Citation:

odp.proc.sr.131.137.1993

Name: (Table 1) Clay mineralogy for hemipelagic mud samples of ODP Site 131-808
Published: 1993
License: https://creativecommons.org/licenses/by/3.0/

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Published: 1993 (exact date unknown) • DOI registered: 2012-07-27

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Abstract:

This paper presents a synthesis of data from X-ray diffraction analyses of clay minerals and X-ray fluorescence analyses of bulk mudstones from Ocean Drilling Program Site 808. The samples come from three closely spaced holes drilled through the toe of the Nankai accretionary prism offshore Shikoku, Japan. Detrital assemblages of clay minerals are unusually uniform throughout the Nankai trench-wedge facies. Illite is the most abundant detrital clay mineral, followed by chlorite, smectite, and

traces of kaolinite. Relative percentages of smectite increase within the upper subunit of the Shikoku Basin stratigraphy. This subunit contains abundant layers of volcanic ash, and the corresponding change in clay mineralogy probably was caused by synvolcanic weathering in source areas during the Pliocene, together with in-situ alteration of disseminated glass shards within the Shikoku Basin.

At a depth of ~555 mbsf, the detrital and/or authigenic smectite component begins its transformation to illite/smectite mixed-layer clay. With increasing depth below this horizon there is a monotonic increase in illite interlayers. The onset of illitization occurs at an estimated temperature of ~65°C. Ordered (R = 1) illite/smectite interlayering first appears at depths of ~1220 mbsf (<2-µm size fraction) and ~1100 mbsf (<0.2-µm size fraction). The depth interval of the smectite-to-illite transformation coincides with a reduction in pore-water chlorinity; however, the absolute abundance of smectite appears to be insufficient to account for the changes in aqueous chemistry via in-situ dehydration reactions. Instead, significant volumes of diluted pore water probably were transported to Site 808, either from sources located deeper in the accretionary prism (where bulk mudstone porosities are lower) or from lateral sources where mudstones originally deposited in the Shikoku Basin may contain higher percentages of smectite. Significantly, we did not detect any anomalies in clay mineralogy or clay-mineral diagenesis within or near the décollement zone (945-964 mbsf).

X-ray fluorescence analyses show that hemipelagic muds and mudstones at Site 808 are chemically uniform throughout most of the section. There are no geochemical perturbations, for example, within the décollement zone. Data from interbeds of volcanic ash demonstrate that the chemical effects of mud/ash dissemination and/or in-situ alteration of pyroclastic material are limited. In addition, ash layers are chemically heterogeneous within Unit III and Subunit IVa, which indicates that tephra was transported from a variety of andesitic to rhyolitic sources on the Japanese Islands during the Pliocene. In contrast, Miocene rocks of Unit V display a clear chemical divergence (little mixing) between rhyolitic tuffs and interbeds of multicolored mudstone.

The most significant geochemical anomaly at Site 808 occurs well below the décollement zone between 1087 and 1111 mbsf. Variegated mudstones in this interval contain unusually high ratios of MgO/Al2O3, Fetotal/Al2O3, MnO/Al2O3, and CaO/Al2O3, together with high concentrations of Ba, Y, Sr, La, and Ce. We attribute this anomaly to hydrothermal alteration and/or precipitation of Ca-carbonate, siderite, barite, and related minerals, but we do not know when the event occurred. Fluid migration may have taken place during late Miocene time early in the depositional history of Shikoku Basin (i.e., above newly formed oceanic lithosphere) or during the Holocene as fluids advected through the Nankai accretionary prism.

Project(s):

Ocean Drilling Program (ODP)

Coverage:

Latitude: 32.352800 * Longitude: 134.944300

Date/Time Start: 1990-04-16T04:00:00 * Date/Time End: 1990-05-02T14:40:00

Minimum DEPTH, sediment/rock: 633.03 m * Maximum DEPTH, sediment/rock: 1280.57 m

Event(s):

131-808C * Latitude: 32.352800 * Longitude: 134.944300 * Date/Time Start: 1990-04-16T04:00:00 * Date/Time End: 1990-05-02T14:40:00 * Elevation: -4686.0 m * Penetration: 1327 m * Recovery: 572.43 m * Location: Philippine Sea * Campaign: * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 108 cores; 1028.5 m cored; 0 m drilled; 55.7 % recovery

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Method/Device	Comment
1	Sample code/label	Sample label		Underwood, Michael B	DSDP/ODP/IODP sample designation
2	DEPTH, sediment/rock	Depth sed	m			Geocode – mbsf
3	Smectite (peak area)	Sme peak area		Underwood, Michael B	X-ray diffraction TEXTUR, clay fraction	<2 µm
4	Illite (peak area)	Ill peak area		Underwood, Michael B	X-ray diffraction TEXTUR, clay fraction	<2 µm
5	Chlorite (peak area)	Chl peak area		Underwood, Michael B	X-ray diffraction TEXTUR, clay fraction	<2 µm
6	Smectite	Sme	%	Underwood, Michael B	Biscaye weighing factor (Biscaye, 1965)	<2 µm
7	Illite	Ill	%	Underwood, Michael B	Biscaye weighing factor (Biscaye, 1965)	<2 µm
8	Chlorite	Chl	%	Underwood, Michael B	Biscaye weighing factor (Biscaye, 1965)	<2 µm
9	Smectite	Sme	%	Underwood, Michael B	Missouri weighting factor	<2 µm
10	Illite	Ill	%	Underwood, Michael B	Missouri weighting factor	<2 µm
11	Chlorite	Chl	%	Underwood, Michael B	Missouri weighting factor	<2 µm
12	Smectite (peak area)	Sme peak area		Underwood, Michael B	X-ray diffraction (XRD)	2-6 µm
13	Illite (peak area)	Ill peak area		Underwood, Michael B	X-ray diffraction (XRD)	2-6 µm
14	Chlorite (peak area)	Chl peak area		Underwood, Michael B	X-ray diffraction (XRD)	2-6 µm
15	Smectite	Sme	%	Underwood, Michael B	Biscaye weighing factor (Biscaye, 1965)	2-6 µm
16	Illite	Ill	%	Underwood, Michael B	Biscaye weighing factor (Biscaye, 1965)	2-6 µm
17	Chlorite	Chl	%	Underwood, Michael B	Biscaye weighing factor (Biscaye, 1965)	2-6 µm
18	Smectite	Sme	%	Underwood, Michael B	Missouri weighting factor	2-6 µm
19	Illite	Ill	%	Underwood, Michael B	Missouri weighting factor	2-6 µm
20	Chlorite	Chl	%	Underwood, Michael B	Missouri weighting factor	2-6 µm

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

1117 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Sample label (DSDP/ODP/IODP sample designation)	2 Depth sed [m] (mbsf)	3 Sme peak area (<2 µm, X-ray diffraction TEXT...)	4 Ill peak area (<2 µm, X-ray diffraction TEXT...)	5 Chl peak area (<2 µm, X-ray diffraction TEXT...)	6 Sme [%] (<2 µm, Biscaye weighing facto...)	7 Ill [%] (<2 µm, Biscaye weighing facto...)	8 Chl [%] (<2 µm, Biscaye weighing facto...)	9 Sme [%] (<2 µm, Missouri weighting factor)	10 Ill [%] (<2 µm, Missouri weighting factor)	11 Chl [%] (<2 µm, Missouri weighting factor)	12 Sme peak area (2-6 µm, X-ray diffraction (XRD))	13 Ill peak area (2-6 µm, X-ray diffraction (XRD))	14 Chl peak area (2-6 µm, X-ray diffraction (XRD))	15 Sme [%] (2-6 µm, Biscaye weighing fact...)	16 Ill [%] (2-6 µm, Biscaye weighing fact...)	17 Chl [%] (2-6 µm, Biscaye weighing fact...)	18 Sme [%] (2-6 µm, Missouri weighting fa...)	19 Ill [%] (2-6 µm, Missouri weighting fa...)	20 Chl [%] (2-6 µm, Missouri weighting fa...)
131-808C-35R-5,83	633.03	17904	9280	9875	24	50	26	16	68	16
131-808C-36R-2,123	638.63	21194	9527	8562	28	50	22	19	68	14
131-808C-37R-1,40	645.90	30405	17405	15988	23	53	24	15	70	15	4745	7696	8944	9	58	33	6	75	20
131-808C-38R-2,63	657.03	94818	6148	8477	70	18	12	60	31	10
131-808C-39R-5,10	670.60	24177	11935	12008	25	50	25	17	68	15	7071	7406	9004	13	54	33	9	72	20
131-808C-40R-2,6	675.76	44441	16463	15532	31	47	22	22	65	14	6627	5462	7197	15	51	34	10	69	20
131-808C-41R-1,92	684.72	25672	10047	8454	31	49	20	21	66	13	8357	5397	6150	20	51	29	13	69	18
131-808C-42R-3,50	697.00	30370	10413	8939	34	46	20	23	64	12	10692	5909	6137	23	51	26	15	68	16
131-808C-42R-4,57	698.57	31088	16646	15695	24	52	24	16	69	15
131-808C-43R-2,70	705.40	36425	9381	9542	39	40	21	28	58	13
131-808C-44R-4,24	717.14	38816	11725	12670	35	42	23	25	60	15	8006	5406	7205	18	49	33	12	67	20
131-808C-46R-2,29	733.49	29304	6919	6773	42	39	19	30	57	13
131-808C-47R-1,21	741.61	53642	13056	12395	41	40	19	30	58	12	18287	5858	6694	33	43	24	24	61	16
131-808C-48R-1,90	752.00	40173	8398	8406	44	37	19	33	55	12
131-808C-49R-1,72	761.42	32286	14621	13355	27	50	23	19	67	14	6521	4447	5034	19	52	29	13	70	18
131-808C-50R-1,12	770.52	38717	8924	9180	42	38	20	31	56	13
131-808C-50R-3,48	773.10	38713	7688	6768	47	37	16	34	55	11
131-808C-51R-1,86	780.96	48527	9395	9597	46	36	18	34	53	12
131-808C-52R-3,19	792.99	29963	7732	5906	41	43	16	29	60	10	10768	5139	5374	26	49	26	17	67	16
131-808C-53R-6,32	807.22	110269	1847	2258	90	6	4	85	11	3
131-808C-54R-4,80	814.40	23302	13604	12705	23	53	25	15	70	15
131-808C-55R-1,13	818.83	52667	16908	17858	34	43	23	24	61	15	6533	5676	7744	15	51	35	10	69	21
131-808C-55R-5,93	825.63	36735	12697	14143	32	44	24	22	62	16
131-808C-56R-1,40	828.80										7730	4916	6129	19	50	31	13	68	19
131-808C-57R-1,37	838.47	37780	11482	15275	33	40	27	24	58	17	8070	6918	9608	15	50	35	10	69	21
131-808C-58R-1,145	848.85	36521	9856	11737	37	40	24	27	58	15
131-808C-59R-2,56	859.16	33573	8312	11651	37	37	26	28	55	17
131-808C-60R-1,137	868.17	28601	11787	14567	27	45	28	19	63	18	12035	6315	8687	22	46	32	15	65	20
131-808C-61R-1,7	876.57	28312	9864	13662	30	41	29	21	60	19
131-808C-62R-3,145	890.55	33698	10971	11943	33	43	24	24	61	15	11265	5850	8563	22	45	33	15	64	21
131-808C-64R-3,130	909.80	37171	10275	14991	34	38	28	25	56	18
131-808C-65R-1,12	915.22	25209	10445	15249	26	43	31	19	61	20
131-808C-66R-2,108	927.38	27945	15716	23162	20	46	34	14	64	21
131-808C-66R-4,108	930.38	24187	10119	18934	24	39	37	17	58	24
131-808C-67R-1,141	935.91	36532	14719	19531	27	44	29	19	62	19	8749	6940	10736	15	48	37	10	66	23
131-808C-68R-1,38	944.58	37409	18947	20064	24	49	26	17	67	16
131-808C-68R-1,130	945.50	28117	10885	13972	28	44	28	20	62	18
131-808C-69R-1,11	953.91	17813	8669	10833	24	47	29	17	65	18
131-808C-69R-2,38	955.68	11779	13509	17165	12	54	34	8	72	20
131-808C-69R-2,133	956.63	25400	9223	17094	26	38	35	20	57	24	2841	3936	5952	9	52	39	6	70	24
131-808C-69R-4,63	958.93	19349	11762	16610	19	47	33	13	66	21	4793	5512	7384	12	53	35	8	71	21
131-808C-69R-5,11	959.91	40079	14290	15864	31	44	25	22	62	16	3726	5487	7224	9	55	36	6	72	21
131-808C-70R-1,25	963.65	9640	10658	14956	12	52	36	8	70	22
131-808C-70R-1,93	964.33	24516	16259	18327	19	52	29	13	69	18	1483	3124	4067	7	57	37	4	74	22
131-808C-70R-4,34	968.24	254265	10171	26258	73	12	15	66	21	12	576	6147	8835	1	57	41	1	75	24
131-808C-71R-1,125	974.35	14046	13077	15891	14	53	32	10	71	19	3365	5703	8065	8	54	38	5	72	23
131-808C-72R-1,143	984.23	19495	11124	15955	20	46	33	14	65	21
131-808C-73R-2,110	994.70	19741	14567	22336	16	47	36	11	66	23	4618	5281	8933	11	48	41	7	67	26
131-808C-73R-6,48	1000.08	19814	12990	24970	16	43	41	12	62	27
131-808C-74R-2,16	1003.46	14699	12716	19495	14	49	37	10	67	23	2547	6023	9081	6	54	41	4	72	24
131-808C-75R-2,35	1013.10	8727	13132	19305	9	53	39	6	71	23
131-808C-76R-5,30	1026.80	5483	8795	13113	8	53	39	6	71	24
131-808C-77R-3,145	1034.35	10082	6133	15200	16	38	47	12	57	32	4846	8346	10984	8	55	36	5	73	22
131-808C-78R-4,28	1043.88	7476	12954	23662	7	49	44	5	67	28
131-808C-79R-1,73	1049.03	6959	11730	18037	8	52	40	5	70	24
131-808C-79R-2,36	1050.16	2086	11954	15593	3	59	38	2	76	22
131-808C-80R-1,28	1058.08	32001	19138	24634	20	49	31	14	67	19	3270	4130	6520	10	50	40	7	69	24
131-808C-81R-2,70	1069.30	9594	11365	15831	11	52	37	7	70	22	3915	6476	8697	8	55	37	5	73	22
131-808C-82R-1,100	1077.50	14676	12036	19094	15	48	38	10	66	24
131-808C-83R-1,55	1086.35	9277	12000	16762	10	53	37	7	71	22	3060	3686	8088	9	43	48	6	63	31
131-808C-84R-2,56	1094.06	19893	9591	17452	21	41	37	16	60	25	6872	5164	11099	14	42	45	10	61	29
131-808C-85R-2,21	1100.01	3679	12135	22299	4	50	46	3	69	28
131-808C-86R-3,3	1111.03	8568	10440	22612	9	44	47	6	63	31	2783	4607	7432	8	51	41	5	70	25
131-808C-87R-1,14	1117.17	17161	12308	21337	16	45	39	11	64	25	3285	5632	8317	8	53	39	5	71	24
131-808C-88R-1,37	1127.27	7984	8357	16477	11	45	44	8	64	28	3677	5464	8603	9	51	40	6	70	25
131-808C-89R-1,93	1137.53	8704	8135	16363	12	44	44	8	63	29
131-808C-90R-1,56	1146.86	16004	11207	22270	15	43	42	11	62	28	3585	3547	6910	11	45	44	8	64	28
131-808C-91R-1,59	1156.49	21478	11504	20122	20	43	37	14	61	24
131-808C-92R-1,120	1166.80	11900	6663	14254	18	40	43	13	59	28	4893	4030	8166	13	43	44	9	62	28
131-808C-93R-1,25	1175.55	13182	8364	15922	17	43	41	12	62	26
131-808C-94R-2,40	1186.80	3101	6418	14158	5	45	50	4	64	32
131-808C-95R-1,14	1194.74	6042	7956	19501	8	41	51	6	61	33
131-808C-97R-1,21	1214.21	8590	11207	19791	9	48	43	6	67	27
131-808C-98R-1,7	1223.77	0	8971	12790	0	58	42	0	76	24
131-808C-99R-1,37	1233.77	6565	9211	11859	10	55	35	6	73	21
131-808C-100R-1,72	1243.72	0	5771	9620	0	55	45	0	73	27	0	2092	2710	0	61	39	0	77	23
131-808C-101R-2,22	1253.92	15939	0	5140	61	0	39	63	0	37
131-808C-101R-4,134	1258.04	0	5723	2565	0	82	18	0	91	9
131-808C-102R-1,30	1261.80	0	9466	2835	0	87	13	0	94	6
131-808C-103R-1,101	1271.91	0	17122	6487	0	84	16	0	92	8
131-808C-103R-3,55	1274.45	31801	0	1788	90	0	10	91	0	9
131-808C-104R-1,17	1280.57	0	13408	7295	0	79	21	0	89	11