Short Notes BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA VOL. es. pp. 119-124 JANUARY 1957 GRAVITY MEASUREMENTS IN ORIENTE PROVINCE, CUBA BY G. LYNN SHURBET AND J. LAMAR WORZEL In 1954 gravity measurements were made in Wright, 1930, p. 56) and the S-48 (Collins, Oriente Province, Cuba, at about 2-mile inter- 1933, p. 16) cruises have been changed by +5 vals from Guantanamo to Holguin via Santiago and +6 mgal, respectively, to base them on the and Bayamo. Additional measurements were Commerce Building Base. The agreement of made between Guantanamo and Baracoa (Fig. the gravimeter value with the pendulum values 1.) These measurements supplement the 15 from the S-21 and CONGER cruises is not com- pendulum observations made in southern pletely satisfactory, but barely within the Oriente Province during 1933 and 1935 by the accuracies of the observations. No explanation U. S. Coast and Geodetic Survey (Dickerson, is offered for the lack of agreement of the gravim- 1940, p. 213). eter value with the pendulum value from the A Frost geodetic gravimeter was used. The S-48 cruise. instrument has a range of about 4000 mgal for a During these measurements in Cuba, stations single setting of the latitude adjustment. The were reoccupied when practical to determine reading spring is linear over the range used with drift of the gravimeter. In Table 2 the gravity a scale constant of 2.667 mgal per scale division. values for all stations, corrected for instrument A reading is accurate to within 0.1 scale divi- drift, are given. A number of stations were oc- sion, and drift is less than the reading error for cupied two or more times as indicated. Inspec- periods up to several days. tion of these values shows that a maximum error Values of observed gravity were determined of about 0.8 mgal may be attributed to unde- relative to a Frost gravimeter station at 18° tected instrument drift during this period. 20.13' N., 64° 57.29' W., on St. Thomas, V. I., Drift during the 5-day interval between com- occupied 5 days after completion of the field pletion of the field work in Cuba and the occu- work in Cuba. No direct connections with our pation of the St Thomas base station is con- laboratory base result from this work because sidered negligible. of difficulties with the gravimeter during its Station elevations in Cuba were determined transport from the laboratory to Cuba and by aneroid barometer with reference to four from St. Thomas back to the laboratory. Inter-American Geodetic Survey bench marks However, the St. Thomas station (978.6835 (at stations 16, 29, 31, 36) and shoreline loca- cm/sec2) was determined in 1952 directly tions where elevations could be estimated from from the Lament Geological Observatory Base #1 (980.2584 cm/sec2) by Shurbet and the sea surface. Repeated aneroid observations Ewing (1956, p. 515). The LGO Base has at various stations indicate that errors up to 50 been connected to the U. S. Coast & Geodetic feet may occur, corresponding to an error in Survey base (980.118 cm/sec2) in the Depart- simple Bouguer anomaly of about 3 mgal. ment of Commerce Building, Washington, D. Positions for the stations were determined C. These connections are probably accurate to by speedometer distances from towns or river within 1 mgal. crossings, which could be located on the Gravity values from various sources for the maps. The positions are probably accurate to Guantanamo Bay station are listed in Table 1. within half a mile, corresponding to an error Values from the S-21 (Vening Meinesz and in gravity anomaly of about .5 mgal. The Inter- 119 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/68/1/119/3441604/i0016-7606-68-1-119.pdf by guest on 01 October 2021 120 SHURBET AND WORZEL—GRAVITY MEASUREMENTS Quaternary & p?^ Cretaceous Cretaceous Tertiary Wlm Sediments ^^^ Sediments Basic Igneous iy,vj..;.ii Basic I'" ••'•'•' Geology from 1946 Sketch of the Geologic Map Commission of the Cuban Ministry of Agriculture Sintiago ^aa 161 Milligals, see text and Guild (I947,p.92l) • Lamont Geo I. Obs.,1954 u.s.c. a G.S * Town —Bouguer Anomalies FIGURE 1.—GRAVITY MEASUREMENTS IN SOUTHERN ORIENTE PROVINCE, CUBA Surface geologic formations adapted from a map by Brodermann, Albear, and Andreu. TABLE 1.—OBSERVED GRAVITY VALUES AT GUANTANAMO BAY, CUBA Elevation Observation Date Latitude Longitude (Meters) Gravity S-21* 1928 19° 54.5 N. 75° 08.9 W. 0 978.748 S-48** 1932 19° 54.5 N. 75° 08.9 W. 0 978.745 USS CONGER, Cruise III*** 1954 19° 54.5 N. 75° 08.9 W. 0 978.748 Frost gravimeter 19S4 19° 54.5 N. 75° 08.9 W. 1.5 978.7528 * Vening Meinesz and Wright (1930, p. 56). ** Collins (1933, p. 16). *** Unpublished data, Lamont Geological Observatory. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/68/1/119/3441604/i0016-7606-68-1-119.pdf by guest on 01 October 2021 SHORT NOTES 121 TABLE 2.—PRINCIPAL FACTS FOR GRAVITY OBSERVATIONS Base station Commerce Building Base, 980.118 cm/sec3. Observer Hugh Traphagen. STO-IOH DATE ELCUtnOH OBSERVES NTERNATION FRCEAIR MUUBCK LATITUDE uoHeiTOae FEET SUAVITY fORMULA HOMAUT axeuBt I9S4 MOUTH WEST SALS sKAvirr IN ANON. MSALS MSALS 1 3 Feb 978.7531 " 10 Feb .7523 II it .7528 " 11 Feb .7528 1* 19-54. 5 75-08.9 5 .7528 978. 6464 107 197 2 3 Feb 978.7814 it 4 Feb .7816 H 6 Feb ,7811 2* 19-59.5 75-00.0 70 .7814 978.6512 137 134 3 4 Feb .7827 3 6 Feb 978.7822 3* 19-58. 1 74-57.0 5 .7825 978. 6498 133 133 4 4 Feb 20-01. 1 74-50. 9 5 .8008 .6527 149 148 5 .8219 II 6 Feb .8219 5* 20-02. 5 74-49.0 30 978. 8219 978. 6541 171 170 6 4 Feb . 8267 H 6 Feb .8267 6* 20-03.5 74-38. 5 80 .8267 978.6551 179 176 7 4 Feb .7262 7 5 Feb 978. 7264 " II .7?70 " 6 Feb .7275 7* 20-21. 1 74-29. 7 15 .7268 578. 6722 >;6 St, 8 5 Feb 20-18.5 74-29.0 60 .7464 .6696 82 80 9 5 Feb 978.7510 " 6 Feb .7518 9* 20-14.5 74-27.0 no .7514 178. 6657 96 92 10 5 Feb 20-20.0 74-28. 5 15 .7358 .6711 66 66 11 6 reb 20-04. 5 74-30.5 5 .7920 . 6560 137 136 12 6 Feb 978.8011 ii 7 Feb . 8016 12* 20-08.0 75-12.0 100 .8014 (78. 6594 151 148 13 " .8014 n 9 Feb . 8014 13* 20-08.0 75-12.5 110 978.8014 978. 659 152 148 14 7 Feb 20-08. 0 75-16.0 160 .8551 .6594 161 155 15 " 20-08. 5 75-18.0 175 .8038 .6599 160 154 16 H 20-08. 5 75-19.5 209 .8019 .6599 162 154 17 II 20-11.0 75-25.0 500 .7800 .6623 165 147 18 7 Feb 20-11.0 75-26. 5 480 978.7792 978.6623 162 145 19 20-11.0 75-28.0 480 .7779 .662: 161 143 20 H 20-11.5 75-29.0 465 .7790 .6628 160 143 21 it 20-11.0 75-30.5 | 550 .7734 .662 163 143 22 H 20-11. 5 75-35.0 555 .7736 .662 163 143 • 23 7 Feb 20-11.0 75-39.0 800 978. 7523 978. 6623 165 136 24 H 20-10.5 75-42.0 895 .7432 .6618 166 133 25 " 20-09.0 75-43. 5 655 .7592 .6604 160 137 26 " 20-08.0 75-45. 5 565 .7592 . 6594 153 132 27 " .7510 * Information adopted for this station Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/68/1/119/3441604/i0016-7606-68-1-119.pdf by guest on 01 October 2021 122 SHURBET AND WORZEL—GRAVITY MEASUREMENTS TABLE 2.—Continued STO-IOH DATE IEUMTXW OBSERVED WERNATION FREEAIR NUMBER LATITUDE LOHSiTuae FEET 6RAVITY FORMULA AMOHAir xuxxn 1954 NORTH WEST I SALS GRAVITY in AMOK MSA is HSALS 27 9 Feb 978. 7507 27* 20-07.0 75-45. 5 650 .7509 978. 6584 154 130 28 7 Feb .7891 It 8 Feb .7891 28* 20-01.0 75-50.0 15 .7891 978. 6526 138 A37 29 8 Feb 978. 7768 11 9 Feb .7768 29* 20-04.0 75-49. 5 213 .7768 978. 6555 141 134 30 8 Feb 20-04. 0 75-51.0 240 .7723 .6555 139 131 31 H 20-03. 5 75-53. 0 301 .7683 .6551 142 131 32 8 Feb 20-03.0 75-54. 5 320 >78. 7688 978. 6546 144 133 33 ii 20-03.0 75-56.5 445 .7624 .6546 150 134. 34 ii 20-03. 0 75-58.0 380 .7936 .6546 175 161 35 M 20-03. 0 75-59.5 715 .7400 .6546 153 127 36 ii 20-04. 0 76-01.0 840 .7315 .6555 155 125 37 8 Feb 20-05. 5 76-01.5 675 978. 7403 978. 6570 147 122 38 ti 20-07.0 76-02. 5 600 .7408 .6584 139 117 39 H 20-08. 5 76-03.0 775 .7251 .6599 138 110 40 ii 20-09. 0 76-01.0 615 ,7326 .6604 130 108 41 H 20-10.0 76-00.0 535 .7358 .6613 125 105 42 8 Feb 20-11.5 76-00.0 570 978.7328 978.