埃德蒙顿华人社区-Edmonton China

 找回密码
 注册
查看: 3141|回复: 1

请高手帮我看看这一段话的语法。

[复制链接]
鲜花(0) 鸡蛋(0)
发表于 2010-12-16 14:44 | 显示全部楼层 |阅读模式
老杨团队,追求完美;客户至上,服务到位!
本帖最后由 zhangpop 于 2010-12-16 14:49 编辑
7 z0 o% o& L' ^) _
+ @3 E: I* B0 ^/ Y: o0 T2 h请坛子里的高人指正,能看出点语法细节错误吗?
3 Y$ b0 K6 |' {/ b7 k. f# o: C5 [! s# y  H2 G
1. The Chinese Loess Plateau has the thickest and oldest eolian sediments on Earth. It has been considered that the winter monsoon winds are responsible for the orientation of the magnetic and sedimentary grains in the loess and paleosol deposits. In order to reconstruct the paleomonsoon routes in the past and present I investigated the anisotropy of magnetic susceptibility (AMS) ellipsoid mean orientations in three geological sections along the east-west transect in the Chinese Loess Plateau. The AMS ellipsoid orientation mirrors the grain’s imbrication and could be used to reconstruct the paleowind preferred direction. This way we could assess the paleomonsoon routes and paleoenvironmental fluctuations during the last 130 kys.  
. Y9 D7 L) Q6 D; E1 b) t; i6 H7 ]. w+ l4 Q7 _
2. The Eocene-Oligocene climate transition (EOT) around 34 Ma marks a period of Antarctic ice growth and a main step from early Cenozoic greenhouse conditions toward glaciated climate condition attributed to the present-day climate. The transition is characterized by an increase in deep-sea benthic foraminiferal oxygen isotope δ18O values. Timing of the EOT in the continent, however, could vary from the ocean. For example, the North American EOT may lag the marine transition at ~0.4 Myr. A stratigraphic section that contains both late Eocene and early Oligocene faunas has not been yet described in Asia and therefore timing of EOT in Asia has always been debatable. I report such section and interpret my result in order to reconstruct timing of the EOT in Asia.. I define an age interval for EOT in the studied section and to compare it with the sections from the same time intervals in Europe and Mongolia in order to identify a linkage to faunal turnover from perissodactyl-dominant to rodents and lagomorphs (a warm subtropical climate changing to a cool and dry condition) during the EOT.
! |- H, F* s9 L/ Z$ S. W. v2 Z, A/ |. X$ o; G( Z- v: y* [
3. Paleoresconstructions of the Asian continent and various models of crustal deformations during Paleogene and Neogene remain controversial because of the rarity of well-dated sediments and effusive rocks. I expect to construct a first paleomagnetic result from horizontal bedding-attitude sediments at 2 magnetostratigraphic sections in north Junggar basin to further examine hypothesis for inclination anomaly and paleoresconstructions of Asia blocks.
鲜花(0) 鸡蛋(0)
 楼主| 发表于 2010-12-16 14:50 | 显示全部楼层
再来一段
. w) C  A) o* [4 mMy first research documented most representative eolian sediments in the Chinese Loess Plateau in order to assess regional as well as eastern Asia – paleomonsoon route and paleoenvironmental fluctuations during the last 130 kys. The AMS measurements evidently show that the maximum susceptibilities group in the SE quadrant and the minimum susceptibilities are clustered in the NW quadrant. To explain such result I postulated that the ellipsoild orientation of anisotropy of magnetic susceptibility is determined by the moist summer monsoon rather than the dry winter monsoon as previously hypothesized. The major stream of the paleowind was generally similar to the present day summer monsoon routes. The summer monsoon was stronger than the winter monsoon and played a major role in the process of formation and magnetic fabrics in the central and west Loess plateau although winter monsoon brings all the eolian sediments to Loess plateau. It is still a matter of the future study to verify if the AMS signal from the northern parts of the Plateau fits in our model. The winter monsoon wind in the north is much stronger than the summer monsoon wind and the magnetic particle could be probably oriented during the winter only. Such scenario may result in the AMS ellipsoid orientations toward NW.
. `  I3 ?' p& X
1 n3 [% t/ n: w! cWe conclude that the sedimentary particles including magnetite were rearranged, settled, and fixed during the windy and rainy summer time, and the measured AMS apparently reveal the orientation of the prevailing summer winds.  Our new study demonstrates that the moist summer monsoon rather than dry winter monsoon as has been commonly accepted, plays a major role for the formation of the AMS ellipsoid orientation. We demonstrate that the summer monsoon has been always stronger than the winter monsoon in the central and western parts of the Chinese Loess Plateau and have been responsible for the magnetic grain imbrication although cold and dry winter monsoons brought all the dust from the northwestern desert areas.# |, ?0 j4 r- o" o# o; a" q* {* H
7 u1 c3 e, E+ X9 r0 z* A
My second study estimates the Eocene–Oligocene paleoclimate transition in central Asia and compared with the record in the Tibet and in the ocean. 8 {9 q( W# F( G& R
My paleomagnetic analysis yielded the reliable ChRM directions from 126 samples. I identified 11 normal polarity and 11 reversed polarity intervals. The detailed magnetostratigraphy was determined by the declination and inclination correlation to the geomagnetic polarity time scale (GPTS) of Cande and Kent (1995). Gradual change to the higher sedimentation rate, approximately at the EOB in our section, suggests that uplift of the Altay Mountains north of the Junggar Basin could have occurred due to shortening of the distance between India and northern Eurasia. Reorganization of faunal compositions of the Junggar Basin between 34.8 and 33.7 Ma fits with marine oxygen isotope data that demonstrate that the marine paleoclimate transition (34.1–33.6 Ma) occurred around the Eocene–Oligocene boundary (EOB, 33.9 Ma). The terrestrial paleoclimate transition in the Junggar Basin and central Asia occurred about the same time interval (34.8–33.7 Ma). It is possible that the central Asia experienced both cooling and aridification around the EOB, The uplift of Tibet and retreat of the Paratethys epicontinental sea triggered the aridification of the continental environment.
: X% f  @0 y- M0 W* j: [/ w7 B0 {& \6 }' O8 x1 U! b" `$ R
In my third research theme I obtain the first paleomagnetic poles for the Junggar block for the time window from ~40 Ma to ~20 Ma and perform tectonic reconstructions of the paleopositions for the Asian blocks relatively to the European continent. The amount of the latitudinal displacements and relative to Europe rotations (12.2°±6.5° and –17.2°±9.6° at 40 Ma and 9.7°±4.1° and       –11.8°±6.1° at 20 Ma) are consistent with with displacement and rotations of India, North China, South China and Tarim cratons, Amuria and Kazakhstan composite terranes as well as Eastern Sayan which could characterize the edge of the Siberian platform. The movement velocity of rotation and shortening is comparable with that of the present day GPS data and the left-slip fault system on the west of Altay Mountains. No significant vertical-axis rotation (5.4°±15.7°) and intracontinental shortening (3.5°±10.6°) between the Junggar block and stable Europe were observed from 40 Ma to 20 Ma. The major intracontinental shortening and rotation between the Junggar block and Europe occurred after 20 Ma. The CCW rotation (–11.8°±6.1°) and northward shortening (9.7°±4.1°) of Junggar block after 20 Ma are interpreted as the result of the enforced uplift of Altay Mountains and increase in tectonic activity in the Baikal Rift Zone.
您需要登录后才可以回帖 登录 | 注册

本版积分规则

联系我们|小黑屋|手机版|Archiver|埃德蒙顿中文网

GMT-7, 2024-11-28 21:37 , Processed in 0.138297 second(s), 10 queries , Gzip On, APC On.

Powered by Discuz! X3.4

Copyright © 2001-2021, Tencent Cloud.

快速回复 返回顶部 返回列表