做了一个伽马射线爆发导致奥陶系灭绝?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 04 - 22 - t08:22:48z //www.hoelymoley.com/feeds/question/2898 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/2898 10 做了一个伽马射线爆发导致奥陶系灭绝? user889 //www.hoelymoley.com/users/0 2014 - 11 - 25 - t09:52:11z 2014 - 11 - 25 - t14:54:56z < p >根据加州大学博物馆Palaontology网页< a href = " http://www.ucmp.berkeley.edu/ordovician/ordovician.php " > < / >奥陶纪时期,奥陶纪末目睹了< / p > < blockquote > < p >当冈瓦纳最终定居在南极上奥陶系,巨大的冰川形成,导致浅海排水和海平面的下降。这可能导致大规模灭绝,奥陶纪末,60%的海洋无脊椎动物属和25%的家庭灭绝。< / p > < /引用> < p >美国宇航局网页< a href = " http://www.nasa.gov/vision/universe/starsgalaxies/gammaray_extinction.html " >在太空爆炸可能发起的古老的地球上灭绝< / >和< a href = " http://cds.cern.ch/record/642831/files/0309415。pdf " >做了一个伽马射线启动奥陶纪末期大灭绝?< / >表明,伽马射线爆发可能是在大约4.4亿年前开始冷却。< / p > < p > < >强有什么palaeoclimatological和地球化学证据来支持或反驳的伽马射线爆发原因奥陶纪末期大灭绝吗? < /强> < / p > //www.hoelymoley.com/questions/2898/-/2899 # 2899 5 答案由理查德·伽马射线爆发导致了奥陶系灭绝? 理查德。 //www.hoelymoley.com/users/330 2014 - 11 - 25 - t12:56:00z 2014 - 11 - 25 - t12:56:00z < p >答案:你问的是在论文中引用的问题:< br / > < a href = " http://cds.cern.ch/record/642831/files/0309415。pdf " >做了一个伽马射线启动奥陶纪末期大灭绝?< / > (Melot et al)。< / p >

Specifically the section titled "ASPECTS OF THE LATE ORDOVICIAN MASS EXTINCTION POTENTIALLY COMPATIBLE WITH A GRB".

But if you're looking for an article summary, here is the evidence they mention that may point to a Gamma Ray Burst (GRB) as a possible source of the extinction:

Rapid global cooling followed by rapid global warming
Specifically, they say that a GRB may cause the production of NO2, which will increase the opaqueness of the atmosphere, causing cooling.

Some species impacted more than others
They mention that this may have happened, but that they would expect:

planktonic organisms or larvae would more likely be affected than benthic organisms because the former are less shielded from radiation.

Similarly, epifaunal organisms would be more affected than infaunal organisms buried and shielded in sediments.

They go on to say that both of these patterns "may exist".

Differential extinction
They probably say this best:

longer planktonic larval phases, when such can be inferred, are associated with increased extinction probability

The mention that species whose adults live within plankton were completely wiped out. This differential extinction is somewhat suggestive of a GRB.

Summary
Ultimately, there's not a clear and definitive link to a Gamma Ray Burst as the sole or primary source of this extinction event. However, there are some correlations. In the author's words,

clearly additional tests are required


source: Did a gamma-ray burst initiate the late Ordovician mass extinction? (Melot et al).

//www.hoelymoley.com/questions/2898/-/2902 # 2902 8 plannapus回答的伽马射线爆发导致了奥陶系灭绝? plannapus //www.hoelymoley.com/users/87 2014 - 11 - 25 - t14:15:42z 2014 - 11 - 25 - t14:54:56z < p >序言,我说我不知道远程银河动态足以知道超新星可能可能在奥陶纪足够近地球影响伽马射线爆发,我也不了解地球化学知道有办法在化石记录中发现此类事件。< / p > < p >,我将尝试回答的问题是:我们需要调用一个外星事件来解释奥陶纪末冰川作用?的分类单元选择性灭绝事件支持伽马线暴假说?< / p > < p >让我们看看不同的假设的冰川作用发生时,最初的难题:如何一个冰期时mid-Ordovician美元p_{二氧化碳}$ < em >认为< / em > 14次四级?<强> Brenchley et al . 1994 < /强>建议奥陶纪海洋环流变化从一个系统在热盐水水域底部与冷底水系统(即温盐而不是haline循环),引发phytoplanktonic开花,然后减少大气美元p_{二氧化碳}美元,引发了一场eutrophization海洋。<强>坎普et al . 1999 < /强>认为赞成构造派生美元p_{二氧化碳}$下降:阿巴拉契亚和加里东造山带造山运动来增加风化,减少美元p_{二氧化碳}$。当然,两个假设并不是相互排斥的,因为风化的增加也意味着增加营养物质在海水中,因此提高初级生产力。< / p > < p >另一个问题是,群体灭绝在冰川作用:最近的研究表明,acritarchs(最多样化的浮游植物群以这一时期)没有遭受这些事件(<强> Vecoli 2008 < /强>);相对底栖生物集团如海百合或者腕足类(参见<强>希恩2001 < /强>审查);一些中上层鱼组织如笔石动物的和鹦鹉螺目动物也受事件期间,其他没有(例如放射虫)。 In summary there is no clear pattern, but there is also no reason to think that there was a preferential extinction of surface organisms over deeper-living ones.

So, does that answer the question: no; but it seems to me that GRB doesn't explain better the event that unfolded during the late Ordovician than other hypotheses (namely the ocean eutrophization and the continental weathering). Does it discard the hypothesis of a GRB: no; but since there is no direct evidence that it indeed happened at that time, and that we can explain the Ordovician events without, it seems, to me, more parsimonious to think that it didn't.

References:
Brenchley et al., 1994. Bathymetric and isotopic evidence for a short-lived Late Ordovician glaciation in a greenhouse period. Geology, 22: 292-298.
Kump et al., 1999. A weathering hypothesis for glaciation at high atmospheric $p_{CO_2}$ during the Late Ordovician. Palaeogeography, Palaeoclimatology, Palaeoecology, 152: 173-187.
Sheehan, 2001. The Late Ordovician Mass Extinction. Annual review of Earth and Planetary Science, 29: 331-364.
Vecoli, 2008. Fossil microphytoplankton dynamics across the Ordovician–Silurian boundary. Review of Paleobotany and Palynology, 148: 91-107.

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