Radlometrlc Ages on File in the Radlometrlc Age Data Bank (RADB) of Rocks from Massachusetts
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DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Radlometrlc Ages on File In the Radlometrlc Age Data Bank (RADB) of Rocks from Massachusetts by Robert E. Zartman and Richard F. Marvin Open-File Report 87-170 Thfs report Is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and strati graphic nomenclature Denver, Colorado 80225 Radlometrlc Ages on File In the Radlometrlc Age Data Bank (RADB) of Rocks from Massachusetts Robert E. Zartman and Richard F. Marvln This Open-File Report contains the records of radlometrlc ages for Massachusetts from the Radlometrlc Age Data Bank of the U.S. Geological Survey. These data were compiled for use In the assignment of ages to rock units portrayed on a new bedrock geologic map of Massachusetts (Zen, 1983). The compilation Is believed to document all radlometrlc ages on samples from the state that have appeared In the published scientific literature through the year 1986. Most of the Information contained herein Is self -explanatory, although the reader Is advised to consult the User's Guide to the Radlometrlc Age Data Bank (Zartman and others, 1976) In order to fully understand the construction of the record. For brevity, certain material Is entered on the record In coded format, and to facilitate the reading of this report, crucial code listings are Included as an appendix. Also, repetition of full literature references has been avoided by giving those citations only at the end of the report keyed to the reference number contained on each record. All radlometrlc ages contained In this compilation have been recalculated to common values of the decay constants (Stelger and Jager, 1977) regardless of the usage of the original authors. Thus, a consistent, direct Inter comparison of ages Is possible among all of the data regardless of the laboratory where the analysis was made. The decay constants to which the age reported herein have been calculated are: Potassium 40 Afi =4.962 x IcT^yr" 1 ; A =0.581 x lo'^yr"" 1 P e 40K/K=:0.01167 atom percent Rubidium 87 \ =1 .42 x 10" 1 ^r" 1 V? A=l. 55125 x lO'^yr" 1 ; 238U/ 235U= 137.88 A=9.8485 x A=4.9475 x 2 Uranium fission X-.n8.46 x 10 yr Lead-alpha t(ml 11 ion years)=[Pb(ppm)/Alpha activity(a/mg-hr)] x 2580 Records are arranged in the same order as they will appear In a forthcoming U.S. Geological Professional Paper to accompany the bedrock geologic map. Primary classification Is by geologic terrane, and within each terrane rock units are presented according to Increasing age as they appear on the Bedrock Geologic Map of Massachusetts (Zen, 1983). Steiger, R. H., and Jager, E., 1977, Convention on the use of decay constants In geo- and cosmochronology: Earth and Planetary Science Letters, v. 36, p. 359-3*62. Zartman, R. E., Cole, J. C., and Marvln, R. F., 1976, User's guide to the Radiometric Age Data Bank (RADB) : U.S. Geological Survey Open-File Report 76-674, 77p. Zen, E-an, editor, and Goldsmith, Richard, Ratcliffe, N. M. , Robinson, Peter, and Stanley, R. S., compilers, 1983, Bedrock geologic map of Massachusetts: Reston, VA. , U.S. Geological Survey, scale 1:250,000. SECTION I PUBLISHED K-AR, RB-SR, AND U-PB AGES OF ROCKS FROM MASSACHUSETTS TACONIC-BERKSHIRE ZONE RADIONETRIC AGE DATA BANK - U.S.6.S. BRANCH OF ISOTOPE GEOLOGY LOCATION SAMPLE IDENTIFICATION COUNTRY.......... UNITED STATES RECORD NUMBER........ 0020003 STATE CODE....... 25 STATE............ MASSACHUSETTS REFERENCE NUMBER..... 66-00019 COUNTY........... BERKSHIRE LABORATORY(IES)...... SD QUAD SCALE QUAD NO. /NAME COMPILED BY It 24000 6ECKET NAME: 2ARTHAN, R.F. LATITUDE......... 42-15-10 N DATE: 86 11 LONGITUDE........ 73-00-31 W COMMENT.......... SMALL QUARKY 350-M EAST OF CUSHMAN BROOK*- BECKET PRECISION OF LOCATION: 2 SOURCE OF SAMPLE: 3 SAMPLE DESCRIPTION ROCK TYPE: GRANITE " LEXICON AGE(S): 361 PETROGRAPHIC.CODE: B240 DESCRIPTION: WHITE, CATACLASTIC MUSCOVITE GRANITE? BERKSHIRE MASSIF URANIUM-THORIUM-LEAD LABORATORY SAMPLE NUMBER: 4 ROCK/MINERAL CODE: MCI ZIRCON COMMENT: 100-150 MESH FRACTION ANALYTICAL DATA: U (PPM).....*............ 323 TH (PPM)................. 27.2 PB (PPM)................. 32.4 ISOTOPIC COMPOSITION OF LEAD (ATOM PERCENTr 204PB 206PB 207PB 208PB 0.111 85.33 7.154 7.404 206PB/238U AGE........... 597 «Y- 6 MILLION YEARS 207P8/235U AGE........... 635 +/- 6 MILLION YEARS 207P3/206PB AGE.......... 774 «Y- 4 MILLION YEARS 208PB/232TH AGE.......... 840 +/- 8 MILLION YEARS INITIAL LEAD ISOTOPIC COMPOSITION (X,Y,Z): 18.0, 15.6, 38.0 ANALYTICAL COMMENTS...... LOWER CONCORDIA INTERCEPT AGE OF ABOUT 400 M.Y, REFLECTS TIME OF INTRUSION SAMPLE SUITE: 00800 COMMENTS: GRANITE IS ABOUT 400 M.Y. OLD. URANIUM-THORIUM-LEAD . LABORATORY SAMPLE NUMBER: 4 ROCK/MINERAL CODE: MCI ZIRCON COMMENT: 150-200 MESH FRACTION ANALYTICAL DATA: U (PPM).................. 298 TH (PPM)................. 24.7 PB (PPM)................. 29.0 ISOTOPIC COMPOSITION OF LEAD (ATOM PERCENT) 204PB 206PB 207PB 208PB 0.108 85.62 7.072 7.198 206PB/238U AGE........... 582 +/» 6 MILLION YEARS 207PB/235U AGE ......... 619 4/- 6 MILLION YEARS 207PR/206PB AGE.......... 7>7 /» 4 MILLION YEARS ?0«PB/232TH AGE.......... 813 + / 8 MILLION YEARS INITIAL LEAD ISOTOPIC COMPOSITION (X*Y*Z)s 18.0* 15.6* 38.0 ANALYTICAL COMMENTS...... LOWER CONCORDIA INTERCEPT AGE OF ABOUT 400 M.Y. REFLECTS TIME OF INTRUSION SAMPLE SUITES 00800 COMMENTS! GRANITE IS ABOUT 400 M.Y. OLD. UKANIUM-THORIUM-LEAD LABORATORY SAMPLE NUMBER: 4 ROCK/MINERAL CODE: MCI ZIRCON COMMENT: 250-325 MESH FRACTION ANALYTICAL DATA: U (PPM).................. 276 TH (PPM)................. 21.6 PB (PPM)................. 24.6 ISOTOPIC COMPOSITION OF LEAD (ATOM PERCENT) 204PB 206PB 207PB 208PB 0.117 85.62 7.078 7.190 206PB/238U AGE, .... 534 4K/- 5 MILLION YEARS 207PB/235U AGE, .... 568 H! /- 6 MILLION YEARS 207PB/206PB AGE,£. ...... .... 705 <»Y- 4 MILLION YEARS 208PB/232TH AGE.......... 698 +/- 7 MILLION YEARS INITIAL LEAD ISOTOPIC COMPOSITION (X,Y,Z): 18.0, 15.6, 38.0 ANALYTICAL COMMENTS...... LOWER CONCORDIA INTERCEPT AGE OF ABOUT 400 REFLECTS TIME OF INTRUSION SAMPLE SUITE: 00800 COMMENTS: GRANITE. IS ABOUT 400 M.Y. OLD. UKANIUM-THORIUM-LEAD LABORATORY SAMPLE NUM3ER: 4 POCK/MINERAL CODE: MCI ZIRCON COMMENT: -400 MESH FRACTION ANALYTICAL DATA: U (PPM).................. 387 TH (PPM). ................ 33.3 PB (PPM)................. 34.0 ISOTOPIC COMPOSITION OF LEAD (ATOM PERCENT) 204PB 206PB 207PB 208PB 0.130 B5.00 7.169 7.705 206PB/238U AGE.. ......... 522 */» 5 MILLION YEARS 207PB/235U AGE.. ......... 553 +/- 6 MILLION YEARS 207PB/206PB AGE... ....... 683 +/- 4 MILLION YEARS 208PB/232TH AGE.......... 635 +/- 6 MILLION YEARS INITIAL LEAD ISOTOPIC COMPOSITION <X,Y,Z> 18.0, 15.6, 38.0 ANALYTICAL COMMENTS...... LOWER CONCORDIA INTERCEPT AGE OF ABOUT 400 M.Y, REFLECTS TIME OF INTRUSION SAMPLE SUITE: 00300 COMMENTS: GRANITE IS ABOUT 400 M.Y. OLD. RAD10METRIC AGE OATA BANK - U.S.Ci.S. BRANCH OF ISOTOPE GEOLOGY LOCATION SAMPLE IDENTIFICATION COUNTRY.......... UNITED STATES RECORD NUMBER.. ...... 0020004 STATE CODE....... 25 STATE............ MASSACHUSETTS REFERENCE NUMBER..... 86*00019 COUNTY........... BERKSHIRE LABORATORY UES>...... SO QUAD SCALE QUAD NO. / NAME COMPILED BY it 24000 OTIS NAME: ZARTMAN* R.E. LATITUDE.. 42*14-03 N DATE: 86 11 LONGITUDE. 73*04-15 V COMMENT.......... NErf WHITING QUARRY* OTIS PRECISION OF LOCATION: 2 SOURCE OF SAMPLE: 3 SAMPLE DESCRIPTION ROCK TYPE: GRANITE LEXICON. AGE (SIi: 361 PETROGRAPHIC CODE: B240 DESCRIPTION: LIGHT-GRAY, FINE-GRAINED* WEAKLY FOLIATED GRANITE; BERKSHIRE MASSIF URANIUM-THORIUM-LEAD LABORATORY SAMPLE NUMBER: 5 ROCK/MINERAL CODE: MCI ZIRCON COMMENT: 100-150 MESH FRACTION ANALYTICAL DATA: U. (PPM).................. 417 TH (PPM)................. 49.8 PB (PPM)................. 47.1 ISOTOPIC COMPOSITION OF LEAD (ATOM PERCENT) 204P3 206P3 207PB 208PB 0.011 88.91 6.272 4.804 206PB/238U AGE........... 711 +/- 7 MILLION YEARS 207PB/235U AGE........... 756 «Y- 8 MILLION YEARS 207PB/206PB AGE.......... «91 « /- 5 MILLION YEARS 208P3/232TH AGE. ......... 923 « /- 9 MILLION YEARS INITIAL LEAD ISOTOPIC COMPOSITION (X*Y*Z): 18.0* 15.6* 38.0 ANALYTICAL COMMENTS...... LObER CONCORDIA INTERCEPT AGE OF ABOUT 400 M.Y REFLECTS TIME OF INTRUSION SAMPLE SUITE: 00800 COMMENTS: GRANITE IS ABOUT 400 M.Y. OLD. - ~ ' . ' ~ - ' URANIUM-THORIUM-LEAD . - LABORATORY SAMPLE NUMBER: 5 ROCK/MINERAL CODE: MCI ZIRCON COMMENTS 150-200 MESH FRACTION ANALYTICAL DATA: U (PPM).................. 372 TH (PPM)................. 39.2 P6 (PPM)................. 36.1 ISOTOPIC COMPOSITION OF LEAD (ATOM PERCENT) 204PB 206PB 207PB 208PB 0.012 89.46 6.126 4.401 ?06Pe/238U AGE ........... 619 / 6 MILLION YEARS ?07P*/235U AGE........... 663 */- 7 MILLION YEARS ?07PB/206PB AGE.......... 825 / 5 MILLION YEARS 70APB/232TH AGE. ......... 813 /- 8 MILLION YEARS INIIIAL LEAD ISOTOPIC COMPOSITION (XrYrZ): 18. Or 15.6, 38.0 ANALYTICAL COMMENTS...... LOWER CONCOROIA INTERCEPT AGE OF ABOUT 400 M.Y, REFLECTS TIME OF INTRUSION SAMPLE SUITES 00800 COMMENTS: GRANITE IS A80UT 400 M.Y. OLD. RADIOMETRIC AGE DATA BANK » U.S.G.S. BRANCH OF ISOTOPE GEOLOGY LOCATION SAMPLE IDENTIFICATION COUNTRY.......... UNITED STATES RECORD NUMBER........ 0020006 STATE CODE....... 25 STATE............ MASSACHUSETTS REFERENCE NUMBER..... 86-00019 COUNTY........... BERKSHIRE LABORATORYCIES)...... SD QUAD SCALE QUAD NO. / NAME COMPILED BY 1: 24000 OTIS NAME: ZARTHAN, R.E. LATITUDE......... 42-13-55 N DATE: 86 11 LONGITUDE........ 73-01-22 V COMMENT.......... WILLIAMS QUARRY, OTIS PRECISION OF LOCATION: 2 SOURCE OF SAMPLE: 3 SAMPLE DESCRIPTION ROCK TYPE: GRANITE LEXICON AGE(S): 361 PETROGRAPHIC CODE: B240 DESCRIPTION: GRAY, MEDIUM-GRAINED, WELL-FOLIATED BIOTITE GRANITE; BERKSHIRE MASSIF URANIUM-THORIUM-LEAD LABORATORY SAMPLE NUMBER: 7 ROCK/MINERAL CODE: MCI ZIRCON COMMENT: 100-150 MESH FRACTION ANALYTICAL DATA: U (PPM).................. 119 TH (PPM)................. 25.2 PB (PPM)................. 10.1 ISOTOPIC COMPOSITION OF LEAD (ATOM PERCENT) 204PB 206PB 207PB 208PB 0.024 85.96 6.011 8.004 206PB/238U AGE..........