Heat-flow measurements in 17 perialpine lakes
PETER FINCKH' Geological Institihe, ETH, Zurich, Switzerland *Present Address: Institute for Geophysics, E TH, 8093 Zurich, Switzerland
Geological%cien/ of America Bulletin, Part II, v. 92, p. 452 - 514,6 figs., 5 tables, March, 1981, Doc. no. M10303
core was'collected for samples on which ABSTRACT thermal conductivity was measured with
Thirty-eight heat-flow measurements the needle probe method after treating
were carried out in 17 perialpine lakes the material to remove exsolved gas bub-
to supplement the scanty information bles. Continuous seismic-reflection and
concerning the thermal conditions in reflection profiles in all of these lakes
the crust underlying central Europe. provided a set of parameters for gradient
A probe of the'corer type was built which correction due to heat-flow refraction.
allowed the measurement of 11 tempera- Additional corrections were applied on
tures at equally spaced subbottom inter- the basis of palynologikally determined
vals to a maximum penetration of 10.5 m. sedimentation rates and for the' influ-
Measurements of this type were made in ence of the last period of glaciation.
Lake Constance, Grejfensee, Lake Zurich, Final heat-flow values obtained in this
Lake Zug,,Lake Lucerne, Baldeggersee, manner are giyen. ' The lesser values
Lake Biel, Lake Mur-ten, Lake Neuchftel, are generally found in the more western
Lake Geneva, Lac d'Annecy, Lac de Rourqet, kakes, north of the Alps; the higher
Lago Maggiore, Lago di Lugano, Lago di values are found in the more eastern
Como, Lago d'lseo, and Lago di Garda. lakes, north and south of.the Alps. The
After retrieval of the probe, a sediment higher values are partially confirmed 452
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 453
by earlier measurements in 1akes.but oceanographic method for measuring heat
show considerable discrepancy with flow in the ocean floor has tempted
measurements from the central Alps. some scientists to use this technique in
This could be explained by the under- suitable lakes-for example, Diment and
thrusting of a cold wedge under the Werre (1965) in Green Lake, Steinhart and
Aar and Gotthard Massif in the late Hart (1965a, 1965b) in Lake Superior and
Miocene and early Pliocene, which then Lake Seneca, and Lubimova and Shelyagin
would lower the temperature gradient (1966) in Lake Baikal. These works
in the central Alps. stimulated others such as H&el (1970)
in southern German lakes and Von HLrzen INTRODUCTION and others (1974) in Swiss lakes. The
Knowledge of the thermal conditions latter made clear that some boundary
in the crust of the alpine region has conditions must be well known and taken
become more and more important because account of in the calculations.
mogt tectonic and chemical processes Heat-flow values from the Alpine region
are strongly temperature dependent. are basic data for the interpretation
Additionally, heat is often the energy of the tectonics and metamorphic history
source of such processes. Thus earth of this region. This paper presents
scientists turned to the investigation additional heat-flow data from 17
of geothermal conditions with many perialpine lakes and shows how the
different methods. One method'is the necessary corrections were made. The
measurement of the heat flowing through geographic and geologic situation of the
the uppermost crust, allowing an estimate coflgidered lakes are given\in Figure 1
of temperatures at greater depths to be (no measurements in Walensee and Lake
made. On land, such measurements are Thun). The glacial deposits over the
usually made in boreholes, mines, or Molasse basin between Lake Constance
tunnels. However, the simple (Bodensee) and Lac de Bourget are not
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 454
'N
...... ,:I . ... '.'.'.'4 z6 ...... -2 ,,3...... '.'.'5 ...... , ...... - ...... 1Wh ...... %:'.,' ...... - ...... - 1_1--
Figure 1. General geographic and geological situation of perialpine lakes. Area 1: Central
and Southern Alps. Area 2: Tertiary sedimentaqy basins: in the west; Bresse Basin; in the
north; Rhinegraben; in the center, Molasse Basin. Aiea 3: Quaternary glacial deposits covering
Tertiary sediments. Area 4: Hercynian massifs. Are3 5: Pliocene-Pleistoncene.sedimentary
basin (poplain). Area 6: Jura mountain chain.
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 45s
shown, in the interests of clarity. surroundings of the locality of the
measurement. In the following, some Theoretical 'Considerations possible' sources of error will be dis-
In the case of constant heat produc- cussed.
tion A and constant thermal conductivity Measuring Techniques. Careful con-
K, the differential equation describing sideration must be given to the accurate
the general case of heat conduction is and frequent calibration of the
reduced to the simple form thermistors used €or the temperature
measurements. Also, frictional heat --d 'T -- -.4 2 K created by the probe penetration into the dz lake bottom must be dissipated before where T is temperature in degrees measurement is begun. The thermal Centigrade and 2 is depth in centimetres. conductivity K that is measured on samples Its solution becomes of a core must be representative- of the
;henna1 conductivity in the lake sub-
(2 bottom; thus, the core should be as long where Q(0) = atz=O as possible and be kept fresh until
Q(0) is the heat flow at the surface of sampled. 2 the considered system in HE'U (ucal/cm 0s) IfZuence of Topography. The 2 -h or in,mW/m . By measuring the tempera- topography has two effects on the 1 ture gradient dT/dz and the thermal temperature field, in the subbottom.
conductivity K, it is possible to dc- The isotherms are compressed by
termine the surface heat flow Q(0). terrain incisions and widened by
How the measured heat flow corresponds elevations. Average air surface
to the regional value depends on the temperature is dependent on elevation.
isotropy, homogeneity, and stability Average water temperature at the bottom
of 'the subbottom and on the immediate of a lake depends on the local conditions
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 456
of inflows, winds, currents, rate of better. conducting material. The strength
overturn, and other iqfluences. This of this effect depends on the contrast
temperature distribution also affects of the conductivities, and the shape of
the tempereture field in the subbottom. the body with varying conductivity and
Several methods have been proposed its contrast must be considered.
in order to correct for topographic and A solution is again available in the
temperature disturbances (for a review, finite-element method, where for each
see Lee and Henyey, 1974). Lee and element a conductivity contrast can be'
Henyey (L974) developed a finite-element defined that is considered in the calcula-
method whereby a vertical section across tion' of the surface heat flow.
c a region down to a certain depth is sub- Distribution of Radiogen&? Heat
divided into triangular elemen'ts, and Sources. The presence of bodies'in the
the top row describes the topography. subbottom enclosing long-life radioactive
For each top element, an average surface isotopes such as U238, U235, Th232, and
temperatbre can be defined. The method K40 affects the heat flow appearing at
calculates the influence on the unit heat the surface. Radiogenic heat production
flow at the base of the section for of rocks occurring in the surface region -> each element upward. has been measured by Rybach (1973) on
Refraction of IIeat FZm by LocaZZy samples collected by Wenk and' Wenk
VariabZe Thema2 Conductivity. The (1969). Thus, an estimate of the
thermal conductivity of consolidated influence of such a body can be made,
rocks is higher than that of soft in the case of a single layer by equation
sediments encountered in lake-bottom 2, and in the case of a more complex
infills. A body of material with less situation by the finite-element method,
conductivity embedded in material with where for each element a heat-generation
higher conductivity creates a deflection rate can be defined and is considered
of the vertical heat flow into the in the heat-flow calculation.
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 ~___ ~
Other Hea't Sources. Decomposition of difficult to estimate and can for the
organic material in lake sediments may time being be discussed only quali-
represent a massive disturbance to the tatively. The circulation is dependent
temperature field in the immediate on the permeability and on the pressure -0
surroundings or the heat-flow station, gradient. Fissures may complicate the
despite the small energy dissipated. picture even more. Very little is known
Arrhenius (1952) showed that organic about the velocity of such circulation
decomposition in oceanic sediments takes at greater depths, but convection currents
place only in the uppermost few centi- in a permeable medium can affect the
metres and decays rapidly below this. temperature field in a very short time,
Zcllig (1956) showed on cores frm four that is, 1,000 to 10,000 yr (Werner,
perialpine lakes that the content of 1975). This question must remain un-
organic material can be considerable answered for the time being.
in the top few centimetres but that IizfZuence oj' Rottom-!,htcr 2mmrizic"c
below 20 cm there is less than 1%organic Variiat?:oiz::. Time-dependent variations
material throughout. This suggests that, of temperatures at Earth's surface
analogous to the oceans, the decomposi- affect the temperature field in the
tion of organic material in lake sedi- subbottom. Short-term phenomena do not
ments takes place at the boundary between extend very far below the surface, but
L water and sediment, and the little yearly or longer-tern events, such as
material in deeper sediments remains un- the last glaciation, must be examined.
changed and therefore produces no heat. A sudden temperature increase To at time
Another possible heat source or heat ! ago influences the temperature field -3- sink may be hydrothermal circulation in the subbottom and can be calculated
of ground waters and of hydrothermal as follows (Carslaw and Jager, 1959,
solutions. The influence of this p. 63):
phenomenon on heat-flow measurements is
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 variation. Two types of sedimentatlon
have to be considered: (1) continuous,
or, taking the derivative with respect regular sedimentation or (2) sudden
to 2, deposition of a layer.
Von Herten and Uyeda (1963) applied
the mathematical solution by Carslaw and
Jaeger (1959. p. 59, 338) to marine
which represents the influence on the heat-flow measurements. Sedimentation
gradient. K is the thermal diffusity rates and their duration in lakes differ
in square centimetres per second. considerably from those in oceans. Figure
The influence of several such tempera- 2 gives on the left the disturbance to the
ture steps at their respective time normal gradient due to different sedisenta- Ti t can be calculated as a combination tion rates and their duration as they i of equation 3 (Cermak, 1977): have occurred during the Quaternary
(Holocene) in perialpine lakes. The
right-hand side of Figure 2 shows the
disturbance due to the sudden deposition
of a layer with different thickness and
the time since deposition of those
Equation 4 allows the calculation of layers. The cuwes are valid to a depth
the influence of any climatic model if of 5 to LO m. Thermal diffusivlty and
the history of the temperature varia- conductivity were chosen to be similar L 2 tions is known accurately. to those of oceanic sediments-0.002 cm /S Influence of Rwaion and Sedimentu- and 2.0 mcal/cm.s (OC), respectively.
tion. Erosion and sedimentation affect Compaction of Sediments. The compac- t* the temperature gradient near the surface tion of soft sediments under the
by the'ir time- and place-dependent influence of gravity forces interstitial
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 459.
TIME ELAPSED SINCE THE BEGINNING OF SEDIMENTATION (YEARS) TIME ELAFSED SINCE SUDDEN DEpOslTlON OF A THICK LAVER (YEARS)
Figure 2. Effect on surface heat flow due to lacustrine sedimentation during
the Quaternary, Left part: continuous Sedimentation rates; right part: sudden
deposition of a sediment layer.
Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 460
waters to the surface and thus transports Wisconsin. They showed tbat water
heat from lower layers, reducing the depths of about 8 m are sufficient for
temperature gradient. Von Herzen Uyeda (1963) estimated that a 10% reduc- depth, oscillations are less than 2 OC. tion of the gradient would necessitate They also showed experimcntally that a current of 50 cm per day, which would ,the influence of oscillations in the I be a very fast compaction. The lake sediment becomes practically negligible floor would have to sink rapidly within below 5 n~ if the oscillations are less a year, but this could not be confirmed than +0.5- OC. As will be shown, many by bathymetry. Thus, compaction can perialpine lakes arc deep enough to keep be excluded as a source of error. the bottom-water temperature variations Thema2 Conditions in Lake Subbottoms. small and are thus appropriate for the A major reason for heat-flow measurements application of oceanographic methods, in lakes is the relatively stable bottom- provided the probe is longer than.5 m. water temperatures when compared to the Measuring Methods daily and seasonal temperature variations on land. The former ranges from a few Earlier heat-flow measurements in tenths to about fl OC, depending some- Swiss Lakes (Von Herzen and others, what on the water depth; the lqtter is 1974) were made with two types of easily *lo OC (SchGepp, 1966). Thus, appd7 atus: a 2-m-long temperature for precise temperature-gradient probe, where no core is obtained (Von measurements, less penetration into Herzen and Anderson, 1972), and a 7.5-m- the subbottom is required. long piston corer to which core-barrel These theoretical considerations temperature sensors were attached have been confirmed by the long-term externally (Gerard and others, 1962). . investigation of Likens and Johnson Von Herzen and others (1974) showed that (1969) in very shallow lakes in absolute temperatures determined within Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 461 i 0 20.02 C and relative temperatures within the electrical cable was possible and led k0.002 0C are satisfactory for this to losses. The electrical cable would problem. have permited.in situ measurements by the Other experiments with a 2-m-long probe needle-probe technique (Von Herzen and described by Hhel (1970) showed the ad- Maxwell, 1959) of the thermal conductivity vantage of direct control of the tempera- at several places, but the use of ture measurements via an electric cable conductivity probes failed during pene- from the surface and of the possiblility tration of the corer into.the sediment, of measuring the thermal conductivity in and these attempts were abandoned. situ. Oving to the shortness of this The digital multimeter at the surface probe, its use was abandoned, and the was equipped with a constant current development of a 10-m-long probe was source of 10 PA to avoid any noticeable undertaken. Measuring methods are heating of the thermistor, which was explained in more detail than usual to chosen to hnvc a resistance of about take intc account the somewhat different 104 KQ at 0 OC. Careful construction boundary conditions compared to oceans. of the termistor assembly with a On the core barrel of a 10-m-long minimal temperature coefficient of -~"/,OC Kullenberg piston corer, 11 outrigger gave sufmient dissipation of the heat thermistors were attached at 1-m intervals. generated by the measuring current. The In all measurements in the year 1973, the resolution of 5!5 digits of the voltmeter thermistors were connected to the surface permitted the measurement of relative by a multiconductor cable where their temperatures with an accuracy of +0.002 resistance was measured with a digital 0C (for details, see Finckh, 1976). multimeter. The corer itself was lowered The disadvantages of two cables during and retrieved with a rotation-free steel coring and measuring procedures became cable running paralled to the electrical obvious, and a new concept was developed cable., Due to entanglements, damage to after 1973. A constant current source Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 462 was switched sequentially to all thermis- highly stable thermostatic bath. tors, and the voltage drop across them was Temperatures were measured with a measured with a 4% digit voltmeter. The platimun resistance thermometer to 0.001 0 readings were changed into BCD-code and C. The resistance R of the thermistors. store digitally in a CMOS memory. The versus temperature follows the function whole unit, with batteries for four months, T-l = A + B log (R) + C log3 (F) (5) was contained in a pressure-proof vessel fixed to the corer's weight head, When with higy accuracy (Steinhart and Hatt,' the corer was retrieved, a digital printer 1968). A, B, and C are constants; T is 0 was connected to produce a list of all K; and several calibration points per- measured data. The probe could ihediately mitted tabulation of resistance values 0 be reused because it need not be opened or versus tempera ?re in steps of 0.01 C recharged (for details, see Finckh and for each thermistor. The termistors others, 1979). With this device, addi- showed almost no drift between the two tional heat-flow measurements were made calibrations four years apart. in 1977 and 1978, r,educing the measure- Temperature Gradient Measurement ments to a simple coring operation with some additional waiting time on the Geographic Position. In 1973 geothermal station for the dissipation of frictional gradients were measured in Lake Zurich; Lake heat from the penetration. Zug, Lake of Lucerne (Viewaldststtersee) , L?go Ihggiore, Lago di Como, Lago d'Iseo, Thermistor Calibration and Lago di Garda. In 1977, a'dditional For all temperature-gradient measure- measurements were made in Lake Constance ments, one set of FENWAL unicurve (Bondensee), Greifensee, Lake Zurich, thermistors was used. The thermistors Bielersee, Murtensee, Lake Neuchatel, we -Le calibrated in 1973 and 1977 at the Lake Geneva, Lac d'hnecy, and Lac de Swiss Office of Standards in Berne in a Bourget; they were complemented in 1978 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 463 by measurements in Baldeggersee and' in level and in other places depth below Lago di Lugano. The general locations average lake level, depending on the are given in Figure 1; Table 1 shows source. The interval between depth the geographic positions of the heat-flow contours is 50 m, except for Baldeggersee stations with the elevation of the lake an'd Lake Lrignno, where it is 20 m. surface above sea level, the water depth No bathymetry was available for Lake at this location as determitled.. from Zurich and Greifensee. All names in a bathymetric map, and the approximate lists, tables, and figures are given in corer penetration estimatcd from mud the local language; however, in the text, traces on the outer side of the corer English expressions may be used. If con- barrel. The sequence of heat-flow fusion could arise, both names are given. stations starts with Lake Constance Thema2 Stabi ZiQ of Luke-Bottom !daters. and rotates counterclockwise around In most of the lakes considered, regular the Central Alps to Lago di Garda. long- term bot tom-water temperature measure- Figure 3 gives the detailcd positions ments were available, usually from the of the heat-flow stations in all con- deepest part bf a lake. Most measurements sidered lakes, the position of 'the were made by public institutions: Lake two-dimensional section uscd for the Constance (Bodensee): Federal Office for topographic correction, and the positions- the protection of environment, Berne, of the seismic-reflection profiles Switzerland ; Grei fensee : JGIWAG, (triangles) and seismic-refraction Dubendorf, Switzerland; Lake Zurich: profiles (arrows) used for determina- Office of Water Supply of the City of tion of the sediment infill (P. F-inckh, Zurich, Switzerland; Lake Zug: Cantonal K. Kelts, and A. Lambert, in prep.). Chemistry Office, Steinhausen, Switzerland; .The bathymetry is taken from various Lake Lucerne (Vierwaldststtersee) and 'sources. The depth contours in some Baldeggersee: EAWAG, Dibendorf, places designate elevations above sea Switzerland; Biclersee: Zoological Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 461 TABLE 1 : GEOGVP!iIC POSITIONS OF HEAT-FLOM STATIONS ~~ ~~ - Lat. Long. Lake level Water depth Approx. corer Hea t-f1 ow station nenetrat ion (N) (El (m) (m) . (m) ' Bodensee no. 1 47' 36' 9' 25' 396 . 248 9.0, no. 2 47O 37' 9' 23' 369 252 10.0, no. 3 ' 47' 38' go 20' 369 240 10.0, r no. 4 47O 37' 9' 24' 369 250 10.0 Grei fensee no. 1 47' 21' 40'' 8' 40' 00' 435 31' .10.0 no. 2 47' 21' 00" 8' 40' 50' 435 ' 32 9.5 Zurichsee 1973 47' 16' 8' 36' ' 406 , . 136 ' '10.5 1977 47' 16' 8' 36' 406 . , . 136 " 10.0 Baldeggersee 47' 11' 50" 8' 15"50' , 463 66 ' 9.5 Zugersee no. 1 470 06' 8' 30' 413' 197 . 10.0 no. 2 47' 06' 8' 30' 413 197 -, 10.0' Vierwa 1ds ta t tersee Weggi s 47O 01' 8' 26' 4 34 150 10.0 Beckenried no. 1 46' 59' 8' 29' 434 215 9.0 no. 2 46' 59' 8' 31' 434 21 5 10.0 Bielersee 47' 07' 7O 11' 429 74 1o;o Murtensee 46' 56' 7' 05' 429 45 10.0 Lac de Neuchdtel no. 1 46' 57' 6' 54' ' 429 138 10.0 no. 2 46' 54' 6' 50' 429 153 10.0 ~acLeman no. 1 46' 27' '. 6' 37' 372 310 : 10.0 no. 2 46' 27' 6' 34' 372 31 0 10.0 no. 3 460 26' 6' 28' 372 310 10.0 Lac d'Annecy no. 1 45" 52' 6' 10' 446 70 . 9.5 , no. 2 45' 48' ' 6' 13' 446 55 8.5 Lac de Bourgct no. 1 "49 45' 5' 52' 230 145 10.0 no. 2 45@ 46' 5' 52'. ' 230 145 10.0 Lago Maggiore no. 1 45' 58' , 8' 39' 193 372 9.5 no. 2 46' 00' 8'41' . 193 372 8.0 Lago di Lugano no; 1 46: 00' 30" 9: Ol'oiO'' 271 288 10.0 no. 2 - 46 01' 9 02' 20" 271 . . 288 10.0 -, no. 3 45' 56' 30" 8O.57' 10" 271 107 10.0 no. 4 45' 55' 50" 8' 53' 50" 271 74 ~ 10.0 no. 5 450 57' 30" 8' 53' 40" 271 95 10.0 Lago di Como Menaggio 46'-61' ' 9' 17' ' . ' 198 286 10.. 5 Argeg no no. 1 45O 55' ' 98 09' 198 , 410 10:5 no. 2 45O 55' 9. 09' ' ' 198 410 10.5 Lago d' Iseo no. 1 45O 43' 10' 04',-- 185 247 10.5 no. 2 45' 44' .h* 10' 04' . 185 247 10.5 Lago di Garda' no. ,,l . 45' 41.' ' 10' 43' 65 350 9 .o no. 2 45O 43' loo 44' - .65 350 9.0 .. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 465 Figure '3. Detailed maps of the surroundings of the heat-flow stations, Stars with Roman numerals give the number of the heat-flow stations. Dash-dot llne indicates position of the cross section for the topographic correction. Triangles I givc the position of the seismic-reflection profiles; arrows show . positions of seismic-reflection profiles. Jumbers give height of particular elevations; shaded areas mark villages or towns with their names. See text for comments on bathymetry. Figure 3 appears on the following frames. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 466 - BODENSEE i 594 I O12345km Figure 3. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 467 ZURICHSEE 893 X Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 468 , Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 469 BALDEGGERSEE N I 794 X 786 X I Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 ZUGERSEE Figure 3, (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 VIERWALDSKISTTERSEE i I I I Figure 3. (Contimed) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 BIELERSEE .'. '. 1382 x. 1902 X Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 473 LAC DE NEUCHATEL Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 474 MURTENSEE Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 475 LAC- LEMAN 1. 1. LAUSANNE N , I 0 1'2 3 4 5km 760 I n 1. Figure 3. (Cmztinued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 476 LAC D’ANNECY Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 477 LAC DE BOURGET' Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 478 . Figure 3. (Continu$) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 479 LAG0 DI LUGANO Y I Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 480 LAG0 DI COMO Fighre 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 481 LAG0 DISK) Figure 3. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 Figure 3, (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 483 -Institute of the University of Berne, Figure 4 and a 'check with Table 1 Berne, Switzerland; Murtensec: no show clearly that deeper lakes measurements available; Lake Neuchatcl: have more stable bottom-water tempera- Cantonal Laboratory, Neuchatcl, tures. The two shallowest lakes, / SwitzerGnd; Lake 'Geneva (Lac L6man) : Greifensee and Bielersee, show the Commission internationale pour la pro- strongest variations, which are quite tection des earn du Lac Lgman contre la similar in their timing and direction; pollution, Lausanne, Switzerland; Lac they appear, in fact, to be seasonal d'hnccy and Lac de Bourget: Station phenomena. d'Hydrobiologie, Thonon, France; Lake The information €or the last three Lugano: Department of Environment, lakes is scanty. The dots in the diagram Bellinzona, Switzerland; Lago Maggiore, for Lago di Como are two identical measure- Lago di Como, Lago d'Iseo, and Lago di ments from the basins of Argegno and Garda: data from various unknown Menaggio at a specific moment, thus shcwini sources, gathered by the Ttalian Insti- a good mixing of bottom waters. In Lago tute of Hydrology in Verbnnia, Italy. di Como and Lago d'Iseo, the tcmperature- More recently, the instruments used were gradient measurements would reveal by thermistors, but some measurements were their linearity whether the bottom-water made with reveral thermometers. Both temperatures are stable; by analogy with methods provided an accuracy of at least the other southern'lakes, a relatively 20.1 OC, according to the source of data. high accuracy could be expected because The data are plotted in Figure 4 of the large masses of water and steep * including measurements taken shores that protect them from long- during a 5-yr period previous to the lasting climatic perturbation.. Note moment when heat flow was measured; that in all lakes the averagelbottom- 0 this is indicatcd by a vertical line water temperature is above 4.0 C, the ending on both sides by triangles. temperature for the highest density of Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 Figure 4. Temperature variation of'bottom water in the deepest part of perialpine lakes. Dots indicate recorded data. Horizontal scale is given 4 in years. Note changes for heat-flow measurements in 1973 and 1977-1978. Vertical lines ending in triangles indicate time of heat-flow measurement(s). Water depths are given in metres. Lake Constance, 248; Lake lurich, 136; Grcifensec, 31; Baldeggersee, 66; Lake Zug, 197; Lake Lucerne: Weggis, 150, Reckenried, 215; Bielersee, 74; Lake Neuchatel, 138; Lake Geneva, 310; Lac d'Annecy, 70; Lac de Bourget, 145; La20 Maggiore, 372; Lago di Lugano: Gandria, 288, Melide; 107, Capolago, 74, Figino, 95; Lago di Como: Menaggio, 286, Argegno, 4lO;'Lago d'Iseo, 247; Lago di Garda, 350. Figure 4 appears on the following frames. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 485 -- .. Figure 4. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 I I I I I I v 5D ------*---+-- 4.5 0. __...... 40 .. -- . I I I I I I A I I I I I I v 50 a*.. -...... - r...... --.... - ...... ------45 .. **.- - - 40 - I I I I I I A h 0 I I I I I I r - 55 0.. 4 .Eoeaa- ...... a. - 0. - ...... 0.- E50- - 3 k 45 ...... - a I I I I I I P I- z5 ix 65 6.0 5.5 50 4.5 4.0 1 I I I I rl 65 I cn -- a - 0. -1 . 0...... 0.. ow 0- -- 5.5 . 0. - . . . 0. ,-.- . 5D 0- . .. I I I' I A1 'Figure 4. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 I I I -_____~ 55- ...... - 0. ....@+...... I 50 ti--- - I 60 - ...... I...... --*...- -3* .- 0...... I ----. ----. -.*e-+o-+&+...& ...... - *&*+-_- ...... _-0. 55 . 0. 0.. 0. 0. . 0.. . 5.0 ...... -. -* .. -- ...... - ... -- .... I r. I I I I LAC DE BOURGET CI I I I I VI ...... I --. .- -%& 155 -.- -0- . . I. 0...... - 0. 0. I I I I I I I, I 1972 73 74 75 76 77 78 79 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 488 LAGO DI LUGAN0 FlGlNO I I I . I I I v -- - 0. 60 -- - . .*n -- *...... 5.5 0. 0.- . I 0. .I - -- . 5.0 - ---t- Al I I I I I A , 78 3 0- 1972 73 74 75 76 77 Figure 4. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 489 ~ water. This is probably because the electrical cable was paid out at the the climate north of the Alps is warm same speed. After tripping of the corer, enough to keep these temperatures some slack was given to the steel cable higher. Table 2 gives the average to avoid any pull on the corer and any air and bottomwater temperatures. change of the position of the thermistors The air temperatures were compiled in the subbottom. In early measurements, by Schcepp (1966) and are averages of 'the decay of frictional heat was checked . the named meteorological stations over on the values displayed on the digital about 50 yr. For the lakes outside multimeter; in the more recent measure- Switzerland the closest Swiss station ments, the measuring cycle started auto- was chosen.,. The elevation above sea matically at the penetration of the corer. level of each station is given. In some This decay could then be checked later on cases, such as Lake Geneva (Lac L6mn) the print-out, and equilibrium was and Lake Garda, the lake level differs attained after 2 or 3 min. In 1973, the considerably from this value. For readings were reco-rded for all these, the average air temperature was thendstors and equilibrium was attained corrected by -0.5 0C for 100 m upward. after several minutes. In 1977-1978 the Average water temperatures were calcu- probe was simply retrieved after 15 to lated as an average of the measurements 20 min. In the meantime, the position of in the given interval. the vessel was determined. In 1973, sex- Temperawe-gradien t Measurements . tant readings on particular shore points A coring platform was towed into the such as mountain peaks or churches we're desired position and anchored to maintain used. Later, during 1977-1978, the its position. The assembled corer was accompanying vessel's radar screen was lowered under echo-sounder control to photographed where the reflections of check on its position relative to the the shore lines permitted the determina- lake bottom. In the earlier measurements, tion of position. The accuracy was Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 490 TABLE 2: AVERAGE AIR AND BOTTOY-WATER TEMPERATURES IN THE CONSIDERED REGIONS Lake Meteorological Eleyation Avg. air ' Avg. bottomwater station tempgrature tempergture (m) ( C) ( C) Bodensee Rohrschach 455 8.8 4.4 Ziirichsee Zurich BG 41 0 8.6 4.2 Grei fensee Zurich BG 410 8.6 4.7 Baldeggersee Muri 480 8.4 4.3 Zugersee Wal Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 491 I about 20 m in small,lakes ahd ab,out the measurements in 1977-1978, all 50 m in large lakes such as Lake available bottomwater temperature data Constance or Lake Geneva. The re- were analyzed for their influenceb,on the covered corer was disassembled and the subbottom temperature field in all lakes core kept in capped PVC tubes for later less than 100 m deep, and for the two conductivity measurements and other measure'qnts in Lake Zurich. No s, .. sedimentological as well as palyriological temperature data were available from analyses. Murtensee; thcre'kore; further computation The resistance readings of the of the heat flow was omitted. Equation thermistors were then changed into 4 was used to calculate this influence temperature value with the help of the for different depths +?. The temperature depth values are give-n for all stations intervals ti were taken from the basic in Figure 5. Stngle presentation data presented in Figure 4. for a station was chosen when In similarity to ocean sediments, K was 2 fluctuations of the bottom-water tempera- assumed to be 0.002 cm 1s. The tempera- tures made corrections necessary (excep- ture versus depth curves in Figure 5 c tion: Lake Lugano stations 4 and 5). were corrected by the rea?klting Com.ections for Bottom-Iibtcr Tertpera- variation, which is ind5cated by X's. This ture FZuctuations. In- deeper lakes, correction improves the linearity of the the gradients prove to-be linear in gradients considerably. The thick straight depths exceeding 4 to 5 m, thus making lines indicate which corrected or un- a correction superyluous. However, in corrected values have been used for the shallower lakes such corrections are determination of the gradients. !!any of necessary because the amplitudes of the the corrections seem to be too large f>uctuations are too large and affect in the upper few metres. Tiiis may be the temperature field Fore deeply. For due to a lower thermal diffusity than the Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 492 Figure 5. Temperature versus depth for heat-flow stations in perialpine lakes. Roman numerals a* station numbers. Individual temperature values for each station: dots = no. 1, diamonds = no. 2, triangles = no. 3, squares = no. 4, stars = no. 5. Crosses in graphs representing a single station are values corrected for bottom-water temperature fluctuations. Figure 5 appears on the following frames. ’ Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 493 I GEEIFENSEE I Figure 5. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 494 Figure 5. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 Figure 5. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 496 I 10 1 IAC DE BOLFIGET P lo- Figure 5, (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 497 0 E u X a’ I nW 10 1 62 64 66 68 ‘IT TI-- 1-11 \ \ I I l0L I Figure 5. (Continued) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 498 ~ one used for the calculations the recovery of the corer. To avoid 2 (0.002 cm s). In the lower parts, faulty measurements, each sample was however, the corrections fit quite well. collected regularly from the halved 1-m A check on the bottom-water temperature section of a core; it was then sealed in a data from the deep lakes show that the polyethylene bag and kneaded for effect of their variation is negligible homogenization of the material and to below 5- to 6 m, and.no such analysis close cavities. After some resting time was necessary for the measurements of for thermal stability, the conductivity 1973, with the exception of Lake was measured. Comparison of this procedure Zurich. Figure 5 makes it, obvious with more frequent measurement at intervals that the reliability of heat-flow of 20 cm showed that the single values measurements with a short probe is for a 1-m section correspond well to questionable; they .are very dependent the average value from the detailed * \ on the season (Hinel, 1970). The derived measurement of the same 1-m section temperature gradients are given for. (Finckh, 1976). The measurements lasted each station in Table 5 in the first for usually 150 s, and several points column. were picked to check on the linearity f.!eaomernant of Yhermai! Conductivity. of the temperature increase versus In Thermal conductivities were measured (t). No measurement had to be rejected. in the laboratory with the needle-probe Conductivity values' for each 1-m section method (Von Ilerzen and Maxwell, 1959) are given in Table 3, together with the on samples from the cores recovered in percentage of water in the wet sample plastic liners at the heat-flow station. determined by desiccation. At the bottom Some problems in the earlier work by of each column is the mean conductivity. Von Herzen and others (1974) were due to value for the station calculated as the the exsolution of gas from the inter- reciprocal of the mean thermal stitial water during decompression at resistivity of the whole core. This value Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 499 TABLE 3: THEWAL CONDUCTIVITY VALUES AND WATER CONTENT Bodensee Creifensee Zurichsee Zugersee Vienia 1ds tattersee Baldeggersee no. 3 no. 4 no. 1 1973 no. 1 no. 2 Weggis Bec kenri ed no. 1 no. 2 KXKZKZKXKXKXKIKIKXYX 2.46 45 3.25 36 2.07 59 2.37 51 3.51 28 2.40 47 2.12 61 2.93 37 2.90 39 2.16 56 2.39 48 2.61 38 2.30 55 2.40. 49 2.70 42 2.39 50 2.20 56 3.01 35 2.75 38 2.04 52 2.44 45 2.91 38 1.99 57 2.35 49 2.58 45 2.65 46 2.26 56 3.08 34 2.75 41 2.14 61 3.01 43 3.15 36 2.05 56 2.32 47 2.50 47 2.57 49 2.30 57 2.67 42 2.67 41 2.05 59 2.41 55 2.54 39 2.30 46 2.35 51 2.46 42 2.98 36 2.44 48 2.80 36 2.71 40 2.12 55 2.54 44 2.72 36 2.30 43 2.53 44 2.53 45 .2.56 43 2.65 43 3.35 29 2.98 36 2.19 55 2.45 42 2.73 38 2.92 36 2.75 40 3.74 23 3.65 25 2.50 53 2.35 44 2.43 50 2.09 49 2.52 2.72 2.23 2.39 2.57 2.64 2.80 2.90 2.92 2.15 ' Bielersee Lac de Neuchdtel Lac LCman Lac d'Annecy Lac dc Bourqet Lago Kaggiore no. 1 no. 2 no. 1 no. 3 no. 1 no. 2 no. 1 KXKXKXKIKZKIKZKIKX 2.22 53 2.37 55 2.36 54 2.80 51 2.50 50 2.51 53 2.U 47 2.04 52 2.34 55 2.22 52 2.37 51 2.42 52 2.19 47 2.47 55 2.6C a7 2.00 44 2.49 46 2.27 47 2.30 50 2.42 .49 3.23 37 2.51 55 2.83 41 ?.E7 46 2.17 46 2.65 45 2.30 46 2.49 50 2.35 50 3.63 30 2.68 49 . 2.96 39 2.83 42 2.24 46 2.32 50 2.45 47 2.65 43 2.35 46 4.15 27 3.22 43 3.20 35 2.35 31 2.30 44 2.36 50 2.22 50 2.72 41 ?.:- 01, 4.43 23 3.10 36 3.45 32 2.57 45 2.08 44 2.60 45 2.62 40 -2.63 40 2.76 25 3.40 30 2.60 46 2.25 40 2.87 39 2.68 41 2.86 36 4.50 24 3.42 29 2.40 41 3.25 34 2.27 2.51 2.58 2.48 2.86 2.91 2.66 2.21 2.52 6 Lago di Lugano Lago di Con0 Lago d'fseo Lago di Carda Henaggio Argegno no. 1 no. 3 no. 4 , no. 1 no. 2 no. 1 no. 2 KXKXKIK%KXKXKXK%KX 2.26 50 2.00 69 1.96 76 2.46 53 3.10 42 2.89 42 2.40 48 2.93 49 2.70 49 2.15 63 2.02 69 2.50 50 2.69 47 3.40 39 2.90 41 2.70 47 2.22 59 1.82 63 1.85 69 2.75 45 3.27 38 3.02 37 2.19 50 1.80 63 1.91 64 2.99 39 3.05 41 2.82 43 2.30 51 2.24 65 . 2.13 60 2.61 47 3.02 41 See 2.93 39 3.10 38 2.82 42 2.19 49 1.97 59 1.97 65 2.70 42 2.50 48 text 3.60 37 2.70 4a 2.93 39 2.30 46 2.03 60 2.08 62 2.75 48 2.57 50 2.11 48 2.35 55 2.01 65 2.80 47 2.53 50 2.50 47 1.78 63 2.17 41 2.28 2.03 1.96 2.72 2.75 2.68 3.09 2."1 2.87 -Note: K = ~al/crn~s~~C~10-~. Percentages are by wet wcight.Last value in K column is average conductivity Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 500 was used for the heat-flow circulation conductivity values in Table 3 are and is listed in Table 5. considerably higher than values In Lac de Bourget, the sample of the published for deep-sea sediments.' ' second l-m section was lost; in Lago di This is probably due to the more Como, Argegno no. 2, the measurements detrital character of the sedimentation were made at 20-cm intervals; thus, they and the coarser components, often very a do not fit into this table, and no coarse sandy fractions. This is water-content analysis was made. particularly the case for Lake Geneva Comparisou with earlier measurements (Lac L6man) no. 1, which is situated at by Von Herzen and others (1974) shows the foot of the Rhone delta. The inflow- that the more recent measurements are ing river is heavily'loaded with sedi- about 152 to 30% higher than the older ments, particularly in the spring. values. Instrumental. error is excluded The core consists mostly of sand3 and is because the same probe was used for both very dry in its lower part. In fact, series of measurements, and the probe these confuctivity values reach values was calibrated anew each time. close to those of solid rocks (Clark, Some in situ conductivity measurements 1966). Very fine grained sediments with the probe described by Hznel and such as those from Greifensee, others (1970) are in concordance with the Baldeggersee, and Lago di Lugano --- new series, and a comparative calibration nos. 3 and 4, on tnc other hand, show low of the in situ probe with the laboratory values and have higher waterrontents. probe imbedded in paraffin showed Correction for lYme-Depen&nt Bom~hy similar values for K for this material. Conditions. The bottoms of most cores Thus, the earlier measurements must were analyzed for their palynological have been partially affected by degas- content. Knowledge of the flora as- s-ing because the material was not semblage pennits an estimiite of the age treated then. Altogether, the range of these lowest sediments and Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 501 therefore also adestimate of the sedi- yr for the slump and thus a sedimenta- mentation rates. Table 4 gives the tion rate of at least 4 m/yr for the basal age ranges for some heat-flow upper sediments. The glacier in this stations where the age was determined. region retreated about 10,000 yr ago; In order to minimize corrections, the thus, with the solution by Von Herzen column with the average sedimentation and Uyeda (1963) the correction is +16.0%. rate was calculated by dividing the core Added to this is the effect of the sudden length by the higher age limit. This deposition of a thick layer, which was average sedimentation rate was assumed calculated with the solution given by to have lasted since the retreat of the Von Herzen and Uyeda (1963) to be 6.0%, glaciers from the perialpine region about giving a total correction of +22.0%. for l'4,OOO yr ago, and the solution given this basin. by Von Herzen and Uyeda (1963) was used In the Weggis basin, the sedimentation to calculate the temperature-gradient rate was estimated by analogy to Lake Zug correction given in the following column to be on the order of 2 m/yr, a value of Table 4. It is valid for a subbottom %mewhat higher than in Lake Zug due to depth range of 5 to 8 m. The last vanre chronology. With the exception of column of Table 4 gives the source of some cores from Lake Lugano, all base the palynological age interpretation. samples from southern alpine lakes con- A particular case is Lake Lucerne tained grapevine pollen. This plant (Viemaldstattersee). Analysis by was brought into this region by the K. Kelts on the two cores from fie basin Romans some 2,000 yr ago, thus giving of Beckenried showed in,--the upper 2.8 m a maximum age for these sediments, a a rhythmic sedimentation, with turbidite minimal sedimentation rate of 4 mm/yr, layers. Underlying this is a 5-m-thick and a correction of +la%. slump deposition. An estimate on vane The rate of retreat of the alpine chronology gives a maximum age of 400 glaciers was fastest sdme 10,000 yr ago'. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 502 TABLE 4: BASAL AGE RANGES OF SEOIHENT CORES FROM SOME SELECTED HEAT-FLOW STATIONS 0 Core Basal age range Average Temperature Reference for age Heat-flow station no. length sedimentation gradient detemination rate correction Bodensee (4) 8.20 2,000- 6,000 . 1.4 6.5 8. Anman.(personal cawnun.) Greifensee (1) 8.00 13.000-15.000 0.53 . 2.5 B. Arrman.(personal cawnun.) Zurichsee (1973) 6.20 13.500 0.5 2.5 Thompson and kl ts, (1974) Baldeggersee 8.30 5.000- 7.000 1.1 4.5 6. hn.(personal carmun.) Zugersee (2) 7.20 5.500- 7.000 1 .o 4.0 Thmpson and Kelts.(1974) Vienal dstattersee Beckenried (1) 7.00 See text 4.0 16 .Ot6 .O K. Kelts.(personal comoun. .see text) Weggis 8.00 See text 2.0 rl 9.0 K. Kelts.(personal carmun. .see text) Bielersee 6.32 2.000- 5.000 1.3 6.0 B. ban.(personal cannun.) Yurtensee 6.17 2,000- 5.000 1.2 5.0 B. ban.(personal cmn.) Lac de Neuchatel (1) 7.90 5.000- 7.000 1 .l 4.5 8. Anman.(personal comrmn.) (2) 8.90 7.000- 9,000 1 .o 4.0 B. APnan.(personal cawnun.) Lac Lhan (1) 8.95 500- 2,000 4.0 18.0 9. J. Cai 1lard. (personal cmn.) (3) 7.99 12,000-14.000 0.6 3.0 H.J. Gdilldrd.(persOndl CaIllIWl.) Lac d'hnecy (1) 5.96 4,000 1 .5 7.5 Chr. Reynaud.(personal cmn.) (2) 6.35 7.000-10.000 0.6 3.0 Chr. Reynaud.(personal comoun.) LdC de Bourget (1) 7.30 4,000- 5,000 1 .5 7.5 Chr. Reynaud.(personal camwn.) Lago tiaggiore (1) 8.13 c 2.000~.~~~ 4.0 18.0 B. A?man.(personal carmun.) Lago di Lugano (1) 9.28 c 2.000 4.0 18.0 B. han.(personal cmn.) (4) 9.00 2,000- 5.000 1.8 8.5 B. Aman.(personal cannun.) Lago di Cow Argegno (1) 8.69 c 2.000 4.0 18.0 B. han.(personal cawnun.) Kenaggio 9.12 c 2.000 4.0 18.0 B. Annan.(personal comrmn.) Lag0 d' Iseo (1) 6.31 c 2,000 4.0 18.0 B. Aman.(persona~ cmn.) Lag0 di Garda (1) 5.50 c 2.000 4.0 18.0 B. ~man.(persona~cmun.) Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 503 At that time, the perialpine lakes were most. No evidence was found for the need no longer under the influence of a cold of a three-dimensional correction. climate; their waters became waxpet, The finite-element method was used to from about 0 OC to today's average estimate the effect of topography and temperature given in Table 2. No of the refraction of heat flow by the sedi- history of the evolution of bottom-water ment infill into the lake basins. On a temperatures is known, although a long cross profile in the neighborhood of a period of 4 OC is likely, Thus, it was heat-flow station, 70 elevations and their assuked that this increase happened in corresponding temperatures described the one single step 10,000 yr ago, and the surface conditions of the finite-element influence of this event was calculated network. The geometry of the refracting with equation 3 for all lakes. This ice- body was taken from seismic-reflection age correction is given in the third and seismic-refraction profiles (Finckh column of Table 5; it is linear within and others, in prep.). The conductivity +2%- in the uppermost 10 m of the contrast wa$ chosen as 0.33 for t,he sediments (Von Herzen and others, 1974). 0.5 * uppermost sediment layer and for the Most of the lake basins considered remaining lake-sediment infill. The bed- here have a pronounced elongated shape. rock conductivity was assumed to be 7 mcal/ The longitudinal extensions of the basins cm * s - OC, which is an average value in the vicinity of the stations are of water-saturated sedimentary and almost flat and of constant bottom-water granite rocks (Clark, 1966). The base of temperatures. Thus, a two-dimensional the network was chosen at a depth of 4 km cross section of the basins parallel below sea level. Figure 6 shows a finite-. to their shortest extension is per- element cross section for the basin of mitted for the topographic reduction Be'ckenried in the Lake of Lucerne. The because the topography in this direc- horizontal distance is' given on the tion affects the temperature field the upper graph in kilometres. The graph Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 504 TABLE 5: SLII#ARY OF HEAT-FLOY STATIONS DATA ~~ ~ Temperature Ice-age Sedinentation Topographic Themal con- Heat flm Heat-flow station gradient correction correction correction ductivity ~ Bodensee no. 1 0.076 0.0097 18.0 0.8 -2.1 2.72 2.77 115.9 no. 2 0.096 0.0097 2.5 0.8 -2.1 2.52 2.75 115.0 no. 3 0.102 0.0097 2.5 0.8 -2.1 2.52 2.91 121.6 no. 4 0.084 0.0097 6.5 0.8 -2.1 2.72 2.79 116.8 Creifensee no. 1 0.112 0.0104 2.5 -6.9 -1.0 2.23 2.60 108.9 no. 2 0.113 0.0104 2.5 -6.9 -1.0 2.23 2.63 109.8 Lurichsee 1973 0.107 0.0093 2.5 ' -0.9 0.0 2.39 2.82 118.0 1977 0.114 0.0093 2.5 -0.9 0.0 2.39 2.99 125.1 Baldeggersee 0.109 0.0095 4.5 -13.5 -1.5 2.15 2.29 95.7 Zugersee no. 1 0.093 0.0099 4.0 -3.3 0.0 2.57 2.74 114.5 no. 2 0.096 0.0099 4.0 -3.3 0.0 2.64 2.95 123.3 Vienaldstdttersee ,W91s 0.097 0.0111 9.0 5.0 0.0 2.80 2.92 122.0 Beckcnried no. 1 0.071 0.0111 22.0 3.2 0.2 2.80 2.86 119.5 no. 2 0.061 0.0111, 22.0 3.2 0.2 2.92 2.61 109.1 Bielersee 0.048 0.0126 6.0 1.0 -2.5 2.27 1.42 59.4 Lac de Neuchatel no. 1 0.056 0.0121 4.5 2.5 -0.1 2.51 1 .a3 76.3 no. 2 0.056 0.0121 4.0 2.5 -0.1 2.58 1 .87 78.3 Lac Lhan no. 1 0.038 0.0115 18.0 0.6 0.0 3.48 2.04 85.5 no. 2 0.050 0.0115 6.5 0.6 0.0 2.86 1.88 78.8 no. 3 0.063 0.0115 3.0 0.6 0.0 2.86 2.21 92.3 Lac d'Annecy no. 1 8.074 0.0121 7.5 -1.6 -0.4 2.91 2.65 110.8 no. 2 0.048 0.0121 3.0 -1.6 -0.4 2.66 1.62 67.7 Lac de Bourget no. 1 0.057 0.0124 7.5 -1.1 -0.1 2.21 1.63 68.1 no. 2 I 0.054 0.0124 7.5 -1.1 -0.1 2.21 1.56 65.2 Lago mggiore no. 1 0.087 0.0130 18.0 1.4 0.4 2.52 2.97 124.1 no. 2 0.090 0.0130 18.0 3.7 -1.0 2.52 3.13 130.8 Lago di Lugano no. 1+2 0.069 0.0121 18.0 -12.8 0.3 2.28 2.18 91.4 no. 3 0.099 0.0121 8.5 -8.4 0.2 2.03 2.24 93.7 no. 4 0.113 0.0121 8.5 -25.3 4.2 1.96 2.66. 111.2 no. 5 0.092 0.0121 8.5 -25.3 4.2 1.96 2.21 92.5 Lago di Con0 Menaggio 0.061 0.0136 18.0 3.8 - 0.7 2.72 2.47 103.2 Argegno. no. 1 0.058 0.0136 18.0 -32.2 -13.0 2.75 1.69 70.6 no. 2 0.064 0.0136 18.0 -32.2 -13.0 7.68 1.79 74.8 Lago d' lseo no. 1 0.057 0.0126 18.0,. 3.1 ,0.2. 3.09 2.61 119.5 no. 2 0.058 0.0126 18.0 3.1, 0.2 2.91 2.50 94.1 Lago di Garda no. 1 0.064 0.0166 18.0 -0.4 3.7 2.87 2.80 117.0 no. 2 0.069 0.0166 18.0 -0.4 3.7 2.87 2.88 120.4 2 fK Heat-flow units are pcal/cn .sec. rradicnts corrected for bottm-v3ter ternerature variations. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 505 Figure 6. Top: Calculated normalized surface heat flow along cross section. Stars and connectkng line represent vertical heat flow; crosses designate horizontal heat flow (see text). Bottom: Two-dimensional cross section with finite element subdivision of Like of Lucerne, basin of .C '... Beckenried. Shaded area represents sediment infill. Vertical exaggcrption is 2.5. Figure 6 appears on the following frame. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 506 LAKE OF LUCERNE. BASIN OF BECKENRIED :t CSl -J u, ..... 8 a:~ w r ~f! N- -. .. j ' --.-.,... I•••••••••••••• IOt~·· ,rt~· 00 e.25 7. 50 8. 75 I . ,z:stl·· " . 75 ,5,,00 . ,6.25 ;.t• .. s N II 1/ 1/ 1\1/1\ 1\ ~,I~~ II 1/ 111\1/1\1/ II 1/1\1/ 11 ~ • "'·-YZ/J'-"If\Lf.YIIIW 11 1\ 1/ \11 1 II 1'l/mrmmtitmm!lI\1I II 1/ II 1\ a 8 II U~U~II V~II I/~ I/~I/ UIIU~ ~ ~ ~ . ~ 1/ 1/1\1//\1/1\1/1\ ~ 1\ 1\ f!z i\ ~I/~I/ I '1/1\ 1\ ~, ~- I-- 1\ z 1\ IVI !III 11 1\ 1\1/" . \ !\II !/I\ L-- 1\ 1/1\ 1/ 1\li I, 1/1\ 1\1/1\ 8~ 11 1/ \ I'i 1/ 1/11 ' II 1/ Ii ~~ "I '> 1/ 1/11 I " I/I\!/I\ 1\ 1\ \ 111\ W 1\ 1\ I\ 8.J 111/111/'\;/ \ . \ I 11 1/ \I/~ ," . 1/1\11111/111/1\ 1\ ~W v 11 1 1 I~ 1\1/ \11 \IJIIIJIIrIIIrII\ ' Iii I 1/1\1/111/111/11 II \I' 1111111/11 1/1\111\11 1 1J1II111111I1I\lIlli~/III1I\I/I\I/I\I\\lI/l\\I/II\I/I\IJII\I/I\1 II "I 1/1/11 1/ I! II Ii Ii II 8 ~ . 11111\1 1\ II ,I\IIi\ 1\11 \\ .\ I \\ 1\1/1\111\11 /1\II,II\\I:/iIl\\II::m11\111\111\111\111\"11\1/1\111 \ a, Figure 6. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 507 also shows the normalized heat flow. The 1 km. A smaller scale, however, could darkened area corresponds to the elements not consider the very variable topography, that were provided with a conductivity and a finer network is not possible due contrast, which represented the sediment to the already considerable need for infill. Vertical exaggeration is 2.5. core memory space by the computer program, Connected stars in the upper graph Clark and Jager (1969) suggested a indicate the vertical heat flow QY; the correction for heat-flow measurements single line indicates the smoothed in the alpine region caused by the vertical heat flow; and the plus signs influcnce of uplift and erosion on the stand for the horizontal heat flow QX, temperature field. This is not meaningful where positive values mcan a direction in lakes where erosion stopped some time from left to right. The values of QY ago and the reverse process of sedimenta- and QX are also given for the particular tion has occurred since. There are I station in Table 5. Uusually the QX indications that-the sediment infill is con- value's are around zero, which means there siderably older than the WGrm glaciation { is only a vertical component at this (Finckh and Kelts, 1976); this correction station. The QY values are usually did not seem meaningful for the measure- on the order of a few percent. The ments presented here and was omitted. exceptions are the high values,of The final heat-flow measurements stations 4 and 5 in Lake Lugano and are given in the last two columns of n stations 1 and 2 in the Argegno basin Table 5; in HFU (pcal/cmL s) and 2 of Lago di Como. All of these stations in mW/m . are characterized by a verf steep and DISCUSSION changing topography and very narrow lake basins. It is likely that in the chosen The heat-flow values from Table 5 scale of 1:50,000, the element size can be compared with measurements from is too large for a basin width of. about lakes by other authors 'or with values Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 508 from land measurements. Hkel (1971) measurements are in agreement with 1 published .several measurements from Lake earlier measurements by Von Herzen and Constance (Bodensee) made with a 2-m-long others (1974). The same can be said for probe, but he gave no detailed results the measurements in Lake Zug'and Lake or corrections. Note the interesting Lucerne in the basin of Beckenried constancy of heat-flow values in this if the blanketing effect of the recent lake, despite the lessening' of the 5-m slump deposit is taken into account in gradient with the approach of the the earlier value. The value from the stations to the Rhine delta. This is Weggis basin is new and fits well partly due to variations in the conduc- into the regional heat-flow distribution. tivity and partly to the application of The values from lakes farther west are 4 different corrections for sedimentation, new, and no comparison with other lake based on age estimates. Thik seems to measurements is possible. The new values confirm the analytical approach by show a generally lower heat flow than the Von Herzm and Uyeda (1963), because previously discussed values, which is . b lateral variations of terrestrial heat possibly due to heat transport by meteoric 9 IL flow are not likely to be very large water flowing from the shrrounding,eleva- in this tectonically quiet region. tions downward under the lake basement. The values from'the Greifensee are These lakes, with the exception of Eake new, but they are similar to .those of Geneva, are bordered by either Mesozoic nearby Lake Zurich. The two values limestones from the Jura mountain chain from Lake Zurich are from -the same (Lake Biel, Lake Neuchatel, Lac de Bourget) locatiod, the second taken four.years or by the Helvetic parautochthonous series after the first. It is not clear why (Lac d'hnecy), which permit easy water the temperature field in the sediments circulation. The gradient measurements changed, as no extraordinary climate in Lake Geneva,confirm the blanketing event was recorded. However, both effect by Rhone sediments; values increase Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 509 away from the delta. However, the bottom-water temperature at the land-lake sedimentation correct'ion does not compen- boundaw. This step is smoothed at the sate entirely for the effect, maybe be- chosen scale within one or two finite cause of the conservative estimates of. elements in the immediate vicinity of the the sedimentation rates. Values on the location of gradient measurement. ,This southern side of the Alps can agai*n be suggests a reduction of these large cor- compared to measurements by Hanel (1974). rectcions. It would br' g the heat-flow 4? 4? No details dre available, but somg as- values of the station &m the Argegno sumptions for corrections in Hinel's basin in Lake Como closer to the one of the work are not very realistic-for example, station at Menaggio in the same lake. a sedimentation rate of only 0.5 mdyr. The measurements, surrounding the Since the boundary conditions afe better central Alps, are in strong contrast to defined with the new measurements, they the lower heat-flow measurements, be- should be more reliable. Important also tween 1.53 and 1.70 HFU, made in drill is the ffct that bottom-water temperature holes or tunnels by Clark and Niblett variations affect the upper few metres, (1956) and Hanel and Zoth (1973) in the and a short temperature probe might show Gotthard region. Other drill-hole distorted results. measurements in the northern Molasse The values from stations 4 and 5 in Basin indicate a gradient of 1 5uke Lugano and from stations 1 and 2 about 30 OC/km (L. Ryback, 1976, per2onal in the Argegno basin of Lake Como must commun.), which is not consistent with be considered less reliable because of the p'resent 'hest-flow measurements. the large topographic corrections. CONCLUSIONS Experiments with various scales5 however, indicate that the corrections for these The discrepancy between heat-flow stations are excc'ssive. This might be a measurements from lakes north and south result of the sharp step of surface to of the alpine chain compared to those Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 h from the central Alps could be explained I so the original measurements were not by the thrusting of a cold crustal wedge altered too much. However, some as yet under the Aare and Gotthard massifs in unknown phenomena might affect the late Miocene and early Pliocene time (Hsi, temperature field in' 1ake.sediment infill- 1979). This would lower the temperature ings to produce relatively high tempera- gradient in the central Alps considerably. ture gradients. To check this, a bore- On the other hand, the "normal" hole was drilled through the sediment gradients from boreholes in the Molasse infill down to the basement in the Basin may.be affected by ground-water locationofthe heat-flow station in + transfer of heat. This ground-water Lake Zurich. Frequent measurements of factor could be less serious in lake temperatures, conductivity, water content, regions because its flow might be and sonic velocities, as well as leaving greatly reduced by higher compaction and a thermistor chain in the hole after lesser permeability in sedimentary rocks completion, permit calibration of these under lakes. A third possibility is results. that lake measurements are not repre- ACKNOWLEDGMENTS sentative heat-flow values and that the a high values are caused by unknown factors, I thank all my friends and collergues such as short-term climatic events. who helped me during the extended field Before the heat-flow measurements work and in the workshop. Thanks are presented here can be used for geo- , due to K. Hsi, R. P. Von Herzen, St. dynamic intcrprctntions, thc tcsults Muller, and L. Rybach for thcir,continu- should be calibrated 'in a location where ous supGort and fruitful discussions. 0 more information about the temperature R. F. Roy and J. H. Sass &viewed an field in the region is available. The early manuscript,. This work was: values were corrected for all known realized under project numbers 2.765.073 factor(s,in a conservative way-that is, and 2.345.70 of the Swiss National Science Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 511 Foundation and with grants by the Swiss geochronologic and heat flow data: Geophysical Commission and by the American Journal of Science, v. 267, Zentenarfonds of the Federal Institute p. 1143-1160. of Technology in Zurich. Clark, S. P., and Niblett, E.R.C., 1956, Terrestrial heat flow in the Swiss REFERENCES CITED Alps: Royal Astronomical Society Arrhenius, G., 1952; Sediment cores from Monthly Notices, Geophysics Supplement the east Pacific, in Petterson, Hans, 7, p. 176-195. ed., Reports of the Swedish Deep-sea Diment, W. H., and Werre, R. H., 1965, Expedition 1947-1948, Volume 5: Gote- Heat flux through the bottom of burg, Sweden, 227 p. metomictic lakes: American Geo- Carslaw, H. S., and Jaeger,~J.C., 1959, physical Union Transactions, v. 47, p. Conduction of hcat in solids (2nd ed.): 175-176. Oxford, Clarcndon Press, ,510p. Finckh, P., 1976, Wbneflussmcssungen Ccmk, V., 1977, Some comments on the in Randalpenseen 1Ph.D. thesis1 : effect of past climatic changes on Zurich, Eidgenossiche Tcchnische the underground temperature field: Hochschule, 105 p. Polish Academy of Sciences, Institute Finckh, P., and Kelts, K., 1976, Geo- of Geophysics, Publications, ser. A, physical investigation into the nature 3, 103, p. 45-56. of preholocenc sediments of Lake Clark, S. P., 1966, Thermal conductivity, Zurich: EC~O~CGeologicae Helvetine, in Clark, S. P., ed., Handbook of V. 69/1, p. 139-148. physical constants: Geological Finckh, P., Strcckeisen, G., and Society of America Memoir 97, p. 459- Wielandt,. E,, 1979, An automatic 482. probe for heat flow measurements: Clark, S. P., and Jiger, E., 1969, Denu- Marine Gcophysicall Researches,.~.4, dation rate in the Alps from p. 207-212. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 512 Gerard; R., Langseth, M. G., Jr., and Lee, T. C., and Benyey, T. L., 1974, * Ewing, M., 1962, Thermal gradient Heat flow refraction across dis- measurements in the water and similar media: Royal Astronomical bottom sediment of the western Society Geophysical Journal, v. 39, Atlantic: Journal of Geophysical - p. 319-333. .O Research, v. 67, p. 785. Likens, G. E., and Johnson, N. M., 1969, 1 Hiinel, R., 1970, A new method for the Measurements and analysis of the annual determination of the heat flow in heat budget for the sediments in two lakes: Zeitschrift FGr Geophysik, Wisconsin lakes: Limnology and V. 36, p. 725-742. Oceanography, v. 14, no. 1, p. 115-135. -1971, Heat flow measurements and Lubimova, H. A., and Shelyagin, V. A., a first heat flow map of Germany: 1966, Heat flow through the bottom of Zeitschrift Fur Geophysik, v.- 37, Lake Baykal: USSR Academy of Sciences, p. 975-992. Doklady, Earth Science, v. 171, p. 25-28. -1974, Heat flow measurements in Rybach, L., 1973, Wkmeproductionsbestim- northern Italy and heat flow,mapsof mungen an Gesteinen der Schweizer Alpen: Eurupe: Zeitschrift Fur Geophysik, Bern, Geotechnischc Serie, Lieferung V. 40, p. 367-380. 51, 51 p. Hkel, R., and Zoth, G., 1973, Heat flow Schuepp, M., 1966, Klimatologie der measuruements in Austria and heat Schweiz:, Lufttemperatur, Heft Nr. 7, flow maps of Central Europe: Herausgegeben von der Schweiz : Zeitschrift Fur Geophysik, v. 39, Zurich, Meteorologischen Zentralanstalt, p. 425-439. 44 p. Hsi, K. J., 1979, Thin-skinned platc- Steinhart, J. S., and Hart, S. R., 1965a, tectonics during neo-alpine oro- Terrestrial heat flow measurements in t genesis: American Journal of lake bottoms: Science, v. 149, p. 1499- Science, v. 279, p. 353-366. 1501. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 513 -1965b, A study of heat flow and Ocean floor: Journal of Geophysical thermal properties in Seneca Lake, Research, v. 68/14, p. 4219-4250. New York: American deophysical Von Herzen, R. g., Finckh, R., and Union Transactions, v. 46/1, p. 175- Hsu, K. J., 1974, Heat flow in Swiss 176. lakes: Zeitschrift Fur Geophysik, -1968, Calibration curves for V. 40, p. 141-172. thermistors: @ Deep-sea Research, Wenk, H. R., .and Wenk, E., 1969, p. 497-506. Physical constants of alpine rocks: Thompson, R., and Kelts, K., 1974, Holo- Schweizerische Mineralogische und cene sediments and magnetic strati- Petrographische Mitteilungen, v.' 49, graphy from Lakes Zug and Zurich, p. 343-348. Switzerland: Sedimentology, v. 21, Werner, D., 1975, Probleme der Geotherplik p. 577-596. am Beispiel des Rheingrabens 1Ph.D. Von Herzen, K. P., and Anderson, R., thesis1 : Karlsrum West Germany, 1972, Implications of heat fxow and University of Karlsruhe, 171 p. bottom water temperature in the Zimmerman, U., 1975, Limnologische eastern equatorial Pacific: Royal Untersuchungen am Trinkwasserspeicher Astronomical Society Geophysical Zbrichsees: Gaz, Eaux, Eaux usees Journal, v. 26, p. 427. 59/9, p. 437. Von Herzen, R. P., and Maxwell, A., Zillig, H., 1956, Sedimente ai? Ausdruck 1959, The measurement of thermal des Zustandes eines Gewassers: conductivity of deep sea Sediments Schweizerisclie Zeitschrift FGr by a needle probe method: Journal Hydrologic, v. 18, p. 487-529. of Geophysical Research, v. 64, MANUSCRIPT RECEIVED BY THE SOCIETY p. 1557-1563. MAY 15, 1979 Von Herzen, R. P., and Uyeda, S., 1963, REVISED MANUSCRIPTrRECEIVED MAY 28, 1980 Heat flow through the eastern Pacific MSCRIPT ACCEPTED JULY 18, 1980 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021 51 4 Contribution No. 142 of the Laboratory of Experimental Geology, Em, Zurich, Switzerland, and Contribu- tion No. 317 of the Tnstaute of Geo- physics, ETH, Zurich, Switzerland Printed :n U.S.A. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/92/3_Part_II/452/3444471/i0016-7606-92-3-452.pdf by guest on 30 September 2021