Jökull


Jökull - 01.01.2016, Side 90

Jökull - 01.01.2016, Side 90
Leó Kristjánsson Figure 4. A very simplified scheme of outcrops sampled by Kristjánsson (2015) and of those added in the present paper (profile names underlined). Lines indicate some of the definite correlations be- tween individual sites which are based on lithol- ogy and the apparent dip but primarily on a coinci- dence of remanence directions (Table 2). Approx- imate distances between the profiles are indicated. – Mjög einfölduð mynd af opnum sem safnað var kjarnasýnum úr 2012–2014 og 2014–2016, sumum tengingum milli þeirra, og fjarlægðum. The large black dots in Figure 5 denote VGP po- sitions from flows DV 9, DW 4, 9, DQ 1, 3 and DI 4 which clearly lie more than 10◦ away from any of the poles making up the red composite pole path from Kristjánsson’s (2015) profiles. The smaller black dots similarly represent poles from flows DE 5, 8, 10, 16 and DF 9, 11, 12 in the profiles of Kristjánsson and Jóhannesson (1996). They are selected for insertion here to emphasize that the movement of the virtual pole during this excursion must be truly complex. Its wanderings do not seem to be confined to any pre- ferred intervals in longitude or latitude. These results show that exposures belonging to the Kleifakot geomagnetic event reach for at least 5– 6 kilometers along strike on both sides of Ísafjörður, measured from profile DF on the southeast side and DV on the northwest side. The new profiles and some of the correlations between them are shown schematically in Figure 4. Table 2 is a list of pairs of remanence directions employed for correlation purposes by Kristjánsson and Jóhannesson (1996), Kristjánsson (2015) and the present study. ON THE INTENSITY OF THE PALEOMAGNETIC FIELD Estimates of the absolute intensity of the geomagnetic field during emplacement of igneous bodies are of sci- entific value regarding its long-term characteristics, especially during transitions and excursions when it is relatively weak (Kristjánsson 2013, Fig. 7). One might expect that such measurements in situations like the Kleifakot geomagnetic event could yield in- teresting results about the field when in an unstable state. From our demagnetization results and other evi- dence on the lavas from the Kleifakot event in Ísa- fjarðardjúp (Kristjánsson, 2015, p. 315), they are however unlikely to pass suitability tests for paleoin- tensity studies. In several of the excursion outcrops at higher altitude in profile JD (Figure 2a), the VRM component in some samples is however small and can be removed by AF treatment at 10 mT or less with minimal effect on the TRM. They might possi- bly provide some satisfactory paleointensity results, if supported by consistency between samples collected from widely spaced sites in a unit as well as between 90 JÖKULL No. 66, 2016
Side 1
Side 2
Side 3
Side 4
Side 5
Side 6
Side 7
Side 8
Side 9
Side 10
Side 11
Side 12
Side 13
Side 14
Side 15
Side 16
Side 17
Side 18
Side 19
Side 20
Side 21
Side 22
Side 23
Side 24
Side 25
Side 26
Side 27
Side 28
Side 29
Side 30
Side 31
Side 32
Side 33
Side 34
Side 35
Side 36
Side 37
Side 38
Side 39
Side 40
Side 41
Side 42
Side 43
Side 44
Side 45
Side 46
Side 47
Side 48
Side 49
Side 50
Side 51
Side 52
Side 53
Side 54
Side 55
Side 56
Side 57
Side 58
Side 59
Side 60
Side 61
Side 62
Side 63
Side 64
Side 65
Side 66
Side 67
Side 68
Side 69
Side 70
Side 71
Side 72
Side 73
Side 74
Side 75
Side 76
Side 77
Side 78
Side 79
Side 80
Side 81
Side 82
Side 83
Side 84
Side 85
Side 86
Side 87
Side 88
Side 89
Side 90
Side 91
Side 92
Side 93
Side 94
Side 95
Side 96
Side 97
Side 98
Side 99
Side 100
Side 101
Side 102
Side 103
Side 104
Side 105
Side 106
Side 107
Side 108
Side 109
Side 110
Side 111
Side 112
Side 113
Side 114
Side 115
Side 116
Side 117
Side 118
Side 119
Side 120
Side 121
Side 122
Side 123
Side 124
Side 125
Side 126
Side 127
Side 128
Side 129
Side 130
Side 131
Side 132
Side 133
Side 134
Side 135
Side 136
Side 137
Side 138
Side 139
Side 140
Side 141
Side 142
Side 143
Side 144

x

Jökull

Direkte link

Hvis du vil linke til denne avis/magasin, skal du bruge disse links:

Link til denne avis/magasin: Jökull
https://timarit.is/publication/1155

Link til dette eksemplar:

Link til denne side:

Link til denne artikel:

Venligst ikke link direkte til billeder eller PDfs på Timarit.is, da sådanne webadresser kan ændres uden advarsel. Brug venligst de angivne webadresser for at linke til sitet.