十四. 空间天文测量与地球动力学

(负责人：黄诚 周硕愚 傅容珊)

Space Astronomy Survey and Earth Dynamics

(Conveners: HUANG Cheng ZHOU Shuoyu FU Rongshan)

1. 基于GPS数据研究新疆伽师地区地壳块体运动变形

秦小军 吴 云 周硕愚 乔学军 赵齐乐 王 琪

（中国地震局地震研究所，武汉，430071）

Research on the Movement and deformation of Crustal Blocks in Jianshi District, Xinjiang, Based on GPS Observation Data

Qin Xiaojun Wu Yun et. al.

(Institute of Seismology, CSB, Wuhan 430071)

Abstract By using Discontinuous Deformation Analysis method, the crustal movement and deformation in Jiashi district, Xinjiang, are simulated according to the data of GPS observation. The result indicate: the principle compression strain in the whole area is mostly with an Ns orientation. In the north east part of Pamir and the South Tianshan, the strain rate is quite high. Especially in the Jiashi district, the principal compression stress is higher than other area. After the plot with high stress being ruptured according to the orientation of its maximum shear stress (NE), the stress of this plot area signally declines. The horizontal velocity field shows that: the North Pamir and South Tianshan have a relative extruding movement orienting north and south; and because of the drafting by the north orienting movement of the Pamir , the Tarimu district has a small dextral movement. A relative sinistral movement appears along the Toteongzi and Keping faults after the rupture of the plot, and it is of the tendency that energy transfers along thr faults orienting NEE.

2.Present-time crustal motion and earthquake dynamics on

the southeast marginal sea region of china continent

Zhou shuo-yu Zhou xin et.al.

Institute of Seismology, China Seismological Bureau, Wuhan 430071, China

Abstract

Based on the Chinese mainland GPS network（1994～1996）,Fujian GPS network（1995～1997）,cross fault deformation network（1982～1998),precise leveling network(1973～1980) and focal mechanism solutions of the recent several tens years, we synthetically and quantitatively studied the present-time crustal motion of the southeast coast of Chinese mainland—Fujian and its marginal sea. We find that this area with its mainland together moves toward SE with a rather constant velocity of 11.23.0 mm/a. At the same time,there is a motion from the Quanzhou bay pointing to hinterland, with a major orientation of NW, extending toward two sides, and with an average velocity of 3.02.6 mm/a. The faults orienting NE show compressing motions, and the ones orienting NW show extending motions. The present-time strain field derived from crustal deformation is consistent with seismic stress field derived from the focal mechanism solutions and the tectonic stress field derived from geology data. The principal stress of compression orients NW(NWW)—SE(SEE). Demarcated by the NW orienting faults of the Quanzhou bay and Jinjiang—Yongan, the crustal motions show regional characteristics: the southwest of Fujian and the boundary of Fujian and Guangdong are areas of rising, the northeast of Fujian are areas of sinking. The horizontal strain rate and the fault motion of the former are both greater than the later. The side-transferring motion of Hymalaya collision zone and the compression of the west pacific subduction zone affect the motion of the research area. The amount of motion affected by the former is larger than the later, but the former is homogeneous and the later is not, which indicates that the events of strong earthquakes in this region relate more directly with western pacific subduction zone.

3. 平极长期漂移与地球平均下地幔粘性估计

杨志根^1,2

¹中国科学院上海天文台,上海 200030

²中国科学院国家天文观测中心,北京 100012

SECULAR POLAR MOTION AND ESTIMATE OF

MEAN LOWER MANTLE VISCOSITY

Zhigen Yang

By using nine long sequences of international latitude observations, the secular

drift of the Earth's pole was re-estimated as such that the drift rate is 3.356 ± 0.142 mas/yr with its direction along the meridian in west longitude 78^°.7 ± 2°.5. Based on the Post-glacial rebound(PGR) model ICE-4G, the theoretical direction of drift with 74°.8(W) was obtained by using the parameters of eight ice sheets on the Earth, and the mean lower mantle viscosity with n_LM = 0.5 ~1.7×10²² P_{a s} was estimated under the constraint of the observed drift rate.

Over the last about million years, the extensive ice complexes over north America and northwestern Europe have repeatedly advanced and retreated almost with a characteristic period of approximately 10⁵ years. In the last deglaciation event began at 21000 years ago, the total mass of the eight ice sheets has the ratio of at least 99.9 percent of all the ice sheet's mass. In addition, we note that the mean geographic mass centric position of zone of the PGR on the Earth's surface is 61^°.6 in north latitude and 72^°.4 in west longitude. Therefore, the estimates of theoretical secular drift of the Earth's pole and n_LM in this paper can probably be acceptable.

4.极地冰芯记录揭示的全球气候环境变化的趋势和影响

康建成¹⁾， J, Jouzel²⁾, M. Stievenard²⁾, J.R.PETIT³⁾，温家洪¹⁾

The ice core records show the tendency of global change

Kang Jiancheng¹⁾， J, Jouzel²⁾, M. Stievenard²⁾, J.R.PETIT³⁾，Wen Jiahong¹⁾

¹⁾ Polar Research Institute of China, Shanghai 200129, China

²⁾ Laboratoire des Sciences du Climat et de l’Environnement, L’Orme des Merisiers, Bat. 709 CEA Saclay, 91191-Gif-sur-Yvette Cedex, France.

³⁾ Laboratoire de Glaciologie et Geophysique de l’Environnement, CNRS, 54,rue Molière, B.P.96 38402 Saint-Martin-d'Hères cedex,France

The deuterium of Vostok 5G ice core (2695-2800m) is analyzed, the age lasts from 231.4–248.8 kyr BP belongs to “7.5 stage” of deep sea d¹⁸O stages, depending on extended glaciological timescale (EGT) model. The resolution is around 10~15years. From the data, it can be got:

1. At beginning of this interglacial, there is a cold reversal term, in which the dD decreases 10 ‰.

2. In the ascending duration of the temperature, there is a steeper increasing, the gradient is 14.23 (‰ dD) / kyr, correspond to 2.5℃/kyr warming.

3. There is a jumping degradation of the temperature at the start of descending duration of the temperature, the dD decrease 10 ‰ in about 10-40 years, and the dD changes 28 ‰ in time on 100-150 years.

4. In the descending duration of the temperature, there is slower decreasing, the gradient is 4.58 (‰ dD) / kyr, correspond to 0.8℃/kyr temperature descension, it is 1/3 of the ascending gradient, but with saw type in which the dD fluctuates 4-7 ‰.

5. At some turning points, the differences of neighbor data of dD are bigger than others it hints that the temperature fluctuations at these points are more violent; the temperature change for decadal time scale is larger. It can be supposed, that a short term (decimal years) of abnormal highest (or lowest) temperature will be followed by a short term of abnormal lowest (or highest) temperature, this may be a paleo-reference used to the long forecast of weather.

The extent of dD fluctuation in this interglacial is -420— -480 ‰, similar with the last interglacial.

Compared with “G stage” (corresponding 5.5 stage of deep sea d¹⁸O stages) in the last interglacial (Jouzel et al 1987), it is in the similar way of the fluctuating process of dD in the two interglacials.