 

and continues, generally without interruption, to about 

12 feet above the crust-melt contact. 

Chemically, the chief subsolidus change which occurs 

in the crust is the oxidation of iron. This change is 

. graphically shown in figure 15, 'Nhere the FezOa: 

0 

I 

I 

0 . .. I 

~ I 

I 

I 

• 

;_= 

• • 

0 I 

I I 

• • 

• • 

0 Hole 1 

e Hole 2 

l!'IGUHE 1;:1.-Graph showing l!'e20a: FeO+Fe20a ratios as a function of depth in drill holes 1 and 2 through the crust of the 

Kilauea Iki lava lake. 

FeO + FezOa ratios of the drill-hole samples are plotted 

against the depth at which they were collected. Although the points show scatter owing to the varying 

amounts of oxidation associated with cracks, the ratio 

indicates a decreasing degree of oxidation of iron with 

depth in the olivine basalt of the lake crust. The minimum value of FezOa : FeO + FezOa of about 0.1 at a 

depth of about 30 feet in hole 2 indicates the probable 

state of oxidation of juvenile or at least very recently 

'· 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B23 

erupted I{ilauea lava. The increase of the ratio toward 

the top of the crust suggests that oxidation is proceeding from the top down and that· the oxidizing agents 

are of atmospheric origin. 

In figure 15 the offset of the average curve of points 

of hole 1 as compared with that of hole 2 is a measure 

of the oxidation which has taken place in the crust during the approximate 1-year interval between drilling 

and sampling of the two holes. 

The measured increase in the oxidation state of the 

iron is probably the result of several processes. The 

late crystallization of opaque minerals at the base of 

the crust has already been noted (fig. 11). These 

opaques, which probably are chiefly magnetite, presumably grow at the expense of FeO in the glass (or 

interstitial melt). Further oxidation of iron in olivine 

occurs at rather shallow depth and at low temperature 

and produces the. orange-brown staining referred to 

a)bove. 

DIFFERENTIATION 

Magmatic differentiation played and continues to 

play ·an important role in the crystalliz·ation of the 

tholeiitic rocks in the crust of the l{ilauea Ikilava lake. 

During ·the 3-year period between December 1959 and 

December 1962, the crust has grown from 0 to .more than 

42 feet thick and fractional crystallization has resulted 

in ·compositional changes between 45.61 and at least 

54.08 percent Si02. The petrographic and chemical 

data also strongly suggest that gas transfer may play an 

important role in desilication of the melt and that -a 

process of transient alkali enrichment occurs in the melt 

immediately below the crust-melt contact. These 

changes in the composition of the crust ·and underlying 

melt have, without much doubt, occurred after the beginning of the formatio~ of the crust and hence are not 

inherited, except indirectly, from original compositional 

differences in the lava of the 17 eruptive phases that 

filled the lake. 

FRACTIONAL CRYSTALLIZATION 

The changes in composition exhibited by most of the 

rocks are due to two processes of fra,ctional crystallization: gravity settling of heavy crystals and filter 

pressing. Gravity settling has influenced the composition of the entire crust, h11t is more apparent-at the 

present·time-only in the upper section. Filter pressing, however, is a more deep-seated process, dependent 

essentially on slow cooling, and is restricted to depths 

below about 20 feet. 

In the upper 14 feet of crust the sinking of rela;tively 

heavy olivine crystals has produced a number of olivineric~ layers that contain as much as 37-mode-percent 

olivine and simultaneously leave a superstratum rela.-

tively poor in olivine (figs. 7, 8, and 9). The olivine 

accumulates rest upon thin layers of dense basalt, which 

probably represent partially digested portions of old 

crust emplaced during the period of crustal foundering 

at the end of the eruption. At depths of more than 14 

feet there is a gradual but erratic decrease in olivine 

content (figs. 8 and 9). Olivine from this zone and the 

melt below is presum·ably building up a thick crystal 

accumulate at the base of the melt in the bottom of the 

lake. 

The range in silica content from 45.61 to 49.61 percent 

in the crustal olivine basalts can be explained solely by 

the addition or removal of magnesian olivine by gravity 

settling (fig. 10). No evidence to support clinopyroxene removal by gravity settling, as advocated by Macdonald and Katsura ( 1961) has been found. On the 

basis of observations made during the 1959 summit 

eruption and 1960 flank eruption, augitic clinopyroxene 

begins to crystallize at about 1100° C (D. H. Richter, 

unpub. data). Hence, clinopyroxene can crystallize 

only in a zone extending upward from about 3 feet below 

t.l!e crust-melt contact (see temp profile, hole 2, table 1). 

However, inasmuch as the crystals formed are small 

(max size 0.08 mm) and the melt is viscous, it appears 

unlikely that the rate of crystal settling is greater than 

the ra~te o:f crustal growth. Possibly, in time, with a 

thicker crust and less steep thermal gradient, the sinking of early-formed clinopyroxene may play a- significant role in the differentiation of the lake lavas. 

The efficacy of filter pressing as a differentiation 

mechanism in the lava lake is manifest by the presence 

of diabase segregations in hole 3 and the ooze from the 

bottom of hole 1. Both of these differentiates 

represent an interstitial liquid that was originally in 

equilibrium with crystallizing clinopyroxene and plagioclase in the transient zone of crystallization. Filter 

pressing becomes an effective separation process when 

a crystal mesh of sufficient cross-sectional density 

screens out crystals and allows only residual fluid to 

pass through. In the Hawaiian tholeiites, the Kilauea 

Iki lavas in particula.r, this condition is reached only 

after the crysta.Hization of most of the magnesian olivine and some of the clinopyroxene and plagioclase. 

The expelled liquid was apparently injected into local 

dilatant zones, such as the continuously forming 

shrinkage cracks, at somewhat higher levels in the crust 

than the source of the liquid. The ooze in the drill 

hole, however, was artificially released by the drilling 

and thus allowed the interstitial liquid to exude from 

the zone of crystallization and to collect in the bottom 

of the ho1e. 

The course of differentiation exhibited by the segregations and ooze is towards enrichment in K20, N a20, 
B24 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

and Ti02 with increasing· silica content (fig. 10). 

Alumina and total iron oxides remain virtually constant, and magnesia and lime show a marked decrease. 

Assuming that the liquid in the parent liquid -crystal 

melt (50 percent Si02) contained more than about 52 

percent Si02, this trend would fall within a continuously changing clinopyroxene-plagioclase control 

field (Richter and others, 1964). The composition of 

the ·.differentiates may also be affected by enrichment 

in' potash and silica that is in addition to simple concentration through fractional crystallization. 

A comparison of refractive indices (fig. 12) indicates 

that the ooze from hole 1 represents the residual liquid 

in an olivine basalt ( 5 to 10 percent modal olivine) 

after crystallization has been 76 to 78 percent complete. 

By inference from the index of refraction and the 

thermal-profile data in figure 12, this differentiate, 

which corresponds chemically to a quartz basalt, has 

a liquidus temperature of approximately 1040°C. 

The diabase segregations, because of their lower silica 

content, were evidently derived from less crystalline 

layers and at somewhat higher temperatures (1050° to 

1060°C) deeper in the zone of crystallization. Although residual liquids persist to levels where temperatures are as low as 970°C, the small volumes of these 

interstitia1ly trapped liquids virtually precludes their 

egress in any substantial amount from the crust. 

However were it possible to continuously remove these 

lower temperature liquids, products approaching the 

composition of granite could readily be formed through 

fractional crystallization alone. 

Analyses of the lava-lake rocks plotted on an AMF 

(alkali-magnesia-iron oxide) diagram (fig. 16) show 

FIGURE 16.-AMF diagram of differentiation trend in Kilauea. 

Iki lava lake (solid circles), Uwekahtma laccolith, Kilauea 

(crosses), and Palolo diabase, Koolau, Oahu (open circles). 

only a very moderate iron enrichment, markedly different from the high iron trend of the 'Skaergaard 

(Wager and Deer, 1939) or the so-called J{ilauea trend 

of J{uno and others (1957). The differentiation trend 

is practically identical with that shown by the U wekahuna laccolith in Kilauea caldera (Murata and Richter, 

1961) and is very similar to that of the Koolau basalts 

and intrusives on the Island of Oahu (l{uno and others, 

1957). Kuno and his colleagues proferred the term 

"IGlauea trend" because of an iron-rich segregation 

vein in an olivine basalt flow in the wall of Kilauea 

caldera; however, as shown in figure 16, iron enrichment in l{ilauea appears to be more the exception than 

the rule. Osborn ( 1959) has pointed out that changes 

in the partial presssure of oxygen in (p02) may be the 

controlling faetor in determining which trend-iron 

. enrichment or alka1i enrichment-will be followed by 

a differentiating basaltic magma. _However, it seems 

difficult to believe that in the similar environment of 

the flows, intrusives, a-nd lava. la-ke on Kilauea, changes 

in p02 would be of sufficient magnitude to affect the 

course of crystallization. 

ALKALI TRANSFER 

Petrochemical studies of melt samples from the lava 

lake strongly suggest that a zone enriched in alkalis, 

especially 1{20, occurs in the melt directly beneath the 

crust-melt contact.. K 20 in this zone shows upward 

of 100 percent enrichment, resulting in a twofold increase in the K 20 : N a20 ratio. After crystallization 

proceeds through . this zone, the resulting. holocrystalline rock sho·ws a normal alkali content and alkali 

ratio. The thickness of the enriched layer is not 

known. 

An attempt 'to explain this phenomenon is portrayed 

diagrammatically in ~the three sections in figure 17. At 

the erid. of the eruption in December 1959, the melt in 

the lake was probably nearly homogeneous, having an 

average K 20: Na20 ratio of 0.24 (fig. 17A). In fact, 

in 17 analyses of the lava that contributed to the filling 

of the lake. the alkali ratio ranged only from 0.23 to 0.26 

(K. J. Murata, unpub. data). In August 1960, when 

the crust was 22 feet thick, the sampled melt had a 

K20: Na20 ratio of 0.29 (fig. 17B); and by April 

1961 this ratio had increased to 0.47 (fig. 170). The 

olivine basa.lt samples from the crust r~tain an average 

alkali ratio about the same as that of the original lavas, 

regardless of their depth in the crust. In the remaining great bulk of melt beneath the alkali -enriched zone, 

there is evidently a complimen!tary decrease in the alkali 

ratio; however, the actual values shown in figures 17 B 

and 0 are highly· conjectural This process of alkali 

enrichment within the melt may be. similar to the 

mechanism advanced by Kennedy ( 1955). He has 
PETROLOGY OF THE KILAUEA IKI LAVA LAKE B25 

shown that under equilibrium conditions, water in a 

quiet magma;tic melt will have a uniform partial pressure throughout its entire volume. To achieve this 

condition, water by means of diffusion will migrate to, 

and concentrate in, areas of least confining pressures 

and lowest temperatures. Utilizing the data of Morey 

and Hesselgesser (1952) who found an extremely high 

solubility of alkali silicates in superheated water vapor, 

l{ennedy further reasoned that water and alkalis should 

tend to associa;te in a magma regardless of whether they 

are in solution or exist as a separate gas pi1ase. Hence 

it appears very reasonruble to expect that, in the lava 

lake, dissolved water in association with abundant alkalis will concentrate in the relatively low temperruturepressure zone beneath the crust-melt contact. 

V pon crystallization of this enriched alkali-water 

zone and concomitant rapid decrease in pressure, ·the 

alkalis, in excess of that required to form plagioclase, 

Melt 

0.24 

' End of eruption 

December 1959 

Crust 22 ft thick 

August 1960 

ilG~6·2DB~~· .. rzili~rtr~~~ 0.47 j~t·t·t ------Melt------- ---------- --------------------- -- ----------

) . 0.20? ~ om"';oc 

c 

Crust 30 ft thick 

April 1961 

FIGURE 17.-Hypothetical sections through Kilauea Iki lava 

lake showing mechanism of alkali enrichment. Thickness of crust is exaggerated and solidified base is o·mitted. 

are apparently released together with water vapor and 

other volatiles (fig. 17 B, 0). Migrating upwards, these 

volatile exhalations deposi·t crystalline sublimates of 

aphthitalite, thenardite, and sulfur in the ·cooler parts 

of the crust. 

The petrologic implications of the ·alkali-enriched 

zone in the melt of the Kilauea Iki lava lake are great. 

Of particular importance is its bearing on the origin of 

the undersaturated alkali basalts. Macdonald ( 1949a, 

b) who has supported fractional crys•tallization to explain the genesis of the alkali basalts from a ·tholeiitic 

parent has alS'o stressed the possible role played by alkali transfer (1949a, p. 1584; 1949b, p. 91). However, 

it was not ·until the first drilling in the lava lake that 

demonstrable evidence was found to sustain these views 

· (Macdonald and Katsura, 1961). Additional data 

gathered subsequently from the lava lake and presented 

in this paper corroborates the presence of an alkali-rich 

melt, at least in part, and demonstrates that Macdonald's one sample was not exceptional. 

If processes similar to those presently active within 

the lava lake occur in the shallow (1 to 5 km deep) 

magma chambers of the Hawaiian volcanoes, there is 

convincing argument to support the deriva;tion of the 

alkali basalts from a primary tholeiitic magma. 

Throughout the early stages of Hawaiian volcanism, 

tholeii·tic lavas are erupted frequently -and voluminously 

without undergoing prolonged storage in the volcanic 

pile. With decadency, however, the tempo of eruptive 

activity declines. The processes of alkali enrichment 

and silica transfer in the Kilauea Iki lava lake may 

have upwards of hundreds of years to operate rather 

than only a few, and the lavas shift ·to the alkalic type. 

It is also significant that 'the total volume of alkalic 

lava erupted is very minor compared with the tremendous volume of tholeiitic basalt com posing the main bulk 

of the volcano. During the long periods of quiescence 

in the waning period of volcanism, extremely slow cool-· 

ing and relatively high lithostatic load should enhance 

the concentration of alkalis in the upper levels of the 

stagnant magma chambers and may also further the 

process of silica transfer. Although desilication of the 

·magma through gas transfer still evades quantitative 

evalu~tion, it is an apparently important process and 

may well be the key in explaining the undersaturation 

of the alkalic basalts. Slow cooling will also significantly increase the efficacy of fractional crystallization 

in the magma. Not only will m·agnesian olivine he 

removed . from the upper part of ·the melt through 

gravity settling, but the early-crystallizing high-silica 

augitic clinopyroxenes should settle out as well. The 

formation of magnesian olivine and augitic accumulates 

in the shallow magma chambers is indicated by the great 
B26 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

abundance of periodoti'te and pyroxenite nodules in the 

alkalic flows (Richter and Murata, 1961), whereas such 

inclusions are almost unknown in Hawaiian tholeiites. 

Eruptions of the postulated alkali-rich melt could 

be effected by an increase in vapor pressure that accompanies the concentration of H 20 in the residual 

melt in the uppermost parts of the magma chambers. 

The need for additional primary material from the 

mantle to act as an accessive force to cause eruption, 

as in the tholeiitic eruptions, doe,s not appear necessary. 

An explosive release of water vapor would follow any 

fracturing of the magma chamber. Indeed, the scattered occurrence of vents and apparent explosive 

character of Hawaiian alkalic eruptions implies a fairly 

shallow origin for the magma, such that fracturing 

from the magma chamber to the surface is geologically 

feasible. 

Recently, evidence has been found to indicate the 

possible beginning of a shift to alkalic tendencies in 

J{ilauea Volcano (J. G. Moore and D. H. Richter, unpub. data). The K 20 : N a20 ratios of prehistoric and 

early historic tholeiitic basalts from Kilauea average 

about 0.19, while recent basalts average 0.24. This 

change is in the same direction as that of the change 

from tholeiitic to alkalic basalt and also of that in the 

changes observed in the lava lake. 

Thus, it appears plausible that a combination of 

alkali and silica transfer and fractional crystallization 

of clinopyroxene within shallow.magma chambers may 

well explain the change from tholeiite to alkalic basalt 

observed in Hawaiian volcanoes. This is opposed to 

the views of Yoder and Tilley (1962) who, principally 

on the basis of laboratory studies, believe that neither 

a tholeiitic nor alkalic magma is the parent of the other 

but that each is derived as separate fluids· from the 

mantle. Although our arguments have been largely 

qualitative, further investigations on the slowly crystallizing Kilauea Iki lava lake should significantly add 

to the presently meager knowledge of magmatic chemical-physical processes. 

REFERENCES 

Kennedy, G. C., 1955, Some aspects of the role of water in rock 

melts, in Poldervaart, A., ed., Crust of the earth-a symposium : Geol. Soc. America Spec. Paper 62, p. 489-503. 

Kuno, Hisashi, Yamasaki, Kazuo, Iida, Chuzo, and Nagashima, 

Kozo, 1957, Differentiation of Hawaiian magmas: Japanese Jour. Geology and Geography, v. 28, p.179-218. 

Macdonald, G. A., 1949a, Hawaiian petrographic province: Geol. 

~oc. America Bull., v. 60, no. 10, p. 1541-1596. 

---1949b, Petrography of the island of Hawaii: U.S. Geol. 

Survey Prof. Paper 214-D, p. 51-96. 

Macdonald, G. A., and Katsura, Takashi, 1961, Variations in 

_ the lava of the 1959 eruption in Kilauea Iki: Pacific Sci., 

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