古生代和中生代海洋

 

Do you like the beach? If so, the Mesozoic may be for you!
::你喜欢沙滩吗?

During the  Mesozoic Era , much of the North American  continent  was covered by vast inland seaways. These seas were home to mosasaurs, ichthyosaurs, ammonites, and a variety of fish while dinosaurs thrived along the shorelines. During this  marine transgression , there was less dry land, but a lot more  beach . Surf's up!
::在地中海时代,北美大陆大部分地区都覆盖着广阔的内陆海道。这些海洋中,恐龙在海岸线上繁衍,而恐龙却在沿岸繁衍,这些海中居住着各种鱼类。在这场海上侵犯中,陆地干燥较少,但海滩更多。海浪上升了!

Marine Transgressions and Regressions
::海洋侵蚀和退化

Sea level  rises and falls over time. During the Paleozoic and Mesozoic, the seas rose over the continents. This is called a  marine transgression . During a  marine regression , the sea level retreats. The Paleozoic had four complete cycles of major marine transgressions and regressions. One additional cycle occurred in the Mesozoic, and another in the Cenozoic ( Figure   ).
::海平面随时间而上升和下降。在Paleozoic和Mesozoic期间,大海横跨各大洲。这被称为海洋侵犯。在海洋回归期间,海平面退缩。Paleozoic有四个完整的重大海洋侵犯和回归周期。一个循环发生在Mesozoic,另一个循环发生在Cenozoic(图 ) 。

 

What makes sea level rise? There are two possibilities: either the land sinks or the  water  level rises. Tectonic processes can cause the land to sink in certain locations. Melting   can cause the water level to rise.  Seafloor spreading  also impacts sea level. At a  mid-ocean ridge , hotter  crust  is buoyed up and can displace the water, causing more of the  continental shelves  to be submerged. However, as the  ocean basin  widens and crust subducts far from the ridge, this can increase the volume of the ocean basin and cause sea level to fall. What else could cause sea level to fall in a marine regression? Land rises up. Glaciers grow. Mid-ocean ridges subside. Just the opposite of what makes sea level rise!
::导致海平面升高的有两种可能性:陆地汇或水位升高。 构造过程可以在某些地点导致土地沉没。 熔化可以导致水位上升。 海平面扩散也影响到海平面。 在洋中脊,热层地壳浮起来,可以取代水,导致更多的大陆架被淹没。 然而,随着海洋盆地扩大和地壳下水道远离海脊,这可能会增加海洋盆地的面积,并导致海平面下降。还有什么还能导致海平面在海洋沉降中下降? 土地上升;冰川增长; 大洋中脊在下方。 与海平面上升正好相反的是,海平面的上升!

Geologists think that the Paleozoic marine transgressions and regressions were the result of the decrease and increase in the size of glaciers covering the lands.
::地质学家认为,Paleozoic海洋侵犯和倒退是覆盖陆地的冰川缩小和增加的结果。

Rock Facies
::摇滚奇观

Geologists know about marine transgressions and regressions from sedimentary  . These events leave characteristic rock layers known as sedimentary  facies . Sand and other coarse grained rock fragments are  deposited  on the beach where the wave  energy  is high. Offshore in lower energy environments, fine-grained silt is deposited. Farther offshore in lower energy waters,  carbonate  mud that later hardens is deposited. The rocks that result are sandstone, shale, and limestone. As the sea moves on or offshore, one rock layer is on top of the other.
::地质学家知道海洋的违规和沉积物的回归。 这些事件留下了典型的岩石层,称为沉积物表。 沙子和其他粗粒的碎石碎片沉积在波浪能高的海滩上。 近海在低能量环境中,细粒的淤泥沉积。 离岸较远的低能量水域,碳酸盐泥沉积在后来硬化的碳酸盐泥中。 由此形成的岩石是沙石、 页岩和石灰岩。 当海洋在海面上或海岸外移动时,一个岩层在另一个岩石层之上。

Summary
::摘要

• Sea level depends on the relationship of the water level to the land.
  ::海平面取决于水位与土地的关系。

• Sea level will rise when glaciers melt. Sea level will fall when glaciers grow.
  ::冰川融化时海平面会升高,冰川生长时海平面会下降。

• Facies are characteristic rock layers, such as sandstone, shale, limestone for a marine transgression. The reverse indicates a marine regression.
  ::其特征是典型的岩石层,如沙石、页岩、石灰石等海洋侵犯物。 反之,则表明海洋倒退。

Review
::回顾

1. How do scientists use sedimentary facies to recognize a marine transgression?
   ::科学家如何利用沉积表面来确认海上违法行为?

1. How do scientists use sedimentary facies to recognize a marine regression?
   ::科学家如何利用沉积表面来识别海洋回归?

1. What are the possible causes of a marine transgression?
   ::海洋侵犯的可能原因是什么?

1. What are the possible causes of a marine regression?
   ::海洋倒退的可能原因是什么?

1. How do geologists know that there were two transgressions and regressions in the Mesozoic?
   ::地质学家如何知道梅索索契克有两起 违法和倒退事件?