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论中国陆相侏罗-白垩系界线

季强、柳永清等

中国地质迷信院地质研讨所

  中国陆相侏罗-白垩系界线题目历久来不断是困扰中国地质学家的争辩比力激烈的迷信题目之一,并且老是与热河生物群的时期归属题目联系关系在一同。归结一下,大抵有三种差别的概念:(The issue about the Terrestrial Jurassic-Cretaceous Boundary in China (TJCBC) has long been one of the hot debated, complicated problems among Chinese geologists, and it is always related to the problem of the geological age of the Jehol Biota in China. In general, three opinions on this problem are su妹妹arized as follows: )

  1.一些学者以为热河生物群的时期该当为晚侏罗世,是以我国陆相侏罗-白垩系界线该当放在义县组顶部或九佛堂组下部。(1. Some scholars hold that the Jurassic-Cretaceous Boundary should be placed on the top of the Yixian Formation or within the lower part of the Jiufotang Formation, because the Jehol Biota is considered to be of an age of Late Jurassic. )

  2.别的一些地质学家以为热河生物群的时期为早白垩世,是以我国陆相侏罗-白垩系界线该当放在土城子组(后城组)与张家口组或义县组之间,界线地位与冀北-辽西地域的地域不整合相分歧。(2. Some geologists think that the Jurassic-Cretaceous Boundary should be placed between the Tuchengzi Formation and Zhangjiakou Formation,which is consistent with the distinct regional unconformity in the northern Hebei and the western Liaoning, because the Jehol Biota is considered to be of Early Cretaceous in age.)

  3.另有一部门古生物学家以为热河生物群的时期为晚侏罗世-早白垩世,是以我国陆相侏罗-白垩系界线该当位于义县组外部。(3. Other palaeontologists consider that the Jurassic-Cretaceous Boundary should be placed within the Yixian Formation, because the Jehol Biota is considered to be of Late Jurassic-Early Cretaceous in age. )

  十分较着,发生差别概念的次要缘故原由是我国专家关于热河生物群的性子、特色、组成和国内比照,和侏罗-白垩系界线的界说和尺度各自有着差别的熟悉和理解。(It is very clear that their different opinions are mainly caused by their different understanding of the nature, components and international correlation of the Jehol Biota, as well as the criteria of the Jurassic-Cretaceous boundary.)

  起首,中国地质学祖传统上采取135Ma或137Ma作为侏罗-白垩系界线的年齿值,次要思索到我国冀北-辽西地域热河生物群的地层散布和土城子组与张家口组之间的地域不整合的存在。可是,西欧学者通常采取144Ma或145Ma作为侏罗-白垩系界线的年齿值。很显然,两者之间就存在7-10Ma的 误差。(Firstly, Chinese scholars traditionally adopt 135Ma or 137Ma as the age value of the Jurassic-Cretaceous boundary, mainly considering the stratigraphic distribution of the Jehol Biota and the regional unconformity between the Tuchengzi Formation and the Zhangjiakou Formation or between the Tuchengzi Formation and the Yixian Formation in the northern Hebei and the western Liaoning, China. However, European and American scholars are generally used to adopting 144Ma or 145Ma as the age value of the Jurassic-Cretaceous boundary. It is obvious that there exists an error of 7-10Ma between the two boundary age values used by them.)

  其次,国内侏罗-白垩系界线次要依据海相化石(菊石等)来界说的,界线层型(GSSP)未来确定选择在海相地层散布区。尽人皆知,中国的海相侏罗系和白垩系散布极其有限,次要在西藏地域,可是我国陆相侏罗系和白垩系极其发育,散布也十分普遍。咱们面对的一个很大艰难在于怎样能力保障海相与陆相生物群之间的切确比照。即便咱们依据陆相化石选择了一条本人以为是界线的“侏罗-白垩系界线”,可是咱们仍旧不清楚这条所谓的J-K界线是不是与国内上用海相化石界说的J-K界线等时。(Secondly, the global definition of the Jurassic-Cretaceous Boundary is mainly based on the marine fossils, and the boundary stratotype (GSSP) will be certainly selected in the regions of marine strata. The marine Jurassic and Cretaceous deposits are very limited in China and mainly distributed in Tibet, but the terrestrial Jurassic and Cretaceous deposits are widely developed in China. As we know, it is very difficult to make an exact correlation between the marine and terrestrial biota. In such a case, even if we select a possible level for the Jurassic-Cretaceous Boundary mainly based on some terrestrial fossils in China, we would wonder whether this level is equivalent to the Jurassic-Cretaceous Boundary defined by marine fossils or not. )

  再者,国内上两大威望机构(IUGS和ICS)前后推选了两个差别的侏罗-白垩系界线年齿值。IUGS和UNESCCO提出以135Ma作为界线年齿值,而ICS则提出以145Ma作为界线年齿值。一样,两者之间就发生了近10Ma的误差。(Thirdly, the two international authority organizations (IUGS and ICS) reco妹妹ended different age values of the Jurassic-Cretaceous boundary respectively. IUGS proposed 135Ma as the age value of the Jurassic-Cretaceous boundary, whereas ICS reco妹妹ended 145Ma as the boundary age value. Clearly, there exists about 10Ma error between these two boundary age values.)

  另外,国内上普通以为德国巴伐利亚索伦霍芬地域产始祖鸟的地层的时期为晚侏罗世提通阶,次要是依据以菊石为代表的晚侏罗世海相无脊椎植物化石来确定的。可是题目在于,谁能知道索伦霍芬地域这套地层的准确的测年结果。究竟上,迄今为止,咱们不见到无关索伦霍芬地域产始祖鸟地层的实践测年数据,次要由于那套地层是泻湖相灰岩,难以举行喷射性同位素测年。能够这么讲,产始祖鸟地层的“150Ma”的所谓年齿是从“144Ma”的J-K年齿值推算进去的。(Additionally, the Archaeopteryx –bearing strata in Solnhofen of Bavaria, Germany is considered to be Tithonian of Late Jurassic in age,because rich Late Jurassic marine invertebrates such as a妹妹onites were found there. The question is, however, who knows the exact dating age of the strata in Solnhofen. Up to now, in fact, there is no report about the isotopic dating age of the Archaeopteryx-bearing strata from Solnhofen, because the Archaeopteryx-bearing strata are composed of lagoon limestones that are not suitable for making isotopic dating. The so-called ‘150Ma’ age of the Archaeopteryx-bearing strata is speculated upon the ‘144Ma’ age value of the Jurassic-Cretaceous Boundary. )

  究竟上,咱们中国粹者今朝面对的最浩劫处在于国内侏罗-白垩系界线层型(GSSP)仍旧不确定,咱们很难选择以135Ma或者145Ma作为J-K界线年齿值。即便这样,咱们中国粹者仍是锲而不舍,为解决中国的陆相侏罗系与白垩系分界题目做了大量事情和测验考试。(In fact, the great embarrassment the Chinese scholars are confronted with is the indetermination of the Jurassic-Cretaceous boundary stratotype (GSSP) yet, and it is very difficult for us to choose 135 Ma or 145Ma as the boundary age value for the moment. Even so, Chinese scholars do much work in the northern Hebei and the western Liaoning recently and try to resolve the problem of the terrestrial Jurassic-Cretaceous boundary in China. )

  2000年,陈丕基传授对中国陆相侏罗系和白垩系的划分和比照举行了普遍的阐发和会商。他依据多年的研讨,将侏罗-白垩系界线置于义县组与九佛堂组之间。(Chen Peiji(2000)made a comprehensive analysis and discussion on the division and correlation of the terrestrial Jurassic and Cretaceous in China. He placed the Jurassic-Cretaceous Boundary between the Yixian Formation and the Jiufotang Formation. )

  2003年,田树刚等人,柳永清等人各自觉表文章,报导了河北滦平盆地“侏罗-白垩系界线层”层序地层学和地质年月学研讨成绩。他们倾向于采取130Ma作为J-K界线年齿值,将该界线置于大败沟组与大店子组之间。(Tian Shugang et al. (2003) and Liu Yongqing et al. (2003) did the study on the sequence stratigraphy and geochronology of the Jurassic-Cretaceous boundary beds in the Luanping Basin of Hebei Province, China. They preferred to putting the Jurassic-Cretaceous boundary between the Dabeigou Formation and the Dadianzi Formation, adopting 130Ma as the boundary age value. )

  2004年,陈丕基等人对IUGS和ICS以往在国内地层表中推选的J-K界线年齿值(130Ma、135Ma、137Ma、142Ma和145Ma)的牢靠性和准确性提出了严峻的质疑。他们依据热河生物群的地层散布和国内比照,和从义县组金刚山层中取得的125.2Ma的实测年齿数据,倾向于采取125Ma作为J-K界线年齿值,将热河生物群归于晚侏罗世提通阶。(Chen Peiji et al. (2004) seriously doubted the correctness of the age values of the Jurassic-Cretaceous boundary (such as 130Ma, 135Ma, 137Ma, 142Ma, or 145.5Ma) reco妹妹ended by IUGS and ICS in the International Stratigraphic Chart. According to the stratigraphic distribution and international correlation of the Jehol Biota and the 125.2Ma dating age from the Jianshangou bed of the Yixian Formation, they were inclined to consider the Jehol Biota to be of Tithonian of Late Jurassic in age, proposing the 125Ma age-value for the Jurassic-Cretaceous boundary. )

  2005年,王五力等人对义县阶的时期和陆相侏罗-白垩系界线举行了专题会商。依据他们的研讨和来自义县阶尺度剖面的测年数据,以为以往国内地层表中推选的144Ma、145Ma和135Ma的界线年齿值不克不及再作为可托的界线尺度,倾向于采取124Ma作为J-K界线年齿值。(Wang Wuli et al. (2005) made a special discussion on the age of the Yixian stage and the terrestrial Jurassic-Cretaceous boundary. According to their current study and the isotopic dating data from the type section of the Yixian stage, they thought that the age values of 144Ma, 145Ma and 135Ma for the Jurassic-Cretaceous Boundary reco妹妹ended in the International Stratigraphic Chart could not be considered as the creditable criterion,and they were inclined to use the 124Ma as the boundary age value. )

国内侏罗-白垩系界线界说和地位
 

 

  如上所述,中国今朝在陆相侏罗-白垩系界线研讨方面有一个较着的倾向,即要依据中国的陆相化石确定一个具备中国特色的界线尺度,界线地位愈来愈高,虽然知道这些所谓的界线年齿值要比国内地层表中推选的J-K界线年齿值要年青得多。(As mentioned above, presently there exists an obvious tendency that some of Chinese scholars try to establish some distinct criteria for the terrestrial Jurassic-Cretaceous boundary in China, although the boundary age values proposed by them are much younger than those in the International Stratigraphic Chart.)

  近十年,咱们也在冀北-辽西地域对热河生物群及相关地层举行了综合性研讨。出格是近三年,咱们增强了地质年月学研讨事情,取得了一批有价值的测年数据,无益于咱们对陆相侏罗-白垩系界线研讨事情的熟悉和理解。(Recent years, we also carried out the comprehensive geological investigation and research on the Jehol Biota and the related strata in the northern Hebei and western Liaoning. We also do some work of isotopic dating and get a set of dating results. They are given as follows:)

  1. 164.6Ma:髫髻山组和蓝旗组底部;158.6Ma:髫髻山组最上部,解释髫髻山组和蓝旗组的时期为卡洛夫阶至早牛津阶。(1. 164.6Ma: from the basal part of the Tiaojishan Formation (or the Lanqi Formation), and 158.6Ma: from the uppermost part of the Tiaojishan Formation. It shows that the Tiaojishan Formation (or the Lanqi Formation) ranges from Callovian to Early Oxfordian in age.)

  2. 139.4Ma:土城子组最上部,解释土城子组的时期为晚牛津阶至贝里亚斯阶。(2. 139.4 Ma: from the uppermost part of the Tuchengzi Formation, showing a range of the Tuchengzi Formation from Late Oxfordian to Berriasian.)

  3. 135.5Ma:张家口组下部,解释该组的时期大抵为欧特里夫阶。(3. 135.5 Ma: from the lower part of the Zhangjiakou Formation,showing an age of Hauterivian.)

  4. 131.9Ma:大店子组底部,解释该组的时期为早巴柔姆阶。(4. 131.9 Ma: from the basal part of the Dadianzi Formation,showing an age of Early Barremian.)

  5. 128.6Ma:义县组下部中华龙鸟层之下玄武安山岩,解释其时期为晚巴柔姆阶。(5. 128.6 Ma: from the basaltic andesites under the Sinosauropteryx-bearing beds in the lower part of the Yixian Formation,showing an age of Late Barremian. )

  6. 125.6Ma和124.7Ma:义县组下部中华龙鸟层,解释其时期为早阿普丁阶。(6. 125.6Ma and 124.7Ma: from the Sinosauropteryx-bearing beds in the lower part of the Yixian Formation,showing an age of Early Aptian.)

  7. 122.3Ma:义县组金刚山层之下的玄武岩,120.3Ma:九佛堂组下部,解释其时期为早阿普丁阶晚期。(7. 122.3 Ma: from the basalt beds under the Jingangshan bed of the Yixian Formation, and 120.3 Ma: from the lower part of the Jiufotang Formation,showing an age of late Early Aptian.)

  8. 2000年, J. Pálfy等人宣布了侏罗系各阶的测年数据,此中贝利亚斯阶底界年齿值为141.8Ma。 (1. J. Pálfy et al. (2000) reported a series of the dating data of the Jurassic stages,giving an age of 141.8Ma for Berriasian (Jurassic-Cretaceous). )

  9. 2005年, J. J. Mahoney 等人报导了承平洋东南地域夏特斯基隆起贝利亚斯阶最下部堆积物中玄武岩的热年齿值为144.6±0.8Ma, 提供了一个最低界线年齿值。(2. J. J. Mahoney et al. (2005) reported that basalt sills cored in lowermost Berriasian sediments on Shatshy Rise in the northwest Pacific yield a mean 40Ar-39Ar incremental heating age of 144.6±0.8Ma, providing a minimum estimate on the age of the Jurassic-Cretaceous boundary. )

  10. 2005年,A. Davis在冀北-辽西地域土城子组(后城组)底部取得了156Ma的年齿,顶部取得了139Ma的年齿,解释土城子组(后城组)的时期大抵为晚牛津阶至贝利亚斯阶。(3. G. A. Davis (2005) obtained the age value of 156-139Ma from the Tuchengzi Formation and the Houcheng Formation in the western Liaoning and the northern Hebei. It shows that the Tuchengzi Formation and the Houcheng Formation are of an age of Late Oxfordian to Berriasian.)

  11. 侏罗-白垩系界线的时间尺度环球是同一的。咱们能够寻觅或选择陆相化石或其他标记来辨认陆相侏罗-白垩系界线,但不成能依据陆相化石去确定一个与国内J-K界线不等时的,却要让国内偕行们接受的“陆相J-K界线”。(1. The time criterion of the Jurassic-Cretaceous boundary is globally uniform. It is impossible to make a boundary definition based on terrestrial fossils or others, the time of which is not equivalent to the global J-K boundary defined by marine fossils. )

  12. 虽然今朝国内侏罗-白垩系界线层型(GSSP)还不确定,可是界线确定是以海相化石,而不是以陆相化石来确定,并且界线层型确定选择在海相地层发育区。中国陆相侏罗-白垩系界线题目的解决无疑有待于国内侏罗-白垩系界线层型(GSSP)确实定,其与国内J-K界线层型之间只是一个被动的比照关系。咱们不任何理由,也不成能依据我国的陆相化石或地域地质特色去标新创新或修改国内J-K界线时间尺度。(2. At present, although the Jurassic-Cretaceous boundary (GSSP) has not been defined yet, the boundary will be surely defined by marine fossils, rather than terrestrial fossils, and the boundary stratotype (GSSP) will be certainly chosen in the region of marine strata. To resolve the problem of the terrestrial Jurassic-Cretaceous boundary in China is surely after the confirmation of the Jurassic-Cretaceous boundary stratotype (GSSP), and it is only a passive correlation relationship to the Jurassic-Cretaceous boundary stratotype (GSSP). We can not make or modify a global definition of the Jurassic-Cretaceous boundary only based on the terrestrial strata and fossils of China.)

  13. 假如IUGS或ICS终极决议采取135Ma作为国内侏罗-白垩系界线年齿值,那末中国陆相侏罗-白垩系界线将在土城子组与张家口组(或义县组)之间,与冀北-辽西地域的地域不整合相吻合,解释热河生物群的时期为早白垩世。(3. If IUGS and ICS finally make a decision to adopt the 135Ma as the age value of the Jurassic-Cretaceous Boundary, then the terrestrial Jurassic-Cretaceous boundary will be placed between the Zhangjiakou Formation and the Tuchengzi Formation and consistent with the regional unconformity between the two formations in the northern Hebei and the western Liaoning, indicating the Early Cretaceous age of the Jehol Biota.)

  14. 假如IUGS和ICS终极决议采取145Ma作为国内侏罗-白垩系界线年齿值,那末中国陆相侏罗-白垩系界线将位于土城子组最上部,象征着土城子组上部有一部门地层纳入贝利亚斯阶。假如情形果真云云,那末冀北地域可能缺失凡兰吟阶的地层,辽西地域可能缺失凡兰吟阶和欧特里夫阶的地层。(4. If IUGS and ICS finally make a decision to adopt the 145Ma as the age value of the Jurassic-Cretaceous Boundary, then the Jurassic-Cretaceous boundary will be placed within the uppermost part of the Tuchengzi Formation, implicating the absence of the Valanginian strata in the northern Hebei and the absence of the Valanginian and Hauterivian strata in the western Liaoning.)

冀北-辽西地域J-K界线层的划分和比照