RESPONSE OF THE OLIGO-MIOCENE BIVALVE FAUNA OF THE KUTCH BASIN (WESTERN INDIA) TO REGIONAL TECTONIC EVENTS

IF 1.5 4区地球科学 Q2 GEOLOGY

Palaios Pub Date : 2021-09-09 DOI:10.2110/palo.2020.040

S. Dutta, Devapriya Chattopadhyay

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引用次数: 0

Abstract

Abstract: Tectonic changes have influenced the evolution of the marine community by changing the land and seaway configuration through time. Two such events during the Oligo-Miocene—the closure of the Tethyan seaway due to development of the Gomphotherium Landbridge leading to separation of the Arabian Sea from proto-Mediterranean Sea (∼ 19 Ma) and significant uplift of the Tibetan Plateau marking the initiation of the monsoon (∼ 16 Ma)—represent a classic case of tectonic shift influencing the regional environment of the Indian subcontinent. We investigated the taxonomic and body-size related response of the shallow marine fauna to this regional change using bivalves from 11 time-constrained shellbeds of the Kutch Basin (western India) from three formations—Maniyara Fort (Chattian), Khari Nadi (Aquitanian) and Chhasra (Burdigalian-Langian) representing a time span of ∼ 9 Ma (24.4–15 Ma). Our collection of over 2000 individuals represents a total of 15 families and 61 morphospecies. The fossils are predominantly calcitic in nature and families of aragonitic composition are often preserved as molds indicating a potential negative effect of diagenesis. The taphonomic nature, however, does not vary substantially across shellbeds and hence, less likely produced a temporal pattern. The five most abundant species, Ostrea latimarginata, Ostrea angulata, Talochlamys articulata, Anomia primaeva, and Placuna lamellata occur in all the formations. The species composition of the Maniyara Fort Formation is substantially different from those of the younger formations, implying the possible effect of biogeographic separation. The absence of proto-Mediterranean taxa in Oligocene shellbeds supports limited faunal exchange between the Mediterranean-Iranian Province (MIP) and the western Indian Province (WIP) as early as ∼ 24.4 Ma (Chattian). Faunal exchange, however, continued between the WIP and the adjacent Eastern African-Arabian Province (EAAP). Formation-specific evenness shows a monotonic decrease from the Maniyara Fort to the Chhasra Formation. However, shellbed-specific analyses of diversity and body size do not show a strong directional trend through time and supports the stasis model. Although it is difficult to rule out the negative influence of taphonomy on the diversity of the studied fauna, the Oligo-Miocene marine bivalve fauna of the Kutch Basin demonstrates little or no influence of the Tethyan closure and Himalayan upliftment on the diversity through time.

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库奇盆地（印度西部）少新世双壳动物群对区域构造事件的响应

摘要：随着时间的推移，构造变化通过改变陆海格局来影响海洋群落的演化。渐新世至中新世期间的两次此类事件——由于Gomphotherium陆桥的发展导致特提斯海道关闭，导致阿拉伯海与原地中海分离（～19Ma），以及青藏高原的显著隆起，标志着季风的开始（～16Ma）——代表了影响印度次大陆。我们使用来自库奇盆地（印度西部）11个时间限制壳床的双壳类，研究了浅海动物群对这一区域变化的分类和体型相关反应，这些壳类来自三个地层——Maniyara Fort（查蒂安）、Khari Nadi（阿基坦阶）和Chhasra（Burdigalian Langian），代表了~9 Ma（24.4-15 Ma）的时间跨度。我们收集了2000多个个体，共代表了15个科和61个形态物种。化石在自然界中主要是钙质的，文石成分的家族通常被保存为霉菌，这表明成岩作用的潜在负面影响。然而，在不同的壳床上，埋藏的性质并没有实质性的变化，因此不太可能产生时间模式。五个最丰富的物种，宽缘鸵鸟、角形鸵鸟、节状Talochlamys articulata、初级Anomia primageva和片状平原鸵鸟出现在所有的地层中。Maniyara Fort组的物种组成与较年轻的组有很大不同，这意味着可能存在生物地理分离的影响。渐新世壳床中原地中海分类群的缺失支持了早在~24.4 Ma（查特语）地中海伊朗省（MIP）和西印度省（WIP）之间有限的动物群交换。然而，WIP和邻近的东非阿拉伯省（EAAP）之间的动物交流仍在继续。从Maniyara Fort到Chhasra组，地层特定均匀度呈单调下降。然而，对多样性和体型的特定于贝床的分析并没有显示出随时间推移的强烈方向性趋势，并支持停滞模型。尽管很难排除taphonomy对所研究动物群多样性的负面影响，但库奇盆地的渐新世-中新世海洋双壳动物群表明，随着时间的推移，特提斯闭合和喜马拉雅隆起对多样性的影响很小或根本没有。

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来源期刊

Palaios 地学-地质学

CiteScore

2.80

自引率

12.50%

发文量

审稿时长

6 months

期刊介绍： PALAIOS is a monthly journal, founded in 1986, dedicated to emphasizing the impact of life on Earth''s history as recorded in the paleontological and sedimentological records. PALAIOS disseminates information to an international spectrum of geologists and biologists interested in a broad range of topics, including, but not limited to, biogeochemistry, ichnology, paleoclimatology, paleoecology, paleoceanography, sedimentology, stratigraphy, geomicrobiology, paleobiogeochemistry, and astrobiology. PALAIOS publishes original papers that emphasize using paleontology to answer important geological and biological questions that further our understanding of Earth history. Accordingly, manuscripts whose subject matter and conclusions have broader geologic implications are much more likely to be selected for publication. Given that the purpose of PALAIOS is to generate enthusiasm for paleontology among a broad spectrum of readers, the editors request the following: titles that generate immediate interest; abstracts that emphasize important conclusions; illustrations of professional caliber used in place of words; and lively, yet scholarly, text.