请教XDF补充第3篇(2772的63-3)

dansy

这是篇关于大陆板块和海底盆地形成的文章。我题目做得尚可，但是对於文章，对於海底盆地的形成还不理解，心里还是发虚。请教关于这篇文章大概的中文描述，让我对于这个过程有个大致的理解。多谢！

雪落无声

终于有人来讨论了，拥抱DANSY MM


这个问题洋鹏同学上课说过，这类理科文章不求读懂，因为除了那些研究这类问题的专家能读懂外其他能读懂的牛不多。只要首字母提炼，把文章说到的几个东西的关系找出来做题目时回原文定位就可以了。虽然羊同学上课胡扯的比较多，但是偶以为这一点还是对的。

dansy

也强烈拥抱你一下。


    我其实很快就要考了，正在做垂死挣扎。不过以后我还是会积极参与讨论的，为二进宫做准备。

tianwan

顶。


我也有同感，题目能做对，每一句话都读的顺，但是文章就是看不懂。读了杨继书里的文章，就是这一篇直到现在也不明白大意，总觉得有个心事似的。杨继的书解释的和没解释没有不同，他看起来也没搞明白，要么就是不负责任，没解释清楚。


那位NN能解释一下这一篇文章？不胜感谢。


    

ziwingfong

我第7题不懂阿，谁能指导一下呢？

spotato

大概意思是，地幔有流体特征。由于大陆下面的地幔温度和海底山脊下面的地幔温度的差异，导致海底下的地幔有上升的力量(convection)，而大陆下面的地幔有下降的力量。这样就导致海底下面的地幔会慢慢升高，而大陆下面的地幔会慢慢降低。通常，海底山脊两边应该都是大陆。由于地幔的缓慢升高和下降，形成中间高两边低的格局，所以两边的板块朝相反的方向漂移（从高的地方向低的地方），最后导致地壳沿着海底山脊断裂，形成海底盆地。

但是这种假说不能解释大西洋山脊和印度洋山脊中间的板块的现象。这个板块在两个方向上都在成长，说明大西洋山脊和印度洋山脊同时在向两边移动。因为产生力的地幔与漂移的地壳是分离的，所以(it would be odd)不太可能convection会与山脊的移动保持完全相同的步伐...

后面大家自己看吧.

mole

我感觉7题好解释,因为前面提到the Sea of Japan,然后是一大堆此物的特征,最后有提到BLACK SEA时前面有"there are a number of older ones of possibly similar origin," such as theGulf of Mexico, the Black Sea, and perhaps the North Sea. BLACK SEA 就是和JAPAN 那个类似的,所以JAPAN的是什么特征,BLACK SEA也就是它的特征.就是答案.B.slowly settling foundation.但这个答案不是直接得来的,是从JAPAN的特征分析出来的.These seas have a typical oceanic floor,except that the floor is overlaid by several kilo-meters of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material on the upper side of the plate might be the cause of such deep basins.

我也很菜,不知对不对呀.

joanna143

PASSAGE 3
        
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper mantle of the earth behaves as a
5) liquid when it is subjected to small forces for long periods and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-
10) ocean ridges and sinking currents under the con-tinents. Theoretically, this convection would carry the continental plates along as though they were on a conveyor belt and would provide the forces needed to produce the split that occurs
15) along the ridge. This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving
20) plate has an impact on the forces that move it,could produce complicated and varying motions.
*On the other hand, the theory is implausible because convection does not normally occur along lines. and it certainly does not occur along
25) lines broken by frequent offsets or changes in direction, as the ridge is. Also it is difficult to seehow the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and
30) since there is no intermediate trench, the two ridges must be moving apart. It would be odd ifthe rising convection currents kept exact pace with them. An alternative theory is that the sink-ing part of the plate, which is denser than the
35) hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has asinking part.
40)
* Another possibility is that the sinking plate cools the neighboring mantle and produces con-vection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of
45) Japan. These seas have a typical oceanic floor,except that the floor is overlaid by several kilo-meters of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material
50) on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earth's surface, and seriously require explanation in because, addi-tion to the enclosed seas that are developing at present behind island arcs, there are a number of
55) older ones of possibly similar origin, such as theGulf of Mexico, the Black Sea, and perhaps the North Sea.

继续请教第七题，

7. According to the passage, the floor of the Black Seacan best be compared to a
(A) rapidly moving conveyor belt
(B) slowly settling foundation
        
(C) rapidly expanding balloon
(D) violently erupting volcano(B)
(E) slowly eroding mountain

虽然我知道是跟日本海比较，可是看不出对应点，能否请大家指教一下。

还有第二题

2.     It can be inferred from the passage that, of the following, the deepest sediments would be found in the 【】

(A) Indian Ocean

(B) Black Sea

(C) Mid-Atlantic

(D) South Atlantic（B）

(E) Pacific

我看不出来为什么他是deepest sediments耶~~

请大牛或班主指导 感谢!!!

xjlv128

以下是引用joanna143在2006-6-8 11:01:00的发言：

PASSAGE 3
  
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper mantle of the earth behaves as a
5) liquid when it is subjected to small forces for long periods and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-
10) ocean ridges and sinking currents under the con-tinents. Theoretically, this convection would carry the continental plates along as though they were on a conveyor belt and would provide the forces needed to produce the split that occurs
15) along the ridge. This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving
20) plate has an impact on the forces that move it,could produce complicated and varying motions.
*On the other hand, the theory is implausible because convection does not normally occur along lines. and it certainly does not occur along
25) lines broken by frequent offsets or changes in direction, as the ridge is. Also it is difficult to seehow the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and
30) since there is no intermediate trench, the two ridges must be moving apart. It would be odd ifthe rising convection currents kept exact pace with them. An alternative theory is that the sink-ing part of the plate, which is denser than the
35) hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has asinking part.
40)
* Another possibility is that the sinking plate cools the neighboring mantle and produces con-vection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of
45) Japan. These seas have a typical oceanic floor,except that the floor is overlaid by several kilo-meters of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material
50) on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earth's surface, and seriously require explanation in because, addi-tion to the enclosed seas that are developing at present behind island arcs, there are a number of
55) older ones of possibly similar origin, such as theGulf of Mexico, the Black Sea, and perhaps the North Sea.

继续请教第七题，

7. According to the passage, the floor of the Black Seacan best be compared to a
(A) rapidly moving conveyor belt
(B) slowly settling foundation 和蓝色的对应吧。我也错了
  
(C) rapidly expanding balloon
(D) violently erupting volcano(B)
(E) slowly eroding mountain

虽然我知道是跟日本海比较，可是看不出对应点，能否请大家指教一下。

还有第二题

2.     It can be inferred from the passage that, of the following, the deepest sediments would be found in the 【】
                

(A) Indian Ocean
                    

(B) Black Sea

(C) Mid-Atlantic

(D) South Atlantic（B）
                    

(E) Pacific

我看不出来为什么他是deepest sediments耶~~我开始也没找到，现在想想只有紫色那部分了

请大牛或班主指导 感谢!!!

open to question

joanna143

同意第二题，所以应该是black sea is similar to Japan sea，

所以日本海的特征也可以运用到黑海上。

谢谢MM。

第七题仍旧不懂，希望有牛牛路过指导一下。谢谢。