利用光释光和<sup>230</sup>Th、<sup>231</sup>Pa等放射性同位素对深海沉积物的年代测定

何乐龙; 江云水; 贺行良; 常文博

doi:10.16028/j.1009-2722.2020.159

利用光释光和²³⁰Th、²³¹Pa等放射性同位素对深海沉积物的年代测定

中国地质调查局青岛海洋地质研究所，青岛 266237

基金项目: 中国地质调查局海洋区域地质调查项目“深海科学钻探井位选址调查”（DD20190236）

详细信息

作者简介: 何乐龙（1989—），男，硕士，工程师，主要从事年轻地质年代学测试技术方面的研究工作. E-mail：helelong@qq.com

通讯作者: 江云水（1985—），男，硕士，高级工程师，主要从事海洋地质工程方面的研究工作. E-mail：yunshui888@163.com

中图分类号: P597

收稿日期: 2020-09-30

录用日期: 2022-02-16

刊出日期: 2022-04-28

Dating deep sea sediments by means of optically stimulated luminescence and ²³⁰Th, ²³¹Pa radionuclides

Qingdao Institute of Marine Geology, China Geological Survey, Qingdao 266237, China

More Information

Corresponding author: JIANG Yunshui, yunshui888@163.com

Received Date: 30 September 2020

Accepted Date: 16 February 2022

Publish Date: 28 April 2022

摘要

摘要:
对2组来自孟加拉湾的深海钻孔柱样进行光释光（OSL）测年的放射性分析时发现，所测深海样品具有较高的²³⁰Th、²³¹Pa等放射性核素活度浓度。利用²³⁰Th_ex、²³¹Pa_ex和²³¹Pa_ex/²³⁰Th_ex等参数计算柱样沉积速率，发现3种计算方式得到的结果较为一致。其中，C3钻孔的平均沉积速率介于16.2～18.2 cm/ka，CB2钻孔的平均沉积速率介于10.3～12.3 cm/ka。和光释光所得的年代数据相比，其平均值相互吻合。光释光的年代数据表明，这2组柱样可能经历了沉积速率加快的沉积过程。
- 光释光 /
- ²³⁰Th /
- ²³¹Pa /
- 深海沉积物 /
- 孟加拉湾
Abstract:
When the two groups of deep-sea samples taking from the Bay of Bengal were analyzed for OSL dating, we found that the samples are high in ²³⁰Th,²³¹Pa radionuclides levels. After calculating the sedimentation rate of the samples with ²³⁰th_ex,²³¹pa_ex and ²³¹pa_ex / ²³⁰th_ex, it is found that the results obtained by the three methods are quite consistent. The average sedimentation rate of C3 is between 16.2 and 18.2 cm/ka and that of CB2 changes between 10.3 and 12.3 cm/ka. Compared with the OSL dating data, the average of the sedimentation rate values is consistent. The OSL dating suggest that the two groups of samples may have experienced a process of sedimentation rate acceleration.
- OSL /
- ²³⁰Th /
- ²³¹Pa /
- deep sea sediments /
- Bay of Bengal

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图 1 ²³⁰Th_ex、²³¹Pa_ex和²³¹Pa_ex/²³⁰Th_ex的活度浓度深度分布

Figure 1.

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图 2 C3柱（左）与CB2柱（右）的OSL年龄

Figure 2.

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表 1 测试样品的采样信息

Table 1. Sampling information

样品编号	中心深度/cm	采样水深/m	采样经纬度
C3-OSL-1	100	3 539	86.11°E，9.65°N
C3-OSL-2	180
C3-OSL-3	260
C3-OSL-4	340
C3-OSL-5	390
CB2-OSL-1	90	3 509	87.56°E，9.49°N
CB2-OSL-2	181
CB2-OSL-3	271
CB2-OSL-4	371

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表 2 样品的光释光测试相关数据和结果

Table 2. The sample information and results of OSL dating

样品编号	铀/10⁻⁶	钍/10⁻⁶	钾/%	含水量/%	等效剂量/Gy	释光年龄/ka
C3-OSL-1	2.86	12.07	2.01	13.38	34.89	9.07
C3-OSL-2	2.67	11.65	1.95	21.71	43.54	12.83
C3-OSL-3	3.07	11.98	2.21	16.84	60.91	15.45
C3-OSL-4	2.71	10.54	1.97	19.50	70.30	20.65
C3-OSL-5	3.30	12.32	2.37	16.06	135.28	32.07
CB2-OSL-1	2.95	15.05	2.63	16.00	37.16	8.08
CB2-OSL-2	3.59	16.04	2.61	17.85	64.31	13.49
CB2-OSL-3	3.15	13.56	2.67	13.89	103.86	22.30
CB2-OSL-4	2.68	12.38	2.25	15.62	187.71	47.60

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表 3 柱样中²³⁰Th、²³¹Pa等核素测量相关数据和结果

Table 3. Sample information and results of nuclides such as sas²³⁰Th, ²³¹Pa etc.

样品编号	活度浓度/(Bq/kg)						²³¹Pa_ex/²³⁰Th_ex
样品编号	²³⁰Th	²³⁴U	²³¹Pa	²³⁵U	²³⁰Th_ex	²³¹Pa_ex	²³¹Pa_ex/²³⁰Th_ex
C3-OSL-1	166.22	40.08	69.20	1.84	126.14	67.36	0.534
C3-OSL-2	160.28	37.53	64.76	1.80	122.75	62.96	0.513
C3-OSL-3	161.11	43.07	59.50	2.02	118.04	57.48	0.487
C3-OSL-4	152.95	38.08	55.30	1.80	114.87	53.50	0.466
C3-OSL-5	151.37	46.29	49.08	2.17	105.08	46.91	0.446
CB2-OSL-1	167.38	41.41	66.21	1.98	125.97	64.23	0.510
CB2-OSL-2	172.15	50.37	60.30	2.37	121.78	57.93	0.476
CB2-OSL-3	153.76	44.26	50.89	2.06	109.50	48.83	0.446
CB2-OSL-4	140.38	37.59	41.62	1.72	102.79	39.90	0.388

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表 4 柱样的沉积速率

Table 4. Sedimentation rates of samples

计算方法	平均沉积速率/(cm/ka)			由OSL年龄计算出的沉积速率/(cm/ka)
计算方法	²³⁰Th_ex	²³¹Pa_ex	²³¹Pa_ex/²³⁰Th_ex	由OSL年龄计算出的沉积速率/(cm/ka)
C3-OSL	16.2	17.9	18.2	4.4～30.5（平均17.2）
CB2-OSL	11.9	12.3	11.7	3.9～16.6（平均10.3）

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