Jökull - 01.01.2014, Side 49

Magnetostratigraphy, K-AR dating and erosion history of Hafrafell, SE–Iceland
Table 1. Stratigraphy of Hafrafell. Division of rock formations into glacial and interglacial stages and their
proposed correlation with the geomagnetic polarity time scale (Gradstein et al., 2012). – Jarðlagaskipan
Hafrafells. Skipting jarðmyndana Hafrafells í jökulskeið og hlýskeið og ætluð tenging þeirra við segultímatal.
Group Form- Field Dip Thick- Mag. Mag. Mag. Mag. 40Ar–39Ar Inf. Er- Ref.
no. and ation classif. of ness pol. chron chron age, Ma total fusion I-G surf. Units4
thickn. lithol. strata2 (m) no. age, Myr stage
H8 HF39 l, pl.ph 0◦ 105 N Brunhes C1n <0.781 0.21±0.01 I12 HR12 HF14–HF33
105 m (HV)1
HF38 s, pebc >130 N Brunhes C1n <0.781 G – –
HF37 sub, band >160 N Brunhes C1n <0.781 G – –
HF36 sub, band >190 N Brunhes C1n <0.781 G – –
HF35 l, th >120 N Brunhes C1n <0.781 I – –
HF34 sub 180 N Brunhes C1n <0.781 G – –
HF33 sub >140 N Brunhes C1n <0.781 G – –
H7 HF32 s, till 75 – Brunhes C1n <0.781 G HR11 Y9–Y11
995 m
HF31 sub, th 55 R? Matuyama C1r.2r 1.072–1.778 G11 HR10 T23
HF30 l, pl.ph 5 R? Matuyama C1r.2r 1.072–1.778 I11 – HJ18
HF29 s, bcon 20 R? Matuyama C1r.2r 1.072–1.778 G10 HR9 HJ18/HJ17
HF28 l, pl.ph 65 R? Matuyama C1r.2r 1.072–1.778 I10 – HJ10–HJ17
HF27 sub, pl.ph 74 R Matuyama C1r.2r 1.072–1.778 1.69±0.29 G9 – T22
(T22)1
HF26 l, pl.ph 34 R3 Matuyama C1r.2r 1.072–1.778 I9 – T19–T21
HF25 l, olb 21 N3 Olduvai? C2n 1.778–1.945 I9 – T16–T18
HF24 l, th 24 R3 Matuyama C2r 1.945–2.581 I9 – T13–T15
HF23 l, th 15◦/320◦ 25 N Matuyama C2n 1.945–2.581 I9 – T6–T12
HF22 l, th 60 R Matuyama C2r 1.945–2.581 I9 HR8 T1–T5
HF21 sub, pl.ph 30 N? Matuyama ?? 1.945–2.581? G8 – HJ3
H6 HF20 l, band 10◦/263◦ 35 N? Matuyama ?? 1.945–2.581? I8 HR7 HJ1–HJ2
448 m
HF19 l, th >6 R? Matuyama C2r 1.945–2.581 I8 – HS86–HS87
HF18 s, bcon 20 – Matuyama C2r 1.945–2.581 G7 HR6 HS86/HS85
HF17 l, th 90 R? Matuyama C2r 1.945–2.581 I7 – HS64–HS85
HF16 s, bcon 24 – Matuyama C2r 1.945–2.581 G6 HR5 HS64/HS63
HF15 l, th 12◦/35◦ 194 R? Matuyama C2r 1.945–2.581 I6 – HS33–HS63
HF14 l, band 51 R? Matuyama C2r 1.945–2.581 I6 – HS29–HS32
HF13 l, th >100 R Matuyama C2r 1.945–2.581 I6 – HS1–HS28
HF12 s, bcon +1, 8 R(T) Matuyama C2r 1.945–2.581 G5 HR4 U60K/U60I
pl.ph
H5 HF11 l, th >246 R Matuyama C2r 1.945–2.581 I5 – U28–U71
739 m
H4 HF10 sub, th 90 R Matuyama C2r 1.945–2.581 2.35±0.22 G4 HR3 HZ
90 m (HZ)1
H3 HF9 l, th+band 10◦/365◦ 78 N Gauss C2An 2.581–3.596 I4 – HP2:14A–29
78 m
HF8 s + l, th 20◦/179◦ 37 N Gauss C2An 2.581–3.596 3.2±0.09 G3? – HL27/HL26
(HL27)1
HF7 l, pl.ph 15◦/338◦ 88 N Gauss C2An 2.581–3.596 I3 – U5–U13
H2 HF6 sub, pl.ph – 31 N Gauss C2An 2.581–3.596 G2 HR2 HM4–HM5
156 m
HF5 l, olb + pl.ph 20 R Gilbert C2Ar 3.596–4.187 I2 – HL18–HL25
HF4 l, th 11◦/340◦ 90 R Gilbert C2Ar 3.596–4.187 I2 – HL6–HL17
HF3 l, th + pl.ph 35 R Gilbert C2Ar 3.596–4.187 I2 – HL2–HL5
HF2 s, bcon+br 11 – Gilbert C2Ar 3.596–4.187 G1 HR1 HF1/HL0
H1 HF1 l, th 5 N or Cochiti? C3n.1n 4.187–4.300 3.92±0.06 I1 – HL1 or
161 m R(T)?6 (HL)1 HFX
Explanations: l: lava flow; s: sedimentary rock; th: tholeiite; band: basalt andesite; pl.ph: plagioclase porphyritic basalt; sub: rock formed under subglacial
conditions; till: tillite; pebc: pebble conglomerate; bcon: boulder conglomerate; br: breccia; I: interglacial stage; G: glacial stage, N: normal magnetic polarity;
R: reverse magnetic polarity; HR1 to HR12: erosional stages/surfaces. 1Dated unit. 2Dip and dip direction of strata. 3R Magnetic polarity as measured with
a handheld fluxgate magnetometer in the field. 4Units of each formation that make up the composite stratigraphic column. 5Dips toward north. 6Weak N or
transitional R.
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