Paleomagnetic record of basaltic volcanism from Pukaki and Onepoto maar lake cores, Auckland Volcanic Field, New Zealand

Figures & data

Fig. 1  Location map of the Pukaki and Onepoto maars in Auckland Volcanic Field (inset: location map of North Island; OVC: Okataina Volcanic Centre; TVC: Taupo Volcanic Centre; TgVC: Tongariro Volcanic Centre; TaVZ: Taranaki Volcanic Zone).

Fig. 2  Magnetic susceptibility, ChRM intensity and inclination, ARM intensity, ARM/? and ARM_30mT/ARM parameters for Pukaki 1-01 (A) and Onepoto (B) cores. The columns on the right show the depth of the main magnetic features and of important volcanic tephra. See Table 1 and 2 for details. The errors associated with the magnetic susceptibility are less than 2% of the measured values and only become significant in the intervals where the values approach the resolution of the instrument (2×10⁻⁶ SI) where they produce a corresponding increase in the errors associated with the ARM/κ values.

Table 1  Magnetic signatures from NRM and ARM intensity records for Pukaki core not shown in Turner et al. (2001). Lithological description from Dickinson (2001).

Core sections	Corrected depth (m)	Description
33	51.32–51.37
34	51.42	clay with sections of a darker colour
34	51.63–51.68	clay with sections of a darker colour
34	51.82
34	51.99
34	52.14
34	52.25
34	52.35
34	52.42
35	53.53–53.60
37	56.87–56.89	tephra? Very dark grey
38	57.91–57.98	fine silt, very dark grey
38	58.14–58.23	fine silt, very dark grey
38	58.26–58.32	fine silt, very dark grey
38	58.54–58.56	fine silt, very dark grey
40	60.44–60.53	laminated sediment
41	61.9	basaltic tephra
41	62.87	white fine silty tephra
42	63.36	fine sand, tephra
43	64.83
45	67.20–67.49	basaltic tephra at 67.20 m
46	68.39
46	68.54
46	68.84
46	69.37–69.53	tephra layers

Fig. 3  Magnetic susceptibility, ChRM, and ARM intensity for Onepoto core. The main magnetic features are identified with numbers also reported in Table 2. A period of probably major volcanic activity in the AVF is indicated on the left.

Table 2  Magnetic signatures and lithological description for the Onepoto core. Identified tephra from Shane & Hoverd (2002) (AVF: Auckland Volcanic Field; Tk: Taranaki volcano; TVZ; Taupo Volcanic Centre)

	Core sections	Corrected depth (m)	Tephra	Description
0	21A	0.21–0.25	Rotoma	white, 4 cm thickness
1	21A	0.64	basaltic tephra?
2	22A	2.32–2.34	Kawakawa	white, 2.5 cm thickness
3	22A	2.51	121AVF
4	22B	2.82	basaltic tephra?
5	23	3.9	Tahuna
6	24	5.12–5.14	95Tk	pink, 2 cm thickness
7	24	5.90	basaltic tephra?
8	25A	6.71	basaltic tephra?
9	25A	7.00	basaltic tephra?
10	25A	7.45	basaltic tephra?
11	25A	7.62	basaltic tephra?
12	25A	8.06	basaltic tephra?
13	26A	9.16	basaltic tephra?
14	26A	9.41	basaltic tephra?
15	26A	10.31	basaltic tephra?
16	27A	11.27	basaltic tephra?
17	27A	11.36	basaltic tephra?
18	27A	11.43	basaltic tephra?
19	27A	11.66	71TK	pink, 2 cm thickness
20	27A	11.78	70TK
21	27A	11.81	basaltic tephra?
22	27A	11.96	68TK
23	27A	12.2	67TK
24	27A	12.26	basaltic tephra?
25	27A	12.32	basaltic tephra?
26	27B	12.58	61TK
27	28	13.21	basaltic tephra?
28	28	13.48	basaltic tephra?
29	28	13.84	basaltic tephra?
30	28	14.09	basaltic tephra?
31	28	14.44	basaltic tephra?
32	29	14.69	basaltic tephra?
33	29	14.81	basaltic tephra?
34	29	14.91–14.93	41TVZ	white, 2 cm thickness
35	29	15.32–15.37	30TK–?	pink, 2 mm thickness

Turner GM Verosub KL Delusina I Venuti A 2001 Preliminary Report on the Paleomagnetism and Environmental Magnetism of the Pukaki 1-01 Core Preliminary Scientific Data Report, Pukaki 1-01, Pukaki maar crater, Auckland, New Zealand Dickinson W. Victoria University of Wellington School of Earth Science, Sciences Research Report 14 43 52

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Dickinson W 2001 Preliminary Scientific Data Report, Pukaki 1-01, Pukaki maar crater, Auckland New Zealand Victoria University of Wellington School of Earth Science, Sciences Research Report 14

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Shane , P and Hoverd , J . 2002 . Distal record of multi-sourced tephra in Onepoto Basin, Auckland, New Zealand: implications for volcanic chronology, frequency and hazards . Bulletin of Volcanology , 64 : 441 – 454 .

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